Upload
independent
View
0
Download
0
Embed Size (px)
Citation preview
ORIGINALARTICLE
Areography of the genus Dendroctonus(Coleoptera: Curculionidae: Scolytinae)in Mexico
Yolanda Salinas-Moreno1, Ma. Guadalupe Mendoza1, Miguel A. Barrios2,
Ramon Cisneros1, Jorge Macıas-Samano3 and Gerardo Zuniga1*
1Laboratorio de Variacion Biologica y
Evolucion, Departamento de Zoologıa. Escuela
Nacional de Ciencias Biologicas-IPN. Prol. de
Carpio y Plan de Ayala s/n, Del. Miguel
Hidalgo, 2Laboratorio de Fanerogamas,
Departamento de Botanica. Escuela Nacional
de Ciencias Biologicas-IPN. Prol. de Carpio y
Plan de Ayala s/n, Del. Miguel Hidalgo and 3El
Colegio de la Frontera Sur. Carretera Antiguo
Aeropuerto km 2.5 Tapachula, Chiapas,
Mexico
*Correspondence: Gerardo Zuniga, Laboratorio
de Variacion Biologica y Evolucion,
Departamento de Zoologıa, Escuela Nacional de
Ciencias Biologicas-IPN, Prolongacion de
Carpio y Plan de Ayala s/n, Col. Sto. Tomas.
C. P. 11340, Del. Miguel Hidalgo, Mexico D.F.
E-mail: [email protected] (or)
ABSTRACT
Objective To analyse whether the geographical ranges of Dendroctonus species
are (1) associated with factors such as host species or elevation, and (2) in
agreement with Halffter’s Nearctic distribution pattern. (3) To identify and
discuss the factors that are likely to act as barriers to the genus’ geographical
distribution. (4) To explore whether there is an association between the size of the
geographical ranges of Dendroctonus species and the number of Pinus host species
used by each of them, and (5) to assess if these host species are most common at
the elevations preferred by the individual Dendroctonus species.
Site Mexico.
Methods Records of 12 species of Dendroctonus were gathered from
entomological collections in Mexico. Distribution ranges were defined by using
the propinquity method (Rapoport, 1975a). Analysed parameters were: (1)
geographical distribution of single species, (2) overlapping of species ranges, (3)
disjunction patterns and barriers by means of isoprobabilistic lines, based on the
morphotectonic subdivision of Mexico (Ferrusquıa-Villafranca, 1998), (4) spatial
variation in species richness with respect to latitude and altitude, (5) size of
geographical ranges, and (6) host species for each Dendroctonus species. A
correlation was determined between area size and number of pine host species.
Results The species ranges varied in shape and size. Geographical ranges tend to
be discontinuous in shape. Composite patterns showed that disjunctions among
ranges do not closely follow Mexico’s morphotectonic subdivision. There are
repeated discontinuities among individual distributions, which define five areas:
(1) Baja California Peninsula, (2) Sierra Madre Occidental (SMOC), (3) northern
Sierra Madre Oriental (SMOR), (4) Sierra Madre de Chiapas, and (5)
SMOR + Faja Volcanica Transmexicana (FVT) + Sierra Madre del Sur. The
isoprobabilistic lines confirm that the inner part of SMOC provides an optimal
environment for the genus, and the FVT province constitutes the broader
corridor for it in the country. Richness does not directly decrease or increase with
latitude. Richness behaviour of the insect is not associated with that of its host.
Elevation distributions showed that most Dendroctonus species move within
broad margins of tolerance and species richness is concentrated in the montane
interval. Dendroctonus attack 24 of the 47 Pinus species distributed in Mexico.
Preferred pine species belong predominantly to Leiophyllae, Ponderosae and
Oocarpae subsections. The Spearman rank correlation between area size and
number of pine host species was not significant. Dendroctonus clearly belongs to a
Nearctic distribution pattern (sensu Halffter, 1987).
Main conclusions Dendroctonus is present in all montane systems of Mexico
and its species coexist within a high geographical sympatry. Overlapping of
species distribution appears to be the result of two elements – generalized
Journal of Biogeography (J. Biogeogr.) (2004) 31, 1163–1177
ª 2004 Blackwell Publishing Ltd www.blackwellpublishing.com/jbi 1163
INTRODUCTION
Mexico is a transitional zone between the Nearctic and
Neotropical regions, whose biota are a composition that
originate from two North American tracks (one from the east
and another from the west) and a Gondwanic track related to
Central and South America (Contreras-Medina & Eliosa-Leon,
2001; Morrone & Marquez, 2001). Several biogeographical
studies of the Mexican montane entomofauna indicate that in
this region there is a convergence of different elements of
Nearctic, Paleoamerican and Mesoamerican origin (Ball, 1968;
Mateu, 1974; Halffter, 1976, 1987; Noguera-Martınez &
Atkinson, 1990; Liebherr, 1991, 1994; Llorente-Bousquets &
Escalante-Pliego, 1992; Thomas, 1993). The distribution range
of these taxa resulted from dispersal events, and differentiation
in situ and vicariant processes occurred in a complex
morphotectonical scenario (Thomas, 1993; Ferrusquıa-
Villafranca, 1998).
At the end of the Cretaceous (65 million years ago (Ma))
the Laramidian orogeny started and determined the main
physiographic features of the mountains in Mexico and
northern Central America, with the exception of the Faja
Volcanica Transmexicana (FVT) whose origin was in the
Oligocene (c. 30 Ma). However, the actual confirmation of the
FVT was not finished until the Holocene. The penetration of
Pinus into Mexico occurred in two stages from the Rocky
Mountains (Farjon & Styles, 1997). The first stage was at the
Oligocene in the Sierra Madre Occidental (Mirov, 1967; Miller,
1977), and the second occurred in the Pliocene (5 Ma) at the
edge of the Gulf of Mexico along the Sierra Madre Oriental
(Martin & Harrell, 1957). Climate changes at the Early
Quaternary promoted the diversification of the genus in
Mexico (Eguiluz Piedra, 1985; Styles, 1993; Farjon & Styles,
1997).
In this scenario, big barriers and corridors would be present
for the expansion of the Pinus genus and the associated
phytophagous insects. Subsequently, the climate and geologic
stability in this region, together with the emergence of the
Isthmus of Tehuantepec after the Miocene (24 Ma), favoured
the penetration of the cold-temperate biota towards south of
Mexico, and the invasion of Central America.
Biogeographical patterns of Mexican entomofauna has been
affected by flora movement, environmental heterogeny, and
geographical barriers. Particularly, geographical distribution of
phytophagous insects have been associated with those of its
host. In this context, the morphotectonic conformation of
Mexico was the frame to Pinus diversification, however, the
time of association between this genus and Dendroctonus is
unknown.
The genus Dendroctonus Erichson is a Holarctic taxon
composed of 19 species, distributed from Alaska to Nicaragua
in North and Central America and across the boreal region
of Europe and Asia (Wood, 1982). At present, no global
biogeographical studies of this genus exist. The only infor-
mation available can be found in a taxonomic monograph
for North and Central American species, which includes
geographical distribution maps (Wood, 1982). Regional
studies on the geographical ranges of these species are
common (e.g. Hendrichs, 1977; Perusquıa, 1978; Gudino,
1985; Zuniga et al., 1999), but they do not include systematic
analyses of size, location, deformation and overlapping areas
of Dendroctonus species, which are important for character-
izing local distribution patterns (Udvardy, 1969; Rapoport,
1975a,b, 1979; Letcher & Harvey, 1994; Brown & Lomolino,
1998). Studies of this kind allow identification of habitats
(host), barriers, corridors or ecological variables that
determine their distribution patterns (Rapoport, 1975a;
Kohlmann & Sanchez, 1984; Antunez & Marquez, 1992;
Ruggiero et al., 1998).
