S +

1. IT DEPENDS E E(2) Keep searching for preferred prey, do not consume non-preferred prey > If is small: S S + X P P(2) Selective Diet Pursuers or Handlers – Put their time into pursuit/handling prey. Small changes in, e.g., beak size/shape results in large tradeoffs between P1 and P2 (cannot be simultaneously efficient at handling foods 1 and 2) B/c they have selective diets – diet choice provides a means of reducing or eliminating competition thereby allowing species to coexist Those species coexisting through diet choice often have highly variable feeding appendages from species to species that most efficiently extract and/or handle preferred food

2. How does diet selection provide a mechanism of coexistence?? Tradeoffs between E’s, S’s or P’s such that 2 (or more) species have distinct prey preferences and therefore do not share resources i.e., noresource competition

3. Caracal Serval Cheetah

4. 5 coexisting cats in the Serengeti: Species mass preferred prey prey mass behavior Lion 190 kg wildebeest, zebra 270-690 kg coop. hunting Leopard 65 kg Impala 60 kg stealth Cheetah 50 kg Thompson gazelles 25 kg speed Caracal 20 kg Hyrax, steenbok 5 kg ??? Serval 13 kg birds 100’s g leaping

5. Meet the Handlers…. Obvious differences in morphology, particularly of feeding appendages, between species

6. IT DEPENDS E E(2) Eat what you find - preferred or not Do not pass up an encountered item < If is large: S S + P P(2) Generalist Diet Searchers – Put their time into searching for prey B/c they have general diets they MUST rely on alternative means to reduce/eliminate competition Species converge onto a similar body plan

7. Four species of coexisting warblers

8. 1 item = 10 sec 1 item = 31 sec - There is a preferred habitat 62s - At low density the population is on the preferred habitat 20s - At higher densities the population is a generalist using both habitats 40s 60s 2 2 2 2 3 3 3 3

9. FISH FOOD FISH FOOD FISH FOOD FISH FOOD

10. The Ideal Free Distribution – individuals settle into habitats such that the benefit (i.e., fitness) of each individual is equalized between habitats and no individual can do better by switching to an alternative habitat. It is a NO REGRETS (optimal) strategy e.g. grocery line, line at passport control, cars on a 3-lane highway AND RATS!! http://www.youtube.com/watch?v=sB4dBRI-qBY

11. (-) Density dependence Fitness i.e., growth rate, reproduction, survivorship 1 2 3 4 N (density)

12. 2 habitats Fitness And individuals are free to choose N (density)

13. 2 habitats Fitness And individuals are free to choose N (density)

14. Fitness N (density)

15. Fitness N* N (density) selective generalist

16. Let’s add a second species and assume it prefers habitat B: F2 N*2 N2 F1 N*1 N1

17. Combine the two figures into one N2 We know these two points from the last two figures: the SWITCH POINTS Both A & B N*2 Selective on B N*1 N1 Selective on A Both A & B

18. N2 Become SWITCH LINES Both A & B N*2 Selective on B N*1 N1 Selective on A Both A & B

19. N2 If species have density dependent effects on one another the switching lines will bend away Both A & B N*2 Selective on B N*1 N1 Selective on A Both A & B

20. Sp 1 sel. on A; Sp 2 generalist Each spp is selective on a unique habitat N2 Both A & B Sp 2 sel. on B; Sp 1 generalist NO COMPETITION N*2 Selective on B N*1 N1 Selective on A Both A & B

21. CONCLUSION: Habitat Selection, as is the case for Diet Choice, can result in 2 species having distinct preferences – that is, each species prefers a unique habitat type, thus eliminating competition. As such, habitat selection provides a powerful mechanism of coexistence - one that is widespread throughout nature.

22. Habitat selection among 5 spp of Parulid warblers in a Maine spruce forest

23. 5 cm 10 cm 15 cm And now for the slippery slope..... Is it habitat or diet that separates competitors??

24. Niche separation in the Seabirds