Lecture 9 Flashcards
What is a simultaneous hermaphrodite?
Male and female simultaneously
What is a sequential hermaphrodite
Changing sex throughout life
What are the costs of sexual reproduction?
- Two-fold cost of males (males don’t produce offspring)
- Reproductive assurance (not all individuals may reproduce)
- STDs
- Sex can break up good combinations of alleles
What is haplo-diploidy?
When sex is determined by if the organism if diploid or haploid eg. ants, wasps, bees
What are different determinations for sex?
- Chromosomal
- Haplo-diploidy
- Environment
What is parthenogenesis?
When a female makes eggs that are genetic copies of themselves
3 observations about asexual species
- Most species reproduce sexually
- asexual species are found on the tips of evolutionary trees
- Asexual reproduction does not persist long and has re-evolved many times
What are the advantages of recombination?
- The Red Queen hypothesis
- Clonal interference slows adaptation in asexual populations
- Recombinations prevents deleterious mutations hitchhiking
What is the “red queen” hypothesis?
Changing selection pressures caused by evolving pathogens and preditors alters which combination of alleles are favored
What is an example of the “red queen” hypothesis?
New Zealand mud snails, sexual females have higher fitness than asexual females
What is an example of clonal interference?
SARS-CoV-2 fixing for some combinations of traits but losing some beneficial mutations
What are some examples of recombination’s evolutionary advantages?
- Influenza virus
- X vs Y chromosome in mammals
Why do species usually have a 1:1 ratio?
Individuals of the rarer sex have higher fitness
What is an example of biased sexed ratios?
In fig wasps, at birth females more likely to leave the fig and propagate genes in next generation, males stay in the fig (when mating ratios are closer to 1:1)
