Evolution & Environmental Change

Speciation is the process by which new species are formed. Which of the following circumstances is most likely to lead to speciation?

A population becomes separated by environmental factors into two groups that do not reproduce with one another

Directions: Select the correct locations in the diagram. The diagram below represents four species of invertebrates as they progress through three stages of embryonic development. Select the two species that are likely to be the most closely related by evolution.

Section A and B

Comparative biochemistry is the study of similarities and differences in _______ among organisms.

DNA sequences

Place the following events in chronological order to show how speciation can occur.

Different populations of the same species become geographically isolated from one another. The separated populations adapt independently to their new environments in response to different selective pressures. Over time, the divided populations accumulate enough difference in their genetic material that they are no longer able to successfully breed with one another.

Severe flooding in an area caused a population of minnows to become split into two separate ponds. Prior to the separation, the male minnows all had a moderate number of spots. Following the separation, the first pond was filled with larger fish that fed on minnows, so male minnows with fewer spots were better able to avoid detection by predators. The minnows in the second pond, however, had very few predators, and female minnows in this pond preferred to mate with males that had the most spots. After many generations, the two minnow populations evolved into different species and could no longer interbreed. Which of the following best describes why the two minnow populations evolved into separate species?

Different selective pressures were acting upon the two populations, leading to an increase in genetic variation and the formation of two new species

The phylogenetic tree below shows the evolutionary relationships among several organisms. Arrange three organisms in the correct order to show the phylogenetic history of a chicken.

Early Vertebrate Early Bird Chicken

The phylogenetic tree below shows the evolutionary relationships among several organisms. Arrange three organisms in the correct order to show the phylogenetic history of a field mouse.

Early Vertebrate Early Mammal Field Mouse

As a fundamental concept of biological science, evolution is supported by multiple forms of observable evidence. Which of the following supports the theory of evolution?

Fossil records, comparative anatomy, comparative embryology, biochemistry.

A population of mammals originally lived in a certain area surrounded by land. Then, some of the organisms were taken to an island. These two populations remained separated for hundreds of years. Which of the following is most likely true of the organisms within the populations?

The organisms on the island are slightly different than those on the mainland.

Nearly all mammals have seven cervical (neck) vertebrae. This fact implies that

all mammals descended from a common ancestor.

Speciation is the process by which new species

are formed.

Many thousands of years ago, more than one species of cheetah roamed the Earth. About 10,000 years ago, however, climate changes led to the extinction of all but one species - Acinonyx jubatus. This rapid extinction led to extensive inbreeding within this species' population.Acinonyx jubatus is still alive today, but its population is rapidly decreasing. One factor that is linked to the cheetah's population decline is its lack of genetic diversity, which was caused by the extensive inbreeding 10,000 years ago. In fact, on average, two individual cheetahs will share over 99% of their genetic material. The lack of genetic variation among individuals of the species Acinonyx jubatus is most likely linked to its sharp decline in population because this causes the species

to be unable to adjust to sudden environmental changes.

Speciation occurs during the evolutionary development, or phylogeny, of a species. In which of the following situations can speciation occur?

when two populations are reproductively isolated

New species of organisms may emerge if

1. naturally occurring selective pressures favor new traits. 2. humans create new environmental conditions.

The following data table summarizes the number of differences in amino acid sequences for a protein found in four different species. Based on the data table, which two species are most closely related?

species B and species C

Which of the following statements provides support for Darwin's theory of evolution?

1. Over time, populations of insects can develop resistance to an insecticide. 2. The 4-million-year-old fossil named "Lucy" belonged to an animal that walked upright like a human but had a smaller, chimpanzee-like brain. 3. The mapping of the human genome shows that humans share more than 98% of their genes with chimpanzees.

Select each correct answer. More than one answer may be correct. Which of the following statements describes how the characteristics of different species of mammals reflect the evolutionary relationships among those species?

1. Similarities in the DNA and protein structures of mammal species suggest that these species evolved from a common ancestor. 2. Shared anatomy among mammals, such as hair and mammary glands, suggests that a common ancestral species had these features.

Directions: Select the correct entries in the table. The nucleotide sequences of four species are shown in the table below. Select the nucleotide sequences of the two species that are most closely related.

B and C

Which of the following facts implies that humans and fish had a common ancestor?

Both species have gill slits when they are embryos.

The amino acid sequence of a certain blood protein was compared among four organisms. The percentage match shared by two organisms can be found at the intersection of each row and column in the table below. Based on the information in the table, which two organisms have the most recent common ancestor?

C and B

Fur seals and sea lions have similar body shapes and features. Based on their anatomy, they seem to have a relatively recent common evolutionary ancestor. What further evidence would best substantiate that the two animals have a recent common ancestor?

The animals have very similar sequences in their DNA

After the last major ice age, sea levels around the world rose. As they did, the rising waters divided what was once a single island in the North Sea into two different islands. A population of rabbits was split between the two islands. Ten thousand years passed with no contact between the two rabbit groups. In recent times, a scientist attempted to breed individuals from the two groups, but he was unsuccessful in doing so. Why were rabbits from the two groups unable to produce offspring together?

The groups had evolved into separate species.

The diagram below shows four animal species at different stages of development. Which of the following statements is supported by the diagram?

There are similarities in the developmental stages of different species in the animal kingdom.

Which of the following best describes why scientists often study embryonic structures when determining evolutionary relationships?

There are sometimes similarities in the embryonic stages of organisms that do not exist in the adult stages.

The fossil record shows that the forelimbs of cats, dolphins, and bats have the same skeletal elements. These skeletal elements have evolved into different shapes and sizes based on their function. For example, the flipper of a dolphin is adapted for swimming and the wing of a bat is adapted for flying. What do the similarities between the skeletal structures of these three species most likely indicate about their evolutionary history?

These three species are distantly related and share a common ancestor

What does it mean to say that two different species of organisms are closely related?

They have a common evolutionary ancestor.

The study of structural differences and similarities among living things is called _______.

comparative anatomy

The study of embryological similarities and differences among species is called _______.

comparative embryology

What is the most likely consequence if a group of living organisms is unable to adapt to changing conditions within the Earth system?

extinction

An earthquake creates a chasm that separates a population of squirrels. The two populations of squirrels evolve into two separate species. What is the name of the process by which isolated populations of the same species become new species?

speciation

Directions: Select the correct location on the diagram. A cladogram is a branching diagram that represents suggested evolutionary relationships among organisms based on the presence of unique traits. A scientist discovers a new organism that lacks limbs and does not have a true backbone. The organism lays eggs to produce offspring and has a cartilage-like rod known as a notochord running along its dorsal surface. On the cladogram below, select the species to which the newly discovered organism is most closely related.

lamprey