AP Biology Unit 7 Introduction to Natural Selection

Which of the following principles is NOT part of Darwin's theory of evolution by natural selection?

Mutations are the ultimate source of genetic variation.

Selective Pressure

any biotic or abiotic factors influencing survivability

Individuals with adaptations have greater (blank)

fitness

Genetic Variation

genetic differences among organisms within a population

Reproductive Success

the production of offspring

Evolution

Change in the genetic makeup of a population over time

What are examples of selective pressure?

Disease, predation, climate, food availability

Which of the following principles are a part of Darwin's theory of evolution by natural selection?

Evolution is a gradual process that occurs over long periods of time. Variation occurs among individuals in a population. More individuals are born than will survive. Individuals that possess the most favorable variations have the best chance of reproducing.

African elephants, Loxodonta africana, are often hunted illegally for their tusks. Both male and female elephants have tusks, although the tusks are much larger in the males. Researchers have followed the elephant population in Gorongosa National Park in Mozambique for many years. Figure 1 shows the percent of tuskless female elephants expected in wild populations throughout the species' range, as well as the percent of tuskless females that survived the hunting between 1977 and 1992 (those over 25 years old) and the percent of female elephants born after 1992 without tusks in the park. The data are based on 200 known female elephants in the park.

Human hunting of elephants with tusks between 1977 and 1992.

The bird, Parus major, is commonly found in man-made habitats. During the summer these birds primarily feed on insects, and in the winter, when insects are scarce, they forage in gardens and bird feeders for seeds, nuts, and berries. Recently, climate change has led to a decrease in food available from gardens, and scientists have observed that the average beak length of the birds has increased. Which of the following best explains the directional shift in beak length in these birds?

Longer beaks allow the birds to better access seeds in bird feeders.

In a stable environment, is a population likely to evolve?

No or the population would evolve very slowly

What does artificial selection result in?

Oftentimes in phenotypic traits not observed in nature that can lead to either more or less genetic diversity

Scientists investigated the role that beak depth plays in the ability of one species of seed-eating finch to reproduce. The scientists calculated the average beak depth of finches in mating pairs and then observed whether or not the pairs produced at least one offspring that survived to the next season. The data are represented in Figure 1.

Parental pairs with a specific beak depth had the highest reproductive fitness

Natural Selection

Process by which organisms, having adaptations suited for a particular environment, have a greater chance of survival and reproduction

What do similar selective pressures lead to?

Similar phenotypic adaptations, such as convergent evolution and analogous structures

Analogous Structures

Similar traits can be observed in distinctly related and unrelated species

What resources do organism compete for?

Space, nutrients, food, mates, and light

Table 1 shows a trend of increasing milk yield for cows. Part of the increase in milk production can be attributed to improved nutrition and health protocols for dairy cows. Based on the information provided, which of the following best describes the source of the rapid increase in milk production from 1976 to 2015 ?

Starting in the 1970s, farmers increased the selective breeding of cows and bulls for offspring that produced more milk.

A current challenge for doctors involves the bacterial strain Clostridioides difficile, which no longer responds to traditional antibiotic treatments. Which of the following best explains why this particular strain of bacteria is resistant to antibiotic treatment?

The bacteria have high genetic variability and high reproductive rates.

Two species of fish that live in extremely cold environments produce near-identical antifreeze glycoproteins, called AFGPs. Scientists have determined the origins of the AFGP gene in both species. Selected characteristics of the two fish species are provided in Table 1. Based on the information in Table 1, which of the following statements best describes the production of nearly identical AFGPs in these two species of fish?

The fish live in environments with similar selective pressures, and those that produce AFGPs are better able to survive.

What does a stable ecosystem determine?

The rate and direction of evolution

What happens to the rate of evolution as an environment becomes unstable?

The rate of evolution would increase

What does variation do?

Variation increases the probability a species will survive under changing environmental conditions

Climate change is disrupting the length of winter in various ecosystems, resulting in less snowfall and milder winters. Scientists in Finland have been observing the tawny owl, a fairly large owl species that is commonly found in woodlands across much of Europe and Asia. Typically, the feathers of the upper body are either brown (BB) or gray (bb). Scientists studying tawny owls in Finland have found that the percentage of tawny owls that have brown feathers has increased over the past 28 years. Which of the following best explains why the brown-feathered phenotype in tawny owls has increased over the past 28 years?

With milder winters, the advantage of gray feathers that blend into a snowy environment has decreased.

Over many years of a breeding program, a zoo has an established population of foxes that is well adapted for living in captivity. A representative sample of wild foxes from the neighboring forest was used to start the zoo population. A study was conducted to compare the behavior of the zoo fox population with the wild fox population in the neighboring forest. The behaviors of equal numbers of foxes from each population were assessed. Each fox's behavior was scored on a continuum from docile to aggressive based on its interaction with a trained behaviorist. The data is shown in Figure 1. The phenotypic variation in behavior between the two populations can best be described as resulting from

artificial selection

competition

organisms that struggle with other organism to get limited resources

Evolutionary fitness is measured by

reproductive success

How is evolutionary fitness measured by?

reproductive success and heritability of adaptations

What are the 5 fingers of evolution?

small or shrinking population, non-random mating (sexual selection), mutations, movement, natural selection (adaptations)

Fitness

the ability of an organism to survive and produce fertile offspring

Heritability

the ability to pass on adaptations to successive generations

Differential Survival

the belief that only the organisms best adapted to existing conditions are able to survive and reproduce

Artificial Selection

the process by which humans select desirable traits in other species and selectively breed individuals with the desired trait

Convergent Evolution

the process by which similar environmental conditions select for similar traits in different populations or species over time

Adaptations

traits that provide an advantage in an environment

Sexual Selection

when individuals (usually females) select mates based on heritable traits