The aim of this paper was to analyse several aspects of the
geographical distribution of 12 Dendroctonus species located in
Mexico, which differ in their host specificity from the rest of
the North American species, because they parasite mainly
Pinus Linnnaeus species and rarely have been reported on
other host species (Cibrian-Tovar et al., 1995; Zuniga et al.,
1999). Specifically, we were interested in determining whether:
1. The geographical ranges of Dendroctonus species are associ-
ated with factors such as host or elevation, which ultimately
limit species distributions. For this, we analysed the geograph-
ical distribution of single species (hereafter called individual
distribution) and the overlapping of species geographical ranges
(hereafter called composite pattern), and the disjunction
patterns by means of isoprobabilistic lines. These analysis
allowed us to identify and discuss the factors that are likely to
act as barriers to the geographical distribution (sensu Rapoport,
1975a,b, 1979), and the patterns of resemblance among
geographical ranges. These analyses can indicate the occurrence
of significant environmental transitions (e.g. biogeographical
ecotones), as well as suggest the effect of common historical
and/or ecological constraints on distribution patterns.
polyphagy inside Pinus and a wide elevation tolerance within mountainous
environments. This behaviour, linked to a high vagility, has allowed the genus
Dendroctonus to expand its distribution across Mexico and to employ
mountainous systems as corridors separated by barriers that exert a low
selective filter effect.
Keywords
Dendroctonus, biogeography, Mexico, bark beetle, Pinus.
Y. Salinas-Moreno et al.
1164 Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd
2. The geographical ranges of Dendroctonus species agree with
Halffter’s Nearctic distribution pattern (Halffter, 1976, 1987;
Halffter et al., 1995). This pattern is followed by Holarctic and
Nearctic genera with relatively recent penetration into the
Mexican Transition Zone. This pattern predicts a species
richness peak for the mountainous entomofauna above
1700 m, and a decrease in richness as the latitude decreases.
Hence, we test whether the spatial variation in the richness of
Dendroctonus species with respect to latitude and elevation
agrees with these predictions.
3. There is an association between the size of the geographical
ranges of Dendroctonus species and the number of Pinus host
species used by each of them. The size, location and
deformation of the species ranges provide useful information
regarding preferential habitats and ecological requirements of
species. The widespread species are more likely to be generalist
with respect to resource used than species with restricted
geographical ranges, which tend to be specialists (Brown, 1984;
Letcher & Harvey, 1994). We estimated the sizes of the
geographical ranges and the host number of each Dendroctonus
species to determine whether there is a correlation between
them.
4. Finally, we tried to elucidate whether Dendroctonus species
preferentially parasite a specific host and if this host species is
the most common in the preferred elevation of the insect. To
achieve this, frequency tables were developed to show how
many pine species were parasitized by each beetle species,
within the preferred elevation interval.
MATERIALS AND METHODS
Data base
Collection records (museum specimens) of Dendroctonus were
gathered from 10 entomological collections in Mexico
(Table 1), which are well distributed in all the mountain
systems. Geographical distribution analysis assumes that the
identification of each species is correct. Data considered for
each collection record were selected on the basis of specific
criteria (determinator, curatorial work and experience)
increasing the reliability of the geographical distribution
records for each species (Brown et al., 1996). All specimens
were checked personally by authors following the latter criteria,
and the external morphology and seminal rod were used to
determine the species of Dendroctonus. In addition, each
collection was considered as an independent observation. The
data base includes species, determinator, locality, elevation and
host species. A total of 854 records were obtained for the
following species: Dendroctonus adjunctus Blandford, D.
approximatus Dietz, D. brevicomis LeConte, D. frontalis
Zimmermann, D. jeffreyi Hopkins, D. mexicanus Hopkins, D.
parallelocollis Chapuis, D. ponderosae Hopkins, D. pseudotsugae
Hopkins, D. rhizophagus Thomas and Bright, D. valens
LeConte, and D. vitei Wood. These collection data can be
consulted in the following web page http://www.cona-
for.gob.mx.
Geographical distributions
Based on these data, we made geographical distribution maps
(scale ¼ 1 : 5,000,000) for each Dendroctonus species. Distri-
bution boundaries were defined by using the propinquity
method (Rapoport, 1975a), which consists of joining the
nearest locations or nodes by means of lines or arcs. This
procedure is displayed on distribution maps depicting a
maximum propinquity tree with all nodes interconnected. All
arcs were measured and arithmetic means were calculated for
all data sets. With a compass and a radius equal to the mean,
contours were traced around each node and on both sides of
the arcs. Finally, a general contour was marked, resulting in
isolated areas separated by distances larger than two arith-
metic means. Distribution areas of each species were projec-
ted on a standardized grid map of Mexico (quadrants of one
geographical degree on a side). The composite pattern (sensu
Udvardy, 1969) was obtained by overlapping individual
distributions.
Disjunctions
The individual distributions and composite patterns were
described and analysed upon the map of morphotectonic
provinces of Mexico proposed by Ferrusquıa-Villafranca
(1998) (Fig. 1). The morphotectonic scenario was used in this
study only as reference frame to describe the geographical
Table 1 Entomological collections used
Colegio de Posgraduados, Montecillos, Mex. (CP)
Centro de Investigaciones Biologicas, Universidad Autonoma del Estado de Morelos, Cuernavaca, Mor. (CIB-UAEM)
Division de Bosques, Universidad Autonoma de Chapingo, Chapingo, Mex. (DB-UACH)
Escuela Nacional de Ciencias Biologicas, Instituto Politecnico Nacional, Mexico, D.F. (ENCB)
Instituto de Biologıa, Universidad Nacional Autonoma de Mexico, Mexico, D.F. (IB-UNAM)
Instituto Nacional de Investigaciones Forestales Agrıcolas y Pecuarias, Secretarıa de Agricultura, Ganaderıa, Desarrollo Rural,
Pesca y Alimentacion, Mexico, D.F. (INIFAP-SAGARPA)
Instituto de Silvicultura, Universidad Autonoma de Nuevo Leon, Linares, Nvo. Leon. (IS-UANL)
Museo Historia Natural, Mexico, D.F. (MHN)
Sanidad Forestal, Secretarıa del Medio Ambiente y Recursos Naturales, Mexico, D.F. (SF-SEMARNAT)
Sanidad Vegetal, Secretaria de Agricultura, Ganaderıa, Desarrollo Rural, Pesca y Alimentacion, Mexico, D.F. (SV-SAGARPA)
Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd 1165
Areography of Dendroctonus in Mexico
distribution from insects. Disjunctions were analysed to
determine whether it is related to the physiographic or
ecologic nature of the habitats within each province.
Isoprobabilistic maps
Isoprobabilistic lines were traced around an arbitrary point
where largest specific richness is present. The quadrants with
the largest specific richness are located at the Faja Volcanica
Transmexicana (FVT), Sierra Madre de Chiapas (SMCH),
Sierra Madre Occidental (SMOC) and Sierra Madre Oriental
(SMOR). From these points, the ratio of number of shared
species to number of species present was calculated for the rest
of the quadrants of the composite pattern. Cells with the same
value were connected by lines, obtaining a map with contour
lines of the same probability that defined those zones where
barriers had been more effective, due to abrupt probability
changes on a short geographical distance.
Resemblance
Based on the fragmentation that described the Dendroctonus
composite pattern, common areas of sympatry or disjunction
areas were established, defining areographic units in which the
general pattern was divided. Then, similarity among these areas
of sympatry was estimated through the Simpson Index (Sanchez
& Lopez, 1988) and data were organized in a similarity matrix.
Species richness patterns
The behaviour of distributions was analysed in an elevation
scenario in relation to those abiotic factors that limit species
distribution. Maximum and minimum limits were determined
for each species, as well as the mean value and standard
deviation. These data were used to represent in box plots the
tendency of the genus. Although we did not have enough data
to compare all 12 species, an attempt was made to use data
from eight species to find out whether each species had a
preferred elevation, that is, the elevation most common to
where a species was collected. The preferred elevation interval
was established for each species using frequency histograms.
These were built using the records found within 500 m
intervals between 1500 and 3500 m elevation range.
To test for the existence of a latitudinal pattern, a species
density map was developed with the total number of species
per cell in the grid map. In addition, mean species density
(med) was calculated for all quadrants in two geographical
degrees, starting at 32� N and ending at 14� N. Data were
displayed on a graph of mean species density vs. latitude.
Locations of maximum richness values were analysed in
relation to historic and ecological characteristics of the
Mexican morphotectonic provinces and in relation to the
Pinus species richness pattern (Farjon & Styles, 1997).
