3 & 4: Adaptation and Speciation Flashcards
Asexual Reproduction
offspring derive from a single parent (clonal reproduction)
Sexual reproduction
two parents contribute genetic information to offspring
Two fold cost of sex
asexual organisms can multiply faster than sexual organisms
Additional costs of sex
requiring finding an appropriate mate, parents are less related to their own offspring, risk of contracting sexually transmitted disease
Recombination
formation of new allelic combination in offspring. Occurs during meiosis like crossing between homologous chromosomes,
Mullers Ratchet
Asexual:
1. The entire genome is passed along as a unit between generations
2. Deleterious mutations accumulate
3. Accumulation of deleterious mutations results in ever increasing genetic lead.
Advantages of Sexual Repro
- combining favorable mutations more quickly, independent mutations can be brought together in recombinant offspring
- Faster adaptation in evolutionary arms race
- allows for faster adaption than asexual reproduction, through genetic diversity
Sexual Selection
- form of natural selection that results from differences among individuals in their ability to mate or fertilize eggs
- Individuals that possess traits that help them to reproduce will be favored by sexual selection.
Sexual Dimorphism
a phenotypic difference between the males and females of a population/.
Anisogamy
when gametes are dissimilar Eggs tend to be larger than sperm, which means that females might need to have a different life history strategy than males to account for the energy spent on producing eggs
Internal Fertilization
Sex differences in certainty of parentage
Selection favors investment in offspring when parentage is more certain (females)
Operational Sex Ratio
ratio of males to females available for reproducing at any given time, determines how strong sexual selection is
Male biased operational sex ratio
Males: invest in fertilizing eggs , more males than females will not be able to mate at all
Females: not limited by the ability to mate; invest in choosing good mates; producing high quality eggs and provisioning offspring
Female biased operational sex ratio
Females: invest in attracting more males
Males: not limited in the ability to mate; invest in choosing high quality mates, offspring care,
Prediction of sexual selection
Members of teh sex under stronger sexual selection will compete: Mating competition
Members of tyhe sex under weaker sexual selection will be choosier: mate choice