Question

can you answer
Environmental factors can influence natural selection because they can increase or decrease
the number of chromosomes in an individual.
the number of chromosomes in a population.
the amount of genetic variation in an individual.
the amount of genetic variation in a population.

Which would most likely result in an increase in genetic variation in a population?
an increase in predators and a decrease in food
an increase in predators and an increase in food
a decrease in predators and an increase in food
a decrease in predators and a decrease in food

Genetic drift in a population affects the gene pool in which of the following ways?
decrease in genetic variation
increase in genetic variation
increased in mutations
decreased in gene flow

A population of birds lives on a small island. Another population of the same species lives on the mainland. The distance between the island and the mainland is too great for birds to fly back and forth. Recently, a series of sandbars and tiny islands have formed between the island and the mainland.

What is the most likely effect of this?
an increase in mutations in both bird populations
an increase in gene flow between the bird populations
an increase in genetic drift between the bird populations
an increase in mutations in the island population

Which term best describes the difference in colors of the birds below?

4 birds are shown. One has light brown feathers with darker wings. One has very dark feathers with lighter wings. Another has medium brown feathers with light wings. The last one has medium brown feathers with very dark wings.
natural selection
reproductive maturity
genetic variation
genetic drift

Answer 1

1) the amount of genetic variation in a population.
- Environmental factors change which traits are favored, altering allele frequencies and thus the genetic variation present in a population.

2) a decrease in predators and an increase in food.
- More resources and lower mortality increase population size and allow more genetic variants to persist, maintaining or increasing variation.

3) decrease in genetic variation.
- Genetic drift (random sampling) tends to reduce genetic variation, especially in small populations.

4) an increase in gene flow between the bird populations.
- The new sandbars/islands provide routes for movement, allowing individuals (and alleles) to move between populations.

5) genetic variation.
- The different feather colors among the birds represent variation in heritable traits within the population.