Chapter 24

Why are the large finches now living on the Galápagos Islands different from the original source population from a nearby island?

- Genetic drift occurred in the two populations - Natural selection favored individuals that were more fit in the new environment - The separation of habitats reduced gene flow between the populations. because: physical isolation, natural selection, and genetic drift are all events that lead to speciation.

Definition of morphological and phylogenetic

- accommodates asexual reproduction - species acceptance criteria can be subjective

Feathers either play a role, or may have played a role, in _____.

- gliding -extended hops courtship - flight because all of these, or may have been functions of feathers

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 _____.

28

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

3 and 5

What is genetic drift?

A change in allele frequencies caused by random events overtime

In the accompanying diagram, the original population of a species of fish in a small lake that lacks predators is shown at the top. After separation by a land mass, the figure at the bottom left of the diagram shows the resulting change. Each color represents a different species. Allopatric speciation occurs when gene flow is disrupted through physical isolation of the original population. Although generally less common, sympatric speciation can occur among individuals in a population living in the same area, such as seen in the bottom right of the figure. Which of the following scenarios would most likely cause sympatric speciation to occur?

A mutation that resulted in green coloration affected female mate choice.

The questions below refer to the following evolutionary tree, in which the horizontal axis represents time (present time is on the far right) and the vertical axis represents morphological change.

A single clade (that is, a group of species that share a common ancestor) can include species that formed by gradualism and other species that formed by punctuated equilibrium.

In the ocean, on either side of the Isthmus of Panama, are thirty species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are fifteen species on the Pacific side and fifteen different species on the Atlantic side. The Isthmus of Panama started rising about ten million years ago. The oceans were completely separated by the isthmus about three 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 of these habitats is likely to harbor the most recently diverged species?

A1

In the ocean, on either side of the Isthmus of Panama, are thirty species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are fifteen species on the Pacific side and fifteen different species on the Atlantic side. The Isthmus of Panama started rising about ten million years ago. The oceans were completely separated by the isthmus about three 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. The Panama Canal was completed in 1914, and its depth is about fifty feet. After 1914, snapping shrimp species from which habitats should be most likely to form hybrids as the result of the canal?

A1 and B1

In the ocean, on either side of the Isthmus of Panama, are thirty species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are fifteen species on the Pacific side and fifteen different species on the Atlantic side. The Isthmus of Panama started rising about ten million years ago. The oceans were completely separated by the isthmus about three 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?

A5 and B5

In the ocean, on either side of the Isthmus of Panama, are thirty species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are fifteen species on the Pacific side and fifteen different species on the Atlantic side. The Isthmus of Panama started rising about ten million years ago. The oceans were completely separated by the isthmus about three 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?

B4

True or false? The last ice age produced many different species mainly because populations dispersed and colonized new habitats.

False because that makes no sense, it produced different species daily because of the things like glaciers which physically separated populations from one another

True or false? A mating between a tetraploid individual and a diploid individual produces biologically fit offspring.

False because the offspring produced from this mating would be triploid and likely produce nonviable gametes with an uneven number of chromosomes

What prevents speciation from occurring in sympatric populations?

Gene flow because gene flow prevents speciation in sympatric populations

How many chromosomes would be found in an allopolyploid plant if its parents had diploid numbers of 2 and 10, respectively?

Haploid number of 6 because the parents contribute one and five chromosomes, respectively, to their gametes, and the zygote is a haploid plant because the chromosomes do not exist in homologous pairs.

In Europe, there is a long narrow hybrid zone, shown in red on the map, between the high-altitude habitat of the yellow-bellied toad and the lowland habitat of the fire-bellied toad. Despite this, there is little gene flow between the two species. Select the correct explanation.

Hybrids have poor survival and reproduction and thus produce few viable offspring with members of either parent species.

