A population of interbreeding birds has been split by a geological event after which the isolated part of the population started to evolve into an incipient species with different mating rituals. Due to a recent environmental change the two populations are now able to potentially mate again in what is called a hybrid zone. Mating does take place every now and then but the hybrid offspring appear less able to survive. As a consequence, mating rituals start to diverge even further. We call this process of continued divergence? O Fusion O Behavioral isolation Reinforcement O Postzygotic isolation O Stability

A population of interbreeding birds has been split by a geological event after which the isolated part of the population started to evolve into an incipient species with different mating rituals. Due to a recent environmental change the two populations are now able to potentially mate again in what is called a hybrid zone. Mating does take place every now and then but the hybrid offspring appear less able to survive. As a consequence, mating rituals start to diverge even further. We call this process of continued divergence? O Fusion O Behavioral isolation Reinforcement O Postzygotic isolation O Stability

Human Biology (MindTap Course List)

11th Edition

ISBN:9781305112100

Author:Cecie Starr, Beverly McMillan

Publisher:Cecie Starr, Beverly McMillan

Chapter23: Principles Of Evolution

Section: Chapter Questions

Problem 1CT

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David Hills of Baylor University noted that three closely related species of leopard frog (genus Rana) exhibit substantialbut not completepostzygotic reproductive isolation when crossed in the laboratory. Field surveys of numerous populations in Texas and surrounding states revealed that populations of the three species breed at various times during the year. Data on the breeding schedule of both allopatric and sympatric populations of these species are presented in the Figure below. Interpret the data in the figure and explain how they may demonstrate that these frogs experience prezygotic reproductive isolation in nature. What type of prezygotic reproductive isolation do the data suggest? Source: D.M. Hillis. 1981. Premating isolating mechanisms among three species of the Rana pipiens complex in Texas and southern Oklahoma. Copeia 1981:312-319.
Which of the following is not part of how we define a species? a. Its individuals appear different from other species. b. It is reproductively isolated from other species. c. Its populations can interbreed. d. Fertile offspring are produced.
Figure 18.22 If two species eat a different diet but one of the food sources is eliminated and both species are forced to eat the same foods, what change in the hybrid zone is most likely to occur?
The reproductive isolating mechanism in which two closely related species live in the same geographic area but reproduce at different times is (a) temporal isolation (b) behavioral isolation (c) mechanical isolation (d) gametic isolation (e) hybrid inviability
How Can We Measure Allele Frequencies in Populations? In a population where the females have the allelic frequencies A = 0.35 and a = 0.65 and the frequencies for males are A = 0.1 and a = 0.9, how many generations will it take to reach HardyWeinberg equilibrium for both the allelic and the genotypic frequencies? Assume random mating and show the allelic and genotypic frequencies for each generation.
Half of the worlds population eats rice at least twice a day. Much of this rice is grown in flooded conditions, and different strains of rice are tolerant (survive) or intolerant (die) under these conditions. Rice breeders used genetic crosses to test whether tolerance to flooding is a dominant trait. Researchers used three true-breeding flood-tolerant strains, FR143, BKNFR, and Kurk, and two true-breeding flood- intolerant strains, IR42 and NB, in the crosses. Results were obtained from three sets of crosses and are reported in the Table below: Results of cross of F1 to tolerant parent: F1 plants were crossed with the tolerant parent of the cross. Number of Plants Progeny Analyzed from Intolerant Tolerant Cross Alive Dead Total 1. F2 results of cross: IR42 FR13A 187 77 264 IR42 BKNFR 192 73 265 NB Kurk 142 52 195 2. Results of cross of F1 to intolerant parent: (F1 of IR42 FR13A) IR42 14 17 31 (F1 of IR42 BKNFR) IR42 15 10 25 (F1 of NB Kurk) NB 21 35 56 3. Results of cross of F1 to tolerant parent: (F1 of IR42 FR13A) FR13A 31 0 31 (F1 of IR42 BKNFR) BKNFR 28 0 28 (F1 of NB Kurk) Kurk 40 0 40 Do the data support the hypothesis that the tolerance trait is dominant? Justify your conclusion by explaining the results from each of the three sets of crosses in terms of genotypes and phenotypic ratios. Source: T. Setter et al. 1997. Physiology and genetics of submergence tolerance in rice. Annals of Botany 79:6777.
The first step leading to allopatric speciation is (a) hybrid inviability (b) hybrid breakdown (c) adaptive radiation (d) geographic isolation (e) paedomorphosis
Why might captive-breeding programs that reintroduce species into natural environments fail?
EVOLUTION LINK Could hawthorn and apple maggot flies be considered an example of assortative mating, which was discussed in Chapter 19? Explain your answer.
Natural Selection Affects the Frequency of Genetic Disorders Will a recessive allele that is lethal in the homozygous condition ever be completely removed from a large population by natural selection?
Two species of fish had recently undergone sympatric speciation. The males of each species had a different coloring through which females could identify and choose a partner from her own species. After some time, pollution made the lake so cloudy it was hard for females to distinguish colors. What might take place in this situation?
Prezygotic is isolating mechanisms: a. reduce the fitness of hybrid offspring. b. generally prevent individuals of different species from producing zygotes. c. are found only in animals. d. are found only in plants. e. are observed only in organisms that reproduce aseually.