Evolutionary Significant Units (ESUs)Evolutionary Significant Units (ESUs)&&
Management Units (MUs)Management Units (MUs)
•• Defining Management Units Within SpeciesDefining Management Units Within Species
•• Diversity is Diverse and ComplexDiversity is Diverse and Complex
•• GGenetic enetic Distinctiveness & ESU’s definitionDistinctiveness & ESU’s definition
•• Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
•• Genetic Variability within PopulationsGenetic Variability within Populations
•• Defining evolutionary conservation value ofDefining evolutionary conservation value of populations or areaspopulations or areas
•• SummarySummary
Evolutionary Significant (ESUs)Evolutionary Significant (ESUs)MManagement Unitsanagement Units ((MUs)MUs)
Lecture OutlineLecture OutlineLecture Outline
•• Evolutionary Significant Units (ESUs)Evolutionary Significant Units (ESUs)
•• Molecular EcologyMolecular Ecology
•• IIdentification of dentification of eevolutionaryvolutionary distinct populationsdistinct populations
•• Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
Difficulties of defining a species can be very informative becauDifficulties of defining a species can be very informative because se it forces us to address organismal behaviour in an evolutionary it forces us to address organismal behaviour in an evolutionary and ecological contextand ecological context
Diversity is Diverse and Complex!Diversity is Diverse and Complex!
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
Conservation genetics is about more than endangered speciesConservation genetics is about more than endangered species
•• it includes understanding theit includes understanding the relationships and diversityrelationships and diversity which which represent biodiversityrepresent biodiversity
•• need not (directly) be an applied science, but need not (directly) be an applied science, but can address issues can address issues relating to understanding diversityrelating to understanding diversity
•• maymay assist planning viable conservation strategiesassist planning viable conservation strategies more than more than conserving directlyconserving directly
Diversity is Diverse and Complex!Diversity is Diverse and Complex!
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
Should we be conservingShould we be conserving speciesspecies??
Species onlySpecies only is a veryis a very simplisticsimplistic approach in the real worldapproach in the real world
•• is diversity only the number of species present?is diversity only the number of species present?
•• are all species equally relevant for biodiversity?are all species equally relevant for biodiversity?
•• must biodiversity be determined entirely by our species definitimust biodiversity be determined entirely by our species definition?on?
Diversity is Diverse and Complex!Diversity is Diverse and Complex!
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
If not, then what else do we need to know?If not, then what else do we need to know?
What questions are really of interest?What questions are really of interest?
•• what (genetic) diversity is present within our taxon of interestwhat (genetic) diversity is present within our taxon of interest??
•• what diversity is present within a region?what diversity is present within a region?
•• what does this tell us about the important processes for creatinwhat does this tell us about the important processes for creating and g and maintaining diversity?maintaining diversity?
•• can we predict the consequences of a particular diversity level?can we predict the consequences of a particular diversity level?
•• if so, what is the appropriate response?if so, what is the appropriate response?
•• what/where should we be saving? what/where should we be saving?
•• can we have objective criteria for prioritization?can we have objective criteria for prioritization?
•• is is human activityhuman activity reducing diversity or is it a natural process?reducing diversity or is it a natural process?
•• is is genetic pollutiongenetic pollution a risk of human movements and introductions?a risk of human movements and introductions?
Diversity is Diverse and Complex!Diversity is Diverse and Complex!
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
More difficult and controversial than defining speciesMore difficult and controversial than defining species
Species clearly require management as separate units, butSpecies clearly require management as separate units, but
•• somesome populationspopulations within species maywithin species may
•• be onbe on the path to speciationthe path to speciation andand
•• showshow significant adaptive differentiationsignificant adaptive differentiation to particular to particular ecological niches orecological niches or
•• significant genetic differentiationsignificant genetic differentiation
justifying theirjustifying their management as separate evolutionary management as separate evolutionary lineageslineages for conservation purposesfor conservation purposes
Defining Managment Units Within SpeciesDefining Managment Units Within Species
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
Evolutionary Significant Units (ESUsEvolutionary Significant Units (ESUs))
genetically differentiated populations that have a high genetically differentiated populations that have a high priority for separate management and conservationpriority for separate management and conservation
closely related (sometime synonymous) toclosely related (sometime synonymous) to
•• subspeciessubspecies
•• distinct population segments (DPS distinct population segments (DPS -- Endangered Species Act)Endangered Species Act)
many authors suggest that ESUs, subspecies and DPS all merit sepmany authors suggest that ESUs, subspecies and DPS all merit separate arate management and have amanagement and have a high priority for conservationhigh priority for conservation
the fundamental idea is thatthe fundamental idea is that conservation should aim to preserveconservation should aim to preserve
•• evolutionary processesevolutionary processes
•• adaptive potentialadaptive potential
•• not just current speciesnot just current species
without regard to losing significant variation within specieswithout regard to losing significant variation within species
Defining Managment Units Within SpeciesDefining Managment Units Within Species
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
What defines an ESU?What defines an ESU?
