Exploring Evolution

Genetic variation is the diversity in gene frequencies between the individual or the differences between population. Different sources of genetic variation are mutation, random mating between organisms, crossing over, and random fertilization. Various factors act to maintain the genetic variation in population such as mutation, selective neutrality, balancing selection, frequency dependent selection, and changing patterns of selection over time or space. Mutation is one of the factors which contribute to rare genetic variation in a population. Selective neutrality arises when there is only a small difference in fitness between the alternate allele of a gene. When the alleles are governed by genetic drift rather than natural selection they are selectively neutral. Balancing selection arises when the heterozygotes have higher fitness than the two homozygous genotypes. These allow both the alleles to be maintained in a population. Frequency dependent selection happen when the individuals ...

    Evolution by natural selection occurs when certain genotypes produce more offspring than other genotypes in response to the environment. It is a non-random change in allele frequencies from one generation to the next .  Charles Darwin described four necessities for evolution by natural selection to occur which are; the trait under selection must be  variable  in the population so that the encoding gene has more than one variant or allele, the trait under selection must be  heritable , encoded by a gene or genes, the struggle of existence that many more offspring are born than can survive in the environment, and that individuals with different alleles have  differential survival and reproduction  that is governed by the fitness of the organism to its environment. Evolution by   natural selection  occurs when the environment exerts a pressure on a population so that only some phenotypes survive and reproduce successfully. The stro...

    From my research, I might have gathered that inbreeding interrupts the evolution of assortative mating. There are several models of assortative mating that show increase of homozygosity in each population, and the theory and empirical data showing benefits of inbreeding is abundant, however studies showing the relationship of the two seem to be basically absent. A study conducted by some graduate students at Uppsala University in 2009 aims at studying the interaction between assortative mating and inbreeding by using the population Cowpea weevil, Callosobruchus maculatus. After six generations of inbreeding, the results show that female fertility was indeed affected by inbreeding depression; females laid fewer eggs after mating with males that were closely related. Both the number of eggs laid, and individuals hatched were significantly reduced over generations, which highlights that inbreeding reduces female fecundity and reproductive rate. The study also indicates that s...

   Migration is a phenomenon which is used to describe movement of individual organisms from one place to another. It takes place when individuals are moved through random mating from one subpopulation to another, when gametes move from one place or subpopulation to another which is then followed by fertilization. Migration results in continuation of gene flow .  Gene flow is referred to the movement of alleles between populations. Migration can be local or long distanced. The phenotypes A, B, C and D according to the question, are alleles from the continent which represents a large fraction of the island gene pool. The gene frequencies in the continent are not affected due to the alleles from the island. Chromosome banding refers to alternating light and dark regions along the length of a chromosome, produced after staining with a dye. Banding is controlled by a single locus. Let us assume, AA and Aa individuals are banded and aa are not banded. From Ontario an...