Exam 24: The Origin of Species

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. -If one builds a canal linking a predator-rich pond to a predator-poor pond,then what type(s)of selection should subsequently be most expected among the mosquitofish in the original predator-rich pond,and what type(s)should be most expected among the mosquitofish in the formerly predator-poor pond?

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 sea water 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?

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 phenomenon of fusion is likely to occur when,after a period of geographic isolation,two populations meet again and

Which of these evolutionary trees represents the situation in the description? (Note: Yakuba (I)represents the island population,and yakuba (M)represents the mainland population.)

The next few questions refer to the following description: Fossil evidence suggests that polar bears,Ursus maritimus,arose from grizzly bears,Ursus arctos.On average,polar bears are slightly larger than grizzly bears in size and weight.The morphological features/adaptations of polar bears make them well suited to survival in a marine environment.Interbreeding and production of fertile offspring between the two species has been recorded in captivity,and more recently in the wild. -Speculate on the most likely reason why two different species may be hybridizing more frequently than before.

Use the following information to answer the question(s)below. A female fly,full of fertilized eggs,is swept by high winds to an island far out to sea.She is the first fly to arrive on this island and the only fly to arrive in this way.Thousands of years later,her numerous offspring occupy the island,but none of them resembles her.There are,instead,several species,each of which eats only a certain type of food.None of the species can fly and their balancing organs (halteres)are now used in courtship displays.The male members of each species bear modified halteres that are unique in appearance to their species.Females bear vestigial halteres.The ranges of all of the daughter species overlap -The largest unit within which gene flow can readily occur is a

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

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 320 kilometres 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. -If a speciation event occurred on Sao Tomé,producing D.santomea from a parent colony of D.yakuba,then which terms apply? I.macroevolution II allopatric speciation III.sympatric speciation

Plant species A has a diploid number of 12.Plant species B has a diploid number of 16.A new species,C,arises as an allopolyploid from A and B.The diploid number for species C would probably be

The Panama Canal was completed in 1914,and its depth is about 15 metres.After 1914,snapping shrimp species from which habitats should be most likely to form hybrids as the result of the canal?

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

Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile.This kind of isolation is most similar to which of the following reproductive isolating mechanisms?

There are currently two large,permanent bridges that span the Panama Canal.The bridges are about 13 kilometres apart.If snapping shrimp avoid swimming at night and avoid swimming under shadows,then what do these bridges represent for the snapping shrimp?

According to the concept of punctuated equilibrium,the "sudden" appearance of a new species in the fossil record means that

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 sea water on either side of the isthmus is separated into five depth habitats (1-5),with 1 being the shallowest. -Which of these habitats is likely to harbour the youngest species?

Which of the following statements about species,as defined by the biological species concept,is (are)correct? I.Biological species are defined by reproductive isolation. II.Biological species are the model used for grouping extinct forms of life. III.The biological species is the largest unit of population in which successful interbreeding is possible.

Two species of frogs belonging to the same genus occasionally mate,but the offspring fail to develop and hatch.What is the mechanism for keeping the two frog species separate?

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 sea water on either side of the isthmus is separated into five depth habitats (1-5),with 1 being the shallowest. -Which habitats should harbour snapping shrimp species with the greatest degree of genetic divergence from each other?

The origin of a new plant species by hybridization,coupled with accidents during nuclear division,is an example of