Shape, size and perimeter of geographical ranges
The size and perimeter for each range were determined by
digitizing individual distributions using AUTOCAD (vers. 2000).
The range deformation was defined by the axis that best
described preferred direction of the composite pattern. The
perimeter to �area ratio was calculated for each species:
deviations from a circle (p/�a � 3.5) suggest areas with
barriers to expansion (Rapoport, 1975a).
Range size vs. host
To determine the probable causes for range size, the number
of Pinus host species for each Dendroctonus species, the
degree of occurrence of Dendroctonus species on each host
species (incidence percentage), and the most frequently used
host species per beetle species were determined. A Spearman
rank correlation was conducted between the size of the
114 889092949698100102104106108110112
0 300 Km
14
16
18
20
22
24
26
28
30
32
UNITED STATES OF AMERICA
GULF OF MEXICO
PACIFIC OCEAN
PBC
PSN
SMOC
MCCHyC
SMOR
MC
FVT
SMS
SMCH
PY
PCG
PCG
Figure 1 Morphotectonic provinces of
Mexico sensu Ferrusquıa-Villafranca (1998).
PBC, Baja California Peninsula; PSN, Plani-
cies and Sierras del Noroeste; SMOC, Sierra
Madre Occidental; MCCHyC, Mesetas and
Cordilleras de Chihuahua y Coahuila; SMOR,
Sierra Madre Oriental; PCG, Planicie Costera
del Golfo; MC, Meseta Central; FVT, Faja
Volcanica Transmexicana; SMS, Sierra Madre
del Sur; SMCH, Sierra Madre de Chiapas; PY,
Plataforma de Yucatan.
1166 Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd
Y. Salinas-Moreno et al.
geographical ranges of Dendroctonus and the number of Pinus
host species. To assess a potential association between range
shape and Pinus distribution, a comparison of Dendroctonus
composite pattern and the geographical distribution pub-
lished for the genus Pinus (Farjon & Styles, 1997) was
established.
Finally, to determine how many hosts were parasitized by
Dendroctonus species within their preferred elevation, we
elaborated association tables among host, altitude and Dendr-
octonus species.
RESULTS
Geographical range patterns
The 12 individual distributions varied in shape and size. The
tendency of the shape is discontinuous for geographical
ranges, with the exception of D. ponderosae, D. jeffreyi and
D. vitei. The patterns of distribution indicated four groups of
species: (1) D. approximatus, D. mexicanus and D. valens are
the species with broadest distribution because they are located
in all mountainous systems of the country. These three species
showed disjunct patterns in the mountain ranges of the
morphotectonic provinces of Peninsula de Baja California
(PBC), SMOR, SMOC, Sierra Madre del Sur (SMS) and
SMCH. The exception to this occurred at the contact zone
between FVT and SMOR, and FVT and SMS, where a wide
and continuous pattern occurred (Fig. 2a–c). (2) D. adjunctus,
D. frontalis and D. parallelocollis were absent from PBC;
however, they show a disjunct pattern similar to D. mexicanus
and D. valens in the rest of the territory (Figs 2d, 3a,b).
3) D. brevicomis and D. pseudotsugae are located only in
the northern portions of SMOC and SMOR (Fig. 3c,d).
4) D. ponderosae and D. jeffreyi distribution patterns are
restricted to PBC (Fig. 3c). Dendroctonus vitei and D. rhizoph-
agus were each unique. Dendroctonus vitei was located
exclusively within SMCH (Fig. 3c) and D. rhizophagus showed
a disjunction within SMOC and PBC (Fig. 3d).
The composite pattern showed that disjunctions among
ranges do not follow closely Mexico’s morphotectonic subdi-
vision (Fig. 4). Taken all together, there is a marginal junction
between FVT and SMOC, and FVT and SMOR, and an evident
continuity between FVT and SMS, such that only PBC and
SMCH are isolated provinces. Several discontinuities or
disjunctions are repeated among individual distributions,
defining five regions where the ranges of multiple species
14
88
16
20
22
24
UNITED STATES OF AMERICA
14
88
16
20
22
24
UNITED STATES OF AMERICA
26
28
30
32
300 Km
104114 108112 110 106
0
PACIFIC OCEAN
GULF OF MEXICO
94102 100 98 96
18
92 90
114 889092949698100102104106108110112
0 300 Km
14
16
18
20
22
24
26
28
30
32
UNITED STATES OF AMERICA
GULF OF MEXICO
PACIFIC OCEAN
300 Km
104114 108112 110 106
0
PACIFIC OCEAN
GULF OF MEXICO
94102 100 98 96
18
92 90
30
32
N
N
N
N
a b
dc26
28
14
88
16
20
22
24
UNITED STATES OF AMERICA
26
28
30
32
300 Km
104114 108112 110 106
0
PACIFIC OCEAN
GULF OF MEXICO
94102 100 98 96
18
92 90
Figure 2 Geographical distribution in Mexico of: (a) Dendroctonus approximatus Dietz, (b) D. mexicanus Hopkins, (c) D. valens
LeConte and (d) D. adjunctus Blandford.
Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd 1167
Areography of Dendroctonus in Mexico
16
14
18
GULF OF MEXICO
N
26
28
30
32
300 Km
104114 108 106110112
PACIFIC OCEAN
0
9698100102 8894 92 90
16
22
20
24
UNITED STATES OF AMERICA30
N28
32
a b
c d
UNITED STATES OF AMERICA
20
22
24
26
N
26
28
30
32
104
300 Km
114 112 110 106108
0
PACIFIC OCEAN
16
22
20
24
UNITED STATES OF AMERICA
GULF OF MEXICO
102 100 98 96
18
909294 88
14
104
300 Km
114 112 110 106108
0
PACIFIC OCEAN
GULF OF MEXICO
102 100 98 96
18
909294 88
14
114 889092949698100102104106108110112
0 300 Km
14
16
18
20
22
24
26
28
30
32
N
UNITED STATES OF AMERICA
GULF OF MEXICO
PACIFIC OCEAN
Figure 3 Geographical distribution in Mexico of species: (a) Dendroctonus frontalis Zimmerman, (b) D. parallelocollis Chapuis,
(c) —— D. brevicomis LeConte, D. jeffreyi Hopkins, w D. ponderosae Hopkins, D. vitei Wood, (d) —— D. rhizophagus Thomas and
Bright, Æ - Æ - Æ - Æ D. pseudotsugae Hopkins.
114 889092949698100102104106108110112
0 300 Km
14
16
18
20
22
24
26
28
30
32
N
UNITED STATES OF AMERICA
GULF OF MEXICO
PACIFIC OCEAN
D. vitei
D. brevicomis
D. jeffreyi
D. ponderosae
D. adjunctusD. approximatus
D. mexicanus
D. frontalis
D. parallelocollis
D. pseudotsugaeD. rhizophagusD.valens
SMOC
N-SMOR
CM (FVT+S-SMOR+SMS)
SMCH
PBC
Figure 4 Composite pattern of the 12
Dendroctonus species present in Mexico. PBC,
Baja California Peninsula; SMOC, Sierra
Madre Occidental; N-SMOR, North of the
Sierra Madre Oriental; CM, Central Mexico;
SMCH, Sierra Madre de Chiapas.
1168 Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd
Y. Salinas-Moreno et al.
Figure 5 Geographical distribution of Pinus
in Mexico sensu Farjon and Styles (1997).
