what is genetic load?
- Genetic load is the burden imposed by the accumulation of deleterious mutations
What is female choice, why and when does it occur?
Female choice is when the female chooses the male she wants to mate with. It occurs because the female puts the most energy into reproduction. By choosing the best/strongest mate she gets direct benefits such as food, nest sites, protection, spermatophores, help raising the young and reduced risk. She also receives indirect benefits that affect the genetic quality of the female’s offspring
What is runaway sexual selection?
- Runaway sexual selection occurs when there is a heritable variation in a trait that affects the ability to obtain mates, then variants conductive to success will become more common overtime. Called a runaway mechanism because it can only be stopped when a sexually selected trait starts to become a serious threat to male’s survival.
When does sexual selection acts on females?
- Sexual selection acts on females when the male provides all of the offspring care. In this case, the females will evolve ornaments, be larger and more aggressive than males.
When does sexual selection acts on males?
Sexual selection acts on males when the female provides most of the offspring care. The female will often choose the largest, strongest male so the traits are passed down to their offspring
is sexual selection stronger on females or on males?
sexual selection is typically stronger on males
When can natural and sexual selection collide?
- When Natural selection and sexual selection collide, something has to give. When sexual selection is strong, natural selection has to work to overcome the sexual selection to allow an individual to survive. On the otherhand, if natural selection is too strong, sexual selection has to work so the individuals are able to attract mates and produce more offspring.
Why is female choice common, but male choice rare?
- Female choice is common because they invest more into raising offspring. In males, the certainty of paternity is low because the female may mate with other males as well. Since the female knows the offspring is hers, she will invest the time to raise and care for it. On the other hand, the males benefit by mating with many different females to ensure the production of some offspring.
What is sperm competition and what are examples?
- Sperm competition is a form of sexual selection that arises after mating when males compete for fertilization of a female egg. For example, seed beetles have sharp spines on their penises. If the female has already mated with another male, the spines allow the male to remove sperm from the earlier male. The longer the spines, the more likely the male will be to fertilize the eggs Additionally, primates have evolved larger testicles to place large amounts of sperm in a female’s reproductive tract. Lastly, in deer mice, the sperm will join together so it can swim faster to fertilize the egg first.
Define sexual conflict
Sexual conflict is the evolution of phenotypic characteristics that confer a fitness benefit to one sex, but a fitness cost to another.
What are alternative male mating strategies and why do they exist?
- An alternative male mating strategy is mating with a single female, trying to fight off other males and helping to raise the offspring. This prevents the males from competing for females to mate with and the chance their sperm will not be used after mating.
What is the concept of the sneaker male?
- A sneaker male is a male that pretends to be a female. During the courtship process of a territorial male, the sneaker male interrupts and tries to mate with the female.
When is male competition and combat expected?
male competition is expected when the 2 males vying for the female are of about the same size/physical ability
paternal investment
the energy and time expended in both constructing and caring for an offspring
reproduction
the formation of new individual organisms
hermaphrodites
individuals that produce both female and male gametes
twofold cost of sex
asexual lineages multiply faster than sexual lineages because all progeny are capable of producing offspring. in sexual lineages, half of the offspring are males who cannot themselves produce offspring. this effectively haves the rate or replication of sexual species.
muller’s ratchet
the process by which the genomes of an asexual population accumulate deleterious mutations in an irreversible manner
red queen effect
for coevolving populations, to maintain relative witness, each population must constantly adapt to each other. term is used to refer to the biological arms race such as those between parasites and their host
anisogamy
sexual reproduction involving the fusion of 2 dissimilar gametes, individuals producing larger gametes are defined as females and the individual producing the smaller gamete as male
fecundity
the reproductive capacity of an individual such as the number or quality of egg or sperm. as measures of relative fitness, fecundity refers to the number of offspring produced by an organism
certainty of paternity
the probability that a male is the genetic sire of the offspring his mate produces
operational sex ratio (OSR)
the ratio of male to female individuals who are available for reproducing at any given time
sexual selection
differential reproductive success resulting from the competition for fertilization, which can occur through competition among the same sex or through attraction of the opposite sex
