Disentangling the Web of Life

Jordi Bascompte(2009), Science 425:416-419

A summary of:

Incorporating network theory in Ecological Studies◦ Review◦ Benefits

Examine interaction patterns vs. species composition

Overview

Paper Overview Entangled Bank Biodiversity Architecture

◦ Architecture of Biodiversity◦ Architecture Influences Robustness◦ Architecture Influences Network Size◦ Beyond Species Interactions

Conclusion

Outline

“In the case of every species, many different checks,

acting at different periods of life, and during different seasons or years, probably come into

play; …When we look at the plants and bushes clothing an entangled bank, we are tempted to attribute

their proportional numbers and kinds to what we call chance. But how false a view is this!”

The Entangled Bank

http://www.fossilmuseum.net/Evolution/Darwin.htm

Paper Overview Entangled Bank Biodiversity Architecture

◦ Architecture of Biodiversity◦ Architecture Influences Robustness◦ Architecture Influences Network Size◦ Beyond Species Interactions

Conclusion

Outline

Definition:◦ the diversity of plant and animal life in a

particular habitat (or in the world as a whole); "a high level of biodiversity is desirable“

Value:◦ At the ecosystem level, biodiversity provides the

conditions and drives the processes that sustain the global economy – and our very survival as a species

Biodiversity

wordnetweb.princeton.edu/perl/webw

Past Studies:◦ Count species, not their interactions◦ Assume homogeneous interactions

Need:◦ Incorporate network theory

Biodiversity

Paper Overview Entangled Bank Biodiversity Architecture

◦ Architecture of Biodiversity◦ Architecture Influences Robustness◦ Architecture Influences Network Size◦ Beyond Species Interactions

Conclusion

Outline

Food Webs = Trophic interactions◦ Predator/Prey/Herbivore/Plant

Architecture of Biodiversity

cmore.soest.hawaii.edu

Food Webs = Trophic interactions◦ Mutualism (pollinations/seed dispersal)

Architecture of Biodiversity

Architecture of Biodiversity

Montoya, J, S L Pimm, R V Sole (2006) Ecological Networks and their fragility. Nature, 442:doi:10.1038/nature04927

Architecture of Biodiversity

Montoya, J, S L Pimm, R V Sole (2006) Ecological Networks and their fragility. Nature, 442:doi:10.1038/nature04927

22.11/0.013-

k/3.998-

k P(k)

lawpower truncatedPle P(k)

lexponentiaAn

ke

55.42/0.2822-

1.512-

k P(k)

lawpower truncatedPlk P(k)

lawpower An

ke

k/8.861-e P(k)

lexponentia

Paper Overview Entangled Bank Biodiversity Architecture

◦ Architecture of Biodiversity◦ Architecture Influences Robustness◦ Architecture Influences Network Size◦ Beyond Species Interactions

Conclusion

Outline

Biodiversity Threats◦ species extinctions,◦ habitat loss◦ anthropogenic influence

Coextinction avalanches◦ phylogenetically similar species◦ trophically unique species

Architecture Influences Robustness

Architecture Influences Robustness

Rezende, E, J E Lavabre, P R Guimeraes, P Jordano, J Bascompte (2007) Non-random coextinctions in phylogenetically structures in multualistic networks. Nature, 448:925-928.

Architecture Influences Robustness

Petchey, O, A Eklof, C Borrvall and B Ebenman (2008)Trophically Unique Species Are Vulnerable to Cascading Extinction. The American Naturalist, 171:569-579

Architecture Influences Robustness

Trophic ModulesNetwork Motifs

Paper Overview Entangled Bank Biodiversity Architecture

◦ Architecture of Biodiversity◦ Architecture Influences Robustness◦ Architecture Influences Network Size◦ Beyond Species Interactions

Conclusion

Outline

Size: Number of species that can be supported by a network◦ example

Architecture Influences Network Size

Challenges linking architecture & function◦ population dynamics network topology ◦ multiple interaction types◦ species invasions, climate change, and other

challenges

Architecture Influences Network Size

Paper Overview Entangled Bank Biodiversity Architecture

◦ Architecture of Biodiversity◦ Architecture Influences Robustness◦ Architecture Influences Network Size◦ Beyond Species Interactions

Conclusion

Outline

Other types of ecological networks◦ Habitat Fragments

Beyond Species Interactions

Other types of ecological networks◦ Genetic variation in space

Beyond Species Interactions

Paper Overview Entangled Bank Biodiversity Architecture

◦ Architecture of Biodiversity◦ Architecture Influences Robustness◦ Architecture Influences Network Size◦ Beyond Species Interactions

Conclusion

Outline

Networks useful descriptors of ecological systems

Conclusion

Assessment of perturbations/predictions

Enable heterogeneous studies Show generalities among disparate systems

Thanks