![]() This also helps reduce the risks associated with inbreeding, the mating of closely related individuals, which can have the undesirable effect of bringing together deleterious recessive mutations that can cause abnormalities and susceptibility to disease. When scientists are involved in the breeding of a species, such as with animals in zoos and nature preserves, they try to increase a population’s genetic variance to preserve as much of the phenotypic diversity as they can. The diversity of alleles and genotypes within a population is called genetic variance. The greater the hereditability of a population’s phenotypic variation, the more susceptible it is to the evolutionary forces that act on heritable variation. Heritability is the fraction of phenotype variation that can be attributed to genetic differences, or genetic variance, among individuals in a population. Link to Learningīefore Darwinian evolution became the prevailing theory of the field, French naturalist Jean-Baptiste Lamarck theorized that acquired traits could, in fact, be inherited while this hypothesis has largely been unsupported, scientists have recently begun to realize that Lamarck was not completely wrong. ![]() If there is a genetic basis for the ability to run fast, on the other hand, this may be passed to a child. For example, if an athlete works out in the gym every day, building up muscle strength, the athlete’s offspring will not necessarily grow up to be a body builder. Acquired traits, for the most part, are not heritable. ![]() ![]() Because alleles are passed from parent to offspring, those that confer beneficial traits or behaviors may be selected for, while deleterious alleles may be selected against. Natural selection and some of the other evolutionary forces can only act on heritable traits, namely an organism’s genetic code. ![]()
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