Macroevolution

Macroevolution is a term used by Creationists to distinguish between what they perceive as different processes within the Theory of Evolution. However, scientists do not make this distinction, noting that the only difference between micro and macro evolution is the amount of time involved.

Macroevolution refers to the theory that natural selection can, given enough time, lead to the creation of new clades, which are groups of organisms consisting of a single common ancestor and all the descendants of that ancestor. While details of macroevolution are continuously studied by the scientific community, the overall theory behind macroevolution (i.e. common descent) has been overwhelmingly consistent with empirical data. Predictions of empirical data from the theory of common descent have been so consistent that biologists often refer to it as the on as the "fact of evolution".

Creationists accept that evolutionary change is possible within species ("microevolution"), but deny that one species can evolve into another ("macroevolution"). These arguments are rejected by mainstream science, which holds that there is ample evidence that macroevolution has occurred in the past.

Methods of Macroevolution

natural selection - is the mechanism by which allele frequency within a population changes over time due to genetic variation and selection pressures.

genetic drift - is the statistical effect that results from the influence that chance has on the survival of alleles.

sexual selection - is the hypothesis proposed by Charles Darwin that states that the frequency of traits can increase or decrease depending on the attractiveness of the bearer.

neutral evolution - is the vast majority of molecular differences are selectively "neutral." The molecular changes represented by these differences do not influence the fitness of the individual organism. As a result, these genomic features are neither subject to, nor explicable by, natural selection.

allopatric speciation - is when a population splits into two geographically isolated allopatric populations then undergo genotypic and/or phenotypic divergence as they become subjected to dissimilar selective pressures or they independently undergo genetic drift.

peripatric speciation - is when new species are formed in isolated, small peripheral populations which are prevented from exchanging genes with the main population.

parapatric speciation - is when the zones of two diverging populations are separate but do overlap.

sympatric speciation- is when species diverge while inhabiting the same place.

See also

• Microevolution
• Theory of evolution