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. Fly species W, found in a certain part of the island, produces fertile offspring with species Y. Species W does not produce fertile offspring with species X or Z. If no other species can hybridize, then which of the following statements about species W and Y are true?I) Species W and Y have genomes that are still similar enough for successful meiosis to occur in hybrid flies.II) Species W and Y have more genetic similarity with each other than either did with the other two species.III) Species W and Y may fuse into a single species if their hybrids remain fertile over the course of many generations.

I, II, and III are correct. Submit

A population of birds colonizes an area in which the insects upon which they feed live inside trees. Which of the following events accounts for an observed increase in average beak size in the bird population over time?

Increased fitness of large-beaked birds, leading to natural selection

The peppered moth provides a well-known example of natural selection. The light-colored form of the moth was predominant in England before the Industrial Revolution. In the mid-nineteenth century, a dark-colored form appeared. The difference is produced by a dominant allele of one gene. By about 1900, approximately 90% of the moths around industrial areas were dark colored, whereas light-colored moths were still abundant elsewhere. Apparently, birds could readily find the light moths against the soot-darkened background in industrial areas and, therefore, were eating more light moths. Recently, use of cleaner fuels has greatly reduced soot in the landscape, and the dark-colored moths have been disappearing. Should the two forms of moths be considered separate species?

No.

How can an allopolyploid plant become a biologically fit new species?

Nondisjunction event during mitosis because a nondisjunction event occurred that resulted in chromosome doubling, the plant's ability to undergo meiosis would be restored and it could then produce viable gametes.

Which of these is an example of temporal isolation?

One species is nocturnal, and the other species is not.

Adaptive radiations on archipelagos (island chains) represent some of the best-understood speciation events. Why is an ancestral species more likely to give rise to multiple descendent species on an archipelago than on an equal-sized area of mainland?

Populations on nearby islands are more likely to be genetically isolated than populations that are equally close to one another on the mainland. because regions that are highly subdivided by geographic barriers such as archipelagos typically have more species than do regions with fewer barriers. The barriers lead to reproductive isolation between populations, initiating allopatric speciation.

The common edible frog of Europe is a hybrid between two species, Rana lessonae and Rana ridibunda. The hybrids were first described in 1758 and have a wide distribution, from France across central Europe to Russia. Both male and female hybrids exist, but when they mate among themselves, they are rarely successful in producing offspring. What can you infer from this information?

Postzygotic isolation exists between the two frog species.

Which of the following statements about reinforcement is true?

Reinforcement is a type of natural selection because reinforcement is a type of natural selection called disruptive selection, which favors extreme phenotypes over intermediate phenotypes

Which term is used to describe populations that live close enough to interbreed?

Sympatry because it describes populations that live close enough to interbreed

What would be the ploidy of the viable gametes produced by a tetraploid individual if nondisjunction of all chromosomes occurred in meiosis I?

Tetraploid because tetraploid gametes would be produced if all chromosomes migrated to one pole during meiosis I.

A subset of a population of birds leaves its habitat on the mainland and colonizes a nearby island. The birds, after a period of time, become reproductively isolated. The island sinks and the population of birds that lived on the island returns to itsoriginal habitat. Which of the following statements about these bird populations is true?

The populations will not be able to interbreed because they are different species because they won't create viable species

Which of the following statements about autopolyploid individuals is true?

They contain more than two haploid sets of chromosomes because all polyploid individuals contain more than two haploid sets of chromosomes

In the ocean, on either side of the Isthmus of Panama, are thirty species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are fifteen species on the Pacific side and fifteen different species on the Atlantic side. The Isthmus of Panama started rising about ten million years ago. The oceans were completely separated by the isthmus about three 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. Why should deepwater shrimp on different sides of the isthmus have diverged from each other earlier than shallow-water shrimp?

They have been geographically isolated from each other for a longer time.

True or false? A flood that separates a population of frogs onto opposite sides of a lake is an example of a vicariance event that may result in allopatric speciation.

