Which phenomenon would a biologist describe as microevolution?

Under the biological species concept, a species is a group of organisms that

The biological species concept is

Under the biological species concept, the gap between species is maintained by reproductive isolation.

The phylogenetic species concept defines a species as a set of organisms that shares a common ancestor and forms one branch on the tree of life.

The morphological species concept relies upon comparing the DNA sequences of organisms.

The ecological species concept identifies species in terms of their ecological niches.

Two populations of organisms belong to the same biological species when they

A pair of species could interbreed but one species mates at dusk and the other at dawn. Which type of reproductive barrier separates these two species?

A pair of insect species could interbreed but one lives on goldenrod plants and the other on autumn daisies in the same general area. Which type of reproductive barrier separates these two species?

A pair of moth species can interbreed but the females' mating pheromones are not attractive to the males of the other species. Which type of reproductive barrier separates these two species?

Two flowering plant species could interbreed but one has a deep flower tube and is pollinated by bumblebees whereas the other has a short, narrow flower tube and is pollinated by honeybees. Which type of reproductive barrier separates these two species?

Which type of reproductive barrier separates two species of sea cucumbers whose sperm and eggs often bump into each other but do not cross-fertilize because of incompatible proteins on their surfaces?

Two species that occasionally mate and produce zygotes, but that have incompatible genes that prevent the resulting embryo from developing, are affected by

Two species interbreed occasionally and produce vigorous, fertile hybrids. When the hybrids breed with each other or with either parent species, however, the offspring are feeble or sterile. These species are affected by

Frequently, a group of related species will each have a unique courtship ritual that must be performed correctly for both partners to be willing to mate. Such a ritual constitutes a ________ and ________ reproductive barrier.

The Monterey pine and the Bishop's pine inhabit some of the same areas of central California. The Monterey pine releases pollen in February, while the Bishop's pine does so in April. This is an example of ________ isolation.

The geographic isolation of a population from other members of the species and the subsequent evolution of reproductive barriers between it and the parent species describes ________ speciation.

Uplift and formation of a mountain range divide a freshwater snail species into two isolated populations. Erosion eventually lowers the mountain range and brings the two populations together again, but when they mate, the resulting hybrids all produce sterile young. This scenario is an example of

Diane Dodd raised different fruit fly populations on different food sources. She found that after about 40 generations the evolution of reproductive isolation was under way. Diane Dodd's experiments using fruit flies demonstrated that

Speciation without geographic isolation is called ________ speciation.

Most polyploid species arise from

Sympatric speciation commonly occurs through ________ in plants but is more likely to occur through ________ in animals.

The Galápagos finch species differ in their feeding habitats.

The evolution of the Galápagos finches is an excellent example of adaptive radiation.

Most speciation events of the Galápagos finches occurred when some finches made it to another island, evolved in isolation, and accumulated enough changes to become a new species.

Each island in the Galápagos chain has one and only one isolated, unique species of Darwin's finch.

What would tend to promote adaptive radiation?

A group of ants escaped from a picnic basket carried to the top of a mountain and thrived in this area where there were no other ants. Many years later descendants of these ants crawled into a picnic basket on the mountain and traveled back to the valley from which their ancestors had come. Which of these observations would cause you to conclude that the ants on top of the mountain had become a different species from those in the valley?

Two bird species overlap in a hybrid zone. They are isolated by a slight difference in the male songs and by the females' tendency to select males with the "correct" song. Hybrid offspring tend to have reduced fertility compared to either of the parent species. What effect might natural selection have in this situation?

In a hybrid zone, ________ can occur if the reproductive barrier between two species is weak, as seen among cichlids in the murky waters of modern Lake Victoria.

The ________ suggests that speciation occurs in brief spurts.

Which description best represents the gradual model of speciation?

Speciation has become complete when

Allopatric speciation is unlikely to occur when

Speciation often occurs when a habitat becomes more heterogeneous. In Lake Victoria different species of cichlids are found in different areas of the lake. The best explanation for this speciation is that

A new plant species may arise in a single generation by

For speciation to occur there must be

In a population of plants with a diploid number of 12, a new individual appeared with a chromosome number of 24. If this organism could self-fertilize, forming offspring with the same number of chromosomes (24), scientists would consider this an example of

Which butterfly has changed gradually but significantly from its ancestor through microevolutionary events that were not part of a speciation event?

If the divergence illustrated here is based on some female insects preferring large males and others preferring small males, then this would be an example of 

These data collected from the finches studied by the Grants show that

Which of these is the best hypothesis about what led to the change seen in the data?

The data in this graph indicate

In the North Pacific Ocean, two groups of the same species of killer whales (Orcinus orca) appear to be forming two different species based on what they eat. One group eats fish and the other eats mammals such as seals. Scientists can tell what they eat based on their teeth, because whales that feed on fish have significantly different wear patterns.

Which procedure would be the least useful to perform in determining whether or not this speciation has occurred?

In the North Pacific Ocean, two groups of the same species of killer whales (Orcinus orca) appear to be forming two different species based on what they eat. One group eats fish and the other eats mammals such as seals. Scientists can tell what they eat based on their teeth, because whales that feed on fish have significantly different wear patterns.

Which type of speciation is occurring in these whales?

In the North Pacific Ocean, two groups of the same species of killer whales (Orcinus orca) appear to be forming two different species based on what they eat. One group eats fish and the other eats mammals such as seals. Scientists can tell what they eat based on their teeth, because whales that feed on fish have significantly different wear patterns.

Another difference between the two groups is in how they hunt. Whales that hunt fish tend to travel in large pods (groups of whales) and vocalize often. Whales that hunt seals, however, tend to travel in very small groups and vocalize very little, likely because of the excellent hearing ability of seals. If these differences brought about speciation, the separation would be considered