Original ESU's definitionsOriginal ESU's definitions (Ryder, 1986; Waples, 1991)(Ryder, 1986; Waples, 1991) had two componentshad two components
•• reproductive isolationreproductive isolation (and consequently, genetic distinctness)(and consequently, genetic distinctness)
•• ecological distinctnessecological distinctness (unique adaptations)(unique adaptations)
Recent definitions emphasize more genetic distinctivenessRecent definitions emphasize more genetic distinctiveness
Defining Managment Units Within SpeciesDefining Managment Units Within Species
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
RationaleRationale
Although genetics has assumed an important roleAlthough genetics has assumed an important role in conservation in conservation biologybiology
•• genetic surveys ofgenetic surveys of managed species are far from routine managed species are far from routine
•• therethere is a perception that genetic analyses are of moreis a perception that genetic analyses are of more significance significance to longto long--term than shortterm than short--term needsterm needs
•• genetic genetic analysis has analysis has lower priority than demographiclower priority than demographic analysisanalysis
MoritzMoritz
•• ttheory and practice heory and practice are are so far apartso far apart because the relevancebecause the relevance of of genetic analyses to practical issues ingenetic analyses to practical issues in wildlife management have not wildlife management have not been adequatelybeen adequately explained and demonstratedexplained and demonstrated
•• genetic markers (mtDNA and microsatellites) should be used to genetic markers (mtDNA and microsatellites) should be used to define management units within speciesdefine management units within species
GGenetic enetic DistinctivenessDistinctiveness & ESU’s definition& ESU’s definition
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
Moritz's definitionMoritz's definition
ESU’s should showESU’s should show
•• significant divergencesignificant divergence and and reciprocal monophylyreciprocal monophyly for mtDNAfor mtDNA
•• significant divergence of allele frequencies at nuclear locisignificant divergence of allele frequencies at nuclear loci
Moritz's Moritz's ESU’s ESU’s definition definition impliesimplies
•• bothboth historicalhistorical andand recent restriction ofrecent restriction of gene flowgene flow
it makes criteria for genetic it makes criteria for genetic distinctiveness more concretedistinctiveness more concrete
•• evidence forevidence for long term divergencelong term divergence, , continuingcontinuing in the presentin the present
divergencedivergence in mtDNA reflectsin mtDNA reflects long term restriction of gene flowlong term restriction of gene flow
congruence of slow and fast markerscongruence of slow and fast markers (microsatellites) (microsatellites) is is evidence for historical isolation thatevidence for historical isolation that persists todaypersists today
GGenetic enetic DistinctivenessDistinctiveness & ESU’s definition& ESU’s definition
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
Reciprocal MonophylyReciprocal Monophyly
each ESU is a monphyletic groupeach ESU is a monphyletic group (ancestral population and all (ancestral population and all descendant populations) that does not include any portion of thedescendant populations) that does not include any portion of the otherother
GGenetic enetic DistinctivenessDistinctiveness & ESU’s definition& ESU’s definition
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
ESU 1ESU 1 ESU 2ESU 2
mtDNA is a powerful tool in evolutionary biologmtDNA is a powerful tool in evolutionary biologyy
•• rapid rate of base substitutionsrapid rate of base substitutions
•• effectivelyeffectively haploidhaploid
•• maternal inheritancematernal inheritance
reduces reduces NNee
increases sensitivity toincreases sensitivity to genetic driftgenetic drift
•• ease of isolation and manipulationease of isolation and manipulation
mtDNA can producemtDNA can produce results of considerableresults of considerablepracticpracticaal importancel importance, but , but
•• the conservation goalsthe conservation goals must be clearly must be clearly defined first and the analysesdefined first and the analysesdesigned to fit the goalsdesigned to fit the goals
GGenetic enetic DistinctivenessDistinctiveness & ESU’s definition& ESU’s definition
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
Critics to the ESU conceptCritics to the ESU concept
•• evolutionary significant units areevolutionary significant units are essentially equivalent to, and essentially equivalent to, and should be abandoned in favour of, should be abandoned in favour of, phylogenetic speciesphylogenetic species
(Cracraft, 1997)(Cracraft, 1997)
•• genetically defined ESUs ignore adaptive differencesgenetically defined ESUs ignore adaptive differences(Crandall et al., 2000)(Crandall et al., 2000)
•• unlikely detectedunlikely detected within species within species with high gene flowwith high gene flow
even though populations may have adaptive differences even though populations may have adaptive differences and warrant separate managementand warrant separate management
•• populations populations with low gene flowwith low gene flow that have been differentiated that have been differentiated by genetic drift may be designated as seprate ESUs by genetic drift may be designated as seprate ESUs
even even though they may not be adaptively distinctthough they may not be adaptively distinct
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
