Chapter 24 The Species Concept

Feathers either play a role, or may have played a role, in _____. extended hops flight courtship gliding all of these

All of these

The appearance of an evolutionary novelty promotes _____. gene flow paedomorphosis adaptive radiation mass extinction mutation

adaptive radiation

In practice, how do scientists distinguish most species? by using the ecological species concept by using the phylogenetic species concept by using the biological species concept by using the morphological species concept None of the listed responses is correct.

by using the morphological species concept

What is the most important factor that holds a gene pool of a species together and prevents speciation? gene flow prezygotic barriers behavioral isolation hybridization sexual selection

gene flow

Prezygotic barriers __________. prevent donkeys and horses from mating prevent fertilization of gametes from members of closely related species are necessary in order for speciation to occur only occur in asexual organisms prevent a hybrid zygote from developing into a viable, fertile adult

prevent fertilization of gametes from members of closely related species

Eastern and western spotted skunks breed at different times of the year. Therefore, they are prevented from interbreeding by _____ isolation. behavioral temporal mechanical habitat

temporal

Two species of water lilies in the same pond do not interbreed because one blooms at night and the other during the day. The reproductive barrier between them is an example of __________. mechanical isolation ecological isolation hybrid breakdown temporal isolation gametic isolation

temporal isolation

The phylogenetic species concept emphasizes __________. phenotypic differences common ancestry the evolution of reproductive isolation the ability to hybridize ecological niches

common ancestry

Species concept Phylogenetic

Criteria Common evolutionary history Advantages Based on actual relationships, works for asexual and extinct species Disadvantages Requires good evolutionary histories

Species concept Morphological

Criteria Similarities in body structures Advantages Easy to apply, works for asexual and extinct species Disadvantages Researchers may disagree on which structures are important

According to the phylogenetic species concept, what is a species? a population that interbreeds and produces fertile offspring a clone of genetically identical organisms a set of organisms with a unique genetic history a population that is physically able to mate even if there are no offspring or the offspring are infertile a population with a distinct fossil record

a set of organisms with a unique genetic history

In evolutionary terms, an organism's fitness is measured by its _____. genetic variability mutation rate health contribution to the gene pool of the next generation stability in the face of environmental change

contribution to the gene pool of the next generation

Which species concept defines a species as a set of organisms with a unique genetic history? biological species concept ecological species concept morphological species concept phylogenetic species concept None of the listed responses is correct.

phylogenetic species concept

The largest unit within which gene flow can readily occur is a hybrid. phylum. population. species. genus.

species

You read about soapberry bugs and select the correct statement describing relative fitness in these individuals. A soapberry bug with high relative fitness has a relatively high number of offspring that survive to reproductive age. A soapberry bug with high relative fitness feeds more successfully on fruits than do other bugs. A soapberry bug with high relative fitness has more mates than other bugs.

A soapberry bug with high relative fitness has a relatively high number of offspring that survive to reproductive age.

_____ is rapid speciation under conditions in which there is little competition. Genetic drift Microevolution Gene flow Paedomorphosis Adaptive radiation

Adaptive radiation

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. Prezygotic Barriers

Behavioral Isolation Description Differences in mating rituals or displays Ex. Beetle mating displays show different spot patterns Mechanical Isolation Description Reproductive structure incompatibility Ex. Flowers accommodate different insect pollinators Habitat Isolation Description Differences in habitat occupied Ex. Two fish species spawn at different depths Temporal Isolation Description Differences in the timing of mating Ex. Birds are active during different times of the day Gametic Isolation Description sperm and egg are incompatible Ex. A coral's sperm can't fertilize another's eggs

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 structure Phylogenetic Based on evolutionary history Morphological and Phylogenetic Accommodates asexual reproduction Species acceptance criteria can be subjective Morphological, Phylogenetic, and Biological Used by scientists in classification

Species concept Biological

Criteria Ability to create viable, fertile offspring Advantages Objective criteria, meshes well with gene flow concept Disadvantages Not applicable to extinct or asexual species

What is the first thing that must happen in order for speciation to occur? The populations must become reproductively isolated. A catastrophic event must cause geographic separation of two populations. A hybrid zone must be established. Gene flow between populations must be interrupted. One of the populations must become polyploid.

Gene flow between populations must be interrupted.

At which point in the adaptation of a population is it clear that speciation has occurred? Viable, fertile hybrids occur. Gene pool changes establish reproductive barriers between two populations. An allopatric separation occurs. Gene pool changes adapt a population to a local environment. All of the listed responses are correct.

Gene pool changes establish reproductive barriers between two populations.

