AP Biology: 18.2 Formation of New Species

hybrid inviability

when hybrid individuals cannot form normally in the womb and simply do not survive past the embryonic stages

hybrid sterility

when reproduction leads to birth and growth of a hybrid that is sterile and unable to reproduce offspring of their own

what are the only two ways variation can be passed to the next generation within a species?

-asexual reproduction (reproducing cell possesses the changed trait) -sexual reproduction (gamete must possess the changed trait.)

what are the two groups of allopatric speciation?

-dispersal (few members of a species move to a new geographical area) -vicariance (natural situation arises to physically divide organisms)

Which situation would most likely lead to allopatric speciation? A. A flood causes the formation of a new lake. B. A storm causes several large trees to fall down. C. A mutation causes a new trait to develop. D. An injury causes an organism to seek out a new food source.

A; A flood causes the formation of a new lake

Which type of speciation, allopatric or sympatric, is more common? Why? A. Allopatric speciation is more common because it prevents gene flow between the species. B. Allopatric speciation is more common because it involves stronger prezygotic barriers. C. Sympatric speciation is more common because it prevents gene flow be tween the species. D. Sympatric speciation is more common because it involves stronger prezygotic barriers.

A; Allopatric speciation is more common because it prevents gene flow between the species.

What is unique about speciation due to adaptive radiation? A. It leads to multiple species forming from one parent species. B. It only occurs on or around island archipelagos. C. It requires a population to disperse from its parent species. D. It is a special kind of sympatric speciation.

A; It leads to multiple species forming from one parent species.

What are two primary sources of genetic variation? A. Mutations and sexual reproduction B. Isolation and sexual reproduction C. Sexual reproduction and asexual reproduction D. Migration and sexual reproduction

A; Mutations and sexual reproduction

What is least likely to be a factor that increases the probability of speciation by adaptive radiation? A. There are vacant ecological niches nearby. B. Genetic drift in a population increases. C. There are isolated regions with suitable habitats. D. There are few competitor species.

B; Genetic drift in a population increases.

What role do prezygotic and postzygotic barriers play in speciation? A. Prezygotic and postzygotic barriers allow for the formation of less - fit hybrids that reinforces speciation. B. Prezygotic and postzygotic barriers prevent interbreeding of species such that there is no gene flow between them. C. Prezygotic and postzygotic barriers prevent migration of the two species, causing them to remain in contact with each other and begin to interbreed. D. Prezygotic and postzygotic barriers are present only in newly formed species, allowing scientists to identify the time of divergence of the species.

B; Prezygotic and postzygotic barriers prevent interbreeding of species such that there is no gene flow between them.

In a hybrid zone, in addition to interacting, what else do two closely related species do? A. Compete B. Reproduce C. Transition D. Fuse

B; Reproduce

Which statement best describes the relationship between genetic variation and speciation? A. Without genetic variation, speciation would occur more slowly. B. Without genetic variation, speciation would not be possible. C. Genetic variation influences sympatric speciation, but not allopatric speciation. D. There is no relationship between genetic variation and any form of speciation.

B; Without genetic variation, speciation would not be possible.

If a population stopped reproducing sexually, but still reproduced asexually, how would its genetic variation be affected over time? Could speciation occur in this situation? A. Genetic variation would increase, and speciation would be possible . B. Genetic variation would increase, and speciation would not be possible. C. Genetic variation would decrease, and speciation would be possible. D. Genetic variation would decrease, and speciation would not be possible.

C; Genetic variation would decrease, and speciation would be possible.

What do scientists focus on to distinguish between species? A. Ecological niches B. Morphological differences C. Reproductive barriers D. Genetic changes

C; Reproductive barriers

What is the main difference between an autopolyploid individual and an allopolyploid individual? A. Number of extra chromosomes B. Functionality of extra chromosomes C. Source of extra chromosomes D. Number of mutations in the extra chromosomes

C; Source of extra chromosomes

Which situation is an example of a prezygotic barrier? A. Two species of fish produce sterile offspring. B. Two species of flowers attract different pollinators. C. Two species of insects mate, but the zygote does not survive. D. Two species of lizards mate, but the offspring dies before reproducing.

C; Two species of insects mate, but the zygote does not survive.

Until recently, three species of short-tailed pythons, Python curtus, Python brongersmai, and Python breitensteini were considered one species. However, due to the different locations in which they are found, they have become three distinct species. What is this an example of? A. divergent evolution B. sympatric speciation C. allopatric speciation D. variation

C; allopatric speciation

Which statement best describes what happens when an antibiotic is applied to a population of bacteria? A. The bacteria develop resistance to the antibiotic in direct response to its application. B. The bacteria's genetic material mutates in response to the antibiotic, resulting in resistance. C. A gene for resistance, already present in the population, decreases in frequency D. A gene for resistance, already present in the population, increases in frequency

D; A gene for resistance, already present in the population, increases in frequency.

