In a hypothetical situation, a certain species of aphid feeds only on sugar maple trees. In forests of the eastern United States, sugar maples are only one of a number of different tree species. If some of the aphids develop a strong preference for feeding on Black Walnut trees and mate only with other aphids that prefer black walnut trees, then over time, which of the following processes should occur. (Remember, the host species can be considered the aphids' "habitat."): 1.reproductive isolation 2.allopatric speciation 3.habitat isolation 4.prezygotic barriersv

Options for the questions are not given. They are as follows :

A ) 1,2,3

B) 2,3

C)1 ,3, 4

D)1

E) 1 through 4

C) 1,3,4

Explanation:

Some aphids make black walnut trees their habitat in the forest and only prefer to mate with aphids who have the same habitat. This is an example of reproductive isolation since these aphids now have different mating preferences and hence are isolated from rest of the aphids. The isolation occurred on the basis of difference in habitats so it is also an example of habitat isolation. Since the mating is prevented all together it is also an example of prezygotic barrier i.e. formation of zygote is inhibited. However, it is not an example of allopatric speciation since the aphids are not separated geographically from each other. They are present in the same area but have different habitat preference. Hence, option C is correct answer.

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation:

as the gila monster consumes the eggs or young of the desert cottontail and gambel's quail, thus its main food supply is only accessible for a restricted time duration every year. however, for this, the gila monsters exhibit three adaptations, which elevate their survival rate in the desert condition.  

first, is that they possess huge bodies, and can consume greater concentrations of food during a small period. secondly, they require to feed infrequently as they can accumulate fat in their tails. ultimately, their rate of metabolism is very low, so that they can burn their reservoirs of fat gradually.