The Evolution of Dilution Andrew PaitselAllen Patton

Co-evolutionary Arms Race Predator/Prey Survival AdaptionsFaster prey = faster predatorsBetter eyesight = better camoflauge

Other Survival Adaptations-Warning calls-Mobbing behaviors-Traveling in herds (Dilution Effect)

Questions to AddressWhat is the Dilution Effect?What are the advantages/disadvantages?What species has practiced this trait?

What is the Selfish Herd theory?How does it affect the population?

What other ways do animals behave due to predation?

Dilution Effectthe assumption that everyone has an equal chance of survival while in large groups due to the fact that no individual is being singled out by a predator.

Advantages More eyes watching out for predatorsPredator not being able to choose the easiest preyPrey species spend more time foraging instead of scanning for predators

The frequency of scans as a result of relative dangerBednekoff et al, 1998.

DisadvantagesMore likely to be seen by predatorsMore competition over resourcesMore competition over mate selection

Examples

Stotting

StottingAlarm signal hypothesisSocial cohesion hypothesisConfusion effect hypothesisPursuit deterrence hypothesis

Disadvantages of StottingTime Cost

Energy Cost

Survivorship Cost

The Selfish HerdCompetition for safer positioning within the herd. Middle position has overall higher survival probability that individuals on the outer partsIncreasing your overall fitness at the expense of others

Future ResearchDetermine if traveling in herds is a learned or genetic traitLook into how predators counteract the Dilution EffectIs stotting a learned or inherited trait

Continue to evolve until someone gets the upper hand

ReferencesAlcock J. 2005. Animal Behavior: An Evolutionary Approach. Sinauer Associates, Inc. 8:176-199Bednekoff P.A., Lima S.L. 1998 Re-examining safety in numbers: interactions between risk dilution and collective detection depend upon predator targeting behaviour. The Royal Society. 265:2021-2026Caro T.M. 1986. The Functions of Stotting in Thomsons Gazelles: some tests of the predictions. Animal Behaviour. 34(3):663-684Caro T.M. 1985. Functions of Stotting. Animal Behaviour. 34(3):649-661Cresswell W., Jakobsson S., Kaby U., Lind J., Quinn J.L. 2003. Animal Behaviour. 66:643-648Garay J. 2008 Cooperation in defence against a predator. Journal of Theoretical Biology 257:45-51

References Cont.Pictureshttp://static.howstuffworks.com/gif/gazelle-body-language-1.jpghttp://www.teameveresttravel.com/main/images/stories//InternationalVacations/gallery-africa/Day3/Herds_Maasai_Mara.jpghttp://images.google.com/imgres?imgurl=http://www.travelphotos.in/thumbs/lrg-106-img_3500_cheetah_brothers.jpg&imgrefurl=http://www.serengeti.in/index.php%3Fcat%3D102&usg=__-6gpONj-zFPa-tqP3oSTLkZk2s0=&h=459&w=400&sz=76&hl=en&start=28&tbnid=ltIijJbwd6BUDM:&tbnh=128&tbnw=112&prev=/images%3Fq%3DCheetah%2Bvs.%2Bherd%26gbv%3D2%26ndsp%3D18%26hl%3Den%26sa%3DN%26start%3D18http://images.google.com/imgres?imgurl=http://scienceblogs.com/clock/upload/2006/06/zebra%2520lion.jpeg&imgrefurl=http://scienceblogs.com/clock/2006/06/bio101_lecture_7_physiology_co_1.php&usg=__4u3AfFA8W3wSxJwtO7X3est7kng=&h=323&w=448&sz=102&hl=en&start=2&tbnid=XCMpf2ZkAhcQLM:&tbnh=92&tbnw=127&prev=/images%3Fq%3DZebra%26gbv%3D2%26hl%3Denhttp://images.google.com/imgres?imgurl=http://lh4.ggpht.com/_ntEIaR868hs/RpwQkCU_I0I/AAAAAAAAA3w/nN0Qbe1dr3o/Africa-227.JPG&imgrefurl=http://picasaweb.google.com/lh/photo/O9qg8k9BUkfv5fxiJgZY6g&usg=__qmMBImFnwIvSowsez5V1Ayeaaig=&h=1068&w=1600&sz=11&hl=en&start=3&tbnid=CbmEpymRX0P63M:&tbnh=100&tbnw=150&prev=/images%3Fq%3DWildabeest%2Bherd%26gbv%3D2%26hl%3Den

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