How are species born? Where does all this biodiversity on Earth come from? Biologist Martine Maan attempts to answer this question by examining fish from Lake Victoria, Africa, and appears to be on the trail of a promising mechanism of speciation.
To enter the fish laboratory of Martine Maan and her colleagues, you have to go through several doors. “It’s really only because we have special lighting conditions here,” says Maan. There are several systems in the lab. “The fish, the water and the temperature are all the same, but we are looking at different lighting conditions.”
And all this to answer the question: how are species born? How can a group of animals of the same species be divided into two distinct species? Of course, from Darwin we know it’s a process of natural and sexual selection, but how exactly does it work?
For a long time, biologists thought that different groups of a species should be separated from each other, for example because a group ends up on a separate island. But that doesn’t seem like a condition: even if the animals continue to live nearby, new species can emerge.
To this end, Maan searches his laboratory for between 500 and 1000 cichlids from Lake Victoria in Africa, a species that is the subject of much research. “Lake Victoria is quite cloudy. This means that not all colors penetrate light equally well. You often get a slight redshift in light. Light with a short wavelength, like blue light, is absorbed by particles in the water. “
Colors are very important for communication between men and women
Why is this important? “Colors are very important for communication between males and females. And fishes adapt their visual system very quickly to the prevailing light conditions. These two things together could well be a speciation mechanism. Because these animals then adjust their eyes, it affects how females perceive males’ colors, and therefore what they think is beautiful and ugly. “
Prefer a red
So the theory is this: Cichlids that (start to) live at greater depths, see more red light, adjust their eyes accordingly, and begin to find the red congeners more attractive. This created a difference between two groups of the same kind, and the start of speciation may have been triggered.
But is this theory correct? This is exactly what Maan is looking for in his fish lab, and the results seem to indicate that it indeed works that way. Females who grow up without blue light prefer red males.
At the same time, many questions remain. For example, it is not the case that females with the redder pigment in their eyes also prefer red males. In addition, fish from different groups can still have children with each other, which means that they are not yet separate species. But these unanswered questions are precisely what makes the research so fascinating to Maan.
British scientist Charles Darwin owes his fame to the theory of evolution and his research on the role of natural selection in the development of species. Who exactly was he? You read it on NPO Knowledge.
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