BIOL 112 Lecture Notes - Lecture 4: Allopatric Speciation, Parapatric Speciation, Sympatric Speciation

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kurtzkm

11 Apr 2019

School

College of Charleston

Department

Biology

Course

BIOL 112

Professor

Harold

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Document Summary

If gene flow stops, allele frequencies in isolated populations can diverge. Divergence may occur as a result of mutation, natural selection, and genetic drift. This genetic divergence may eventually result in speciation. Speciation is a splitting event that creates two or more distinct species from an ancestral species. Genetic isolation happens when populations become geographically separated. Populations that live in different areas are in allopatry. Speciation that begins with geographic isolation is called allopatric speciation. A physical barrier splits a population into subgroups that are physically isolated from each other. A population moves to a new habitat, colonizes it, and founds a new population. Biogeography : the study of how species and populations are distributed geographically. Tells us about occurrence of dispersal and vicariance events. Localized colony diverges from original parent population. Hybrid zone: geographic area where interbreeding between two populations occurs and hybrid offspring are common.

Related Questions

Which of the following statements best explains the process of allopatric speciation?

Genetic differences accumulate between populations that are isolated by a geographic barrier, eventually leading to reproductive isolation.

Genetic differences accumulate through recombination between populations that are interbreeding, eventually leading to reproductive isolation.

Genetic differences accumulate in a population through selective mate choice, leading to two groups that breed independently, causing reproductive isolation.

Two populations in the same geographical area accumulate genetic differences by random chance, eventually leading to reproductive isolation.

Genetic changes within a population as the result of genetic drift influences traits involved with mate choice, eventually leading to reproductive isolation.

What is the basic difference between allopatric and sympatric modes of speciation?

Sympatric speciation takes place between populations that migrate away from each other.

Sympatric speciation takes place between populations in the same geographic area.

Allopatric speciation takes place between populations in the same geographic area.

Sympatric speciation takes place over long periods of time; allopatric speciation occurs within a single generation.

Allopatric speciation is thought to occur much less frequently than sympatric speciation.

sangriaswan287

1. Scientists found that different beak shapes lead to differentmating songs in Darwin's finches. This result best supports whichhypothesis?

	A. Darwin's finches are not different species according to theBiological Species Concept.
	B. Behavioral isolation in Darwin's finches is unrelated to beakshape.
	C. Adaptation to different food sources likely occurred afterreproductive isolation in Darwin's finches.
	D. Adaptation to different food sources indirectly led tobehavioral isolation in Darwin's finches.

2. Which of the following could occur if two partiallyreproductively isolated populations become sympatric? Check allthat apply.

	A. Gene flow between the populations will occur
	B. The populations may eventually become separate speciesthrough reinforcement
	C. The populations will continue to be partially reproductivelyisolated
	D. The populations may eventually lose their geneticdistinctiveness
	E. Hybrids will be inviable or infertile

3. In which population would the rate of genetic drift be thegreatest?

	A large population that is geographically isolated from itsparent population
	A small population that is geographically isolated from itsparent population
	A large population that is not completely geographicallyisolated from its parent population
	A small population that is not completely geographicallyisolated from its parent population

4. Indicate true or false that the following organisms would beconsidered separate species according to the biological speciesconcept. (T/F)

1. Lions and tigers can interbreed successfully to produce viable,fertile offspring, but lions live in open grasslands and tigerslive in dense forests. (T/F)
2. Black bears in the United States can have coat colors rangingfrom blonde to jet black, but bears with different coat colorsoccupy the same habitat and interbreedsuccessfully. (T/F)
3. Many leopard frogs in the eastern United States look the sameand can mate to produce a fertilized egg, but the embryo does notdevelop past the early stages. (T/F)
4. Many of Darwin

cyanbuffalo931

1). Thyroid hormone (TH) has been identified as one of the factors promoting phenotype development in the Mexican axolotl salamander. Which of the following statements regarding the impact of TH is FALSE?

A). Axolotls maturing in water with high concentration of TH (thyroxine; T4) metamorphose into a terrestrial form.

B). A genome-wide scan of both the axolotl and its sister species found a large reduction in the number of mRNA transcripts that regulate the production of TH.

