18.3 The Process of Speciation

What is a species?

• A group of organisms that can mate with each other and produce fertile offspring. 

• A group of organisms that genetically are very different from each other. 

• A group of organisms that can mate and produce offspring even if those offspring are infertile.

• Indivual organisms that live in the same environment. 

Answer explanation

A species is a group of organisms that can mate with each other and produce fertile offspring.

In the Great Lakes region of North America, gray wolves and coyotes are similar species but do not mate because their breeding periods occur at different times of the year.

• Geographic isolation

• Behavioral isolation

• Temporal isolation

Answer explanation

Gray wolves and coyotes do not mate due to temporal isolation, as their breeding periods occur at different times of the year.

The females of two species of fruit fly, Drosophila melanogaster and Drosophila simulans release slightly different mating hormones called pheromones, which are used to attract male mates.

• Geographic isolation

• Behavioral isolation

• Temporal isolation

Answer explanation

The correct choice is 'Behavioral isolation'. Females of Drosophila melanogaster and Drosophila simulans release different pheromones to attract male mates.

A type of isolation in which two populations become separated by a physical barrier such as a canyon, river, lake, preventing the two populations from interbreeding.

• Geographic isolation

• Behavioral isolation

• Temporal isolation

Answer explanation

Geographic isolation is a type of isolation where two populations are separated by a physical barrier, such as a canyon or river, preventing interbreeding.

A type of isolation in which two populations with complex courtship displays or rituals become different enough that they no longer respond to the other’s actions.

• Geographic isolation

• Behavioral isolation

• Temporal isolation

Answer explanation

Behavioral isolation is a type of isolation where populations with complex courtship displays or rituals become different enough to no longer respond to each other's actions.

The American toad (Anaxyrus americanus) and Fowler's toad (Bufo fowleri) live in the same area. However, The American toad mates in early summer while Fowler’s mates in late summer.

• Geographic isolation

• Behavioral isolation

• Temporal isolation

Answer explanation

The American toad and Fowler's toad live in the same area but mate at different times. This is an example of temporal isolation, where their mating times are different, preventing interbreeding.

A population of chimpanzees was separated when the forest that they lived in had a section cut down and a town was built. After a long period of time, the chimpanzees came back into contact but were incapable of breeding. Which of the following best describes the process that occurred?

• adaptation

• speciation

• convergent selection

• stabilizing selection

Answer explanation

The process that occurred is speciation, where the population of chimpanzees became incapable of breeding after being separated and coming back into contact.

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Which of the following must occur for speciation to happen?

• geographic isolation

• reproductive isolation

• temporal isolation

• behavioral isolation

Answer explanation

Reproductive isolation is necessary for speciation to occur. It prevents gene flow between populations, leading to the formation of new species.

Gentoo penguins will present a mate with a pebble that they find to attract a mate. Emperor penguins have a specific call and movement that they make to attract a mate. Which type of isolation do these penguins demonstrate?

• temporal isolation 

• behavioral isolation

• geographical isolation

• anatomical isolation

Answer explanation

Gentoo and Emperor penguins demonstrate behavioral isolation, where they use specific behaviors to attract mates.

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What is speciation?

• The change from one species into two or more distinct species. 

• The movement of a group of organisms into a new area. 

• The ability to mate and reproduce.

• The death of an entire species. 

Answer explanation

Speciation is the process of one species evolving into two or more distinct species.

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