New species appear depending on how the female chooses the male

Eye color and hair color play an important role in finding partners in humans, but visual stimulation can also decide to choose a partner in the animal kingdom. In many species, the probability of male success in finding partners is determined by the eye-catching suit.

Research on brightly colored fish has shown that this trait is less related to aesthetics, which is related to the child's visual sensitivity, varying according to the ability to adapt to the lips. school The females that are in harmony with the green will choose their metallic blue partner, while the ones that can look red will choose their bright red partner. Selecting such partners can lead to the formation of new species - in case the diversity of habitats is not interfered by human activity.

The role of selection in new species formation has not been fully explained in evolutionary biology. The development of colorful cichlids in African lakes is only a few thousand years - a short period of evolution - reinforcing the hypothesis that the choice of partners contributes to species formation, in which species collection is not geographically isolated. In the case of cichlids, selection is the cause of the difference in color perception. Convincing evidence for this theory was first provided in the study published in the journal Nature.

Observe and be observed

In the study, evolutionary biologist Ole Seehausen (of the University of Eawag and Bern) and co-authors demonstrated that children of cichlids from Lake Victoria who have a sensitive vision of green often choose a blue partner, while sensitive females with red color choose males with red color. The different pigment receptor organs are distinguished by the team based on DNA and protein sequences. The DNA sequence of genes that underlie visual pigmentation also shows that specialization does not appear casually but depends on natural selection.

Fish Pundamilia nyererei.The color of the males of the pundamilia nyererei and pundamilia pundamilia cichlid adapts to the red and green colors of the surrounding habitat and the corresponding visual sensitivity of the female.(Photo: Eawag)

Sensitivity to color differs depending on the depth at which fish live. Females living in deeper water are more sensitive to red, and those that live in shallower layers are more sensitive to blue. Adaptation of the visual receptor to the color of the surrounding gives the fish an advantage at a certain depth. They are easier to navigate and can find food more easily than unsuitable fish. Obviously, males also adapt to the situation: males with red dominate in deeper water, while those with blue are superior in shallow water.

Two new species were formed when ambient light changed slowly with increasing depth, in relatively clear water conditions. This means that different genetic changes can still arise to take advantage of the competitive advantage of visual and color specialization.

Serious decline in the number of species

In addition to explaining how new species were formed, the latest findings provide an explanation for the dramatic decline in species diversity that has occurred in Lake Victoria over the past 25 years. Agricultural waste, deforestation and urbanization have increased the turbidity of the lake water. Therefore, light in the water environment changes in a way that is only a few meters apart from each other.

Different ecosystems exist too close to each other so the genetic adaptation mechanism cannot work. The authors found that in muddy water locations, instead of dividing into red and blue species, a neutral form prevailed, with no specific adaptation to any kind of light. The merger of species, caused by environmental changes, contributed significantly to the decline of cichlids in Lake Victoria, from 500 to 250 species of cichlids.

Species definition?

Many species definitions can be found in evolutionary biology. The common feature is that a group of organisms is converted into another species if they coexist in nature through generations for the same site without genetically merging. Sometimes some species are bred but still different if there are mechanisms to prevent gene flow. Defining a species is a group of individuals that cannot cross-breed with members of other species as a misconception.