Transcript Sex - Brian O`Meara

Sex
© BBC 2001, distributed under license from BBC Worldwide Limited |, downloaded from http://dsc.discovery.com/convergence/beasts/photo/slide_05.html
Brian O’Meara
EEB464 Fall 2016
What can lead to increased
diversification rate?
A: Increased Speciation
B: Decreased Extinction
C: Neither
D: Both A and B
Learning objectives
Why is sex weird?
Why has it evolved?
How does sex ratio evolve?
How does sexual selection evolve?
Sex
No Sex
Two-fold cost
Two-fold cost
Sex
No Sex
Half
mother’s
genes
All
mother’s
genes
Groups with parthenogenetic species
Cnemidophorus inornatus, C. neomexicanus, C. tigris
Stick insects
Many plants
Aphids
Lizards
Bees
etc...
Alistair J. Cullum
Sex
No sex
Wikimedia commons
Muller’s ratchet
http://www.youtube.com/watch?v=KjH9MwulnV0
Muller’s ratchet
Muller’s ratchet
♥
♥
Jokela et al. The maintenance of sex, clonal dynamics, and host-parasite
coevolution in a mixed population of sexual and asexual snails. The American
Naturalist (2009) vol. 174 (S1) pp. 43-53
Mean (±SE) proportion of sexual snails (male %) in the shallow-habitat zone of
Lake Alexandrina (black) and mean (±SE) prevalence of infection by Microphallus
sp. (gray) between 1994 and 2005. Proportion of males corresponds closely to
proportion of asexual females and can be used as a surrogate of frequency of
sexuals in the population (Jokela et al. 2003).
Jokela et al. The maintenance of sex, clonal dynamics, and host-parasite
coevolution in a mixed population of sexual and asexual snails. The American
Naturalist (2009) vol. 174 (S1) pp. 43-53
http://www.youtube.com/watch?v=hHdaEbcIOSM
Even sex ratio
What is expected fitness of each of these?
Jordal et al. Extraordinary sex ratios and the evolution of male neoteny in sib-mating Ozopemon beetles. Biol J Linn Soc (2002) vol. 75 (3) pp. 353-360
Sexual selection
Male-male competition
http://www.youtube.com/watch?v=DU4xW79ASsg
Female choice
http://www.youtube.com/watch?v=GPbWJPsBPdA
http://www.youtube.com/watch?v=Wz9h-5z60Xc
Ryan 1990
Andersson and Iwasa. Sexual selection. Trends Ecol Evol (1996) vol. 11 (2) pp. 53-58