Ch 24 HW

Part C Identify the dependent variable in this study.

the reproductive isolation values for pairs of dusky salamander populations

Part F Calculate the value of the reproductive isolation index if salamanders were equally successful in mating with members of their own population and members of another population.

0

Part E - Calculating reproductive isolation values Calculate the value of the reproductive isolation index if all of the matings within a population were successful but none of the matings between populations were successful.

2.0

Part A Of the 59 matings in the experimental groups, how many were between like-adapted flies (flies adapted to the same medium)?

42

Part A What is genetic drift?

A change in allele frequencies caused by random events

Part B _____ is rapid speciation under conditions in which there is little competition.

Adaptive radiation

Part A - 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

Part C Which of the following statements is supported by the data from the control group matings?

Flies were about as likely to mate with flies from different starch-adapted populations as with flies from their own starch-adapted population.

Part I - Evaluating hypotheses Which hypothesis suggests a possible cause of the relationship shown in the scatter plot?

Geographically separated populations of dusky salamanders gradually diverge, and the divergence increases with geographic distance.

Part F 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

Part D Which of the following statements about reinforcement is true?

Reinforcement is a type of natural selection.

Part A - Understanding experimental design What hypothesis did the researchers test in this study?

Reproductive isolation increases with geographic distance between dusky salamander populations.

Part H What does the scatter plot suggest about the process of allopatric speciation?

Reproductive isolation is more likely to occur as populations become separated by greater distances.

Part G - Interpreting a scatter plot Review the scatter plot (Figure 2) of reproductive isolation value versus geographic distance for 27 pairs of dusky salamander populations. (Select Figure 2 from the drop-down menu above the data table.) How do reproductive isolation values change with geographic distance among pairs of dusky salamander populations?

Reproductive isolation values increase with geographic distance.

Part C - 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 I Species 2: LE Species 3: G J

Part E 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 its original 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.

Part B Which of the following statements is best supported by the data on matings in the experimental groups?

The starch-adapted flies and maltose-adapted flies are not different species, but a reproductive barrier is forming between the populations.

Part D A similar control experiment was performed with flies adapted to maltose, and similar results were obtained. What were these control experiments testing?

These control experiments tested whether flies were more likely to choose mates from their own population than from another population adapted to the same medium.

Part B - 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 barrirs 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

Part C Mass extinctions create conditions that promote _____.

adaptive radiation

Part D The appearance of an evolutionary novelty promotes _____.

adaptive radiation

Part E The different finch species found on the Galápagos Islands probably arose as a result of _____.

adaptive radiation

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

all of these

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

all three

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

false

Part A 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 _____.

fusion

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

gene flow

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

punctuated equilibrium

Part B Identify the independent variable in this study.

the geographic distance between dusky salamander populations

Part D Why did the researchers set up four possible matings for each pair of populations: female A + male A; female B + male B; female A + male B; female B + male A?

to compare the proportion of successful matings within populations to the proportion of successful matings between populations

Part G 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