Mastering Biology Ch. 24

LC?: The species concept based on careful analysis of the anatomical details of the specimen in question is ________.

the morphological species concept

Two species of frogs belonging to the same genus occasionally mate, but the embryos stop developing after a day and then die. These two frog species separate by _____.

reduced hybrid viability

Use the data provided in the table to calculate the percent frequency of the +/+ genotype in A. gambiae over time (from pre-2006 to post-2006). Note that "frequency" refers to the proportional representation of an allele or genotype in a population.Indicate the percent frequency of the +/+ genotype in A. gambiae during the periods specified. 1. Pre-2006 2. 2006 3. Post-2006

1. 30.0% 2. 34.8% 3. 4.8%

LC?: 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

2 and 4- sympatric speciation and polyploidy

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

Which conclusion can be drawn from this evolutionary tree?

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.

Which of these habitats is likely to harbor the most recently diverged species?

A1

In which habitat should one find snapping shrimp most closely related to shrimp that live in habitat A4?

B4

Comparing species definitions Three of the most prominent definitions of species are the biological species concept, the phylogenetic species concept, and the morphological species (morphospecies) concept. Drag each characteristic to the appropriate bin based on the species concept(s) to which it applies.

Biological: not applicable for extinct species Morphological: relies on similarities in structures Phylogenetic: based on evolutionary history Morphological and Phylogenetic: accommodates asexual reproduction, species acceptance criteria can be subjective Morph. Phylo, and Biological: used by scientists in classification

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. What is the best way to promote fusion between two related populations of mosquitofish, one of which lives in a predator-rich pond and the other of which lives in a predator-poor pond?

Build a canal linking the two ponds that permits free movement of mosquitofish, but not of predators.

LC?: True or False? Sympatric speciation is where a physical barrier keeps two populations from mating and they evolve away from each other over time.

False

Which of the following best describes the change in kdr genotype frequencies over time in A. coluzzii?

From pre-2006 to post-2006, the frequencies of the r/r and +/r genotypes increased dramatically while the frequency of +/+ decreased dramatically.

Which of the following best describes the change in kdr genotype frequencies over time in A. gambiae?

From pre-2006 to post-2006, the frequency of the r/r genotype increased dramatically while the frequencies of +/+ and +/r genotypes decreased dramatically.

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

Gene flow between the two populations is extensive.

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

Which of these is an example of temporal isolation? See Concept 24.1

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

Gene flow and the biological species concept Recall that the biological species concept defines a species as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring. This means that all members of these populations (called conspecifics) can contribute to a common gene pool. Conspecifics are organisms or populations that belong to the same species. Genes are transferred between conspecific populations through both direct and indirect gene flow.Biologists studying disease susceptibility in mice used genetic techniques to look for gene flow in 12 wild populations of mice. The populations (designated A through L) were located along a 210-km transect line.The researchers found evidence of gene flow between some, but not all, pairs of populations. In the grid below, a "+" indicates a pair of populations in which direct gene flow was detected, and a "-" indicates a pair that showed no evidence of direct gene flow. For help reading this grid, see Hint 2. The researchers discovered that the 12 populations could be organized into 3 distinct species. Populations A, B, and C each belong to a different species.Use the data in the grid to sort each population to the species to which it belongs. Species 1: K D F H ISpecies 2: LESpecies 3: G J

Species 1: K D F H I Species 2: LE Species 3: G J

Select the correct statement describing sympatric speciation.

Sympatric speciation can occur in a single generation.

Based on these observations, do you think that the number of malaria cases will increase, decrease, or stay the same in the future?

The number of malaria cases will increase.

Based on these data alone, which of the following conclusions is consistent with the observed changes in genotypic frequency for A. gambiae and A. coluzzii? Select all that apply.

