09.11.2015 change 09.11.2015

Geneticist: Hybrids are bridges for transferring genes between species

Photo: Fotolia Photo: Fotolia

Animals avoid breeding with members of other species. But it turns out that hybridisation has its benefits. Hybrids serve as bridges that carry certain genes between species, said geneticist Dr. Wiesław Babik.

"It is estimated that between 5 and 10 percent species of animals in nature cross-breed with at least one other species. In plants, in turn, it is very common: few tens percent" - said in an interview with PAP evolutionary biologist Wiesław Babik of the Jagiellonian University . For his research, including work on the adaptive evolution of animals, he received the prestigious National Science Centre (NCN) Award in Life Sciences. The results of his research may help in the development of new strategies to protect endangered animals and shed new light on the emergence of new species.

"Globally speaking, animals generally avoid interbreeding with other species, because the offspring may be not the best quality" - said the biologist. He admitted that, for example, hybrids may be less attractive for representatives of the species from which they originate, or have more difficulties surviving in their environment. However, there are positive aspects of hybridisation. "Hybrids may serve as a bridge on which genes are transferred between species" - said the researcher.

In his research, Dr. Babik focused on certain particular genes: major histocompatibility genes (MHC). In humans, these genes are responsible for graft rejection. On a daily basis, they serve another, important function - they enable the immune system to distinguish between own cells and strangers, thus allow to fight pathogens.

"Histocompatibility genes differ from other genes: for them to perform their function well, very large diversity of these genes within species is needed. Each new form of MHC gene increases the chances of identification of the parasite, which others failed to recognize. This gives some individuals an advantage over others" - described Dr. Babik. Interbreeding with other species allows to obtain the MHC genes, which earlier were not found in the gene pool of a species.

In his work Dr. Babik investigates what happens in the process of breeding two different species of newts. One species of amphibians lives in the Carpathian Mountains, the other - almost entire Europe. These species diverged approx. 3 million years ago, but still may have fertile offspring. Dr. Babik admitted that the offspring of the two species may have malformations or, for example, more difficulties with obtaining food. Even so, hybrids breed often enough to pass on their genes.

"Most of the genes that are disadvantageous in a species are >>diluted<< in subsequent generations, they cease to matter. But genes that are beneficial gain advantage. There are more and more of those" - said the biologist. He emphasised that the point is not that histocompatibility genes from another species are better, but that they are different. Hybrids carry them from one species to another. "They can provide a ready-made recipe for combating parasites in the species, which gets them" - said the researcher.

"Our team actually was the first to demonstrate that MHC genes to pass between species more easily than other genes" - described Dr. Babik. He emphasised that at the same time publications appeared indicating that the same mechanism concerning these genes also occurred in human history - 20-30 thousand years ago the human gene pool received histocompatibility genes from Denisovans, an extinct species of human.

Dr. Babik revealed that some hypotheses suggest that major histocompatibility genes affect the perception of attractiveness of another person. Some studies show that people consider the smell of people with completely different MHC genes than their own more attractive. The mechanism is similar in mice. "We have tested similar mechanisms in bears. But our research has not showed anything like it" - admitted Dr. Babik.

The scientist hopes that research on histocompatibility genes will help to develop new strategies to protect endangered species. "If the population of a species is small, hybridisation with another species could help it survive" - said the researcher. He added that in extreme cases, endangered species are crossed with its most similar species. "People who deal with conservation of the species, do so reluctantly - they believe that this can cause pollution of the gene pool of a dying species. But studies show that sometimes the benefits can outweigh the costs" - noted the researcher.

PAP - Science and Scholarship in Poland, Ludwika Tomala

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