Chromosome is to cactus as gene is to needle.
<span>The need for a polymerase that wouldn't denature at high temperature. Obviously, organisms that live in hot springs and the like will have adapted enzymes that can survive at these temperatures.</span>
Speciation is b. the process by which new species are formed. They are often caused by the isolation of certain organisms in terms of environment or geographical area. This is part of the evolutionary changes that various species undergo to brought about by natural selection.
It is an example of directional selection.
The different kinds of natural selection can influence the distribution of phenotypes within a population. In stabilizing selection, an average phenotype is preferred.
In directional selection, a modification in the surrounding changes the spectrum of the observed phenotypes, and in diversifying selection the extreme values for a trait are preferred over the transitional values. This kind of selection usually pushes speciation.
The directional selection, in the field of population genetics, refers to a mode of natural selection in which an extreme phenotype is preferred over other phenotypes, making the allele frequency to change with time in the orientation of that phenotype.
