24 Nov 17
2 edits
Originally posted by @moonbusyes, indeed.
http://www.bbc.com/news/science-environment-42103058
A new species has emerged and we saw it happen.
It says "...This new finch population is sufficiently different in form and habits to the native birds, as to be marked out as a new species, and individuals from the different populations don't interbreed... "
So this new species is at a result of hybridization between two related species but then followed by rapid further changes via evolution so that they are now rapidly become so different in characteristics from either of their two parent species that they no longer interbred with either of their two parent species thus, by any reasonable definition of species, they are now a new species.
This observation of such a rapid species change is yet further evidence in support of punctuated equilibrium (see https://en.wikipedia.org/wiki/Punctuated_equilibrium) although the evidence for punctuated equilibrium was already so strong that it really was already scientific fact.
25 Nov 17
Originally posted by @moonbuswell, just the combination of these mechanisms;
It certainly indicates that evolution proceeds by multiple mechanisms, not only natural selection and genetic mutation.
1, natural selection
2, random genetic mutation and/or the occasional hybridization
25 Nov 17
1 edit
Originally posted by @moonbusnatural selection cannot work without genetic variation but natural selection by itself cannot produce genetic variation. So there must be at least one more mechanism to produce that genetic variation first so that natural selection can then act on it else no evolution. That gives just three possible combinations.
Three separate mechanisms gives a total of seven possible combinations.
Possibly one more mechanism to add to those three depending on how you define things; gene recombination via sexual reproduction. But not sure if one can validly squeeze that into the same category as "random mutation" because that is stretching its meaning a bit.