Imagine that part of a population of South American finches is blown by a storm onto an island far offshore and manages to survive and reproduce there for a period of 10,000 years. After that period, a climate change results in lower sea levels and the reconnection of the island with the mainland. Members of the formerly isolated island finch population can now interact freely with members of the original mainland population. Which of the following observations would, by itself, lead you to conclude unequivocally that the island finch population had evolved into a distinct species, according to the biological species concept? The island birds all have red feathers, but the mainland birds have green feathers. Individuals from the different populations frequently direct courtship behavior toward members of the other population. Hybrid offspring of matings between individuals from the two populations do not look like either parent. Individuals from the different populations sometimes mate with each other, but all of the resulting eggs are sterile. The preferred food of the island birds is quite different from the diet of mainland birds.

Individuals from the different populations sometimes mate with each other, but all of the resulting eggs are sterile.

According to the experiment of Diane Dodd, can adaptive divergence of allopatric fruit fly populations lead to reproductive isolation? Yes. After several generations, the reproductive barrier (behavioral isolation) between the starch- and maltose-fed populations was complete. Yes. After several generations, the reproductive barrier (mechanical isolation) between the starch- and maltose-fed populations was complete. No. After several generations, the formation of a reproductive barrier (behavioral isolation) was evident, but not absolute. No. After several generations, the formation of a reproductive barrier (mechanical isolation) was evident, but not absolute. No. Even after several generations, there was no evidence of a reproductive barrier forming between the populations.

No. After several generations, the formation of a reproductive barrier (behavioral isolation) was evident, but not absolute.

A biologist spends her summer break collecting frogs from a remote jungle in Peru. She discovers two distinct color forms that could be variants of a single species or two different species. What would be the most direct test of their species status under the biological species concept? Compare the color patterns of the two groups. If they are distinct enough, the two forms belong to different species. Observe mating in the natural environment of the two groups. If the two forms do not mate with each other, they are different species. Compare the habitat use of the two groups. If they use different habitats, they must be different species. Compare the DNA of the two groups. If their genes are different, they must be different species.

Observe mating in the natural environment of the two groups. If the two forms do not mate with each other, they are different species.

Lake Victoria, in Africa, is home to a group of related fishes known as cichlids. Many of these fishes are similar in appearance but have different feeding habits. What is the best method for scientists to determine conclusively whether the fish are members of a population that has a lot of variation or members of entirely different species? Compare DNA sequences, because the DNA of members of the same species should be identical. Study the fossil record. Observe the fish in their natural environment for possible instances of interbreeding leading to several generations of fertile offspring. Do studies on comparative anatomy, especially looking for homologous structures. All of the listed responses are correct.

Observe the fish in their natural environment for possible instances of interbreeding leading to several generations of fertile offspring.

Which of these is an example of temporal isolation? One is a type of primate, the other is a type of marsupial. One species performs a specific courtship dance. the other species does not. One species is found only in New York, the other only in London. One species is nocturnal, and the other species is not. The average weight of the individuals in one species is 45 kg; in the other species the average is 290 kg.

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. Favorable mutations are more likely to arise on an archipelago as populations try to adapt to conditions on their specific island. By chance, different species will colonize different islands in a chain.

Populations on nearby islands are more likely to be genetically isolated than populations that are equally close to one another on the mainland.

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. Postzygotic Barriers

Reduced Hybrid Fertility Description Hybrid offspring are produced but are sterile Ex. Offspring of two newts are sterile Reduced Hybrid Viability Description Hybrid offspring are produced but are feeble or unable to compete for mates Ex. Lion-tiger hybrids don't reach maturity

The fruit fly Drosophila melanogaster has an allele that confers resistance to DDT and similar insecticides. Laboratory strains of D. melanogaster have been established from flies collected in the wild in the 1930s (before the widespread use of insecticides) and the 1960s (after 20 years of DDT use). Lab strains established in the 1930s have no alleles for DDT resistance. In lab strains established in the 1960s, the frequency of the DDT-resistance allele is 37%. Which statement is correct? Alleles for DDT resistance arose by mutation during the period of DDT use because of selection for pesticide resistance. The evolutionary fitness associated with the heritable trait of DDT resistance changed once DDT use became widespread. Resistance to DDT evolved in some fruit flies in order to allow them to survive.

The evolutionary fitness associated with the heritable trait of DDT resistance changed once DDT use became widespread.

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 have many genes in common. The two forms have similar food requirements. The two forms are very similar in coloration. The two forms live in similar habitats. The two forms interbreed often in nature, and their offspring have good survival and reproduction.

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

Which of the following is an example of a postzygotic reproductive barrier? Two pheasant species perform different courtship dances. The sperm of a marine worm can only fertilize eggs of the same species. One species of frog mates in April, but another mates in May. One species of flower grows in forested areas, another in meadows. Two fruit flies of different species produce sterile offspring.

