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

24. To address these questions we have used stalk-eyed flies in the genus Cyrtodiopsis. In some species, such as this Cyrtodiopsis whitei, a male’s eye span can exceed his body length.
Males use eye span to assess body size during head-to-head contests. When two males of similar size encounter one another, ritualized fights result in which forelegs are extended and one male attempts to dislodge the other by grabbing him.
Winners of a contest control access to nocturnal aggregation sites on rootlets which attract from 1 to 25 females at dusk. Females prefer to roost with long eye span males. In the morning, one male mates with as many of these females as possible. We have observed up to 24 copulations in 30 minutes in the field.

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

26. C. dalmanni C. whitei C. q. Maximum Parsimony Phylogram
10 changes
100 96 99 76 60 67
Maximum Parsimony Phylogram
= average sex ratio
C. dalmanni
C. whitei
The red lines summarize the results of Kruskal Wallis one-way ANOVAs and indicate that the sex ratio distributions differ between species, but not between populations of each species.
Comparison the progeny sex ratio which would be expected if a female mated at random shows drive is absent in CQ, present but relatively weak in each of the four CD populations, and similarly strong in the two populations of CW.
We developed a phylogenetic hypothesis for these populations using about 1 kb of mtDNA sequence which we obtained from 5 individuals in each population. The high bootstrap values indicate that these populations have been genetically isolated for some time. Thus, X chromosome drive appears to be conserved over short evolutionary time scales as expected if it is maintained in a stable polymorphism.
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