Critics to the ESU concept Critics to the ESU concept (Crandall et al., 2000)(Crandall et al., 2000)
TThehe reciprocal monophyly criterion reciprocal monophyly criterion may bemay be overly strictoverly strict
•• guaranteesguarantees that that historical restriction of gene flowhistorical restriction of gene flow occurredoccurred
•• ecologically important genetic differences ecologically important genetic differences may havemay haveaccumulated without thisaccumulated without this pattern pattern
•• cconversely, onversely, long accumulation of neutral genetic long accumulation of neutral genetic differences differences may result inmay result in littlelittle ecological divergenceecological divergence
If the goal is If the goal is to maintain adaptive potentialto maintain adaptive potential, need to , need to
•• consider these possibilitiesconsider these possibilities
•• restorerestore focus on adaptations, not just neutral genetic variationfocus on adaptations, not just neutral genetic variation
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
CrossCross--hair Analysis hair Analysis (Crandall et al., 2000)(Crandall et al., 2000)
Populations can be classified according to whether they show Populations can be classified according to whether they show recent or historical ecological or genetic exchangeabilityrecent or historical ecological or genetic exchangeability
CrossCross--hair analysis hair analysis attempts to delineate whether there isattempts to delineate whether there is
•• there isthere is adaptive differentiation adaptive differentiation
•• there isthere is gene flowgene flow
•• historicalhistorical
•• due to recent admixturedue to recent admixture
CrossCross--hair analysis hair analysis leads toleads to
•• more adequate management recommendationsmore adequate management recommendations
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
CrossCross--hair Analysis hair Analysis (Crandall et al., 2000)(Crandall et al., 2000)
Populations are given Populations are given ++ or or -- classificationsclassifications
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
++//--++//--HistoricalHistorical
Time FrameTime Frame
RecentRecent
HH00 ExchangeabilityExchangeability
++//--++//--
++ reject reject HH00 of exchangeabilityof exchangeability, evidence exists for divergence, evidence exists for divergence
-- accept accept HH00 of exchangeabilityof exchangeability, failure to detect divergence, failure to detect divergence
CrossCross--hair Analysis hair Analysis (Crandall et al., 2000)(Crandall et al., 2000)
Genetic ExchangeabilityGenetic Exchangeability
•• concerned with theconcerned with the limits of spread of new genetic variation limits of spread of new genetic variation through gene flowthrough gene flow
rejected (rejected (++)) when there is when there is evidence evidence ofof restricted gene flowrestricted gene flow
accepted (accepted (--)) when there is when there is evidence evidence ofof ample gene flow ample gene flow
•• evidence for gene flow is ideally evidence for gene flow is ideally based on multiple nuclear loci based on multiple nuclear loci but also on mtDNA or cpDNAbut also on mtDNA or cpDNA
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
++//--++//--HistoricalHistorical
Time FrameTime Frame
RecentRecent
HH00 ExchangeabilityExchangeability
++//--++//--
CrossCross--hair Analysis hair Analysis (Crandall et al., 2000)(Crandall et al., 2000)
Ecological ExchangeabilityEcological Exchangeability
•• based on the factors that define thebased on the factors that define the
•• fundamental fundamental nicheniche
•• the the spread ofspread of new genetic variantsnew genetic variants through genetic drift through genetic drift or natural selectionor natural selection
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
++//--++//--HistoricalHistorical
Time FrameTime Frame
RecentRecent
HH00 ExchangeabilityExchangeability
++//--++//--
CrossCross--hair Analysis hair Analysis (Crandall et al., 2000)(Crandall et al., 2000)
Ecological ExchangeabilityEcological Exchangeability
rejected (rejected (++)) when there is when there is evidence evidence for population differentiation for population differentiation due to due to genetic drift or natural selectiongenetic drift or natural selection
features interpreted as reflectingfeatures interpreted as reflecting adaptive differentiationadaptive differentiation
•• life history traitslife history traits•• morphologymorphology•• habitathabitat•• QTL traits under selectionQTL traits under selection
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
++++//--HistoricalHistorical
Time FrameTime Frame
RecentRecent
HH00 ExchangeabilityExchangeability
++++//--
CrossCross--hair Analysis hair Analysis (Crandall et al., 2000)(Crandall et al., 2000)
Recent and historical time frames Recent and historical time frames distinguishdistinguish
•• natural evolutionary processes of limited gene flownatural evolutionary processes of limited gene flowHH00 rejected (rejected (++) ) in thein the historicalhistorical--genetic categorygenetic category
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
++//--++HistoricalHistorical
Time FrameTime Frame
RecentRecent
HH00 ExchangeabilityExchangeability
++//--++//--
CrossCross--hair Analysis hair Analysis (Crandall et al., 2000)(Crandall et al., 2000)
Recent and historical time frames Recent and historical time frames distinguishdistinguish
•• natural evolutionary processes of limited gene flownatural evolutionary processes of limited gene flowHH00 rejected (rejected (++) ) in thein the historicalhistorical--genetic categorygenetic category
