explain each in terms of natural selection1.convergent evolution and the similarities among species in a particular biome. 2. insecticide...

Convergent evolution is the
same biological trait in two species derived from different ancestry, within a biome. If
that trait provides an advantage to the organism, it would be fit and could potentially
reproduce and pass it down to offspring. It could also be called an
analogous trait. For example, a bird has a wing and a
butterfly has a wing however, bird wings contain bones and muscle and butterfly wings
are more membranous. Although both can fly, their traits were not arrived at from common
ancestry. Insecticide resistance is due to the fact that
not all individuals in a species are exactly alike, according to the natural selection
theory and due to pressure in the environment, for example, an insecticide, those with
the best adaptations will live and pass on those adaptations. Perhaps when spraying
insecticide, most insects will die, but a few will have a natural resistance in their
genetic makeup. Those individuals will survive and pass this resistance gene to their
offspring. Speciation and isolation has to do with the fact
that if two species are separated geographically, for example, for a long period of time
and then, if they should at some point, be reunited, if they can no longer produce
viable offspring, they are considered two different species. While they were separated,
different environmental adaptations would be selected for in each different environment
the two populations inhabited. Therefore, after a long period of time, they may have so
many differences, they can no longer interbreed. An example is the Galapagos Island
finches. The theory is that an ancestral group of finches emigrated from Ecuador to the
Galapagos and over a 2 million year separation, evolved into several new finch species.
Heterozygote advantage illustrates why some genetic
mutations persist in a population although they seem to be detrimental. An example of
this is the gene for sickle cell anemia. The gene for sickle cell is codominant to
normal red blood cells. There are three genotypes then, NN(normal) ss(sickle cell
anemic) and NS(trait). The people in countries with malaria, who are heterozygous or
have sickle cell trait (NS) actually have an advantage. They don't usually get the
disease malaria. Thus, the heterozygotes have an advantage that people with normal red
cells or sickle cells, don't have.