20
22
24
26
28
30
32
a b
c d
108 106
0
104 102
300 Km
90 88
14
16
18
108 106
0
104 102
300 Km
.1.3
.4
.4
20
22
24
26
28
30
32
UNITED STATES OF AMERICA
.5
.3
PACIFIC OCEAN
114 112 110
.1
.6 .5.3
.2
GULF OF MEXICO.1
.3
.4
.6.5
.7.9
92100 98
.3
.8
.6
.7
.5
96 94
.4
.2
.6 .5
GULF OF MEXICO.3
.5
.1
.4
8
.6.5
.3
.7
.1
.3.4
.1
.1 .3.4
.5.4 .3
14
16
18
.5.4
.1
92100 98
.8
.6
.7
.4.5.6
.1.3
96 94 90 88
.2
92100 98
.2
90 88
.2
GULF OF MEXICO
.6.5
.8
.2.3
.5
.8.6
.3
.3
.5.4
.8 .1
.4
.3
8
.1
.1
.5
.5
.5
.3
.7
.3
.5
.8
.2
108 106
0
104 102
300 Km
.5.3
.2
.2.3
20
22
24
26
28
30
32
UNITED STATES OF AMERICA
.5
.1
PACIFIC OCEAN
14
16
18.8
.7.8
.5.3.6
96 94
6 .6.3.5
114 112 110
.3
.4
.8 .6.5
GULF OF MEXICO.1
.5.6
.8
.3
UNITED STATES OF AMERICA
PACIFIC OCEAN
114 112 110
.3
.3
.5.3
.7
.5 .3
.8
.3
.5
.2
.2
20
22
24
26
28
30
32
.1
.7
.1
UNITED STATES OF AMERICA
PACIFIC OCEAN
114 112 110108 106
0
104 102
300 Km
.3.2
.7.5
.2
90 88
.2
14
16
18
.3
.2
.3
92100 98
.8 6
.6
.2.3
96 94
Figure 6 Isoprobabilistic lines from four main density species centres. (a) Sierra Madre Occidental, (b) Sierra Madre Oriental, (c) Faja
Volcanica Transmexicana and (d) Sierra Madre de Chiapas.
Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd 1169
Areography of Dendroctonus in Mexico
overlap extensively in concentrated areas of sympatry that
correspond to: (1) PBC, (2) SMOC, (3) northern SMOR
(N-SMOR), (4) SMCH, and (5) the area integrated by the
southern SMOR (S-SMOR) + FVT + SMS (here called Cen-
tral Mexico, CM) (Fig. 4).
Comparisons between distributions of the genus Pinus
(Fig. 5) and Dendroctonus better reflect the beetle’s com-
posite pattern, especially at the intersection of FVT, where
SMOR joins, and SMS. A more accurate picture of the
beetle disjunction pattern is depicted by the isoprobabilistic
curves (Fig. 6). In fact, all maps confirmed that PBC and
SMCH provinces are separated from the rest. Additionally,
these maps suggest that SMOC is independent of FVT and
that the inside of SMOC provides optimal environment for
the distribution of the genus. However, lines of equal
richness support the relationships among SMOR, FVT and
SMS.
In terms of environmental restrictions, FVT showed the
most favourable conditions for Dendroctonus. It is the broadest
corridor in the country, with an east–west orientation and
marginally extending, in its eastern part, towards the Meseta
Central Province.
Resemblance
There was high similarity (0.5–1.0) among all five centres of
sympatry (Table 2). Minimum values are between PBC
sympatric area and those areas from SMOC, N-SMOR,
CM and SMCH. SMOC and N-SMOR had perfect similar-
ities.
Species richness patterns
Dendroctonus exhibited a heterogeneous species density in
Mexico (Fig. 7). Nine geographical quadrants had a species
density ‡ 50% (six to eight species), one quadrant in each of
the following provinces: PBC, SMOR, SMS, SMCH and FVT,
and four in SMOC.
This suggests that SMOC represents a favourable environ-
mental mosaic for the genus. Species density was the least
heterogenous within FVT, with five species within each of
seven quadrants.
Mean species density does not directly decrease or increase
with latitude (Fig. 8). Its behaviour is homogeneous through
the latitude gradient, except in the ending portions of SMOC
and SMOR, and the ending of the SMCH. However, the
analysis of total richness pattern in each quadrant showed a
low richness pattern at high latitude (PBC), attaining an
increment (eight species) towards 26�–24� N (SMOC and
SMOR), and ending in a lower diversity (six species) at low
latitudes (SMCH). One would expect that such geographical
behaviour of richness would show some association with that
of their host. However, that is not the case, because pine
reaches a maximum richness at the western side of FVT
(Farjon & Styles, 1997), whereas Dendroctonus depicts a higher
richness above FVT.
Dendroctonus was distributed from 800 m to 3929 m. The
distributions analysis suggests that each species have a
preferred elevation range (Table 3); however, confirmation of
this is needed. The mean elevation per species shows a more
Table 2 Pairwise similarity matrix among areas of sympatry of
Dendroctonus estimated by Simpson’s index
PBC SMOC N-SMOR CM SMCH
PBC
SMOC 0.66
N-SMOR 0.5 1
CM 0.5 1 1
SMCH 0.5 0.85 0.85 1
PBC, Baja California Peninsula; SMOC, Sierra Madre Occidental;
N-SMOR, North of the Sierra Madre Oriental; CM, Central Mexico;
SMCH, Sierra Madre de Chiapas.
0 200
4
1
37
1 3 3
37
2
8
22
2 2284
11 6
32 1
111
113
4 4
22 2
45
555555
2 4 6 3 1 14
2 2 631 2 3 6
1
1
41
16
UNITED STATES OF AMERICA
GULF OF MEXICO
PACIFIC OCEAN
114 110 106 102112 108 104 98100 9496 9092 88 86
12
14
16
18
20
22
24
26
28
30
32
Figure 7 Density of Dendroctonus species in
Mexico. Each quadrant shows species num-
bers present inside each area.
1170 Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd
Y. Salinas-Moreno et al.
regular condition (Fig. 9), because 90% mean elevation falls
between 1700 and 2300 m. This richness is concentrated in this
montane interval, an exception is D. adjunctus, which can live
in this interval, but more frequently is found in locations above
3000 m.
Shape, size and perimeter of the geographical
ranges
Because information is scarce for D. jeffreyi, D. ponderosae and
D. vitei, it was not possible to apply the propinquity method to
define the boundaries of their ranges. The median and mean
area size for the remaining nine species were 364,730.9
and 390,640.2 km2, respectively (Table 4). Areas were
mostly similar, three were larger than the estimated average
and six were smaller.
Range deformation analysis to the composite pattern shows
six main axes (Fig. 10). They describe a NW–SE orientation,
the exceptions are the axes located in the middle part of the
country (FVT and SMS). All ranges follow the orientation of
the main mountain systems.
Ranges deformation described by perimeter to �area ratio
diverges from the expected values for a circular expansion
(Table 4). Dendroctonus mexicanus and D. valens exhibit the
two highest values (15.45 and 15.05, respectively), whereas
D. pseudotsugae and D. brevicomis exhibit the two lowest values
(5.43 and 6.01, respectively).
Area size vs. host
Species of Dendroctonus attack 24 of the 47 Pinus species
distributed in Mexico (Farjon & Styles, 1997). Dendroctonus
pseudotsugae is the only species that has been found on
Pseudotsuga menziesii (¼P. flahaulti). The number of host
species attacked by these bark beetles varies widely. Whereas
D. mexicanus and D. valens infest 20 or more species, D. jeffreyi
and D. vitei infest only one species (Table 5). Among the
Dendroctonus species that can be found on several host
species, a preference for one conifer is observed. For example,
D. mexicanus, D. parallelocollis and D. valens are most
frequently found on Pinus leiophylla Schiede ex Schlechtendal
& Chamisso (Table 5). Preferred pine species are predomin-
antly Leiophyllae, Ponderosae and Oocarpae, subsections of
Pinus.
Species with the maximal area extension do not necessarily
parasitize a larger number of hosts (rs ¼ )0.216, P ¼ 0.515).
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
32–30 30–28 28–26 26–24 24–22 22–20 20–18 18–16 16–14
Spe
cies
mea
n di
vers
ity
Latitude (North degrees)
Figure 8 Mean diversity of species vs. latitudinal distribution
of Dendroctonus species.
Table 3 Elevation range and preferred elevation range of each
Dendroctonus species in Mexico
Species
Elevation range
(m a.s.l.) Preferred interval
Dendroctonus adjunctus 1600–3929 3100–3500
D. approximatus 1900–2800 2100–2500
D. brevicomis 1680–2835 Data unavailable
D. frontalis 960–2835 1100–2000
D. mexicanus 800–3400 2100–2500
D. parallelocollis 800–3100 2100–2500
D. rhizophagus 1200–2600 2100–2500
D. valens 1100–3760 2100–2500
D.
brev
icom
is
D.
fron
talis
D.
mex
ican
us
D. p
aral
lelo
colli
s
D.
rhiz
opha
gus
D. v
alen
s
Species
Ele
vatio
n (m
)
D.
adju
nctu
s
D.
appr
oxim
atus
4000
3000
2000
1000
Figure 9 Distribution of Dendroctonus species by elevation above
sea level. The box plot was constructed with mean elevation, one
standard error, and maximum and minimum elevation values.