formform•• recent population isolationrecent population isolation
++ in thein the recentrecent--genetic categorygenetic category
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
++//--++//--HistoricalHistorical
Time FrameTime Frame
RecentRecent
HH00 ExchangeabilityExchangeability
++//--++
CrossCross--hair Analysis hair Analysis (Crandall et al., 2000)(Crandall et al., 2000)
Recent and historical time frames Recent and historical time frames distinguish alsodistinguish also
•• secondary contactsecondary contactHH00 accepted (accepted (--)) in thein the recentrecent--genetic categorygenetic category
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
++//--++//--HistoricalHistorical
Time FrameTime Frame
RecentRecent
HH00 ExchangeabilityExchangeability
++//----
CrossCross--hair Analysis hair Analysis (Crandall et al., 2000)(Crandall et al., 2000)
Recent and historical time frames Recent and historical time frames distinguish alsodistinguish also
•• secondary contact secondary contact HH00 accepted (accepted (--) ) in thein the recentrecent--genetic categorygenetic category
formform•• long termlong term--gene flowgene flow
HH00 accepted (accepted (--)) in thein the historicalhistorical--genetic categorygenetic category
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
++//----HistoricalHistorical
Time FrameTime Frame
RecentRecent
HH00 ExchangeabilityExchangeability
++//--++//--
CrossCross--hair Analysis hair Analysis (Crandall et al., 2000)(Crandall et al., 2000)
•• 16 categories of divergence 16 categories of divergence between two populationsbetween two populations
•• recommended management actionsrecommended management actions are given for are given for 8 categories8 categories•• strong emphasis on top right quadrantstrong emphasis on top right quadrant
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
++//--++//--HistoricalHistorical
Time FrameTime Frame
RecentRecent
HH00 ExchangeabilityExchangeability
++//--++//--
CrossCross--hair Analysis hair Analysis (Crandall et al., 2000)(Crandall et al., 2000)
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
separate speciesseparate species
EcologicalEcologicalGeneticGenetic
++++HistoricalHistorical
RecentRecent ++++
++--
++++
--++
++++treat as separate speciestreat as separate species
CrossCross--hair Analysis hair Analysis (Crandall et al., 2000)(Crandall et al., 2000)
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
++++HistoricalHistorical
RecentRecent ++-- treat as distinct populationstreat as distinct populations•• recent admixturerecent admixture•• loss of genetic disctinctivenessloss of genetic disctinctiveness
EcologicalEcologicalGeneticGenetic
++++HistoricalHistorical
RecentRecent --++
treat as single populationtreat as single population•• if natural convergence on if natural convergence on
ecological exchangeabilityecological exchangeabilitytreat as distinct populationtreat as distinct population
•• if if anthropogenic convergence anthropogenic convergence
Diceros bicornisDiceros bicornis
Assignment examples Assignment examples –– Black RhinocerosBlack Rhinoceros
O’Ryan et al. (1994) used mtDNA to argue for two subspecies withO’Ryan et al. (1994) used mtDNA to argue for two subspecies withseparate managementseparate management
CrossCross--hair Analysis hair Analysis
•• insufficient grounds to reject either genetic or insufficient grounds to reject either genetic or ecological exchangeabilityecological exchangeability
•• populations showpopulations show gene flowgene flow
•• habitats are similarhabitats are similar
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
----HistoricalHistorical
RecentRecent ----
The species should beThe species should be managed as a single populationmanaged as a single population
Assignment examples Assignment examples –– African ElephantAfrican Elephant
Georgiadis et al. (1994) found a Georgiadis et al. (1994) found a reciprocal monophyetic reciprocal monophyetic relationship among mtDNA relationship among mtDNA
•• authors argued that the genetic diversity was simply authors argued that the genetic diversity was simply isolation isolation by distance due to driftby distance due to drift across their geographic rangeacross their geographic range
•• habitat of different populations is suffifiently similar to habitat of different populations is suffifiently similar to acceptacceptecological exchangeabilityecological exchangeability
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
----HistoricalHistorical
RecentRecent --++
The species should beThe species should be managed as a single populationmanaged as a single population
Loxodonta africanaLoxodonta africana
Assignment examples Assignment examples –– Cryan’s BuckmothCryan’s Buckmoth
Legge et al. (1996)Legge et al. (1996)
•• adequate gene flow adequate gene flow •• no evidence to reject no evidence to reject geneticgenetic exchangeabilityexchangeability based based
on either mtDNA or allozymes on either mtDNA or allozymes
•• evidence to reject recentevidence to reject recent but not historical but not historical ecological ecological exchangeabilityexchangeability between populationsbetween populations
•• adaptive significance of the ecological differentiationadaptive significance of the ecological differentiation
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
----HistoricalHistorical
RecentRecent ++--
The species should beThe species should be managed as distinct populations managed as distinct populations although although gene flow consistent with current population structure is allowagene flow consistent with current population structure is allowableble
Hemileuca sp.Hemileuca sp.