The r allele was present in A. gambiae before 2006 and increased over time because individuals with the r allele are resistant to insecticides and pass their resistant genes to new generations. The r allele was not present in A. coluzzii before 2006, but was present in A. coluzzii populations after hybrid individuals carrying the r allele were observed in 2006. This suggests that A. gambiae ×× A. coluzzii hybrids mated with A. coluzzii individuals, leading to the transfer of the adaptive allele r into A. coluzzii populations.

Bird guides once listed the myrtle warbler and Audubon's warbler as distinct species. Recently, these birds have been classified as eastern and western forms of a single species, the yellow-rumped warbler. Which of the following pieces of evidence, if true, would be cause for this reclassification?

The two forms interbreed often in nature, and their offspring have good survival and reproduction.

LC?: Rank in order the following reproductive isolating mechanisms from early-acting to late-acting in a timeline of biological events which would result in reproductive isolation. 1st choice Different mating calls reduce gene flow between populations 2nd choice Offspring are infertile 3rd choice Populations mate at different times 4th choice Offspring are inviable 5th choice Two species live in different habitats

Two species live in different habitats<Populations mate at different times<Different mating calls reduce gene flow between populations<Offspring are inviable<Offspring are infertile

Do these observations indicate that hybridization can lead to the transfer of adaptive alleles?

Yes; the r allele was not present in A. coluzzii before 2006, but was present in A. coluzzii populations once hybrid individuals carrying the r allele were observed in 2006.

According to the phylogenetic species concept, what is a species? See Concept 24.1

a set of organisms with a unique genetic history

Classifying reproductive barriers According to the biological species concept, individuals belong to the same species if they can interbreed in nature and produce viable, fertile offspring. Prezygotic and postzygotic barriers ensure that members of different species do not reproduce with one another. This diagram shows some of these barriers along with examples of the barriers at work. Complete the diagram by following these steps: Drag blue labels onto blue targets only to identify the two main types of reproductive barriers. Drag pink labels onto pink targets only to identify specific barriers. Drag white labels onto white targets only to identify examples of barriers

a. prezygotic barriers b. postzygotic barriers c. behavior isolation d. mechanical isolation e. temporal isolation f. gametic isolation g. reduced hybrid fertility h. 2 fish species spawn at diff. depths i. a coral's sperm can't fertilize another's eggs j. offspring of 2 newts are sterile k. lion-tiger hybrids don't reach maturity

A hybrid zone is properly defined as _____.

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

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

an increasing number of viable, fertile hybrids is produced over the course of the next 100 generations

LC?: According to the Biological Species concept, two animals are considered members of different species if they _____.

do not mate or produce viable, fertile offspring in nature

A certain species of salamander was split into two populations by a wide, dry valley, and the populations began to diverge from each other. After a period of time, some members of the two populations began to interbreed in a hybrid zone at the southern end of the valley. Only weak reproductive barriers existed by this time, so the two populations could freely interbreed and re-establish gene flow. This outcome in a hybrid zone is known as _____. See Concept 24.3

fusiom

LC?: Which of the following is NOT a postzygotic mechanism of reproductive isolation?

gamete isolation

Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. Pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species. These two juniper species are kept separate by _____.

gametic isolation

What is the most important factor that holds a gene pool of a species together and prevents speciation? See Concept 24.1

gene flow

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 two hundred 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.Using only the information provided in the paragraph, which of the following is the best initial hypothesis for how D. santomea descended from D. yakuba?

habitat differentiation

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?

morphological

According to the _____ model, evolution occurs in spurts; species evolve relatively rapidly then remain unchanged for long periods. See Concept 24.4

punctuated equilibrium

Among known plant species, which of these have been the two most commonly occurring phenomena that have led to the origin of new species?

sympatric speciation and polyploidy

LC?: Which of the following types of reproductive barriers separates a pair of species that could interbreed except that one mates at dusk and the other at dawn?

temporal isolation

Hybrid zones provide an opportunity to investigate _____. See Concept 24.3

the evolution of reproductive isolation