KA 3: variation and sexual reproduction: costs and benefits of sexual reproduction Flashcards
name and describe a cost of sexual reproduction
cost: males unable to produce offspring
description: only half of each parent’s genome passed onto offspring, disrupting successful parental genomes
benefits of sexual reproduction outweigh costs due to…
an increase in genetic variation in the population
what does genetic variation provide and what does that do?
the raw material required for adaptation,
giving sexually reproducing organisms a better chance of survival under changing selection pressures
what explains the persistence of sexual reproduction?
the red queen hypothesis
what may select for sexually reproducing hosts?
co-evolutionary interactions between parasites and hosts
hosts better able to resist and tolerate parasitism have…
greater fitness
parasites better able to feed, reproduce and find new hosts have…
greater fitness
what happens is hosts reproduce sexually?
the genetic variability in their offspring reduces the chances that all will be susceptible to infection by parasites
why can asexual reproduction be a successful reproductive strategy?
as whole genomes are passed on from parent to offspring
describe asexual reproduction
just one parent can produce daughter cells and establish a colony of virtually unlimited size over time
when is maintaining the genome of the parent an advantage?
particularly in very narrow, stable niches or when re-colonising disturbed habitats
what is parthenogenesis?
reproduction from a female gamete without fertilisation
give examples of sexual asexual reproduction in eukaryotes?
-vegetative cloning in plants
-parthenogenesis in lower plants
-animals that lack fertilisation
offspring can be reproduced more often and in larger numbers with…
asexual reproduction
where is parthenogenesis more common in and who does this disadvantage?
-cooler climates
-parasites, or regions of low parasite density or diversity
Asexually reproducing populations are not able to adapt easily to changes in their environment but…
mutations can occur that provide some degree of variation and enable some natural selection and evolution to occur
prokaryotes can exchange genetic material…
horizontally
what does horizontal gene transfer result in?
faster evolutionary change than in organisms that only use vertical transfer
Organisms that reproduce principally by asexual reproduction also often have mechanisms for…
horizontal gene transfer between individuals to increase variation
for example:
plasmids of bacteria and yeasts