Which option is the best definition of species? A. A group of individual organisms with significant genetic similarities B. A group of individual organisms with significant genetic similarities that share external and internal characteristics C. A group of individual organisms that interbreed D. A group of individual organisms that interbreed and produce viable, fertile offspring

D; A group of individual organisms that interbreed and produce viable, fertile offspring

Using adaptive radiation , how can the diversification of the finches Darwin observed in the Galapagos be explained? A. The finches likely shared a common ancestor when they came to the island, but exhibited different traits. Each species of finch settled the island where its particular traits would be the most adaptive. B. The finches likely originated as one parent species, but over time mutations caused them to develop reproductive barriers and separate into different species. To reduce competition, the species then radiated out to inhabit different islands. C. The finches likely dispersed from one parent species, and natural selection based on different food sources in differing habitats led to adaptive changes, evidenced in the different beak shapes of the different species , each suited to a different food type. D. It is likely that a series of cataclysmic events caused an original finch species to diverge into the many finch species that inhabited the islands when Darwin observed them. The different species then radiated out to the different islands and adapted to the different conditions on each.

D; It is likely that a series of cataclysmic events caused an original finch species to diverge into the many finch species that inhabited the islands when Darwin observed them. The different species then radiated out to the different islands and adapted to the different conditions on each.

Which situation means reinforcement is more likely to occur in the hybrid zone? A. The hybrid offspring are more fit than the parent species. B. Reproductive barriers weaken. C. The hybrid offspring are about as fit as the parent species. D. Reproductive barriers strengthen.

D; Reproductive barriers strengthen.

Which statement about postzygotic barriers is false? A. They occur after fertilization. B. They include hybrids that are sterile. C. They include hybrid organisms that do not survive the embryonic stage. D. They include reproductive organ incompatibility.

D; They include reproductive organ incompatibility.

what are wheat, cotton, and tobacco plants all a type of?

allopolyploids

postzygotic barriers

block reproduction after fertilization occurs -hybrid inviability -hybrid sterility ex: darwin's finches, northern and mexican spotted owls, and hawaiian honeycreeper

prezygotic barriers

block reproduction prior to formation of a zygote -temporal isolation -habitat isolation -behavioral isolation -gametic barrier

polyploidy

cell or organism has an extra set, or sets, of chromosomes -error in meiosis in which all of the chromosomes move into one cell instead of separating -autopolyploidy=individual will have two or more complete sets of chromosomes from its own species -allopolyploid= when individuals of two different species reproduce to form a viable offspring

microevolution

changes in allele frequencies within a population over generations

gene pool

collection of all the variants of genes in the species

temporal isolation

differences in breeding schedules -type of reproductive isolation

gametic barrier

differences in their gamete cells (eggs and sperm) prevent fertilization

macroevolution

evolution of new species when populations diverge from a common ancestor and become reproductively isolated from the original population

speciation

formation of two species from one original species -evolve in such a way that it becomes impossible for individuals from the two new populations to interbreed

allopatric speciation

geographic separation -"other" 'homeland" - free-flow of alleles is prevented -gene pool=homogeneous -frequency of an allele at one end of a distribution will be similar to the frequency of the allele at the other end -environmental conditions within two populations differs=natural selection favors divergent adaptations

species

group of individual organisms that interbreed and produce fertile, viable offspring -species are distinguished from one another if it is not possible for matings between individuals from each species to produce fertile offspring -closer relationship two organisms share, the more DNA they have in common -share gene pool

what is the only type of trait that can evolve?

heritable

reproductive isolation

inability to interbreed due to the genetic and phenotypic differences of two populations that result in non-viable or infertile offspring -prezygotic (blocks reproduction) and postzygotic (after zygote formation) barriers

hybrid

mating between two different species -inviable and sterile ex: mule (horse x donkey)

sympatric speciation

mechanisms that occur within a shared habitat -"same" "homeland" -does not require a geographic barrier -explains how many different species can inhabit the same area -occurs when there is competition for food among species ex: serious chromosomal error during cell division (polyploidy) -cichlid fish in africa's lake victoria

habitat isolation

occurs when populations of a species move or are moved to a new habitat in a place that no longer overlaps with the other populations of the same species -specie becomes genetically independent

biological species

organisms that combine genetic information by sexual reproduction and produce viable and fertile offspring

behavioral isolation

presence or absence of a specific behavior prevents reproduction from taking place ex: fireflies' light patterns for mating; whale calls

adaptive radiation

single ancestral species gives rise to many new species -population of one species disperses throughout an area, and each population finds a distinct niche or isolated habitat-varied demands of their new lifestyles lead to multiple speciation events originating from a single species ex: hawaiian honeycreeper, darwin's finches