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The Evolution of Dilution

The Evolution of Dilution. Andrew Paitsel Allen Patton. Co-evolutionary Arms Race. Predator/Prey Survival Adaptions Faster prey = faster predators Better eyesight = better camoflauge Other Survival Adaptations - Warning calls - Mobbing behaviors - Traveling in herds (Dilution Effect).

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The Evolution of Dilution

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  1. The Evolution of Dilution Andrew Paitsel Allen Patton

  2. Co-evolutionary Arms Race • Predator/Prey Survival Adaptions • Faster prey = faster predators • Better eyesight = better camoflauge • Other Survival Adaptations - Warning calls - Mobbing behaviors - Traveling in herds (Dilution Effect)

  3. Questions to Address • What 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?

  4. Dilution Effect • the 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.

  5. Advantages • More eyes watching out for predators • Predator not being able to choose the easiest prey • Prey species spend more time foraging instead of scanning for predators

  6. The frequency of scans as a result of relative danger Bednekoff et al, 1998.

  7. Disadvantages • More likely to be seen by predators • More competition over resources • More competition over mate selection

  8. Examples

  9. Stotting

  10. Stotting • Alarm signal hypothesis • Social cohesion hypothesis • Confusion effect hypothesis • Pursuit deterrence hypothesis

  11. Disadvantages of Stotting • Time Cost • Energy Cost • Survivorship Cost

  12. The Selfish Herd • Competition for safer positioning within the herd. • Middle position has overall higher survival probability that individuals on the outer parts • Increasing your overall fitness at the expense of others

  13. Future Research • Determine if traveling in herds is a learned or genetic trait • Look into how predators counteract the Dilution Effect • Is stotting a learned or inherited trait

  14. Continue to evolve until someone gets the upper hand

  15. References • Alcock J. 2005. Animal Behavior: An Evolutionary Approach. Sinauer Associates, Inc. 8:176-199 • Bednekoff 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- 2026 • Caro T.M. 1986. The Functions of Stotting in Thomson’s Gazelles: some tests of the predictions. Animal Behaviour. 34(3):663-684 • Caro T.M. 1985. Functions of Stotting. Animal Behaviour. 34(3):649-661 • Cresswell W., Jakobsson S., Kaby U., Lind J., Quinn J.L. 2003. Animal Behaviour. 66:643-648 • Garay J. 2008 Cooperation in defence against a predator. Journal of Theoretical Biology 257:45-51

  16. References Cont. Pictures • http://static.howstuffworks.com/gif/gazelle-body-language-1.jpg • http://www.teameveresttravel.com/main/images/stories//InternationalVa cations/gallery-africa/Day3/Herds_Maasai_Mara.jpg • http://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%3D18 • http://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%3Den • http://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 • http://pro.corbis.com/images/CB012940.jpg?size=572&uid=%7B001FD655-525A-4DFD-8B6A-8C548047F4D5%7D

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