Terms in this set (46)
The model that assumes that evolution proceeds with slow successive change in a given evolutionary line is referred to as ?
The type of separation that results in the formation of separate species as a result of geographic isolation is called _____ speciation.
When species are kept separate by preventing the formation of hybrid zygotes, the mechanism that keep the species separate is known as ____ isolating mechanism.
A type of isolating mechanism that leads to reproductive isolation after a hybrid zygote has formed is called a ______ isolating mechanism.
Which isolating mechanism is postzygotic?
Evolution acts at the level of the
Hybridization regularly occurs between three species of Darwin's finches on Daphne Major, but the finches are still considered different species because?
They occupy different niches
According to the Biological Species Concept, two groups of organisms that are unable to form fertile, viable hybrids are considered to be different ?
In 1938, scientists found a population of coelacanths in the Indian Ocean. This fish species is considered a "living fossil" and appears not to have changed morphologically for 80 million years. This discovery supports the ______ model of evolution.
If population within the same area split into species, the process is known as ?
If species are competing for the same resource, one species is likely to go extinct through competitive exclusion, or natural selection will drive the evolution of ?
Scientists found that different beak shapes lead to different mating songs in Darwin's finches. This result best supports which hypothesis?
Adaptation to different food sources indirectly led to behavioral isolation in Darwin's finches.
Once species have formed, they keep their identity by ?
Many species might coexist in a particular environment by occupying ecological ?
Males of several marsupial species have forked penises that are incompatible with female placental mammals. This is an example of what type of isolating mechanism?
Prezygotic mechanisms lead to reproductive isolation by preventing the formation of ?
In the southeastern US, two species of wild lettuce do not usually form hybrids, because they bloom at different seasons. The means of isolation appears to be ?
Prezygotic and temporal
The hundreds of species of Drosophila in Hawaii exhibit different mating rituals. This isolating mechanism is ?
Prezygotic and behavioral
Scientists studying a group of related bird species on an island archipelago discover that these species are always more closely related to each other within an island than they are between any two islands. The most likely explanation for this result is that?
One bird species colonized each island and then evolved into distinct species on that island through character displacement
Very rapid speciation occurred when cichild fishes were isolated in Lake Victoria. Widespread extinction was dramatically seen when ?
predatory fish were added
Species formation among alpine buttercups in New Zealand was promoted by ?
Periodic isolation by glaciation
Studies of snapping shrimp on either side of the Isthmus of Panama have shown that each Caribbean shrimp species is more closely related to a Pacific shrimp species than it is to any other Carribean shrimp species. The most likely explanation for this result is?
Snapping shrimp species diverged after the formation of the Isthmus of Panama
The sunflower species Helianthus anomalus is thought to have been formed by hybridization between the sunflower species H. petiolaris and H. annuus because it contains genetic material of both parental species. H. anomalus is most likely an example of instantaneous speciation through ?
Punctuated equlibrium propsed by Eldredge and Gould in 1972 is an evolutionary process that involves ?
"Spurts" of change observable in the fossil record followd by periods of stasis
A virgin pine forest covers a valley, and one of the inhabitants is a red squirrel species. A large volcanic eruption occurs and seperates the valley with a huge lava flow that the squirrels cannot cross, thus producing two isolated populations of squirrels. What change needs to occur for the two populations of squirrels to become separate species?
The two squirrel populations become reproductively isolated
Two bird species have different mating calls, occupy different habitats in nature, and when they hybridize, the hybrids are infertile. Which isolating mechanisms maintain these species?
ecological isolation, behavioral isolation, and hybrid sterility
Adaptive radiation is best described as the
Existence of groups of closely related species currently evolved from a common ancestor
The most common mechanism for sympatric speciation in plants is ?
Lake Victoria is famous for its variety of cichlid fishes. In fact, they offer the most diverse assembly of vertebrates presently known to science. One trait that scientists have focused on as one possible reason for their adaptability is ?
A second set of jaws in their throats
Two populations that inhabit the same area but remain genetically distinct can best be called?
The biological species concept of Ernst Mayr cannot be applied to ?
Which statement is true about speciation on island archipelagos?
Most speciation occurs allopatrically
Which form of speciation is most rapid?
Sympatric speciation via polyploidy
Several species of sea urchins may inhabit the same tide pool and their reproductive periods overlap. Although they practice external fertilization, they seldom interbreed because eggs produce chemicals that are only attractive to sperm of their own species. This is an example of a ____ barrier involving _____.
Prezygotic; gametic isolation
Many male songbirds have very distinctive songs that are used to attract females. These songs are an example of an _____ isolating mechanism.
Due to character displacement, two closely related species may differ most morphologically when they,
Several new tetraploid species of plant known as the salsifies have arisen in western North America. These new species arose from diploid species that went through the process of allopolyploidy. This mode of speciation is known as _____ and it occurs _____.
sympatric speciation; almost instantaneously
Imagine two species of birds with similar beak sizes and diets. Where the two species are allopatric, we would expect that their beak sizes ?
Should differ less than when sympatric
If two species are able to mate and produce an offspring which can mate with itself, but is unable to mate with either parents' species, it is an example of ?
Sympatric speciation via polyploidy
IF a new species is produced by the interbreeding of two members of distinct species, this would be ____ speciation acheived via ______.
Choose the best cause and effect sequence for the process of speciation by natural selection.
An example of temporal isolation would be ?
One plant species blooms in June-July and a second plant species blooms in August-Septmeber
Reinforcement is most likely to drive the evolution of ?
Prezygotic isolating mechanisms, because selection favors alleles that prevent hybrdization
NASA Scientists send a small population of dogs to a new planet in order to test if it will be hospitable for human colonization. Through a random lottery, only Great Dane and St. Bernard dog breeds are sent, and the resulting population consists of tall, longhaired dogs. After 100 years these dogs return to earth and are no longer able to mate with earth dogs. This scenario is an example of ?
Allopatric speciation through genetic drift
Scientists investigating speciation in fruit flies divided a single population of flies into separate populations that each lived in their own cage on one of two food sources: maltose based food or starch based food. After several generations, the flies' mate peference was tested, and it was found that flies strongly preferred to mate with other flies that were raised on the same food source. These results suggests that ?
Selection on food source indirectly led to the evolution of reproductive isolating mechanisms
Diversification of mammals after the extinction of the dinosaurs is considered an adaptive radiation because a few mammal species rapidly evolved into most of the current mammalian lineages in a relatively short amount of time. This diversification was partially driven by the evolution of endothermic homeostasis in mammals, which is an example of ?
A key innovation
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