TEKS B.7(D) - Natural Selection in Action

White-tailed deer are seasonal breeders. female white-tailed deer begin their reproductive cycle in the fall. Rising testosterone levels in male white-tailed deer cause them to start their breeding season around the same time. Offspring are born the following spring and summer.

What is the most likely explanation for white-tailed deer having a seasonal breeding cycle instead of a monthly breeding cycle like many domesticated animals?

• Male and female deer come into contact with each other only in the fall.

• Large predators are not found in deer habitats during the spring and summer months.

• Giving birth only in the spring and summer ensures that offspring are born when food is most available.

• Deer give birth in the spring and summer in order to avoid being pregnant during the hot summer months.

The green frog (Liithobathes clamitans clamitans) is found in many parts of the United States. The table contains some information about this frog.

Why does the ability to lay 1,000 to 5, 000 eggs increase the fitness of the species L. clamitans clamitans?

• It increases opportunities for offspring to compete for limited resources.

• It increases the probability that some offspring will survive long enough to reproduce.

• It increases the probability that moving water will promote gene flow from one population to another.

• It increases the chance of the recombination of alleles, leading to genetic drift in the population.

​ ​ (a)   is essential for natural selection to result in a new species.

• An inherited variation
• Unlimited resources
• A static environment
• A long life span

The giant octopus lays 20,000 to 100,000 fertilized eggs. After hatching, most octopuses become prey to larger marine organisms, and less than 5% will reach adulthood to reproduce.

One benefit of the giant octopus laying many eggs is to —

• increase the average body size for surviving individuals to avoid predation

• decrease competition between different octopus species to maintain resources in the population

• increase the chance that more individuals will survive to maintain the population

• decrease the likelihood of offspring being consumed by predators

This dichotomous key can be used to identify some conifers.

Based on the key, which of these best describes the leaves and cones of the longleaf pine?

• cones are small and needles are sharp at the end

• cones are large and needles are in groups of 2 or more

• Cones are large and needles are single and sharp at the ends

• Cones are large and needles are single and rounded at the ends