what part of darwin's natural selection theory couldn't he explain? whose work was discovered after darwin's death to fill gaps in his theory? people lease respond!!!!

Question

anonymous · Answer

The first main problem was that Darwin relied on the purely observational evidence of *inheritance* and *variation* ... but did not have an understanding of how inheritance worked, or how variation was replenished rather than species evolving to a state of uniform "fitness" with no variation.

This was solved with the discovery of genetics as the basis of heredity, and the many mechanisms of *mutation*, which is the source of new variation, as well as the mechanics of sexual recombination.

The second main problem is that there are clearly traits that can survive in a population despite the fact that they are not subject to selection, or in some cases are harmful, and we would expect them to disappear completely due to selection.

This was solved with the understanding of recessive genes and with the concept of genetic drift, which is a key part of the field called population genetics.

A third problem was that the fossil record occasionally showed sporadic and relatively "sudden" (by geological timescales) appearances of major new forms. This contradicted Darwin's concept of strict gradualism ... that evolution occurred at a steady, invariant pace.

This was solved with our understanding of punctuated equilibrium ... the fact that organisms can remain in a state of slow evolution (equilibrium) for long periods of time, interrupted (punctuated) by periods of rapid evolution. The periods of rapid evolution could follow a mass extinction, or a discovery of some new feature or principle that increases 'evolvability' in some branch of organisms.

There has been a lot of scientists that helped to refine Darwin's theory of evolution, but I think the most important are Gregor Mendel (discovery of genetics), August Weismann (germ plasm theory), T. H. Morgan (mutation theory), JS Gould (punctuated equilibrium theory), among many others.

anonymous · Answer

okay thanks!