Ancient Hybridization and Lake Victoria’s Stunning Fish


(Dr. Patrick Trischitta) #1

Reported last week at the Origins of Adaptive Radiation meeting here, the work is “a tour de force, with many lines of evidence,” says Marguerite Butler, a functional morphologist at the University of Hawaii in Honolulu. It joins other research suggesting that hybridization is a powerful force in evolution. “What hybridization is doing is allowing the good stuff to be packed together,” Butler says.


(S. Joshua Swamidass) #2

Pretty cool:

WAIMEA, HAWAII— In the shallow waters of Lake Victoria, the world’s largest tropical lake, swim some 500 species of cichlid fish with a dizzying variety of appearances, habitats, and behaviors. Genomic studies have shown they arose from a few ancestral species in just 15,000 years, a pace that has left researchers baffled about how so much genetic variation could have evolved so quickly. Now, extensive sequencing of cichlids from around Lake Victoria suggests much of it was there at the start, in the cichlids’ ancestors. Ancient and more recent dallying between cichlid species from multiple watersheds apparently led to genetically diverse hybrids that could quickly adapt to life in the lake’s many niches.

Reported last week at the Origins of Adaptive Radiation meeting here, the work is “a tour de force, with many lines of evidence,” says Marguerite Butler, a functional morphologist at the University of Hawaii in Honolulu. It joins other research suggesting that hybridization is a powerful force in evolution. “What hybridization is doing is allowing the good stuff to be packed together,” Butler says.

And in case you are wondering, hybridization is consistent with common descent, but produces a structure very different from a tree.


(Jon Garvey) #3

The cichlids of Lake Victoria are a special case, of course, but I’ve long felt that we’re going to find hugely significant, and sudden, evolutionary events will turn out to be down to hybridization.

This work actually seems to vindicate my friend, the Creationist Arthur Jones, one of the very few people to be awarded a PhD in evolutionary biology for a non-evolutionary thesis. Back then, of course, it was trees with everything, and even to his own surprise the cichlids did not appear to fit a tree structure, but something different. Can’t link to the thesis as it’s not online.


(Dr. Patrick Trischitta) #4

Are you saying in some way that hybridization is NOT part of or NOT a powerful force in evolution? Please explain.


(Jon Garvey) #5

No, I’m saying it’s a more powerful force than was realised in the past, and (as Joshua says) it is one way in which tree-structures are disrupted. It can change things very greatly and very quickly as well. Darwin’s natura non facit saltum becomes a potentially doubtful dictum.

Another instance: a good number of bird of paradise species turn out to be hybrids. Apart from making mincemeat of Fisher’s theory of sexual selection (always opposed by Wallace, who studied them in the field), the potential for a new species to form from two over one or two generations opens a whole range of possibilities up.


(Ashwin S) #6

I think it also makes phenotypic plasticity important…
Otherwise hybridisation wouldn’t help much in speciation.