Checking Your Understanding: Speciation

Front

Primary cause of speciation

Back

Reproductive isolation

Answer explanation

While it is the predominant way we classify species, this is only based on the biological definition of speciation.

Front

Definition of speciation relating any two species over time

Back

Phylogenetic Speciation

Answer explanation

Because phylogenetic looks at species who have a common ancestor, you could theoretically trace back all species to a common unicellular species.

Front

Geographic separation of squirrels

Back

Formation of the Grand Canyon

Answer explanation

The correct choice explains that the Grand Canyon geographically separated members of a single squirrel species, leading to the development of two similar species on either side due to isolation and evolutionary divergence.

Front

Speciation type for similar squirrels in Grand Canyon

Back

Allopatric

Answer explanation

Allopatric speciation occurs when populations are geographically separated, leading to the development of distinct species. The squirrels on opposite sides of the Grand Canyon likely evolved separately due to this geographic barrier.

Front

Population divided by a new river

Back

Allopatric Speciation

Answer explanation

When a population is divided by a physical barrier, like a river, it leads to Allopatric Speciation. This process occurs as the separated groups evolve independently, potentially resulting in the formation of new species.

Front

Speciation type of apple maggot flies

Back

Sympatric - not separated by location

Answer explanation

This is an example of sympatric speciation because the apple maggot flies are not separated by location. They have diverged into two groups based on their host fruit preferences, leading to reproductive isolation despite living in the same area.

Front

Speciation requires:

Back

Isolation

Answer explanation

In speciation, isolation is crucial as it prevents gene flow between populations, allowing them to evolve independently. This can lead to the development of new species over time, making isolation the key factor in the speciation process.

Front

Postzygotic barrier example

Back

Hybrid offspring are sterile

Answer explanation

Hybrid offspring being sterile is a postzygotic barrier because it occurs after fertilization, preventing the hybrid from reproducing. The other options are prezygotic barriers, which prevent mating or fertilization.

Front

Prezygotic barrier example

Back

Different mating calls of frog species

Answer explanation

A prezygotic barrier prevents mating or fertilization between species. The different mating calls of the two frog species prevent them from recognizing each other as potential mates, thus serving as a prezygotic barrier.

Front

Reproductive barrier in male damselfly mating

Back

Mechanical isolation

Answer explanation

The reproductive barrier described is mechanical isolation, as it refers to the physical differences in genitalia that prevent certain males from mating with females whose genitalia do not fit.