12 Flashcards
Which is slower, sexual or asexual reproduction?
Sexual
Costs of sexual reproduction? 3*
*Finding an appropriate mate
*Parents are less related to their own offspring (r = 0.5 for parents and r = 1 for clonal individuals)
*Risk of contracting sexually-transmitted disease
How common is sexual reproduction?
Over 99% of eukaryotes reproduce sexually.
Why is sexual reproduction is so common?
Recombination: the formation of new allelic combinations in offspring. It occurs during meiosis via crossing over between homologous chromosome. Also other kinds of genetic exchange.
Costs of asexual reproduction?
Muller’s Ratchet:
Entire genome is passed along as a unit between generation. Deleterious mutations can accumulate, and this accumulation result in ever-increasing genetic load.
Genetic load?
Reduction of selective value in a population compared to what the population would have if they all have the best genotypes.
Muller’s Ratchet in sexual lineages? 4*
*The same basic process of accumulation of deleterious mutations occur.
*When two individuals mate, recombination can happen
*Recombination allows unfavourable mutations to be purged by natural selection
*By chance, some offspring will have none or few deleterious mutations, while others may have many.
Weeding out bad mutations from a population
Does sexual or asexual reproduction achieve favourable genotypes faster?
Sexual reproduction
In asexual reproduction, why does favourable genotypes evolve slower?
Mutations occur sequentially within that lineage.
In sexual reproduction, why does favourable genotypes evolve faster?
Not only does mutations occur sequentially, but they also occur between sex.
What type of reproduction is faster in adaptation in evolutionary arms race?
Sexual reproduction
The red queen effect?
the outcome of an evolutionary arms race between parasites and hosts. They evolve genetic adaptations that give them a competitive advantage, at least briefly.
Sexual reproduction is strongly favoured by selection in organisms that are or not highly parasitized?
Highly
Populations with more males are more or less likely to be parasitized?
More
Why are there more parasites when male density is higher?
Sexual reproduction is favoured by selection in populations with high parasitism.
Sexual reproduction is the fusion of how many gametes?
Two
Simultaneous Hermaphrodites?
Individuals have both male and female gametes, and can use either in a sexual encounter.
Sequential hermaphrodites?
Undergo one-way transition from males to females, or females to males.
Anisogamy?
When gametes are dissimilar.
How can anisogamy lead to differing life-history traits between males and females?
Since eggs tends to be larger than sperm, females may need to acquire different life-history traits to account with the more energy spent on producing eggs.
Because of anisogamy, when internal fertilization happens, it usually occurs in males or females?
Usually in females.
Sex differences and internal fertilization happening in a certain sex can lead to?
Certainty of parentage, the sex with internal fertilization can be certain that they are the genetic parent of their offspring.
Selection favours greater or lesser investment in offspring when parentage is more certain?
Greater
Operational sex ratio (OSR)?
Ratio of males to females available for reproducing at any given time. it determines how strong sexual selection is.
Biased OSR?
When there tends to be a greater density of a sex compared to another.
A more biased OSR can lead to?
higher variances in reproductive success. Sex dependent
Higher densities of a sex available to mate can lead to higher or lower variances in reproductive success for that sex?
Higher
Higher variances in reproductive success lead to stronger or weaker sexual selection?
stronger
Male-biased operational sex ratio leads to?
Invest in fertilizing eggs (many more males than females will not able to mate at all). Females are not limited by the ability to mate, producing high-quality eggs and provisioning offspring.
Female-biased operational sex ratio?
Females invest in attracting mates (more females will not be able to mate). Males are not limited in the ability to mate, invest in choosing high quality mates, offspring care.
Sexual selection will be stronger in mating systems where the variance in reproductive success is?
higher
Sexual selection is stronger/weaker in monogamous organisms?
Weaker.
Members under stronger sexual selection tends to be more?
Competitive
Members under weak sexual selection tend to be?
Choosier
Post-copulatory mating competition?
Competition for mating after mating.
Sperm competition?
Sperm from several different males compete for binding to eggs after copulations
Strategies for males facing sperm competition?
*Produce a lot of sperm
*Remove sperm that are already there
*Prevent the next male’s sperm from getting in.
Mate choice direct benefits?
*Territories or nests
*Help raising young
*Food
*Protection from other males
*Reduced disease/parasite risk
Mate choies indirect benefits?
*Good genes
*Arbitrary choice
*Combination models
Cryptic female choice?
Females of many species can store sperm, and can influence which sperm fertilize her eggs.
In hermaphrodite species, how does mate selection work?
The male or female role depending on the relative costs and benefits.
Sexual conflict?
When the interests of mating partners or potential partners are opposed
Antagonistic coevolution?
Known as an evolutionary arms race.
Cannibalism?
Females typically eats the males.