Assignment examples Assignment examples –– Puritan Tiger BeetlePuritan Tiger Beetle
•• mtDNAmtDNA show show low genelow gene flow and flow and significant differentiationsignificant differentiation
•• evidence to reject evidence to reject geneticgenetic exchangeabilityexchangeability
•• not not ecological exchangeableecological exchangeable based on habitat parametersbased on habitat parameters
Genetical & Ecological ExchangeabilityGenetical & Ecological Exchangeability
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
EcologicalEcologicalGeneticGenetic
--++HistoricalHistorical
RecentRecent ++++
•• strong adaptive differentiationstrong adaptive differentiation
•• recommendation torecommendation to manage manage the two populationsthe two populations as separate as separate units for conservation purposesunits for conservation purposes
Cicindela puritanaCicindela puritana
It is important to distinguish betweenIt is important to distinguish between
1.1. Gene ConservationGene Conservation
•• the use of genetic information to measure and manage the use of genetic information to measure and manage geneticgenetic diversity for its own sakediversity for its own sake
2.2. Molecular EcologyMolecular Ecology
•• genetic analyses as agenetic analyses as a complement to ecological studies of complement to ecological studies of demographydemography
•• moremore straight forwardstraight forward
•• of more use to wildlifof more use to wildlife e managers faced with shortmanagers faced with short--term managementterm management prioritiespriorities
Conservation GoalsConservation Goals
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
MManaging genetic diversity isanaging genetic diversity is more relevant tomore relevant to
longlong--term planningterm planning
policypolicy
than to than to
shortshort--term management of threatenedterm management of threatened populations populations
few noticeable exceptionsfew noticeable exceptions (e.g.(e.g. translocationstranslocations ) )
Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
mtDNA has been used in this contextmtDNA has been used in this context toto
•• measure genetic variation within populationsmeasure genetic variation within populations,, especially especially ones thought to have declinedones thought to have declined recentlyrecently
•• iidentify evolutionary divergent sets ofdentify evolutionary divergent sets of populations, including populations, including thethe resolution ofresolution of ESUsESUs
•• assess conservation value of populations orassess conservation value of populations or areas from areas from an evolutionary or phylogenetican evolutionary or phylogenetic perspectivperspectivee
Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
mtDNA has been used in this contextmtDNA has been used in this context toto
•• measure genetic variation within populationsmeasure genetic variation within populations,, especially especially ones thought to have declinedones thought to have declined recentlyrecently
oo iidentify evolutionary divergent sets ofdentify evolutionary divergent sets of populations, including populations, including the the resolution ofresolution of ESUsESUs
oo assess conservation value of populations orassess conservation value of populations or areas from areas from an evolutionary or phylogenetican evolutionary or phylogenetic perspectivperspectivee
Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
Genetic Variability within PopulationsGenetic Variability within Populations
AAim of quantifying mtDNA variation withinim of quantifying mtDNA variation within populations populations
•• test for thetest for the loss of genomicloss of genomic variabilityvariability, , generallygenerally as a as a consequence of reductionconsequence of reduction in population sizein population size
conservation significance if the loss ofconservation significance if the loss of variation translates variation translates to reduced individual fitnessto reduced individual fitness
This is aThis is a weak application of mtDNAweak application of mtDNA
lacklack of any theoretical or empirical evidence for aof any theoretical or empirical evidence for a strongstrongcorrelation between mtDNA diversity andcorrelation between mtDNA diversity and diversity in the diversity in the nuclear genomenuclear genome
llow mtDNA diversity is correlated with lowow mtDNA diversity is correlated with low nuclear gene nuclear gene diversity is some case but not othersdiversity is some case but not others
Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
Genetic Variability within PopulationsGenetic Variability within Populations
