Exam 24: The Origin of Species

In a hypothetical situation, a certain species of flea feeds only on pronghorn antelopes. In rangelands of the western United States, pronghorns and cattle often associate with one another. If some of these fleas develop a strong preference for cattle blood and mate only with other fleas that prefer cattle blood, then over time which of these should occur, if the host mammal can be considered as the fleas' habitat? 1)reproductive isolation 2)sympatric speciation 3)habitat isolation 4)prezygotic barriers

Which of the following factors would not contribute to allopatric speciation?

Beetle pollinators of a particular plant are attracted to its flowers' bright orange color. The beetles not only pollinate the flowers, but they mate while inside of the flowers. A mutant version of the plant with red flowers becomes more common with the passage of time. A particular variant of the beetle prefers the red flowers to the orange flowers. Over time, these two beetle variants diverge from each other to such an extent that interbreeding is no longer possible. What kind of speciation has occurred in this example, and what has driven it?

The next few questions refer to the following description. In the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest. -Which factor is most important for explaining why there are equal numbers of snapping shrimp species on either side of the isthmus?

What is true of the flightless cormorants of the Galápagos Islands?

The next few questions refer to the following evolutionary tree, whose horizontal axis represents time (present time is on the far right) and whose vertical axis represents morphological change. -Which species is most closely related to species W?

When male horses (stallions)and female donkeys (jennets)mate, they produce a sterile hybrid called a hinny. Hinnies occur much less frequently than do mules, but are just as healthy and robust as mules. Logically, which of the following best accounts for the relative rarity of hinnies, and what kind of prezygotic isolating mechanism is at work here?

The next few questions refer to the following description. In the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest. -Which habitats should harbor snapping shrimp species with the greatest degree of genetic divergence from each other?

Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools?

What does the biological species concept use as the primary criterion for determining species boundaries?

According to the punctuated equilibria model,

A narrow hybrid zone separates the toad species Bombina bombina and Bombina variegata. What is true of those alleles that are unique to the parental species?

In order for speciation to occur, what must be true?

The most likely explanation for the high rate of sympatric speciation that apparently existed among the cichlids of Lake Victoria in the past is

Among known plant species, which of these have been the two most commonly occurring phenomena that have led to the origin of new species? 1)allopatric speciation 2)sympatric speciation 3)sexual selection 4)polyploidy

The next few questions refer to the following description. On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago. -Which of the following reduces gene flow between the gene pools of the two species on Sao Tomé, despite the existence of hybrids?

The next few questions refer to the following description. In the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest. -In which habitat should one find snapping shrimp most closely related to shrimp that live in habitat A4?

Which of the following statements about speciation is correct?

The next few questions refer to the following description. On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated, freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences. -Which two of the following have operated to increase divergence between mosquitofish populations on Andros? 1)improved gene flow 2)bottleneck effect 3)sexual selection 4)founder effect 5)natural selection

You are confronted with a box of preserved grasshoppers of various species that are new to science and have not been described. Your assignment is to separate them into species. There is no accompanying information as to where or when they were collected. Which species concept will you have to use?