Male seahorses - natural mothers

Male seahorses are real 'mothers' when their fatherhood also includes the responsibility for pregnancy.

Although the male fish role is the mainstay of the family is perfectly normal, the fact that the male is pregnant is a complex process only unique in the Syngnathidae family, including lime fish and seahorses. and sea dragons. Evolutionary biologist Adam Jones and colleagues at Texas A&M University are working to understand how the body structure needed for pregnancy can evolve. Researchers hope to gain insight into the evolutionary mechanism responsible for changes in the structure of species over time.

Jones said: 'We use seahorses and their relatives to target one of the most interesting areas of research in modern evolutionary biology: the source of complex traits. The male seahorse pouch and lime key where males hold eggs during mating are an interesting trait that has a great impact on the biology of the species due to the male's ability to conceive. completely change the dynamics of mating action '.

A pair of seahorses.(Photo: PracticalFishKeeping)

When seahorses mate, the female puts its egg-laying part into the male's hatchery bag (the organ is located outside the male's body) then lays unfertilized eggs into the incubator bag. The male then ejaculates into the incubator bag to fertilize the egg. Jones said: 'If the bag is simply a skin patch for the female to lay normal eggs in it then the eggs that grow inside the bag instead of growing up on the ocean floor are nothing interesting. . But the fact that the male is pregnant in some species of seahorses or lime fish in terms of physiological function is much more complicated. '

After the female lays the unfertilized egg into the male pocket, the outer shell of the egg breaks. The male sperm will surround the egg. After fertilization, the male is responsible for controlling the habitat of the embryo in the incubator bag. It will keep the blood circulating around the embryo, control the salt concentration in the incubator, supply oxygen and nutrients to the development of young offspring through a placental-like organ until birth.

The fact that the male is pregnant has an interesting meaning about the role of gender in mating. Because in most species, males are often fighting for females, so we often see minor evolutionary traits that show the sex of the male, such as the peacock's tail or the gauze. deer species.But in some lime fish species, the role of the two sexes is reversed. Because males can become pregnant, the size of the hamlet is limited, so the females compete with each other to gain the male that is "lonely". Therefore, secondary sexual characteristics (such as bright colors, for example) evolved in females instead of males.

Jones said: 'From a research point of view, this is very interesting because there are few species in nature whose gender role is reversed. This is a rare opportunity to explore sex selection in the context of a reversed role. '

To explore mating behavior in seahorses and lizardfish, Jones' lab used molecular markers in legal analysis as a mother to find out which female seahorses are the mother of children. in male seahorse belly. The group found that the lizard fish mate in the 'classic' polynomial method , the male receives eggs from a female but the female can mate with many males. Because attractive females can mate many times, this mating method causes fierce competition in selection for mating. Females have evolved important secondary sex characteristics.

(Photo: snapscot)

However, seahorses are a faithful breeder in pairs during a breeding season . For this method, if the sex ratio is equivalent, there will be no competition among females because the number of males is enough to pair. So in seahorses there are no important secondary sexual characteristics that evolve like lime fish.

Pregnancy of males also causes disturbance in gender-related behavior. Jones said: 'Female seahorses have competitive behaviors that are characteristic of males, while males' picky and picky fish '- a characteristic of females'. His experimental group also studied evolutionary steps leading to reversal behavior and the role of hormones in this transformation.

At the same time, the team also studied how the original hatchery bag evolved in seahorses and fish key lime.'A big question about evolutionary biology is how such an incredible organism has all the genes and components needed to complete its function. We are trying to understand the way in which the incubator is as well as the genes needed for the males 'pregnancy to develop during the evolutionary phase.'

One of the interesting things about the male incubator is that it seems to evolve independently many times . There are two main groups of seahorses and key lime fish: incubating and hatching. The incubator structure also evolved independently in two groups.

Another aspect of Jones' research is the evolutionary steps that form the unique unity of seahorses. Jones said: 'How do we learn an unusual species like horses from ordinary shaped fish? Certainly there are many evolutionary steps involved in this process. '

John explained that the first step in the evolutionary process is the stretching of the body - the group is currently studying this step. The second step is the formation of more unique structural features that seahorses possess as transformed into a characteristic shape. The head of the seahorse species is unlike most other fish species. It is perpendicular to their bodies. Seahorses also have a tail that can be grasped, which means that unlike other fish they have a tail that holds things.

'These are all interesting changes. We are very interested in learning how these unusual traits appear and the evolutionary steps that make up those characteristics. Basically, I hope to have a deeper understanding of some evolutionary mechanisms that help shape the incredible changes in organism that occur throughout the history of life on the left. land'.