Two fruit flies of different species produce sterile offspring.

Mass extinctions create conditions that promote _____. paedomorphosis microevolution gene flow adaptive radiation genetic drift

adaptive radiation

The different finch species found on the Galápagos Islands probably arose as a result of _____. gene flow mass extinction adaptive radiation paedomorphosis artificial selection

adaptive radiation

Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian Islands have different elaborate courtship rituals. These rituals involve fighting other males and making stylized movements that attract females. What type of reproductive isolation does this represent? temporal isolation gametic isolation postzygotic barriers habitat isolation behavioral isolation

behavioral isolation

Can you complete this paragraph about species concepts?Part A Drag the terms to their correct locations in the paragraph. Biologists have several different ways to define species According to the _________ concept, a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring. The separation between species is maintained by ____________ isolation, which prevents gene flow between species. But in some cases, distinct species can occasionally interbreed, producing __________ offspring. Alternatively, the ____________ species concept identifies species based on physical traits or body form. This species concept can be applied to ________________________ species, and it is the way most of the 1.8 million named species have been identified. In the ________________ species concept, species are defined by their niche--the role they play in the environment. The _________________ species concept defines species as the smallest group of individuals that share a common ancestor and form one branch on the tree of life.

biological reproductive hybrid morhpological asexual and extinct ecological phylogenetic

Which of the following most accurately measures an organism's fitness? how much food it is able to make or obtain how many fertile offspring it produces its mutation rate how strong the organism is when pitted against others of its species its ability to withstand environmental extremes

how many fertile offspring it produces

Sometimes two phenotypically different populations interbreed to a limited extent, so that it is difficult to determine whether they are clearly separate species. This is not a concern to scientists because this __________. happens only among plants, not among animals supports the theory of punctuated equilibrium is true for almost every species is quite rare may indicate that the formation of a new species is in progress

may indicate that the formation of a new species is in progress

In _____ isolation, it is physically impossible for two species to mate with each other, often because their genitalia do not fit together properly. behavioral temporal mechanical habitat

mechanical

Which of the following reproductive barriers actually prevents individuals of closely related species from copulating successfully? hybrid breakdown hybrid inviability gametic isolation mechanical isolation hybrid sterility

mechanical isolation

Three species of frogs, Rana pipiens, Rana clamitans, and Rana sylvatica, all mate in the same ponds, but they pair off correctly because they have different calls. This is a specific example of a __________ barrier, called __________. prezygotic ... behavioral isolation prezygotic ... temporal isolation postzygotic ... hybrid breakdown prezygotic ... gametic isolation postzygotic ... mechanical isolation

prezygotic ... behavioral isolation

Which of the following conditions is necessary for speciation to occur? adaptive radiation mass extinction reproductive isolation interbreeding among neighboring populations sympatric speciation

reproductive isolation

Darwin thought that significant evolution was much too slow to be witnessed in a human lifetime. Recent experiments by biologists have _____. confirmed Darwin's view indicated that evolution takes place extremely quickly; in fact, individuals can evolve to become new species within their life spans shown that evolutionary change takes even longer than Darwin imagined shown that some populations can evolve quite rapidly, with important changes occurring over several generations in the laboratory

shown that some populations can evolve quite rapidly, with important changes occurring over several generations in the laboratory

The process of speciation starts with a single species. It often involves the following steps: (1) two populations become physically separated from one another by a barrier to dispersal and stop exchanging genes; (2) the populations experience independent evolutionary changes; (3) changes in one or both populations result in development of reproductive isolating mechanisms that prevent interbreeding; further changes in geography may bring the groups back into contact. When do you officially have two separate species? step 1 step 2 step 3 none of the above

step 3 changes in one or both populations result in development of reproductive isolating mechanisms that prevent interbreeding; further changes in geography may bring the groups back into contact.

Bird guides once listed the myrtle warbler and Audubon's warbler as distinct species that lived side by side in parts of their ranges. However, recent books show them as eastern and western forms of a single species, the yellow-rumped warbler. Apparently, the myrtle warbler and Audubon's warbler __________. successfully interbreed and produce fertile offspring are merging to form a single species are almost identical in appearance live in the same areas have undergone coevolution

successfully interbreed and produce fertile offspring

There are two groups of pine trees that appear to be very similar phenotypically and genotypically. However, one releases pollen in January, when the female structures of that group are receptive, and one in March. What kind of reproductive barrier is this? temporal isolation mechanical isolation hybrid inviability gametic isolation a geographic barrier

temporal isolation