Evidence In Evolution

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by CL718
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Evolutionary Biology

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Evidence In Evolution

Fossil Record By Darwin's time, scientists knew that fossils were the remains of ancient life and that different layers of rock had formed at different times. By comparing fossils from older rock layers to younger ones scientists could show that life had changed over time. Darwin noticed that the sizes, shapes, and varieties of related organisms preserved in the fossil record changed over time. Darwin argued that the fossil record proved that living things had been evolving for millions of years.

Evidence in Evolution By: Cole Lackowski

Chemical and Anatomical SimilaritiesEvidence of evolution can be found in living animals. The limbs of reptiles., bids, and mammals vary greatly in form and function but are all constructed from the same basic bones. Each limb has adapted in various ways to allow organisms to survive in their environment. Despite different functions these limb bones all develop from the same clumps of cells in embryos. Homologous structures provide strong evidence that all four-limbed vertebrates have descnded, with modifications, from common ancestors. Not all homologous tructues serve important functions. The organs of many animals are reduced in size to the point where they are just traces of homologous organs in other species. An organism may possess an organ with little or no function since it may not affect an organism's ability to survive and reproduce. Natural selection would not cause the elimination of that organ.

Phylogenetics: the branch of life science concerned with the analysis of molecular sequencing data to study evolutionary relationships among groups of organisms. Cladistics: the classification of organisms based on the branchings of descendatn lineages from a common ancestor.Phylogeny: the history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms. Clade is a life-form group consisting of an ancestor and all its descendants representing a single "branch" on the "tree of life ".

The study of one type of evidence of evolution is called embryology, the study of embryos. An embryo is an unborn (or unhatched) animal or human young in its earliest phases. Embryos of many different kinds of animals: mammals, birds, reptiles, fish, etc. look very similar and it is often difficult to tell them apart. Many traits of one type of animal appear in the embryo of another type of animal. For example, fish embryos and human embryos both have gill slits. In fish they develop into gills, but in humans they disappear before birth. This shows that the animals are similar and that they develop similarly, implying that they are related, have common ancestors and that they started out the same, gradually evolving different traits.

Natural selection is the gradual process by which heritable biological traits become either more or less common in a population as a function of the effect of inherited traits on the differential reproductive success of organisms interacting with their environment. It is a key mechanism of evolution. Natural selection acts on the phenotype, or the observable characteristics of an organism, but the genetic (heritable) basis of any phenotype that gives a reproductive advantage may become more common in a population (see allele frequency). Over time, this process can result in populations that specialise for particular ecological niches and may eventually result in the emergence of new species.

Geographic DistributionBiogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, isolation and habitat area. Biogeography comprises two disciplines: historical biogeography, which is concerned with the origins and evolutionary histories of species on a long time scale, and ecological biogeography, which deals with the current interactions of species with their environments and each other on a much shorter time scale.


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