Effects of habitat complexity on intraguild predation and

Effects of habitat complexity on intraguild predation and cannibalism in an assemblage of size -structured predators Shannon Carter Baylor University Class of 2014 Patrick Crumrine, Ph. D Rowan University Dept. of Biology © Peter J. Bryant June 4, 2013 http: //bugguide. net/node/view/233847

Community interactions typically depicted in a food web • Fails to account for size structure • No cannibalism • Neglects many intraguild predation relationships http: //ohs-bio. www 1. 50 megs. com/ch 47/Food%20 Web. jpg

Complex community interactions between three species • Generalist Predators • Feed on anything smaller than themselves • Promotes IGP and cannibalism • Still a simplification

Intraguild Predation • Mix of competition and predation • Mathematical models predict it should be rare (Holt and Polis, 1997) • Common in aquatic, terrestrial, and marine communities • What facilitates this interaction that is not accounted for in the models?

Habitat Complexity • All natural interactions occur across a continuum of habitat complexity • How do IGP and cannibalism change across this continuum? – Predator-prey interactions have been shown to shift in either direction www. savecalifishing. org www. allfreedownload. com/cattails_beside_pond

Study Organisms Cybister fimbriolatus • • • Predaceous Diving Beetle Top Predator 3 instars Active predator Mechanical hunter Anax junius • • • Green darner dragonfly Intermediate Predator 13 instars Sit-and-wait predator Visual hunter

Study System • Red arrows represent predator combinations • Size-structured cannibalism • Intraguild Predation • Set up across high and low habitat complexity

Experimental Design Treatment Grouping 1 Grouping 2 Grouping 3 Grouping 4 Grouping 5 Grouping 6 Large High C. fimbriolatus Habitat Large Small Complexity A. junius C. fimbriolatus Large A. junius Small A. junius Large Small A. junius C. fimbriolatus Small C. fimbriolatus A. junius Large Low Habitat C. fimbriolatus Large Small Complexity A. junius C. fimbriolatus Large A. junius Small A. junius Large Small A. junius C. fimbriolatus Small C. fimbriolatus A. junius 1 predator of each type and standardized 10 shared prey per treatment

Methods • Response variables – Survival – Headwidth • Statistical analysis – ANOVA for prey survival – G-tests for predator survival

Question 1: Does habitat complexity affect the frequency of cannibalism and IGP among A. junius and C. fimbriolatus?

Question 2 Do A. junius and C. fimbriolatus respond similarly to changes in habitat complexity?

Question 3 Will the introduction of habitat complexity allow A. junius to become a more effective predator on C. fimbriolatus?

Question 4 Could habitat complexity facilitate coexistence between A. junius and C. fimbriolatus?

Significance • Results will elucidate complex predator-prey interactions and could show community’s vulnerability to changes in habitat structure • Application in agricultural biocontrol and wildlife conservation http: //www. nwf. org/news-and-magazines/nationalwildlife/animals/2005/good-bugs-gone-bad Animals. nationalgeographic. com/coyote

Projected Timetable • June 3 rd- June 23 rd: Identify collection sites, filtered water to tank, prepare mesocosms with stems • June 24 th-July 21 st: Trials begin. 3 temporal blocks, 2 replicates each, following this weekly schedule: Monday Collect Tuesday Wednesday Thursday Friday Collect/setup Begin observation Continue observation Complete observation, tear down • July 21 st- Data collection complete, begin analysis and writing • July 30 th- Project presentation

Questions?