True

Three populations of crickets look very similar, but the males have courtship songs that sound different. What function would this difference in song likely serve if the populations came in contact?

a behavioral reproductive isolating mechanism

According to the phylogenetic species concept, what is a species?

a set of organisms with a unique genetic history

The largest unit within which gene flow can readily occur is _____.

a species

A hybrid zone is properly defined as _____.

an area where mating occurs between members of two closely related species, producing viable offspring

Definition of phylogenetic

based on evolutionary history

Two animals are considered members of different species if they _____.

cannot mate and produce viable, fertile offspring Submit

What is the most important factor that holds a gene pool of a species together and prevents speciation?

gene flow because the flow refers to the transfer of alleles among populations and as long as the population is exchanging alleles, speciation is unlikely

Which of the following describes the most likely order of events in allopatric speciation?

genetic isolation, genetic drift, divergence

Which of the following is the first step in allopatric speciation?

geographic isolation because allopatric speciation occurs when a population of organisms is geographically separated long enough for significant changes to occur. After a period of time, the populations may no longer be able to interbreed.

Refer to the paragraph about the formation of the Isthmus of Panama. If the isthmus formed gradually rather than suddenly, what pattern of genetic divergence would you expect to find in these species pairs?

greater percentage of difference in DNA sequence between species that inhabit deep water than between species that inhabit shallow water

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?

habitat isolation

Two populations of birds with somewhat different coloration live on opposite sides of a peninsula. The habitat between the populations is not suitable for these birds. When birds from the two populations are brought together artificially, they produce young whose appearance is intermediate between the two parents. These offspring will breed with each other or with birds from either parent population, and all offspring of these pairings appear intermediate to various degrees.What keeps the two populations separate in nature?

habitat isolation

According to the punctuated equilibria model,

most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species.

Two populations of birds with somewhat different coloration live on opposite sides of a peninsula. The habitat between the populations is not suitable for these birds. When birds from the two populations are brought together, they produce young whose appearance is intermediate between the two parents. These offspring will breed with each other or with birds from either parent population, and all offspring of these pairings appear intermediate to various degrees. The two populations are _____.

not different species, under the biological species concept

The production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) is an example of _____.

reduced hybrid fertility

Definition of morphological

relies on similaritiesin structure

About 3 million years ago, the Isthmus of Panama (a narrow strip of land connecting North and South America) formed, dividing marine organisms into Pacific and Caribbean populations. Researchers have examined species of snapping shrimp on both sides of the isthmus. Based on the morphological species concept, there appeared to be seven pairs of species, with one species of each pair in the Pacific and the other in the Caribbean. The different species pairs live at somewhat different depths in the ocean. Using mitochondrial DNA sequences, the researchers estimated phylogenies and found that each of these species pairs, separated by the isthmus, were indeed each other's closest relatives. The researchers investigated mating in the lab and found that many species pairs were not very interested in courting with each other, and any that did mate almost never produced fertile offspring. (N. Knowlton, L. A. Weigt, L. A. Solorzano, D. K. Mills, and E. Bermingham. 1993. Divergence in proteins, mitochondrial DNA, and reproductive incompatibility across the Isthmus of Panama. Science 260:1629-32.)Refer to the paragraph about the formation of the Isthmus of Panama. The sister populations on opposite sides of the isthmus are true species under which species concept?

the morphological species, biological species, and phylogenetic species concepts

In the ocean, on either side of the Isthmus of Panama, are thirty species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are fifteen species on the Pacific side and fifteen different species on the Atlantic side. The Isthmus of Panama started rising about ten million years ago. The oceans were completely separated by the isthmus about three 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?

the relative shortness of time they have been separated

Definition of morphological, phylogenetic, and biological

used by scientists in classification

Sympatric speciation is _____.

the appearance of a new species in the same area as the parent population because it is due to a radical change in the genome

Definition of biological

not applicable forextinct species