Sexual Selections Learning Materials

University:
The University Of Western Ontario
Course:
Biology 2290F | Scientific Method in Biology
Academic year:

2022
Views:

480

Pages:

3
Author:

Kyuwon J.

Sex ● Allows to make new multilocus combination ● Adds in genetic variations Dioecious vs Monoecious ● Dioecious ○ Each individual is male and female ● Monoecious ○ Each individuals could be either male and female ○ Simultaneous ■ Both sexes at the same time (certain flowers) ○ Sequential monoecy ■ Born one sex ■ Change during its life time from certain threshold ■ clownfish Asexual Reproduction ● Identical offspring ○ Parthenogenesis ○ Binary fission ● Not all reproduction involves sex ○ Diploid eggs gets activated to produce clones Size advantage Model ● Choose when it is more advantageous to be one sex over the other ○ Protandry ■ Male to female ■ After certain threshold one sex is more advantageous then other sex Protogyny ■ Female to male Cost and benefits of sexual reproductions ● Costs ○ Mating is risky ○ Time consuming ○ Only female grow population (not always) ○ Half of my allele are passed on ○ Sexual selection may favour certain traits ■ Does not have to do with survival ■ But increases mating success rate ■ Reproduction is very costly ● Benefits ○ Muller’s Ratchet principle ■ Get rid of harmful allele ○ Lottery Principle ■ More sex in unstable environment = more chance that some of the offspring will survive ○ Red Queen principle ■ Evolutionary Arms race ■ Genotype that can survive is always created ■ Sex favored in environment with lots of parasites Sexual selection ● Intrasexual vs Intersexual selection ○ Competition for mating vs attracting mates ● Parental investments ○ Which sex choose mate ○ Which sex competes to be chosen ○ Low investing sex has to compete for access ■ Mating with high invested sex ● High invested sex ○ Produce few large eggs (limited reproductive opp ○ Invest in gestation (longer pregnancy) ○ Only reproduce in once per breeding season ● Low investing sex ○ Produce abundant small sperm ○ No parental care ○ Intensely access for female ex) Dominant male tends to fight to control females Deers= male fight for access to females during the rutting season ● If both parents are equally investing= there are sexual selection for both sexes Differentiation of selection forces ● Male access to females ● Female gamete time and effort should be present Potential vs Relative fitness ● Both sexes must have equal relative fitness for sexual selection ● Male have higher potential fitness ○ Females choose best male to increase their own fitness ■ To pass on their own allele to the next generation Choosy? ● Direct benefits ○ Attractive mates have good parents ● Indirect benefits ○ Attractive mates must have good allele ○ Pass it onto offspring ■ Sexy sons hypothesis