C). Adding TH (thyroxine; T4) to the water in which axolotl individuals are reared causes them to remain in a larval stage.

D). Most salamander species produce a burst of TH when they move from water to land.

2).What would be an appropriate evolutionary explanation of the fact that the ordering of some homeotic genes (such as Hox genes) on vertebrate chromosomes parallels the ordering of homeotic genes on fruit fly chromosomes?

A). The similarity is a coincidence, not documented in other invertebrates and largely a result of random mutations.

B). Homeotic genes show that insects and vertebrates are closer relatives than the traditional classification system indicates.

C). Homeotic genes of different animal lineages might be ordered in a similar fashion, yet their sequences are completely different.

D). The similar ordering of homeotic genes in animals, both vertebrate and insect, is due to ancient homology.

3). Which of the following correctly defines "homeotic genes"?

A). Homeotic genes encode proteins that control the cellular environment in a differentiated cell tissue.

B). Homeotic genes are DNA sequences that turn off, but not on, the expression of other genes and are controlled by "master-switch" genes.

C). Homeotic genes are "master-switch" genes that control other genes in a set sequence and thereby affect cell size, shape, division, and the positioning of the cells within the organism.

D). Homeotic genes are DNA sequences that turn on, but not off, the expression of other genes and are controlled by "master-switch" genes.

4). Which of the following is NOT considered a type of heterochrony (change in the rate and timing of development)?

A). hypermorphosis

B). acceleration

C). neoteny

D). ontogeny

5). How does the dominance theory explain why the heterogametic sex is at a disadvantage in Haldane's rule?

A). Beneficial dominant alleles will never be fully expressed in hybrids as they only carry one copy of the sex chromosome that carries the allele.

B). If a dominant allele has a negative effect on the fitness of hybrids, it will always be expressed in the heterogametic hybrids that possess that allele because they only need one copy of the respective sex chromosome.

C). If a recessive allele linked to a sex chromosome has a negative effect on the fitness of hybrids, that allele will always be expressed in the heterogametic hybrids that possess that allele because they only have one copy of the sex chromosome that carries the allele.

D). If a recessive allele linked to a sex chromosome has a positive effect on the fitness of hybrids, that allele will never be expressed in the heterogametic hybrids that possess that allele because they only have one copy of the sex chromosome that carries the allele.

6). In a hypothetical flowering plant species, one population evolves a different response to environmental stimuli and begins to bloom significantly later in the season than nearby populations. What type of reproductive isolating mechanism would this be?

A). hybrid sterility

B). postzygotic

C). prezygotic

D). gametic incompatibility

7). In a study of red spruce trees and black spruce trees, scientists found that the red spruce was living in a smaller geographic area and had much less genetic variation than the black spruce. They proposed that the red spruce might have arisen from a southern population of black spruce, which became geographically isolated from other black spruce populations at some point during the Pleistocene glaciations. What is this an example of?

A). allopatric speciation with the vicariance model

B). sympatric speciation

C). allopatric speciation with the peripheral isolate model

D). sympatric speciation with the ring species model

8). Which of the following defines Haldane's rule and its predictions?

A). If among hybrid offspring one sex is absent, rare, or sterile, that sex is always male.

B). If among hybrid offspring one sex is absent, rare, or sterile, that sex is always female.

C). If among hybrid offspring one sex is absent, rare, or sterile, that sex is heterogametic (has two different sex chromosomes).

D). If among hybrid offspring one sex is absent, rare, or sterile, that sex is homogametic (has two of the same sex chromosomes).

8.) Which of the following statements best explains secondary reinforcement?

A). If the reproductive isolating mechanisms that developed during the geographic isolation are strong but the hybrids have higher fitness than the parent species, then the speciation process will cease.

B). If the reproductive isolating mechanisms that developed during the geographic isolation are somewhat weak but the hybrids between two populations have lower fitness, then the speciation process may continue.

C). If the reproductive isolating mechanisms that developed during the geographic isolation are sufficiently weak as to allow free interbreeding across reunited populations, then the speciation process will halt and a single species will remain.

D). When geographic isolation comes to an end, two populations always complete the divergence process and become separate species.

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BIOL 112 Lecture Notes - Lecture 4: Allopatric Speciation, Parapatric Speciation, Sympatric Speciation

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