Evolution & Natural Selection

Fish with enlarged pectoral fins were able to glide out of the ocean to escape predators, increasing their fitness.

Fish with larger fins escaped predators more often, so they survived and reproduced more, passing on the trait.

Fish were able to glide out of the ocean and into other bodies of water to mate with other species.: Flying fish don't glide to other bodies of water to mate with other species.

Fish were able to live both on land and in the water as a result of their larger pectoral fins.: These fish don't live on land.

Fish changed their DNA to express enlarged pectoral fins, changing the allele frequency of the population.: Organisms can't change their own DNA on purpose. Selection acts on variation that already exists.

There will be an increase in the number of colorful guppies.

Predators had been selecting against bright colors. With fewer predators, colorful guppies survive and reproduce more, so their number increases.

The mortality rate of the guppies will increase.: With fewer predators, the death rate is more likely to decrease.

Offspring will stop competing for resources.: Moving to a new area doesn't stop competition for resources.

There will be an increase in mutations in the offspring.: Fewer predators don't cause more mutations.

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

Deer are herbivores. Fawns born in spring and summer, when plants are plentiful, are more likely to survive, so this timing was favored by natural selection.

Male and female deer come into contact with each other only in the fall.: Male and female deer come into contact all year.

Large predators are not found in deer habitats during the spring and summer months.: Predators are in deer habitats all year.

Deer give birth in the spring and summer in order to avoid being pregnant during the hot summer months.: Some deer are still pregnant during the summer.

Faster rabbits will survive and reproduce increasing the average speed of the rabbit population.

Faster rabbits are more likely to escape predation, survive, and pass heritable traits to offspring, increasing average speed over generations.

The rabbits will mutate their genes and express genes that increase their speed.: Individuals do not choose to mutate in response to a predator; selection acts on existing variation.

Slower rabbits will develop stronger legs and pass this trait to their offspring.: Acquired muscle development is not the mechanism of natural selection described here.

Rabbits will mate and produce offspring with a different species that has faster runners.: The predator does not cause interspecies mating; it changes which rabbits survive and reproduce.

Food sources that are hard to find

The specialized finger helps the lemur locate and extract hidden insect larvae, so difficult-to-find food is the selective pressure described.

Limited availability of water: The passage describes obtaining insects, not conserving or locating water.

Competing for mates: The adaptation is used for feeding rather than attracting or competing for mates.

Large numbers of natural predators: The finger helps extract food, not escape predators.

beneficial traits passed from parents to offspring

Natural selection increases heritable beneficial traits across generations, producing adaptations such as this color-change response.

selective breeding of lizards by humans: The question describes a natural adaptation, not humans selecting breeding pairs.

geographic isolation that prevented genetic mutation: Isolation does not prevent mutation, and heritable variation is needed for selection.

environmental pollutants that changed their genotype: An adaptation in a population is not produced by pollutants intentionally changing every individual's genotype.

Viceroy butterflies are able to deter predators in the same way as the monarch butterflies.

The resemblance causes predators to avoid viceroys as they avoid bad-tasting monarchs, increasing survival.

Viceroy butterflies are able to reproduce with the monarch butterflies.: Looking similar does not make the two species reproductively compatible.

Viceroy butterflies are able to follow the migratory patterns of the monarch butterflies.: The advantage described is predator avoidance, not migration.

Viceroy butterflies are able to find additional sources of food used by the monarch butterflies.: Similar appearance does not provide access to the monarch's food sources.

The resistant insects are able to survive to reproduce and create a population that is also resistant.

Resistant insects survive pesticide exposure and pass the heritable resistance to offspring, increasing its frequency in the population.

The resistant insects change the toxin on the plants, making it safe for others.: The insects do not chemically change the pesticide on the plants.

The resistant insects grow larger and eat less of the plants.: The pesticide fails because resistance spreads, not because insects eat less.

The resistant insects eat the contaminated surface and leave the rest for others.: Avoiding the toxin is not the heritable mechanism described.

help individuals outcompete other individuals for food resources to increase survival and reproductive success

Hovering and a long tongue improve access to nectar and pollen, increasing feeding success and potential survival and reproduction.

lead to an increase in predation by other species of animals: These feeding adaptations do not exist to increase predation on the bats.

show that most DNA mutations are necessary and advantageous but do not increase survival or reproductive success: Natural selection favors heritable adaptations precisely because they can increase reproductive success.

are the result of intentional breeding: The passage describes natural selection in a wild population, not intentional breeding.

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

With very high juvenile mortality, producing many eggs increases the chance that at least some offspring survive to reproduce.

increase the average body size for surviving individuals to avoid predation: The number of eggs does not directly determine each survivor's body size.

decrease competition between different octopus species to maintain resources in the population: Producing more offspring does not necessarily reduce interspecific competition.

decrease the likelihood of offspring being consumed by predators: The passage states most are preyed upon; the benefit is that enough survive despite that mortality.

The tuna is most closely related to the gray whale because the only difference in the amino acid sequence provided is at amino acid 12.

The gray whale shares every listed amino acid with tuna except the amino acid at position 12. The full response names the gray whale and supports that conclusion with this evidence.

Locations 1 and 6

Locations 1 and 6 are most likely to share a most recent common ancestor with Location 3 because they are in the same nearby geographical region without a separating barrier.

Species T

Species T has three amino acids in the same positions as the unknown species, more than any other species shown.

Species R: Species R has no amino acids in the same positions as the unknown species.

Species S: Species S has only two amino acids in the same positions as the unknown species.

Species U: Species U has only one amino acid in the same position as the unknown species.