•• low mtDNA diversity has beenlow mtDNA diversity has been reported in rapidly expanding species reported in rapidly expanding species •• northern elephant seals northern elephant seals •• parthenogenetic gekosparthenogenetic gekos
•• moderate to high mtDNA diversity hasmoderate to high mtDNA diversity has been observed in declining been observed in declining species subjected to intense harvesting or in species otherwise species subjected to intense harvesting or in species otherwise suggestedsuggested to be inbredto be inbred
•• coconut crabscoconut crabs•• humpback whaleshumpback whales
Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
Megaptera novaeangliaeMegaptera novaeangliae
Mirounga angustirostris Mirounga angustirostris
Birgus latroBirgus latro
mtDNA has been used mtDNA has been used toto
measure genetic variation within populationsmeasure genetic variation within populations,, especially especially ones thought to have declinedones thought to have declined recentlyrecently
•• iidentify evolutionary divergent sets ofdentify evolutionary divergent sets of populations, including populations, including thethe resolution ofresolution of ESUsESUs
oo assess conservation value of populations orassess conservation value of populations or areas from areas from an evolutionary or phylogenetican evolutionary or phylogenetic perspectivperspectivee
Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
IIdentification of dentification of eevolutionaryvolutionary distinct populationsdistinct populations
IIdentification of dentification of taxataxa with independentwith independent evolutionary historiesevolutionary histories
•• pprerequisite for managing biodiversity rerequisite for managing biodiversity
•• groupings variously referred to as groupings variously referred to as
•• sspeciespecies
•• ssubspeciesubspecies
•• evolutionary significant units (ESUs)evolutionary significant units (ESUs)
mtDNA phylogeniesmtDNA phylogenies can can
•• provide unique insights intoprovide unique insights into population history population history
•• suggest hypotheses aboutsuggest hypotheses about the boundaries of genetically the boundaries of genetically divergent groups (i.e., cryptic species)divergent groups (i.e., cryptic species)
Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
IIdentification of dentification of eevolutionaryvolutionary distinct populationsdistinct populations
•• mtDNA phylogeniesmtDNA phylogenies must be used in conjunction withmust be used in conjunction withnuclear markersnuclear markers because given thebecause given the
•• lower effective number of geneslower effective number of genes
•• greatergreater dispersal by malesdispersal by males than femalesthan females
mtDNA canmtDNA can diverge while nuclear genes do notdiverge while nuclear genes do not
Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
Recognition of ESUsRecognition of ESUs
CCriteria for defining an ESU remainsriteria for defining an ESU remains to be establishedto be established
SSuggested thresholds rangeuggested thresholds range from from
•• any population that contributes substantiallyany population that contributes substantially to the overall genetic to the overall genetic diversity of the species anddiversity of the species and is reproductively isolatedis reproductively isolated
to to
•• populations showingpopulations showing phylogenetic distinctiveness of alleles acrossphylogenetic distinctiveness of alleles acrossmultiple locimultiple loci
The question that plagues the approach is The question that plagues the approach is
HowHow much difference is enough?much difference is enough?
Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
Recognition of ESUsRecognition of ESUs
HowHow much difference is enough?much difference is enough?
•• no theoretical or empirical justificationno theoretical or empirical justification for setting an for setting an amount of sequence divergenceamount of sequence divergence beyond which a set of beyond which a set of populations is recognized as an ESUpopulations is recognized as an ESU
AlthoughAlthough
•• comparisons to divergences withincomparisons to divergences within an among related species an among related species may provide an empiricalmay provide an empirical yardstickyardstick
Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
[[Evolutionary Significant Evolutionary Significant & M& Management Units]anagement Units]
Recognition of ESUsRecognition of ESUs
QQualitative criterionualitative criterion
avoiding the quantitative question of avoiding the quantitative question of hhow much is enoughow much is enough??