Table 4 Size of geographical ranges (km2) and perimeter to �area
ratio for Dendroctonus species in Mexico
Species
Geographical
area (km2)
Perimeter/
�area
Dendroctonus approximatus 553,852 10.9
D. parallelocollis 531,908 9.93
D. pseudotsugae 466,707 5.43
D. brevicomis 386,581 6.01
D. frontalis 376,645 10.97
D. valens 352,473 15.05
D. mexicanus 336,158 15.45
D. adjunctus 335,824 12.12
D. rhizophagus 175,608 8.41
Average 390,640
Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd 1171
Areography of Dendroctonus in Mexico
Finally, the preferred elevation–preferred host comparison
showed no strict association between these elements, given
that Dendroctonus species attacked more than one Pinus
species within the preferred elevation range of the insect
(Table 6).
DISCUSSION
Contrary to other coleopteran genera occupying montane
habitats, Dendroctonus in Mexico underwent few events of
diversification, resulting in only a single endemic species and
Table 5 Host species and percentages of Dendroctonus species incidence on each one of them
Pinus species
(Farjon & Styles,
1997)
Dendroctonus species
D. adjunctus D. approximatus D. brevicomis D. frontalis D. jeffreyi D. mexicanus D. parallelocollis D. rhizophagus D. vitei D. valens
P. arizonica 2.7 15 1.8 2.5 2.1 24.3 7.6
P. ayacahuite 0.4 0.7
P. cembroides 0.4 1.4
P. devoniana 22.2 3.6 9.4 12.8 4.3 100 9.0
P. douglasiana 3.6 0.8
P. durangensis 5.3 3.7 40 3.6 1.2 6.4 14.3 3.5
P. engelmannii 7.4 15 1.2 44.3 4.9
P. gregii 1.2 2.8
P. hartwegii 80 14.8 1.8 1.2 4.3 3.5
P. herrerae 1.3 0.4 0.7
P. jeffreyi 3.7 100 0.4 4.3 1.4
P. lawsonii 1.8 0.8
P. leiophylla 2.7 14.8 15 3.6 35.6 27.7 20.1
P. lumholtzii 0.4 4.3 1.4
P. maximinoi 1.3 1.2
P. montezumae 1.3 7.4 1.8 7.4 21.3 10.4
P. oocarpa 3.7 1.5 37.5 5.7 4.3 9.0
P. patula 2.7 4.9 2.0
P. pinceana 1.3
P. ponderosae 4.3 1.4
P. pringlei 19.7 1.6 2.1 2.0
P. psudostrobus 3.7 5.4 9.0 4.3 6.9
P. quadriflora 0.7
P. teocote 1.3 18.5 16 13.9 14.9 9.7
Total host 10 10 5 12 1 21 10 7 1 20
Numbers in bold represent higher percentages of incidence.
114 889092949698100102104106108110112
0 300 Km
14
16
18
20
22
24
26
28
30
32
UNITED STATES OF AMERICA
GULF OF MEXICO
PACIFIC OCEAN
Figure 10 Preferred directions of the
Dendroctonus composite pattern.
1172 Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd
Y. Salinas-Moreno et al.
another that shares endemism with a contiguous region in
Guatemala. Despite complex morphotectonic scenario in the
mountainous environment and the heterogeneity of pine
species distribution (Farjon & Styles, 1997), interspecific
geographical disjunction is not the main characteristic of
Dendroctonus distribution patterns. It can be said that Mexico
represents an area of overlapping of species with wide
distribution and of species with restricted ones. All of them
nested in five areas of sympatry. The causes for this
disjunction are probably biotic, climatic and geological
barriers present at this time or the result of conditions
imposed by the geological, paleogeological or paleoclimatic
history of Mexico.
If we analyse the sympatry location areas with respect to the
physiographic and geological scenery of Mexico, the disjunc-
tions where the genus is distributed do not correspond
specifically to the morphotectonic provinces, with the excep-
tion of PBC, SMOC and SMCH. In other words, the
disjunction patterns do not directly reflect the origin and
formation of Mexico’s tectonic units. However, they are more
similar with patterns for other mountainous taxa vicariants
and speciation centres (Ball, 1968; Noonan, 1988; Liebherr,
1991).
An example is the vicariation hypothesis pattern revealed by
the general area cladogram for Carabidae (Liebherr, 1991).
This predicts that the relationship among these areas can be
used to analyse the behaviour of other taxa that are ecologically
restricted to mountainous forests and that have sister groups
inhabiting North America. SMOR appears to be subdivided
into two, with the northern portion having a close affinity to
SMOC, a situation that might be the result from an old
relationship during the Pleistocene, when conditions were
more mesic at the Chihuahua desert. In Dendroctonus, such
north–south division, in addition to the relation of the north
portion with SMOC, is confirmed with isoprobabilistic lines,
the similarity values between both zones, and by the exclusively
shared presence of D. pseudotsugae and D. brevicomis. How-
ever, the southern region of SMOR seems more related to FVT
and SMS than to the northern areas. Such a relationship would
in Dendroctonus help explain the eastern location of the area of
sympatry that we called CM, which is clearly shown in the
isoprobabilistic lines.
This close connection between FVT and SMS observed in
Carabidae (Liebherr, 1991), Dendroctonus and other species is
explained through the continuous mountainous habitat
offered by the Mountains of Oaxaca, which in turn favours
biotic exchange. Nevertheless, loss of continuity with the west
of SMS is due to the Balsas Basin, which has acted as an
important biogeographic barrier for many groups of organ-
isms, among them insects and pines.
The other areas of sympatry – PBC and SMCH – can be
explained by significant barriers, such as the Sonora desert and
the Tehuantepec isthmus, respectively, for taxa with Nearctic
affinities.
Analysing the average similarity among the areas of
sympatry, it becomes evident that at least two-thirds of the
present species are shared by several of them, which might
imply that fragmentation of Dendroctonus ranges are rather
the result of ecological restrictions than due to historical
events. It seems that dispersal activities of Dendroctonus
individuals in conjunction with their high vagility could be
the causes of this distribution pattern (Noonan, 1988;
Turchin & Thoeny, 1993; Byers, 2000).
The only exception to this condition is PBC, because it
exhibits the greatest differentiation with respect to the rest of
the areas. These values result from the presence of D. jeffreyi
and D. ponderosae, exclusive to this zone, and the absence of
D. frontalis, D. adjunctus and D. parallelocollis, species broadly
distributed in Mexico. However, PBC is a province with a flora
and fauna known for its singularity and for its greater affinity
with the Californian province to the north than with the rest of
the provinces in Mexico (Alvarez & de Lachica, 1974;
Rzedowski, 1981; Morrone et al., 2002).
The fact that disjunction patterns among most species are
congruent, suggests that individuals of those species are
closely linked to common habitats and, therefore, limited by
similar factors. The topographic diversity of the continent,
position and orientation of mountain ranges might be very
important in determining the location and the shape of
geographical ranges (Brown & Maurer, 1989). Nevertheless,
climate must set the absolute limits of a species distribution
and habitat is important in the discontinuities in species
assemblages (Letcher & Harvey, 1994). Disjunctions common
to all Dendroctonus species are directly explained by the
absence of pines, if we consider most pine species in Mexico
as confined to mountains or high plateaus. Isolation of PBC
is due to the loss of elevation above sea level, and the
mountains of Baja are surrounded by desert zones with
xerophytic vegetation. Disruption between SMOC and FVT,
despite their short distance, can be explained because pine
forest continuity is interrupted by depressions like the Valley
of the Mezquital River and by the Santiago River watershed,
both of which are covered by deciduous tropical forest.
Between the northern and southern parts of SMOR,
physiographic and ecological conditions impose pine char-
acteristic patterns and consequently affect Dendroctonus too.
