8.1 Microevolution Flashcards

Question

Which source of variation brings more diversity into a gene pool of a sexually reproducing species? Explain.

Answer 1

Sexual Reproduction -In sexually reproducing organisms, variation due to the scrambling of existing alleles, including those that originated as mutations in earlier generations -each offspring receives a new combination of alleles

Answer 2

Mutation -some change an organism’s phenotype -can have an effect on an organism’s fitness in the environment -especially important as a source of variation in ASEXUALLY reproducing organisms that clone themselves rapidly, such as bacteria

Answer 3

Directional selection - By spraying crops with poisons to kill insect pests, humans have favoured the reproduction of insects with inherited resistance to the poisons over those with no resistance. -Most survivors of the first pesticide treatments were insects with genes that somehow enabled them to resist the chemical attack. -Their offspring inherited the genes for pesticide resistance. -In each generation, the percentage of pesticide-resistant individuals in the insect population increased. -The population underwent directional selection. -The alleles that produce higher pesticide resistance increase in the population

Answer 4

stabilizing(centre chosen), directional(one end chosen) and disruptive selection(both ends chosen)

Answer 5

Disruptive selection -takes place when individuals at the upper and lower ends of the range of phenotypes are favoured -may lead to the rise of two distinct phenotypes within a population because 2 phenotypes are favoured by the environment

Answer 6

diversifying selection

Answer 7

Several factors may disrupt Hardy-Weinberg equilibrium, or in other words, cause microevolution. These include natural selection, sexual selection, artificial selection, genetic drift, and gene flow.

Answer 8

Disasters such as earthquakes, floods, droughts, and fires may drastically reduce the size of a population, which also reduces the size of its gene pool

Answer 9

-form of natural selection in which individuals with certain inherited traits are more likely to obtain mates than other individuals. -in sexual selection, other individuals of the same species screen the traits e.g. -in widow birds, females pick males with long tails -male peacocks with elaborate tails evolved because females preferred to reproduce with those males

Answer 10

Peppered Moths -light-coloured peppered moths are better camouflaged against a pristine environment; likewise, dark-coloured peppered moths are better camouflaged against a sooty environment -as the Industrial Revolution progressed, the colour of the moth population shifted from light to dark dark-coloured moths were favoured by the environment

Answer 11

Rabbits -grey and himalayan (grey+white) rabbits are better able to blend with a rocky environment than white rabbits, resulting in diversifying selection grey and himalayan were favoured over white by the environment

Answer 12

Robins -robins typically lay four eggs, larger amounts of eggs may result in malnourished chicks, while smaller amounts of eggs may result in no viable offspring 4 eggs were favoured over any other amount of eggs by the environment

Answer 13

a) lesser frequency of recessive alleles in the population b) disruptive selection because animals need 2 copies of the recessive allele, so the animals will favour animals carrying heterozygous alleles and homozygous dominant alleles.

Answer 14

it would not be maintained because sexual selection disrupts the equilibrium female widow birds favour males with long-tails and would mate with them= sexual selection

Answer 15

yes because this follows the conditions for the equilibrium to be maintained which are: 1. Random Mating 2. Large Population 3. No movement in/out of the population (NO gene flow) 4. No mutations 5. No Natural Selection

Answer 16

no it would not be maintained because genetic drift disrupts the equilibrium -this would be an example of the bottleneck effect and would reduce the size of the polar bear population = eq. disrupted -it needs to be a large population for the equilibrium to be maintained

Answer 17

no it would not be maintained because one of the conditions required for the equilibrium is that there is NO movement in or out of the population and there can't be a small population -it would be disrupted because the rats would get stepped on or killed, which would cause movement out of the population and would reduce the size of their population

Answer 18

sexual selection -the advantage is that the females will be more attracted to those males and will mate with them

Answer 19

effect on original population -decrease in size -less genetic variation -decreased ability of a population to adapt to their environment because of such small numbers effect on founding population -changes allele frequencies due to the genetic makeup of the founders of the colony -more of the new population because there are fewer predators

Answer 20

-in some African populations, it affects about one in 25 individuals, so they are more likely to have the disease -if they have offspring with North Americans, the frequency of the sickle-cell allele will be more frequent in our population because the alleles from the people of African descent will pass to their offspring

Answer 21

Sexual Selection would disrupt Random Mating Genetic Drift would disrupt a Large Population Gene flow would disrupt No movement in/out of the population Artificial Selection would disrupt No mutations Natural Selection would disrupt No Natural Selection

Answer 22

gene flow -when people cut down forests and destroy habitats to build houses, it causes animals to have to migrate to a different place which will cause them to mate with other animals of the same species (interbreeding)