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GARY A. POLISINTRAGUILD PREDATION
Presented by: Maria Vozzo, BIOL 7083
April 16, 2013
Mini-Biography
Education: Ph.D., Biology, UC-Riverside, 1977 M.A., UC-Riverside, 1975 Loyola University, 1969
Professor of Ecology at University of California – Davis 1998-2000
Vanderbilt University 1979-1998 Oregon State University 1977-1979 Drowned in a boating accident in the Sea of
Cortez while on a field expedition in 2000
Gary Allan Polis, 1946-2000
www.news.ucdavis.edu
Field Studies
“The evidence argues that actual community food webs are extraordinarily more complex than those webs cataloged by theorists. I argue that most cataloged webs are over simplified caricatures of actual communities…that they poorly represent real biological communities. Consequently, the practice of abstracting empirical regularities from such catalogs yields an inaccurate and artifactual view of trophic interactions within communities. Contrary to strong assertions by many theorists, patterns from food webs of real communities generally do not support predictions arising from dynamic and graphic models of food-web structure.”
Polis 1991
Research Interests
Scorpions, spiders, desert communities Food web complexity Trophic Cascades Intraguild Predation (IGP)
“The killing and eating of prey species by a predator that also can utilize the resources of those prey”
Competition and predation by species in the system
Polis et al., 1989
Research Interests
Scorpions, spiders, desert communities Food web complexity Trophic Cascades Intraguild Predation (IGP)
“The killing and eating of prey species by a predator that also can utilize the resources of those prey”
Competition and predation by species in the system
Polis et al. 1989
Key papers
Polis, G. A., C. A. Myers and R. D. Holt. 1989. The ecology and evolution of intraguild predation: Potential competitors that eat each other. Annual review of ecology and systematics 20: 297-330.Cited by 1118
Polis, G. A. and R. D. Holt. 1992. Intraguild predation: The dynamics of complex trophic interactions. Trends in Ecology & Evolution 7: 151-154. Cited by 489
Holt, R. D. and G. A. Polis. 1997. A theoretical framework for intraguild predation. The American Naturalist 149: 745-764. Cited by 530
Key Concepts
Omnivory: consuming resources from more than one trophic level
Competition vs. Predation Competition theory: Resource use,
coexistence, exclusion, and alternative stable states among species
Predation theory: How predators and prey persist, predator impacts on prey, oscillations among populations
Polis and Holt 1992
Shared Resource
(Basal prey)
Intr
aguild
Pre
dati
on
Polis et al. 1989
Intermediate Predator
(Intraguild or IG Prey)
Shared Resource
(Basal prey)
Intr
aguild
Pre
dati
on
Polis et al. 1989
Top Predator (Intraguild or IG Predator)
Intermediate Predator
(Intraguild or IG Prey)
Shared Resource
(Basal prey)
Intr
aguild
Pre
dati
on
Polis et al. 1989
Top Predator (Intraguild or IG Predator)
Intermediate Predator
(Intraguild or IG Prey)
Shared Resource
(Basal prey)
Intr
aguild
Pre
dati
on
Polis et al. 1989
Top Predator (Intraguild or IG Predator)
Intermediate Predator
(Intraguild or IG Prey)
Shared Resource
(Basal prey)
PredationIn
traguild
Pre
dati
on
Polis et al. 1989
Top Predator (Intraguild or IG Predator)
Intermediate Predator
(Intraguild or IG Prey)
Shared Resource
(Basal prey)
Predation
Competition
Intr
aguild
Pre
dati
on
Polis et al. 1989
Intraguild Predation
Polis and Holt 1992
Intraguild Predation
Polis and Holt 1992
Predators, Consumers & Resource (no
IGP)
Intraguild Predation
Polis and Holt 1992
Predators, Consumers & Resource (no
IGP)
IGP
Theory
Holt and Polis 1997
Symbol Definition
a’ Functional response of IG predator to resource
α Functional response of IG predator to IG prey
a Functional response of IG prey to resource
m, m’ Density dependent mortality rates
b, b’ Resource consumption IG prey and IG predator reproduction
β IG predator benefit from consuming IG prey
Without IGP
Isocline of predator (species A)Isocline of prey (species B)
Polis et al. 1989
No IGP - A excludes B; IGP enhances A
No IGP - priority effect; IGP - dominance by A
No IGP – B excludes A; IGP – priority effect
No IGP - B excludes A; IGP - coexistence
Competitors coexist with no IGP; IGP A and B
Must species B be a superior competitor in order to exist in IGP?
