Ch05 competing for resource
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1. The document discusses several examples of competition between individuals or groups over resources such as food, mates, and territory. 2. Key concepts discussed include evolutionary stable strategies, the hawk-dove game, ideal free distribution of resources among competitors, producers and scroungers strategies, and alternative mating strategies involving different morphs or behaviors. 3. Alternative strategies can be maintained in a population at an equilibrium, and in some cases strategies may cycle over time, as seen in examples of side-blotched lizards and ruffs.
Ch05 competing for resource
- 2. Evolutionaryily Stable Strategy(ESS) ݻ (Smith & Price, 1973) A strategy that was adopted by all members of a population, cannot be bettered by alternative strategy. ESS 2
- 3. The Hawk-Dove game Each strategy does best when it is relatively rare. 3
- 4. The stable mixture V<C h = the proportion of Hawks in population H average= -25h + 50 (1-h) D average= 0 h + 25 (1-h) h = 1/2 In V<C ? V/C (the stable proportion of Hawks) If V>C, then Hawk is an ESS! 4
- 5. Competition by exploitation : the ideal free distribution The ideal free model ģ (Fretwell, 1972) YԴSėa ߵr£wڅ 춸^ٵĵYԴء Fig. 5.1 The ideal free distribution. 5
- 6. Which line will you choose? 6
- 7. Competition by exploitation : the ideal free distribution Competing for food: sticklebacks and ducks 7
- 8. Competing for food: sticklebacks (Milinski, 1979) 8
- 10. Competing for food: Ducks (Harper, 1982) N=33 10
- 11. Fish and Ducks settle in a stable distribution between feeding patches. Numerical prediction ֵAy Equal intake prediction zȡAy Prey risk prediction CLUAy 11
- 12. Competing for mates: dung flies What is the optimum time to spend waiting for females at each cowpat? 12
- 13. Fig. 5.3 ţSϵۼSω SrgӶp ڲͬĵȴrg ۼSωĽɹʽһ Males adopt evolutionarily stable waiting times. (Parker, 1970) 13
- 14. Competition by resource defence : the despotic distribution Mķց Fig. 5.4 (Brown, 1969) 14
- 15. The ideal free distribution with unequal competitors 2:1 The Competitive unit model (Parker & Sutherland, 1986) Hypothesis: the number of competitive units , rather than the number of individual, is equalized across patches. 8:4 8:4 Fig. 5.5 15
- 16. Habitat Selection in Gill aphid (Whitham, 1978) ~Ƭe խ~ ÿbxӴ ֳɹڲͬ ĸ߽ԟo@ Fig. 5.6 ÿƬ~ϵĴx 16
- 17. Leaf is not a homogeneous habitat. Average success is equal on leaves of different quality, but individuals near the leaf base do better. 17
- 18. The economics of resource defence Economic defendability ĿɷR (Brown, 1964) Fig. 5.7 18
- 19. Box 5.1 The Economics of territory defence in the Golden-Winged sunbird (Gill & Wolf, 1975) Metabolic costs Forage time Net energy saving of defending Extra cost of defence 19
- 20. The economics of resource defence Shared resource defence YԴĹͬR With satellite NO satellite With satellite Fig. 5.8 20
- 21. Producers and scroungers acͶC Fig. 5.9 Make the best of a bad job. 21
- 22. The variable foraging techniques of ruddy turnstone (Whitfield, 1990) Routing expose prey Hammering barnacles Stone turning Surface pecking Digging Probing 22
- 24. Variation could also be maintained in a population even if there was no difference in competitive ability between individuals. 24
- 25. The stable equilibrium frequency of producers and scroungers Covered (Mottley & Giraldeau, 2000) Uncovered pridected stable equilibrium 25
- 26. Alternative mating strategies and tactics Ľcg Strategy A genetically based decision rule, so differences between strategies are due to differences in gene. Tactic A behaviour pattern played as part of a strategy. 26
- 27. Conditional strategies with alternative tactics Natterjack toads: callers & satellites (Arak, 1983) ɱ callers satellites Fig. 5.11 27
- 28. Satellite males make adaptive choice concerning which callers to parasitize. Fig. 5.12 28
- 29. Morphological switches with body size: dung beetles and earwigs Fig. 13 29
- 30. Fig. 5.14 30
- 31. The threshold morphological switch between alternative within a conditional strategy. (Gross, 1996) (Hunt & Smon, 2001) ֵ Fig. 5.15 31
- 32. Use selection experiment shows : Threshold has a genetic basis (Emlen, 1996) Fig. 5.16 32
- 33. forceps How selection has shifted a threshold switch in morphology (Tomkins & Brown, 2004) Knoxes Reef Bass Rock B K K B (22uϵĽY) Forcept׃LܱoԽ 33
- 34. Alternative strategies: equilibria and cycles ƽcѭh Fitness fig.5.9 (b) Proportion of scroungers 34
- 35. Ruffs: fighters, satellites and female mimics 35
- 36. A marine isopod with three male morphs alpha beta gamma Each male morph gains equal success. 36
- 37. Side-blotched lizards: cycles of orange, blue and yellow 37
- 38. Thanks for your Listening 38