It is a mountainous system with low elevation zones
(< 1000 m) between 21� N and 23� N, with ample plateaus
and low elevation covered with xerophytes, shrubs and
deciduous tropical forests.
Table 6 Incidence percentages of Dendroctonus species on their
preferred host within their preferred elevation range
Bark beetle species Preferred host
Preferred
elevation % Incidence
Dendroctonus adjunctus Pinus hartwegii 3100–3500 83.3
D. approximatus P. devoniana 2100–2500 38.4
D. frontalis P. oocarpa 1100–2000 42.3
D. mexicanus P. leiophylla 2100-2500 34.9
D. parallelocollis P. leiophylla 2100-2500 23.8
D. valens P. leiophylla 2100-2500 33.3
Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd 1173
Areography of Dendroctonus in Mexico
The disjunction between CM and SMCH is given by the
Tehuantepec isthmus. This barrier represents a depression below
1000 m, covered with evergreen and deciduous tropical forests.
However, the isoprobabilistic analysis shows the existence of
zones within SMOC and CM, where faunistic similarity
decrease rapidly. The reason for this, in the case of SMOC, is
the high discontinuity of Dendroctonus species ranges.
Although it is a system where 65% of its surface is between
2000 m and 3000 m, it is formed by numerous isolated
mountains that represent an elevation and climatic mosaic for
many Dendroctonus species. This tendency of elevation
heterogeneity is enhanced towards the south. In this zone,
the conifer forest is interrupted by deciduous tropical forests
giving rise to isolated forested areas, observed in the composite
pattern as centres of major sympatry.
The CM is a distinctive case, which may be perceived by
Dendroctonus as a homogeneous area despite being a hetero-
geneous physiographic and elevation system. The wide separ-
ation of the isoprobabilistic lines at the eastern portion seems
to be explained by its predominant elevation between 1500 m
and 2500 m, while the western half, with some exceptions, lies
below 1500 m. Thus elevation and climatic conditions are
more favourable in the east portion.
The isoprobabilistic lines showed that the main corridors
were associated with mountain ranges, thus the geographical
barriers could be related to elevation and presumably to
climatic factors, such as temperature and humidity.
The relationship among elevation, Dendroctonus richness
tendency and host species in Mexico indicates a preference of
these beetles for montane systems, which are rich in Pinus
species (Farjon & Styles, 1997). High host richness promotes
greater habitat availability and permits high species richness of
beetles.
Some facts suggest that distribution of the genus Dendroc-
tonus is determined by cold temperate climate conditions
(Williams & Liebhold, 2002). First, the distribution limit of
some Dendroctonus species is northern rather than southern in
Mexico. Secondly, the highest species richness is found in the
north and their values increase at the FVT latitudinal belt,
where Mexico has its highest peaks. Thirdly, the lack of a
match between geographical location of species richness
centres of Dendroctonus and Pinus. Several studies seem to
confirm that scolytid distribution is influenced by environ-
mental factors such as temperature during winter and summer
(Swaine, 1925; Lekander et al., 1977; Heliovara et al., 1991;
Ungerer et al., 1999).
If we accept the hypothesis for the Nearctic origin of the
genus Dendroctonus (Zuniga et al., 2002a,b) and its association
with the dispersal of its main host, the genus Pinus, into
Mexico (Mirov, 1967; Farjon & Styles, 1997; Millar, 1998), it is
possible to explain the northern sites with the highest density
of species, located in PBC, SMOR and SMOC, not only as a
result of elevation, latitude, climate and host diversification,
but also of dispersal.
These richness centres are characterized by three groups of
species. The first composed of boreal species, such as
D. brevicomis, D. jeffreyi, D. ponderosae and D. pseudotsugae,
which are typical of the western region of the USA and south-
western Canada and whose geographical distribution in
Mexico is narrow. The second group is formed by widely
distributed species in North America, such as D. adjunctus,
D. approximatus, D. frontalis and D. valens. The third group
includes species that are indigenous to Mexico such as
D. mexicanus, D. parallelocollis and D. rhizophagus.
The species richness centres located at FVT, SMS and SMCH
are compose of widely distributed species such as D. adjunctus,
D. approximatus, D. frontalis and D. valens, as well as by
Mesoamerican native elements (sensu Maldonado-Koerdell,
1964) such as D. mexicanus, D. parallelocollis and D. vitei. The
absence of boreal elements and the presence of indigenous
ones make the composition of species in this region different
from that of the north.
From the 17 Dendroctonus species of North and Central
America, 62% occurr in Mexico. Of these, 50% reach
distribution limits in northern Mexico, and most have used
SMOC, SMOR, FVT and SMS as dispersion corridors towards
Mesoamerica. Following this line of thought, with the excep-
tion of PBC, there is a real latitudinal decrease in Dendroctonus
species richness within the continent, despite its increase in
FVT. Finally, because of its presence in conifer forests, and
their major specific richness located above 1700 m, we are led
to consider that Dendroctonus belongs to the Nearctic distri-
bution pattern (sensu Halffter, 1987).
Although area deformation suggests that Dendroctonus track
mountain systems, the perimeter to �area ratio reveal that
their distribution is not homogeneous (within the altitudinal
range that characterizes the Nearctic pattern) and that there
are some degrees of environmental resistance.
For phytophagous insects, the area size is important in order
to determine habitat (Udvardy, 1969; Hengeveld, 1990;
Gaston, 1991, 1996) and host availability (Anderson, 1984;
Gaston, 1990, 1996). Therefore, it would be expected that taxa
having a wide area would have better ecological opportunities
than those with narrow areas.
Trends in range size of Dendroctonus species in Mexico agree
with the general assumption that most taxa occupy small ranges
(Rapoport, 1975a; Gaston, 1990). However, our results suggest
that ranges inhabited by Dendroctonus in Mexico do not depend
on how widespread these species are in different mountain
systems (e.g. D. mexicanus occupies a small size area), nor in the
number of host species (i.e. correlations were not significant).
When distribution of herbivore species are independent of the
host species distribution, as is the case for Dendroctonus and
Pinus which exhibit richness centres at different latitudes, it
suggests that others factors (tolerance, dispersal ability, beha-
viour) could be involved (Kennedy & Southwood, 1984). This
could explain why species with narrow distributions such as
D. brevicomis and D. rhizophagus, and others with wide
distributions, including D. adjunctus, D. mexicanus, D. frontalis
and D. valens, have area sizes below the average.
The data show that the majority of Dendroctonus species in
Mexico have a low specificity towards its host (Pinus), the host
1174 Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd
Y. Salinas-Moreno et al.
species ranges are wider than those of the insects that feed on
them, and the number of pine species is four times larger than
that of Dendroctonus. Of 24 species that could potentially be
infested, only P. arizonica Engelmann, P. hartwegii Lindley,
P. montezumae Lambert, P. durangensis Martınez (subsec.
Ponderosae), P. oocarpa Schiede ex Schlechtendal, P. teocote
Schiede ex Schlechtendal & Chamisso (subsec. Oocarpae) and
P. leiophylla (subsec. Leiophyllae) are used by at least 50% of
the Dendroctonus species (Zuniga et al., 1999). Only 30% of
Dendroctonus species show an exclusive relationship, including
D. adjunctus that shows an 80% incidence on P. hartwegii. The
rest of the species have just one preferred host but their
incidences are not higher than 44%. Although 75% of the
records show that D. mexicanus has a preference for P. devoni-
ana Lindley, P. leiophylla, P. montezumae, P. pseudostrobus
Lindley and P. teocote, this species infests 21 host species along
its distribution range in Mexico (Zuniga et al., 1999). All of
this suggests that Dendroctonus behaves more as a polyphagous
generalist inside the genus Pinus, with a potential for frequent
host switching. The correlation observed among the Dendr-
octonus species and host species belonging to certain Pinus
subsections (Kelley & Farrell, 1998) seems to be only the result
of ecological opportunities exploited by the insect rather than a
strict evolutionary association between both taxa, for example,
D. adjunctus, D. brevicomis, D. frontalis, D. ponderosae and
D. valens, which attack host species of the Ponderosae,
Oocarpae and Leiophyllae subsections (Zuniga et al., 1999),
have been found on other pine species beyond Mexico (Wood,
1982). In the same sense is the fact that P. leiophylla is the
preferred host of D. parallelocollis, D. mexicanus and D. valens,
but the distributions of these species are found outside the
range of P. leiophylla.
