1. List and describe the mechanisms that can reproductively isolate species and prevent them from interbreeding....

1. List and describe the mechanisms that can reproductively isolate species and prevent them from interbreeding. Explain speciation and how it might benefit or harm a population.

2. Describe the various types of fossils and the unique circumstances under which they can form. Next, list and describe conditions that will prevent fossilization. What kinds of organisms are most likely and least likely to be preserved as fossils? Explain how fossils can illustrate the lineage between an ancestor species and its modified present-day descendants. Now, compare and contrast relative and radiometric dating. Finally, interpret a fossil record using a combination of relative and radiometric dating to order and date the fossils it contains.

Expert Solution

1. A species consists of group of individuals with similar basic characters which can interbreed under natural conditions and produce fertile offsprings. The formation of new species from the existing species is called speciation. For speciation reproductive isolation is must as it helps in accumulation of variations leading to speciation. Reproductive isolation prevents gene flow between sister-populations and thus the population splits into two independent species

The various mechanisms that reproductively isolate species and lead to speciation include geographical barriers, ecological barriers, genetic drift, DNA changes in the germ cells etc.

Geographical barriers(glaciers, oceans or mountain ranges) restrict gene flow between sub-populations and make them reproductively isolated. The migration of individuals to new area which is reproductively isolated from original range also leads to speciation. These populations become different from each other due to genetic drift and natural selection which operate differently in these different geographical areas.

Within the same geographical area the population may become reproductively isolated and lead to speciation due to ecological barriers ( having different habitats) or due to ethological barriers ( having different breeding behaviours) .

A sudden, large and inheritable change in the genetic material (DNA) can also lead to speciation. It may involve change in the nucleotide pairs of a gene or change in the chromosomes of germ cells of an individual. These species may be morphologicaly similar but reproductively isolated.

Speciation leads to the formation of evolved species which are better adapted to the environment but sometimes speciation can lead to loss of gene pool.

gladiator answered 2 years ago

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