Answer to Question #188164 in Evolution for juanita

Question

discuss the role of gene flow in evolution. and the attributes of biological species that ensure that different species do not interbreed

Answer 1

The spatial movement of genes is called gene flow. When an individual migrates from one population to another, it carries genes that are representative of its own ancestral population into the recipient population. If it successfully establishes itself and breeds it will transmit those genes between the populations. The transfer of genes is called gene flow. If the two populations originally had different gene frequencies and if selection is not operating, migration (or, to be exact, gene flow) alone will rapidly cause the gene frequencies of the different populations to converge.

Members of two species may appear very similar, yet fail to interbreed because of reproductive barriers. Barriers to reproduction may either prevent mating, or prevent development of a fertilized egg after mating. Elaborate courtship behaviors, including the blinking pattern of fireflies or the songs of birds, are often required to elicit mating behavior – and limit mating to members of a species. Different breeding seasons, such as flowering dates, can also prevent interbreeding. Molecular differences between even closely related species may prevent sperm or pollen from actually fertilizing eggs. Once the eggs are fertilized, chromosomes may be so incompatible that mitosis and meiosis cannot proceed normally; if the zygote cannot develop, offspring do not survive. All of these barriers between species work to ensure successful reproduction within species, keeping specific, useful adaptations “in the family;" thus, they are a logical way for us to distinguish members of one species from members of another.