It has been proposed that insect species richness is a function
of the range size of hosts; thus hosts with wide distribution
present an increase in the numbers of phytophagous species
(Strong, 1979). In this context, the hosts preferentially attacked
by Dendroctonus, P. devoniana, P. durangensis, P. engelmannii
Carriere, P. hartwegii, P. leiophylla and P. oocarpa are distri-
buted only in three of the six Mexican morphotectonic
provinces where these insects are located.
Species specialization is a complex process involving
ecological and historical factors (Thompson, 1994). The scarce
specialization observed in phytophagous insects can be the
result of either a low diversity in secondary chemistry of the
host (Tahvanainen & Niemela, 1987), or insect-plant associ-
ations that are casual, haphazard or labile (Strong, 1979). In
Dendroctonus, the comparison of their molecular phylogeny
with their host (Pinus, Picea, Pseudotsuga and Larix) suggests a
poor association among them, despite sibling species attacking
similar groups of pine species (Kelley & Farell, 1998).
In summary, Dendroctonus habits montane systems of
Mexico and their species show a high geographical sympatry.
The coexistence of species appears to be the result of the
polyphagy inside the genus Pinus and wide elevation tolerance.
This behaviour corresponds to ecological opportunities
rather than to a direct host association. Despite wide host
distribution, some species limit their ranges to the northern
forest of Mexico. The high vagility of species has allowed the
genus Dendroctonus to expand its distribution across Mexico
and to perceive mountainous systems as corridors.
ACKNOWLEDGMENTS
We thank A. Ruggiero, J.J. Morrone, J.L. Hayes, A. Cognato,
S.T. Kelley, J. Moser, O.J. Polaco, S. Sanchez Colon and
R. Galvan for review and constructive comments on the
manuscript. This work was supported by a CONAFOR
research grant (CO1-5829).
REFERENCES
Alvarez, T. & de Lachica, F. (1974) Zoogeografıa de los ver-
tebrados de Mexico. El Escenario geografico. (ed. by
A. Flores-Dıaz, L. Gonzalez- Quintero, T. Alvarez and F. de
Lachica), pp. 218–275. SEP-INAH, Mexico.
Anderson, S. (1984) Areography of North American fishes,
amphibians, and reptiles. American Museum Novitates, 2082,
1–16.
Antunez, A. & Marquez, A.L. (1992) Las escalas en biogeo-
grafıa. Monografıas de Herpetologıa, 2, 31–38.
Ball, G.E. (1968) 1970 Barriers and southward dispersal of the
holartic boreo-montane element of family Carabidae in the
mountains of Mexico. Anales de la Escuela Nacional de
Ciencias Biologicas, Mexico, 17, 91–112.
Brown, J.H. (1984) On the relationship between abundance
and distribution of species. The American Naturalist, 124,
255–279.
Brown, J.H. & Lomolino, M.V. (1998) Biogeography. Sinauer,
MA.
Brown, J.H. & Maurer, B.A. (1989) Macroecology. The divi-
sion of food and space among species on continents. Science,
243, 1145–1150.
Brown, J.H., Stevens, G. & Kaufman, D.M. (1996) The geo-
graphic range: size, shape, boundaries, and internal struc-
ture. Annual Review of Ecology and Systematics, 27, 597–623.
Byers, J.A. (2000) Wind-aided dispersal of simulated bark beetles
flying through forest. Ecological Modelling, 125, 231–245.
Cibrian-Tovar, D., Mendez Montiel, J.T., Campos Bolanos, R.,
Yates, H.O., III & Flores Lara, J. (1995) Insectos Forestales de
Mexico/Forest insects of Mexico COFAN/NAFC. Universidad
Autonoma de Chapingo, Mexico.
Contreras-Medina, R. & Eliosa-Leon, H. (2001) Una vision
panbiogeografica preliminar de Mexico. Introduccion a la
Biogeografıa en Latinoamerica: Teorıas, conceptos, metodos y
aplicaciones (ed. by J. Llorente-Bousquets and J.J. Morrone),
pp. 197–211. Las Prensas de Ciencias, UNAM, Mexico.
Eguiluz Piedra, T. (1985) Origen y evolucion del genero Pinus
(con referencia especial a los pinos mexicanos). Dasonomia
Mexicana, 3, 5–31.
Farjon, A. & Styles, B. (1997) Flora neotropica. Monograph 75.
Pinus (Pinaceae). Organization for Flora Neotropica, New
York Botanical Garden, New York.
Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd 1175
Areography of Dendroctonus in Mexico
Ferrusquıa-Villafranca, I. (1998) Geologıa de Mexico: Una
sinopsis. Diversidad Biologica de Mexico: Origenes y Distrib-
ucion (ed. by T.P. Ramamoorthy, R. Bye, A. Lot and J. Fa),
pp. 3–108. Instituto de Biologıa, UNAM, Mexico.
Gaston, K.J. (1990) Patterns in the geographical range of
species. Biological Reviews, 65, 105–192.
Gaston, K.J. (1991) How large is a species’ geographic range?
Oikos, 61, 434–438.
Gaston, K.J. (1996) Species-ranges-size distribution: patterns,
mechanisms and implications. Trends in Ecology and Evo-
lution, 11, 197–201.
Gudino, J.L. (1985) Contribucion al conocimiento de la dis-
tribucion de los escarabajos del genero Dendroctonus Erichson
(Coleoptera: Scolytidae) en Mexico. Tesis de Licenciatura.
Instituto Politecnico Nacional, Mexico.
Halffter, G. (1976) Distribucion de los insectos en la zona de
transicion mexicana, relaciones con la entomofauna de
Norteamerica. Folia Entomologica Mexicana, 35, 5–62.
Halffter, G. (1987) Biogeography of the montane entomofauna
of Mexico and Central America. Annual Review of Ento-
mology, 32, 95–114.
Halffter, G., Favila, M.E. & Arellano, L. (1995) Spatial dis-
tribution of three groups of Coleoptera along an altitudinal
transect in the Mexican transition zone and its biogeo-
graphical implications. Elytron, 9, 151–185.
Heliovara, K., Vaisanen, R. & Imnonen, A. (1991) Quantitative
biogeography of the bark beetles (Coleoptera: Scolytidae) in
Northern Europe. Acta Forestalia Fennica, 219, 1–35.
Hendrichs, N.J. (1977) Distribucion ecologica y geografica de las
especies primarias de descortezadores de pino del genero
Dendroctonus (Coleoptera: Scolytidae) en Mexico. Tesis de
Licenciatura. Instituto de Estudios Superiores de Monterrey,
Mexico.
Hengeveld, R. (1990) Dynamic biogeography. Cambridge Uni-
versity Press, Cambridge.
Kelley, S.T. & Farrell, B.D. (1998) Is specialization a dead end?
The phylogeny of host use in Dendroctonus bark beetles
(Scolytidae). Evolution, 52, 244–256.
Kennedy, C.E.J. & Southwood, T.R.E. (1984) The number of
species of insects associated with British trees: a re-analysis.
Journal of Animal Ecology, 53, 455–478.
Kohlmann, B. & Sanchez, S. (1984) Estudio aerografico del
genero Bursera Jack. Ex. L. (Burceraceae) en Mexico: Una
sıntesis de metodos. Metodos cuantitativos en Biogeografıa
(ed. by E. Escurra, M. Equihua, B. Kohlman and S. Sanchez),
pp. 41–115. Instituto de Ecologıa, A. C., Mexico.
Lekander, B., Bejer-Petersen, B., Kangas, E. & Bakke, A. (1977)
The distribution of bark beetles in the Nordic countries.
Acta Entomologica Fennica, 32, 1–37.
Letcher, A.J. & Harvey, P.H. (1994) Variation in geographical
range size among animals of the Palearctic. The American
Naturalist, 144, 30–42.
