What mechanisms account for speciation and macroevolution?

// What different patterns of evolution have been identified and what mechanisms are responsible for each of these patterns?





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Heredity and Evolution -- Evolutionary Biology


(Topic: Mechanisms of Evolution)
What mechanisms account for speciation and macroevolution?
Four main types of speciation:





- Allopatric (geographic).


- Peripatric (mostly geographic)


- Parapatric (somewhat geographic)


- Sympatric (non-geographic)





As in your last question, the following site can explain things better with illustrations than I can here:


http://en.wikipedia.org/wiki/Speciation





As for the relationship between speciation and macroevolution ... the mechanisms for speciation is part of *both* microevolution and macroevolution ... since microevolution is defined as evolution at or below the level of species ... while macroevolution is evolution at or above the level of species (and thus both include evolution *at* the level of speciation).





In other words, speciation is both a result of the same processes of evolution responsible for slow change in a single species ... *and* is the mechanism by which macroevolution (further diversification of species, birth of new genera,families, etc) occurs.
Reply:Anything that causes mutation is sufficient to account for "macro-evolution". All you need is sufficient time for changes to make the two separated populations no longer viable.





One of the common arguments against speciation is the lack of increased information. Examples of changing the "information" is a type of mutation known as an insertion or sometimes deletion. Eukaryotic Organisms have evolved a mechanism to randomly insert transportable segments of DNA known as transposums. That is they evolved a method to allow greater evolutionary efficiency.


http://en.wikipedia.org/wiki/Transposabl...


http://en.wikipedia.org/wiki/Speciation#...





Another example of increasing the information is gene duplication. It is basically when entire genes or chromosomes are copied more than once.





You also get various kinds of errors when the genes are crossing over or genetic recombination in Meiosis. If the genes don't match correctly, it often increases the size.


"The result can be a local duplication of genes on one chromosome and a deletion of these on the other, a translocation of part of one chromosome onto a different one, or an inversion."


http://en.wikipedia.org/wiki/Crossing_ov...
Reply:crossing over


natural selection


migration/change in habitat


look 'em up