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Are there really 1000 “species” of cichlid?

mbuna cichlids/Haplochromis, GNU

From New Scientist:

Why one lake contains more than 1000 species of the same fish

One thousand species of the “same fish” in Lake Malawi?

We used to think the word “species” meant something.

The huge number of closely related species living together has meant they feature prominently in models of species diversification. But what made them so diverse has remained a mystery.

Some think environmental forces drove the diversification, others that the underlying cause was biological, says Scholz. For example, some females are colour-blind to males that are a different colour to them, which can drive sexual isolation between different groups of fish.

In humans, we call that  behaviour “demography.” People who don’t speak the same language or move in the same social circles tend not to marry each other.*

Over time, we could get separate human “species” out of that, couldn’t we? Or could we? How, exactly, are “species” classified here? Definition?

Anyway, one team found that changed water levels in the lake, based on sediment records from about 1.3 million years, might have separated fish, resulting in diversification.

Thomas Kocher at the University of Maryland isn’t convinced that the changes in the lake water levels alone drove the diversification of cichlids.

What the findings do show, however, is why the cichlids came to dominate the lake: they were able to “out-evolve” other groups of fish while these changes were occurring, he says. More.

Will the next big story be that hybridizing cichlids are “a rapid expansion of new species”?

See also: All the breathless “new species” stories below riff off the same fish: The hybridizing threespine stickleback, whose clan life seems to be fairly complicated:

Mating males can create new species?

Superfast evolve-o-fish found in Swiss lake

Researchers: Humans “speeding up” evolution

<em>Teapot</em> Cobalt Blue * Yes, it happens a lot in stories, but that’s why they are stories. It’s not a story if it is just demography.

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Cichlids will interbreed in captivity. They're not different species, just different varieties, lie different dog breeds. aarceng
The creator seems to have an inordinate fondness for cichlids. Mung
This is a great example for creationists. The creatures easily changed into all types. and since the flood. In fact i say it was like this after the flood and earth was filled with types from a certain kinds. in fact i think these fish change the same way humans did. nOt selection on mutations but other mechanisms innate. No big deal. this is why species is a failed concept. these fish prove its a bio division but very weak and the origin is very flexible. Robert Byers

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