7. Imagine that on your visit to a mythical island near a mythical continent you observe that one species of salamander occurs in several colors, but most of the salamanders are yellow. This same color mix and predominance of yellow occurs on the adjacent mainland. Ten years later you visit the same island and observe that most of the salamanders are blue. Explain this change in color frequency as though it were based solely on each of the following processes. a) Sexual selection - There were a high success in the sexual offspring of the blue salamanders due the high attraction between the opposite sexes. This made sexual reproduction happen more frequent. b) Genetic drift- c) Gene flow- d) Natural selection- There were a selective advantage
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This means that blue salamanders had a higher chance of attracting mates and producing offspring. Over time, this could lead to an increase in the number of blue salamanders on the island. Show more…
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Two subspecies of salamanders in Southeast Asia, salamander S1 and Salamander S2, are thought to have diverged genetically and morphologically through sympatric speciation. At the southern tip of their respective native ranges, they can co-occur in secondary contact. They can mate successfully and produce viable, fertile offspring; the offspring can therefore also reproduce. However, the hybrid offspring have a coloration that is disproportionately attractive and easily detectable by predators, leading to decreased survival. The relatively low fitness of the S1 x S2 hybrid salamander would be an example of: a. postzygotic behavioral isolation b. gametic incompatibility c. mechanical isolation d. reinforcement e. prezygotic isolation Assuming that mating occurs freely in secondary contact, what is the fitness of the parent salamanders S1 and S2 in the scenario? a. low. Fitness involves reproductive success and survival; if survival is low in the offspring, the parents cannot pass their genes on to future generations. b. zero. c. high. Fitness involves reproductive success and survival, the parents are reproductively successful and able to survive. d. high. Fitness of the parents is not related to the fitness of the progeny. e. none of the above
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9. Salamanders are amphibians with very interesting mating rituals. The males perform species-specific dances that attract females to mate. Male salamanders deposit spermatophores (mucus packets filled with sperm) on leaves, twigs, or the ground and guide females over them so females can take them up into their cloaca. Mating dances like this result in internal fertilization in many salamander species. Why are salamanders not entirely terrestrial in spite of exhibiting internal fertilization in many species? [4 pts]
Two distinct phenotypes are found in the salamander Plethodon cinereus: a red form and a black form. Some biologists have speculated that the red phenotype is due to an allele that is dominant over an allele for black. Unfortunately, these salamanders will not mate in captivity, so the hypothesis that red is dominant over black has never been tested. One day, a genetics student is hiking through the forest and finds 30 female salamanders, some red and some black, laying eggs. The student places each female with her eggs (about 20 to 30 eggs per female) in a separate plastic bag and takes them back to the lab. There, the student successfully raises the eggs until they hatch. After the eggs have hatched, the student records the phenotypes of the juvenile salamanders, along with the phenotypes of their mothers. Thus, the student has the phenotypes for 30 females and their progeny, but no information is available about the phenotypes of the fathers.Explain how the student can determine whether red is dominant over black with this information on the phenotypes of the females and their offspring.
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