Without IGP
Isocline of predator (species A)Isocline of prey (species B)
Polis et al. 1989
No IGP - A excludes B; IGP enhances A
No IGP - priority effect; IGP - dominance by A
No IGP – B excludes A; IGP – priority effect
No IGP - B excludes A; IGP - coexistence
Competitors coexist with no IGP; IGP A and B
IGP is ubiquitous in nature
Polis et al. 1989
IGP is ubiquitous in nature
Polis et al. 1989
Community Ecology Implications of IGP
Community structure Exclusion, coexistence, alternative stable
states (Polis et al. 1988, Holt and Polis 1997)
Resource use Superior competitors (Polis et al. 1989)
Direct vs. Indirect effects (Polis and Holt 1992)
Exclude or decrease resources Alter behavioral interactions
Trophic cascades (Polis and Holt 1992)
Predation impacts lower trophic levels
Legacy of IGP: Trophic Cascades
Addition of top predator, suppresses larvae, indirectly benefiting aphids.
Top predator addition can suppress herbivore population
Rosenheim et al. 1993
+
-
Legacy of IGP: Indirect and Direct Effects
Wissinger and McGrady 1993
Legacy of IGP: Indirect and Direct Effects
IG predator presence (Tramea) reduced feeding of IG prey (Erythemis) Indirect effect (behavior) Direct effect (consumption) Wissinger and McGrady
1993
Legacy of IGP
How is IGP influenced by other factors such as habitat structure and complexity?
Janssen et al. 2007
Legacy of IGP: Community Structure, Resource Use, Trophic Cascades, and Indirect & Direct Effects
Research Questions: How does intraguild predation
and habitat structure affect species interactions on an oyster reef? Sheepshead Mud crab-bivalve interaction Resource survival
Consumption or indirect effects?
Oyster Reef Communities
Drastic declines in oyster populations 85% loss worldwide
Oyster reefs provide vital habitat to many species
Common Oyster Reef Residents
SC DNR
Beck et al. 2011
Intraguild Predation
Sheepshead (Archosargus probatocephalus)
Mud crabs
Mussels (Geukensia demissa)
SC DNR
sms.si.edu
Top Predator
Intermediate Predator
Basal Prey
(Panopeus herbstii)
Predator-Prey
Interactions
Trophic Cascades
Holt and Polis 1997, Janssen et al. 2007
IGP and Oyster reef complexity
Sheepshead
Mud crabs
Mussels
SC DNR
sms.si.edu
Top Predator
Intermediate
Predator
Basal Prey
−
+
Low Structure Reef
-
-
-+
High Structure Reef
Sheepshead Mu
d crabs
Mussels
SC DNR
sms.si.edu
Top Predator
Intermediate
Predator
Basal Prey
−
+ +-
-
-
behavioral effectconsumptive effectindirect effects
Vozzo et al. 2012, presentation
IGP and Community Ecology
Community structure Resource use Direct vs. Indirect effects Trophic cascades
“…intraguild predation is a ubiquitous and often powerful interaction central to the
structure and functioning of many natural communities; closer attention to it will
enrich our understanding of population and community ecology.” Polis et al.
1989
Questions?
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Thank you!
Citations
Click icon to add pictureBeck, M. W. et al. 2011. Oyster reefs at risk and recommendations for conservation, restoration, and management. BioScience 61: 107-116. Grawbowski, J. 2004. Habitat complexity disrupts predator-prey interactions but not the trophic cascade on oyster reefs. Ecology 85: 995-1004. Janssen, A. et al. 2007. Habitat structure affects intraguild predation. Ecology 88: 2713-2719. Holt, R. D. and G. A. Polis. 1997. A theoretical framework for intraguild predation. The American Naturalist 149: 745-764. Polis, G. A. 1991. Complex-trophic interactions in deserts: an empirical critique of food-web theory. The American Naturalist 138: 123-155. Polis, G. A., C. A. Myers and R. D. Holt. 1989. The ecology and evolution of intraguild predation: Potential competitors that eat each other. Annual review of ecology and systematics 20: 297-330.Polis, G. A. and R. D. Holt. 1992. Intraguild predation: The dynamics of complex trophic interactions. Trends in Ecology & Evolution 7: 151-154. Rosenheim, J. A., L. R. Wilhoit and C. A. Armer. 1993. Influence of intraguild predation among generalist insect predators on the suppression of an herbivore population. Oecologia 96:439-449. Saxon, Wolfgang. “Gary Allan Polis, 53, an Expert On Scorpions and Desert Ecology”. The New York Times. 01 April 2000. 20 February 2013. < http://www.nytimes.com/2000/04/01/us/gary-allan-polis-53-an-expert-on-scorpions-and-desert-ecology.html>. Wissinger, S. and J. McGrady. 1993. Intraguild predation and competition between larval dragonflies: direct and indirect effects on shared prey. Ecology 74:207-218.
