Mating Games and Signalling

1. Mating Games and Signalling • Searching vs signalling for mates • Hybrid mating avoidance • Courtship control and persistance • Mechanisms of mate choice • Postcopulation signals

2. Consequences of anisogamy • Males produce large numbers of sperm, and can fertilize many females • Males compete for access to females • Sedentary males compete by sperm competition • Mobile males can either search for females, defend resources, or wait for females to encounter them

3. Male mating strategies

4. Sexual selection and signalling • Mate attraction and courtship signalling is influenced by • The operational sex ratio • The male mating strategy • The relative importance of intrasexual (male-male competition) vs intersexual (female mate choice) selection

5. Mobility game Continuous asymmetric scramble among adults with equal sex ratio. Each adult rotates between mate searching, gamete production, courtship, copulation, parental care, and recovery. Each sex seeks strategy that minimizes its cycle time given partner behavior. Which sex should search and which should signal? Operational sex ratio favors sex with shortest gamete + recovery time.

6. Mate searching patterns Males tend to search Females tend to search when there is resource defense since males are tied to resources Nonsearching sex emits attraction signals Exaggerated signals are given by males due to sexual selection

7. Hybrid mating game Discrete asymmetric scramble Mates encounter and must decide whether or not to mate Offspring viability decreases with level of hybrid incompatibility ESS decision thresholds vary with the ratio of investment in male to female gametes, gm/gf Females become more choosy as their investment relative to a male increases and the sex ratio is male-biased Whether mating and fertilization occurs in the conflict area depends on a male’s ability to force matings and female’s ability to control fertilization after mating.

8. Character displacement in damselflies Expect species specificity of mate attraction signal when females emit the signal since they have more to lose from a hybrid mating

9. Courtship persistence games • Discrete courtship persistence game • ESS1: male persists, female passive, when cost of rejecting is high for female • ESS2: female rejects and male nonpersistent, when cost of persisting is high for male • ESS3: male persists and female rejects: when costs of rejecting and persisting are both low • Sexual arms race • Stable ESS requires variation in arms level • Males typically win given their ability to invest in armaments • Sexual war-of-attrition • Females decide contest duration based on perceived value of male

10. Courtship duration patterns • Females control courtship in male resource defense and self-advertisement systems • courtship is typically prolonged and involves many male display behaviors • e.g. most birds, lekking and paternal care species • Females also control courtship in predatory species, e.g. spiders, preying mantis, lions • Males control courtship in female defense systems • courtship is often short or absent, females may even solicit matings to insure fertility • some insect males mate with females before eclosion • some sea slugs use “love darts”

11. Mechanisms of mate choice • Direct benefits (choice influences mate fecundity or survival) • Indirect benefits (genes passed to offspring) • Fisher’s process - predicts arbitrary traits • Good genes - predicts traits indicate genetic quality • Condition dependent indicator traits • Revealing indicator traits

12. Direct benefits of female preferences for male frequency in Australian frogs

13. Fisher’s Runaway process • If females exhibit preference for a male trait • And selection does not act on females • Then sons and daughters will carry genes for both the preference and the trait • This creates a genetic correlation between preference and trait • And leads to geometric increase until further increase in the male trait is opposed by natural selection

14. The Fisher Runaway process

15. Arbitrary traits

16. Arbitrary traits in zebra finch?

17. Good genes models • Require a mechanism for maintaining heritable variation in offspring viability • Recurrent deleterious mutations • Parasite-host coevolution maintains parasite resistance

18. Peahens prefer males with eyespots which have better offspring survival

19. Female preference for repertoire size in Acrocephalus warblers

20. Condition dependent traits Only males in good condition can make a large investment in a trait which then has less affect on their survival

21. Sage grouse condition and display

22. Revealing trait All males attempt to display the trait and pay the same cost, but the effect of the trait is less in low quality males

23. Barn swallow tail effects

25. Cyrtodiopsis population eyespan allometry Swallow & Wilkinson, in prep

26. 60 100 67 96 100 99 100 100 76 100 100 100 10 changes = average sex ratio Maximum Parsimony Phylogram C. dalmanni C. whitei C. q. Wilkinson et al, in press

27. Sperm development predicts SR

28. Eyespan covaries with sperm development

29. Population variation in bowers

30. Bower evolution

31. Postcopulation signals • Synchronizes orgasm • Humans, gibbons? • Females advertise status to other members of social group • Hammer-headed bats, chimps • Females incite competition among males • Elephant seals • Advertise mate guarding by males • Little brown bats