•• to to considerconsider thethe geographic distribution of allelesgeographic distribution of alleles in relationshipin relationshipto theirto their phylogenyphylogeny
gene flow must be restricted for a long periodgene flow must be restricted for a long period to create to create phylogeographicphylogeographic structuring of allelesstructuring of alleles
ESUs shouldESUs should show complete monophyly of mtDNA allelesshow complete monophyly of mtDNA alleles
HoweverHowever
this criterion may bethis criterion may be totooo stringentstringent
well characterized species with paraphyleticwell characterized species with paraphyletic mtDNA mtDNA lineageslineages have been documentedhave been documented
Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
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Recognition of ESUsRecognition of ESUs
Again…Again…
it is important to seekit is important to seek corroborating evidence from nuclear locicorroborating evidence from nuclear loci
Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
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HoweverHowever,, alleles of nuclear genesalleles of nuclear genes are expectedare expected
•• toto take substantially longer to show phylogenetictake substantially longer to show phylogenetic sortingsortingbetween populations or speciesbetween populations or species
larger effective population size larger effective population size
slowerslower neutral mutation rateneutral mutation rate
mtDNA has been used mtDNA has been used toto
measure genetic variation within populationsmeasure genetic variation within populations,, especially especially ones thought to have declinedones thought to have declined recentlyrecently
iidentify evolutionary divergent sets ofdentify evolutionary divergent sets of populations, including populations, including the the resolution ofresolution of ESUsESUs
•• assess conservation value of populations orassess conservation value of populations or areas from areas from an evolutionary or phylogenetican evolutionary or phylogenetic perspectivperspectivee
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Defining evolutionary conservation value ofDefining evolutionary conservation value of populations or areaspopulations or areas
EExtension of the use of mtDNA variation toxtension of the use of mtDNA variation to recognize ESUsrecognize ESUs
•• phylogenetic uniquenessphylogenetic uniqueness should be considered inshould be considered in prioritizing prioritizing species for management species for management
•• define conservationdefine conservation valuevalue taktakinging account of evolutionary account of evolutionary distance distance
particularly well suited to molecular dataparticularly well suited to molecular data
Measuring & ManagingMeasuring & Managing Genetic DiversityGenetic Diversity
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Defining evolutionary conservation value ofDefining evolutionary conservation value of populations or areaspopulations or areas
Then, mThen, movingoving from speciesfrom species toto communitycommunity geneticsgenetics
•• definedefine geographic regionsgeographic regions within whichwithin which multiple species have multiple species have genetically unique populationsgenetically unique populations oror ESUsESUs
•• testing fortesting for congruence ofcongruence of phylogeographic patterns among phylogeographic patterns among speciesspecies to defineto define geographic regions within which ageographic regions within which a substantial substantial proportion of species have had evolutionary historiesproportion of species have had evolutionary historiesseparateseparate from their respective conspecificsfrom their respective conspecifics
•• regions with a high proportion of ESUsregions with a high proportion of ESUs should be accordedshould be accordedhigh conservation priorityhigh conservation priority
•• even if they do not have an array of endemiceven if they do not have an array of endemic species as species as recognized by conventional methodsrecognized by conventional methods
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Defining evolutionary conservation value ofDefining evolutionary conservation value of populations or areaspopulations or areas
‘‘ValueValue’’ skirtsskirts some basicsome basic philosophical and ethical issuesphilosophical and ethical issues……
•• ……wwhat do we mean by thehat do we mean by the SS in Ein ESSU?U?
•• …c…can we justifyan we justify ranking speciesranking species according to a measure of according to a measure of molecular divergence? molecular divergence?
•• wwe can only measure evolutionary significance ore can only measure evolutionary significance or value in terms of value in terms of past historypast history
•• wwe cannote cannot predict which, if any, of thesepredict which, if any, of these units will diversify to units will diversify to produce future biodiversityproduce future biodiversity
•• we must be very clear about the nature of the advice we are we must be very clear about the nature of the advice we are providing when weproviding when we discuss conservation priorities from a moleculardiscuss conservation priorities from a molecularevolutionary perspectiveevolutionary perspective……
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GGeneral area of application eneral area of application that usesthat uses genetics as a tool for ecologistsgenetics as a tool for ecologists
•• to define the appropriate geographic scaleto define the appropriate geographic scale for monitoring for monitoring and managingand managing
•• to provide a means forto provide a means for identifying the originidentifying the origin of individuals in of individuals in migratory speciesmigratory species
•• to test forto test for dramatic changes in populationdramatic changes in population size and size and connectednessconnectedness
In general these applications areIn general these applications are
•• conceptuallyconceptually simpler simpler
•• much moremuch more relevant to shortrelevant to short--termterm management issuesmanagement issues
than are those related to genethan are those related to gene conservationconservation
Molecular EcologyMolecular Ecology
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Defining Management UnitsDefining Management Units or stocksor stocks
SSimple but powerful and practical application ofimple but powerful and practical application of geneticsgenetics
•• aa great deal of effort is spent ongreat deal of effort is spent on monitoringmonitoring populations as part populations as part of the species recoveryof the species recovery processprocess
•• too often, little consideration istoo often, little consideration is given to thegiven to the appropriate appropriate geographic scale forgeographic scale for monitoring or managementmonitoring or management
