Exploring Evolution

Hypertension is a disease of civilization and this post briefly explains how changes in lifestyle may have been associated with its rise. Relying heavily on convenient processed food. Excess sodium consumption has a direct effect on blood pressure. More salt equals more sodium in the blood, which draws water from surrounding tissues into your vessels and increases blood volume. A high-processed-food diet can lead to weight gain, and when people are overweight, the body must pump blood to more tissue, which can raise blood pressure. Having more than one alcoholic drink in a day. Moderate alcohol consumption (one drink per day for women, two drinks per day for men) is often not a problem for people who already drink, and some research suggests it may even help prevent heart disease. However, excessive alcohol consumption, particularly binge drinking episodes, can result in chronically elevated blood pressure. Binge drinking has been linked to an increased risk of developing a...

Speciation is the process by which species develop. It is an evolutionary process of the formation of new and distinct species. The species evolve by genetic modification. The new species are reproductively isolated from the previous species, that is the new species cannot mate with the old species . In parapatric speciation there is no specific extrinsic barrier to gene flow. The population is continuous, but nonetheless, the population does not mate randomly. Individuals are more likely to mate with their geographic neighbors than with individuals in a different part of the population's range. In this mode, divergence may happen because of reduced gene flow within the population and varying selection pressures across the population's range.  Allopatric  speciation is speciation that happens when two populations of the same species become isolated from each other due to geographic changes. Sympatric  speciation  is speciation that occurs when two grou...

    Courtship refers to the display of special behavioral patterns by the males and females to attract mating partners.  Male courtship is highly seen in nature, where the males display a wide range of skills or patterns and attract the females for reproduction. Species of birds exhibit male display behavior, species of drosophila also invest energy in the male display.  Female courtship is rarely seen in nature as they invest a lot of their energy in other tasks like producing their energy-expensive gametes and taking care of the progeny. But there are instances where female display becomes necessary like when the competing males are in short supply in the population. Hence, female courtship evolves.  The female species of pipefish displays a temporary striped pattern ornament to attract males and also to intimidate other competing females.  

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...