FUMC Seminole Because we can all feel like stars

Significant shift in the direction of the relations of organisms of one sex has both theoretical and practical importance, since one of the floors are usually more productive. It has long been observed that female fish exposed certain conditions (environment, hormones, etc.) are transformed into males (gambuzievye, melanohromisy, etc.). Female sex hormone (estrol) and male (methyltestosterone), when added to water or feed override the floor. Japanese geneticist Yamamoto in 1969 turned the females in the male goldfish. With further dilution of all offspring was female.

To date, aquaculturists have learned to change the sex of fish, affecting small doses of hormones on spawn. Also, damage to the endocrine system of fish themselves may cause preferential birth of individuals of one sex. Scientists have reported that emissions of industrial plants cause disturbances in the endocrine system of fish in the early stages of development, which dramatically alters the sex ratio towards males for priority development. But the most interesting – it is social factors of change of sex – that is, adult mature fish change sex at influence “public opinion” so as to optimize the sex ratio in the population. What gives the fish change sex? Found that the number and quality of eggs is directly dependent on the size of females. For males there is no such dependence.

Therefore, a strategy in which the fish first enter into a breeding male, and having grown older and bigger, turning into females, it looks logical. The transformation of males into females under the influence of social factors has been well studied as an example clown fish. A young clown settles from the plankton to the reef under the protection of sea anemones. The biggest fish in the group is female, the second biggest – by a male. The remaining fish are still immature. But if the female dies, the clown-male quickly turns into a female, and the next largest fish matures as a male and takes his place. However, there are times when the success of reproduction depends on the size of males. In cases where the male to defend a harem, spawning territory or to protect the clutch of eggs, large males have an advantage over smaller ones. Therefore, in some species females grow up, grow up and turn into males. In the fish phenomenon often seen in cichlids. On Coral reefs are the fish that do not need to change sex, because they are both males and females. Such fish hermaphrodites mature and spawn, and milk. If two such individuals to meet and enjoy each other, each of them will breed. If there is not a worthy partner, then we can resort to self-fertilization. This strategy has the advantage of deep-sea fishes numerically small, are difficult to find a mate in the ocean depths. But so far committed is not clear why this should coral fish. Coral fish are hermaphrodites live fairly dense populations in which the choice of couples – not a problem. Moreover, the known types of hermaphrodites, which form permanent monogamous pairs for life.

Long ago there was friendship between dog and man. People hunt, got their food, while the wolf-hunting predators, usually ended in failure. And wild animals are eat up food debris left after the people. Later years, the animals are accustomed to helping people to grow roots and become close to human houses. People have noticed that their comrades are excellent herders and hunters and were tame dogs.

It took many centuries since then, and the dogs were devoted friends of man. This myth is retold on the occurrence of affection between man and dog. But, alas, was not so easy. Reality is always more difficult and prosaic. But can it be judged likely to origin of the relationship between humans and dogs, if there are no accurate written confirmation? In this situation, the facts are the archaeological findings, the study scientists. So how do you really, man and dog become friends? Experts say that the first man appeared in the Paleolithic era, which began in 500 thousand years bc. Domestication of the wolf began about twelve thousand years ago. But wild beasts and people went to touch a lot It had been violent relationships.

Most often, one of them became the victim of another. Much in common it was for the first humans and wolves – a meal of both getting the same animals and habitat areas, respectively, were identical. And often, not only the remnants of the mining man ate wild animals, but on the contrary, people did not disdain the remains of a dog eat dinner. As soon as people became more intelligent, stronger and domesticate the dog. In the first period of residence in one area made it possible benefit for both groups. In the case of attacks on parked enemy species, dog guarding its territory, but at the same time, they felt safe because of the proximity to the stronger predator – man. So are the people. Living together gave other results: found that if just emerged puppy, first saw the man, he takes him for his mother. Parts were also cases of children feeding the dog, and vice versa. So gradually created the overall flock: the dog-man. Probably why the dog is so true man, as no other creature on Earth. They never believe people member of his flock.