•• aan exception is withn exception is with fisheriesfisheries, , where it has longwhere it has long been recognized been recognized thatthat species typically consist ofspecies typically consist of
•• multiple stocksmultiple stocks that respond independently tothat respond independently to harvesting and harvesting and managementmanagement
•• populations thatpopulations that exchange so few migrants as to be exchange so few migrants as to be geneticallygenetically distinct will also be demographically distinct will also be demographically independentindependent
Molecular EcologyMolecular Ecology
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Defining Management UnitsDefining Management Units or stocksor stocks
In contrast to ESUsIn contrast to ESUs
•• MUsMUs are defined byare defined by significantsignificant divergence in allele frequenciesdivergence in allele frequenciesregardless of theregardless of the phylogeny of the alleles phylogeny of the alleles
allele frequenciesallele frequencies will respond to population isolation more will respond to population isolation more rapidlyrapidly than phylogenetic patternsthan phylogenetic patterns
mtDNAmtDNA is especially useful for detectingis especially useful for detecting boundariesboundaries between Mbetween MUUss
•• differences betweendifferences between populations will be more readily populations will be more readily detected withdetected with mtDNAmtDNA than with nuclear genesthan with nuclear genes
importantimportant when sample sizes are limited aswhen sample sizes are limited as is often is often the case with threatened speciesthe case with threatened species
•• mtDNA mtDNA it is usuallyit is usually more prone tomore prone to genetic driftgenetic drift than nuclear than nuclear loci loci
aa greater proportion of the variation is distributedgreater proportion of the variation is distributedbetween populationsbetween populations
Molecular EcologyMolecular Ecology
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Identification & Use of Genetic TagsIdentification & Use of Genetic Tags
Useful applicationUseful application of genetics for shortof genetics for short--term managementterm management is tois to provide provide a source ofa source of naturally occurring naturally occurring
•• genetic tagsgenetic tags
genetic variantsgenetic variants that individually or in combination that individually or in combination diagnosediagnose different Mdifferent MUUss
•• iindeliblendelible
•• present in all memberspresent in all members of a population at all agesof a population at all ages
•• can becan be used to determine the source(s) of animalsused to determine the source(s) of animals in in
•• hharvestarvest
•• international commerceinternational commerce
•• areas subjected toareas subjected to impacts or managementimpacts or management
Molecular EcologyMolecular Ecology
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Identification & Use of Genetic TagsIdentification & Use of Genetic Tags
•• particularly useful forparticularly useful for migratorymigratory speciesspecies where where
impacts in one area (e.g., feedingimpacts in one area (e.g., feeding ground) can affect one or ground) can affect one or more distant MUsmore distant MUs
•• most effective where themost effective where the variation within areas is low relative to thatvariation within areas is low relative to thatbetween areasbetween areas
•• maximummaximum likelihood methodslikelihood methods can be used to estimate thecan be used to estimate thecontribution of various MUs to a samplecontribution of various MUs to a sample ofof individuals taken individuals taken from a particular from a particular •• feeding groundfeeding ground•• migratory routemigratory route•• commercial harvestcommercial harvest
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MMigration and changigration and changeses in in population population sizesize
WWildlife managers ildlife managers often face the problem of often face the problem of assessing the degree to assessing the degree to which populations are which populations are
•• connected by migration connected by migration •• changing in sizechanging in size
PPatterns of genetic variationatterns of genetic variation provideprovide•• indirect estimates of indirect estimates of these parametersthese parameters
•• rapid developmentrapid development ofof methodsmethods for using information on for using information on alleleallele distributions and relationshipsdistributions and relationships to inferto infer
longlong--termterm migration ratesmigration ratestrends in trends in NNee
•• significant significant insightinsightss into theinto the longlong--termterm behavior of populationsbehavior of populations•• unclear relevance in unclear relevance in conservation studiesconservation studies ((shortshort--term term
managementmanagement) ) where populations are often fluctuating in where populations are often fluctuating in size and/orsize and/or connectednesconnectednesss
Molecular EcologyMolecular Ecology
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According to the According to the Evolutionary Significant Units (ESUs)Evolutionary Significant Units (ESUs) conceptconcept
•• genetically differentiated populations have a high priority for genetically differentiated populations have a high priority for separate management and conservationseparate management and conservation
•• ESU’s should showESU’s should show
•• significant divergence and significant divergence and reciprocal monophyly for mtDNA reciprocal monophyly for mtDNA allelesalleles
•• significant divergence of allele frequencies at nuclear locisignificant divergence of allele frequencies at nuclear loci
Evolutionary Significant (ESUs)Evolutionary Significant (ESUs)MManagement Unitsanagement Units ((MUs)MUs)
SummarySummarySummary
For the ecological and genetic exchangeability conceptFor the ecological and genetic exchangeability concept
•• populations within a species may justify management as populations within a species may justify management as separate units if they show adaptive genetic differentiationseparate units if they show adaptive genetic differentiation
•• delineation of such population requires information on their delineation of such population requires information on their recent or historical ecological or genetic exchangeabilityrecent or historical ecological or genetic exchangeability
mtDNA has been used mtDNA has been used toto
•• measure genetic variation within populationsmeasure genetic variation within populations
•• iidentify evolutionary divergent sets ofdentify evolutionary divergent sets of populationspopulations
•• assess conservation value of populations orassess conservation value of populations or areas from an areas from an evolutionary or phylogeneticevolutionary or phylogenetic perspectivperspectivee
Evolutionary Significant (ESUs)Evolutionary Significant (ESUs)MManagement Unitsanagement Units ((MUs)MUs)
SummarySummarySummary