Liebherr, J.K. (1991) A general area cladogram for montane
Mexico based on distribution in the platynine genera Elli-
ptoleus and Calathus (Coleoptera: Carabidae). Proceedings of
the Entomological Society of Washington, 93, 390–406.
Liebherr, J.K. (1994) Biogeographic patterns of montane
Mexican and Central American carabidae (Coleoptera). The
Canadian Entomologist, 126, 841–860.
Llorente-Bousquets, J. & Escalante-Pliego, P. (1992) Insular
biogeography of submontane humid forest in Mexico.
Biogeography of Mesoamerica (ed. by S.P. Darwin and
A.L. Welden), pp. 139–146. Tulane University, New Orleans,
LA.
Maldonado-Koerdell, M. (1964) Geohistory and paleogeogra-
phy of Middle America. Handbook of Middle American
Research Institute. Vol. I Natural environment and early
cultures (ed. by R. Wachope). Middle American Research
Institute, Tulane University, TX.
Martin, P. & Harrell B.E. (1957) The Pleistocene history of
temperate biotas in Mexico and eastern United States.
Ecology, 38, 468–480.
Mateu, J. (1974) Sobre algunos linajes de carabidos boreo-
montanos de Mexico y sus relaciones con el pobla-
miento entomologico del Sistema Volcanico Transversal.
Revista de la Sociedad Mexicana de Historia Natural, 35,
181–224.
Millar, C.I. (1998) Early evolution of Pines. Ecology and bio-
geography of Pinus. (ed. by D.M. Richardson), pp. 69–91.
Cambridge University Press, UK.
Miller, C.N. (1977) Mesozoic conifers. Botanical Review
(Lancaster), 43, 217–280.
Mirov, N.T. (1967) The genus Pinus. The Ronald Press Co.,
New York.
Morrone, J.J. & Marquez, J. (2001) Halffter’s Mexican Trans-
ition Zone, beetle generalized tracks, and geographical
homology. Journal of Biogeography, 28, 635–650.
Morrone, J.J., Espinoza-Organista, D. & Llorente-Bousquets, J.
(2002) Mexican biogeographic provinces: preliminary
scheme, general characterizations, and synonymies. Acta
Zoologica Mexicana (nueva serie), 85, 83–108.
Noguera-Martınez, F.A. & Atkinson, T.H. (1990) Biogeography
and biology of bark and ambrosia beetles (Coleoptera: Sco-
lytidae and Platypodidae) of a mesic montane forest in
Mexico, with an annotated checklist of species. Annals of the
Entomological Society of America, 83, 453–466.
Noonan, G.R. (1988) Biogeography of North American and
Mexican insects, and a critique of vicariance biogeography.
Systematic Zoology, 37, 366–384.
Perry, J.P., Graham, A. & Richardson, M. (1998) The history of
pines in Mexico and Central America. Ecology and biogeo-
graphy of Pinus (ed. by D.M. Richardson), pp. 137–149.
Cambridge University Press, Cambridge.
Perusquıa, O.J. (1978) Descortezador de los pinos (Dendroct-
onus spp.) Taxonomıa y Distribucion. Boletın Tecnico
Instituto Nacional de Investigaciones Forestales, SARH.-
DGICF, 55, Mexico.
Rapoport, E. (1975a) Areografıa: estrategias geograficas de las
especies. Fondo de Cultura Economica, Mexico.
Rapoport, E. (1975b) Geographical variation of diversity in
Argentine passerine birds. Journal of Biogeography, 2, 141–
157.
1176 Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd
Y. Salinas-Moreno et al.
Rapoport, E. (1979) Natural and man-made biogeography in
Africa: comparison between birds and phytopathogens.
Journal of Biogeography, 6, 341–348.
Ruggiero, M., Lawton, J.H. & Blackburn, J.M. (1998) The
geographic ranges of mammalian species in South America:
spatial patterns in environmental resistance and anisotropy.
Journal of Biogeography, 25, 1093–1103.
Rzedowski, J. (1981) Vegetacion de Mexico. Limusa, Mexico.
Sanchez, O. & Lopez, G. (1988) A theoretical analysis of some
indices of similarity as applied to biogeography. Folia
Entomologica Mexicana, 75, 119–145.
Strong, D.R. (1979) Biogeographic dynamics of insect-host
plant communities. Annual Review of Entomology, 24,
89–119.
Styles, B.T. (1993) Genus Pinus. Biological diversity of Mexico:
origin and distribution. (ed. by T.P. Ramammorthy, R. Bye,
A. Lot and J. Fa), pp. 397–420. Oxford University Press,
New York.
Swaine, J.M. (1925) The factors determining the distribution
of North-American bark beetles. Journal of Economic Ento-
mology, 56, 261–267.
Tahvanainen, J. & Niemela, P. (1987) Biogeographical and
evolutionary aspects of insects herbivory. Annales Zoologici
Fennici, 24, 239–247.
Thomas, D.B. (1993) Scarabeidae (Coleoptera) of the Chia-
panecan Forest: a faunal survey and chorographic analysis.
The Coleopterists Bulletin, 47, 363–408.
Thompson, N.J. (1994) The coevolutionary process. The Uni-
versity of Chicago Press, Chicago.
Turchin, P. & Thoeny, W.T. (1993) Quantifying dispersal of
southern pine beetles with mark-recapture experiments and
a diffusion model. Ecological Applications, 31, 187–198.
Udvardy, M.F.D. (1969) Dynamic zoogeography. Van Nostrand
Reinhold, New York.
Ungerer, M.J., Ayres, M.P. & Lombardero, M.J. (1999) Climate
and the northern distribution limits of Dendroctonus fron-
talis Zimmermann (Coleoptera: Scolytidae). Journal of Bio-
geography, 26, 1133–1145.
Williams, D.W. & Liebhold, A.M. (2002) Climate change and
the outbreak ranges of two North American bark beetles.
Agricultural and Forest Entomology, 4, 87–99.
Wood, S.L. (1982) The bark and ambrosia beetles of North and
Central America (Coleoptera: Scolytidae). A taxonomic
monograph. Great Basin Naturalist, Memoirs 6. Brigham
Young University, Provo Utah.
Zuniga, G., Mendoza-Correa, G., Cisneros, R. & Salinas-
Moreno, Y. (1999) Zonas de sobreposicion en las areas de
distribucion geografica de las especies mexicanas de Den-
droctonus Erichson (Coleoptera: Scolytidae) y sus
implicaciones ecologico-evolutivas. Acta Zoologica Mexicana
(nueva serie), 77, 1–22.
Zuniga, G., Cisneros, R., Hayes, J.L. & Macıas-Samano, J.
(2002a) Karyology, geographic distribution, and the origin of
the genus Dendroctonus Erichson (Coleoptera: Scolytidae).
Annals of the Entomological Society of America, 95, 267–275.
Zuniga, G., Salinas-Moreno, Y., Hayes, J.L., Gregoire, J.C. &
Cisneros, R. (2002b) Chromosome number in Dendroctonus
micans and karyological divergence within the genus Den-
droctonus (Coleoptera: Scolytidae). The Canadian
Entomologist, 134, 503–510.
BIOSKETCHES
Yolanda Salinas-Moreno is a professor of biogeography at
ENCB-IPN. Her main research interest is the biogeography of
the genus Dendroctonus in North and Central America.
Miguel A. Barrios is a professor at ENCB-IPN and a botanist
interested in the taxonomy and biogeography of the Mexican
flora.
Ramon Cisneros is a biology graduate of the Universidad
Nacional Autonoma de Mexico, with interests in several
aspects of the life history of the genus Dendroctonus, such as
the biogeography, phylogeography and phylogenetic analysis
of American populations of this genus.
Jorge Macıas-Samano is a senior researcher at ECOSUR
whose main interest is the study of interactions between
insects and trees, using trees and scolytids and cerambycids as
models of interactions. He is the Head of Graduate Studies of
ECOSUR.
Gerardo Zuniga is a professor of evolution and population
genetics at ENCB-IPN, and a senior researcher whose main
interests are the population genetics and phylogeography of
Dendroctonus species.
Journal of Biogeography 31, 1163–1177, ª 2004 Blackwell Publishing Ltd 1177
Areography of Dendroctonus in Mexico