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LSU BIOL 1202 - Ch. 24 Mastering Biology Answers
Terms in this set (31)
Three of the most prominent definitions of species are the biological species concept, the phylogenetic species concept, and the morphological species (morphospecies) concept.
4. Morphological & Phylogenetic
5. Biological, Morphological, Phylogenetic
1. Biological: not applicable for extinct species
2. Morphological: relies on similarities in structure
3. Phylogenetic: based on evolutionary history
4. Morphological & Phylogenetic: accomodates asexual reproduction; species acceptance criteria can be subjective
5. Biological/Morphological/Phylogenetic: used scientists in classification
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. Behavioral Isolation
D. Mechanical Isolation
E. Temporal Isolation
F. Gametic Isolation
G. Reduced Hybrid Fertility
H. Reduced Hybrid Viability
I. Two Fish Species Spawn At Different Depths
J. A Coral's Sperm Can't Fertilize Another's Eggs
K. Lion-Tiger Hybrids Don't Reach Maturity
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(A): D F H I K
Species 2(B): L E
Species 3(C): G J
What is the most important factor that holds a gene pool of a species together and prevents speciation?
Hybrid zones provide an opportunity to investigate _____.
the evolution of reproductive isolation
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 _____.
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.
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 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.
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?
- 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.
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.
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
According to the _____ model, evolution occurs in spurts; species evolve relatively rapidly then remain unchanged for long periods.
According to the phylogenetic species concept, what is a species?
a set of organisms with a unique genetic history
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?
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
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 _____.
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?
Which of these is an example of temporal isolation?
one species is nocturnal, and the other species is not
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
Use the following description to answer the question.
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 & 5
In which habitat should one find snapping shrimp most closely related to shrimp that live in habitat A4?
Which of these habitats is likely to harbor the most recently diverged species?
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
A hybrid zone is properly defined as _____.
an area where mating occurs between members of two closely related species, producing viable offspring
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
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
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.
The two forms are very similar in coloration
Which of the following factors would not contribute to allopatric speciation?
gene flow between the two populations is extensive
Select the correct statement describing sympatric speciation.
sympatric speciation can occur in a single generation
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
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