3. costs and benefits of sexual and asexual reproduction

Question 1

costs of sexual reproduction

Answer 1

• males unable to produce offspring;
• only half of each parent’s genome passed onto offspring, disrupting successful parental genomes

Question 2

why do the benefits outweigh costs?

Answer 2

Benefits outweigh costs due to an increase in genetic variation in the population

Question 3

what does genetic variation provide?

Answer 3

Genetic variation provides the raw material required for adaptation, giving sexually reproducing organisms a better chance of survival under changing selection pressures

Question 4

what selects for sexually reproducing hosts?

Answer 4

Co-evolutionary interactions between parasites and hosts may select for sexually reproducing hosts

Question 5

what can asexual reproduction be?

Answer 5

Asexual reproduction can be a successful reproductive strategy as whole genomes are passed on from parent to offspring

Question 6

what happens if hosts reproduce sexually?

Answer 6

If hosts reproduce sexually, the genetic variability in their offspring reduces the chances that all will be susceptible to infection by parasites

Question 7

why is maintaining the genome of the parent an advantage?

Answer 7

Maintaining the genome of the parent is an advantage particularly in very narrow, stable niches or when re-colonising disturbed habitats

Question 8

what is an example of asexual reproduction?

Answer 8

Vegetative cloning in plants and parthenogenesis in lower plants and animals that lack fertilisation are examples of asexual reproduction in eukaryotes

Question 9

what happens with asexual reproduction?

Answer 9

Offspring can be reproduced more often and in larger numbers with asexual reproduction

Question 10

what can’t asexually reproducing population do?

Answer 10

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

Question 10

what is more common in cooler climates?

Answer 10

Parthenogenesis is more common in cooler climates, which are disadvantageous to parasites, or regions of low parasite density or diversity

Question 11

what do organisms that reproduce by asexual reproduction have?

Answer 11

Organisms that reproduce principally by asexual reproduction also often have mechanisms for horizontal gene transfer between individuals to increase variation, for example the plasmids of bacteria and yeasts