Stickleback fish th As the fish moved to fresh-water lakes, they lost their spin

Question

Stickleback fish th As the fish moved to fresh-water lakes, they lost their spines. This was due to at live in the ocean have spines to protect against large-mouthed predators. a spontaneous mutation. D the lack of predators in lakes. gene flow between species with and without spines a mutation in the regulatory region of a developmental gene barrier? Which one of the following is an example of behavioral isolation leading to a prezygotic The females of one species of cichlid fish prefer to mate with males on one color, while the females of another species of cichlid fish prefer to mate with males of different color Mating between a horse and a donkey produces a healthy but infertile offspring. A northern species of skunk mates in the spring, while a southern species of skunk mates in the fall. Two related species of sea urchin breed in the same area, but incompatible surface proteins prevent the sperm of one species of sea urchin from fertilizing the ege of the other sea urchin species. 3. A farmer uses a strong herbicide to control a weed in his field. For the first few years, the pesticide works well and almost all the weed dies; but after several years, the farmer sees more and more weeds. Which of these explanations best describes this observation? Only herbicide resistant weeds survived and reproduced, so each year more weed was herbicide resistant. The herbicide company lost its original formula and started selling poor-quality herbicide Herbicide X-resistant weed has less efficient photosynthesis metabolism. Natural selection caused the weed to mutate, creating a new Herbicide resistant species. 4.) An earthquake almost destroys the squirrel population. The surviving population happens to have broader stripes on average than the initial population, If broadness of stripes is genetically determined, what effect has the squirrel population experienced during the earthquake? disruptive selection a founder event directional selection dgene flow a genetic bottleneclk

Explanation / Answer

Answer of question 1- A mutaion in the regulatory region of of a developmental gene because it was found that Pitx1 gene expression was active in the incipient pelvic girdle of marin sticklebacks but it was not expressed in fresh water sticklebacks fish. In both marine and fresh water sticleback the Pitx1 gene was active elsewhere in the body so it suggested that a change in gene regulation and not change in the gene itself causes the loss of sticlebacks spine of fresh water.

Answer of question 2- The answer of question 2 is (a) because in this prezygotic isolation species differ in their ritual mating which tend to keep these species distinct in nature even they have same place, matching of sound production, visula signals,, courtship rituals,, detection by chemical signals, detection by color etc are the exampe of prezygotic behavioral isolation.

Answer of question 4- The answer is founder efffect (b) because when a few individuals isolated from larger population size, the remaining small group will establish a new gene pool deffer from source is called founder effect.

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