Four birds with sex "Nodogirosito"

Humans have a pair of sex chromosomes and two sexes, but some living things have seven gender. Researchers who have uncovered the evolution of human and bird chromosomes by keeping observing and studying birds with four sexes for thirty years, with birds also having "four sexes". did.

The sparrow with four sexes: Nature News & amp; Comment
http://www.nature.com/news/the-sparrow-with-four-sexes-1.21018

Birds with four sexes are "NoodilosideThat thing. There are two types of nodotiroside, one with white stripes in the head and one with brown stripes.


And those who have white stripes are said to be inversion to one of the pair of chromosome 2 "as if someone cut out the chromosome with scissors and inverted and fitted in." As a result of mutation of chromosomes like this, the white striped nodotiroside has "supergenes". Supergenes are on the same chromosome and the mechanism is unknownGenetic linkageIt is a gene that is inherited from parent to child by.


Changes in chromosome 2 produce differences not only in appearance but also in behavior. For example, the white striped nodojirosito is a whim, not good at raising children, is aggressive and good at singing. On the other hand, nodotiroside with a brown stripeMonogamyHe is good at raising children, has protection, and poor singing.


Even more characteristic is that the female with white stripes is married only with the brown striped male and vice versa. In other words, although it is possible to combine from two individuals, "sexes" usually, Nodogirosito decides individuals to be mated from four elements, and it is in such a state that it can be said that "there are 4 sexes" It is there.


This research was led by Biologist Elaina Tuttle and her husband and biologist Rusty Gonser. Many biologists move projects from one project to another one after another, but the two have continued to study the ecology of nodogillosis for 30 years. According to Catherine Peichel, an evolutionary ecologist, "Because there is little evidence that the process of evolution of sex chromosomes" how it happened ", the second staining mutation of nodotrocytide, which acts like a sex chromosome, There is great benefit to observing how it occurs. "

Mr. Tuttle thought that "Nodogirosito is the key to unraveling the evolution of genes and chromosomes underlying social behavior", and started research in the 1990's. However, it was difficult and costly to analyze the genome of the bird at the time. So Mr. Tuttle gathered behavioral data such as how each individual chooses a pair, where to build a nest, and switched to understand how those behaviors affect the survival of descendants about. Mr. Gonser later joined this research, and the two married in 1994.

Two researchers who understood the ecology of Nodogirosito gradually acknowledged their achievement, and in 2009 they started gene analysis with permission from the National Institutes of Health. And it revealed that the "reversal" phenomenon occurring on chromosome 2 is not a simple one as originally thought, but rather complicated as "a reversal occurs in the inversion". At this time, researchers have also succeeded in identifying genes that alter the color and behavior of individuals.

And based on the results of 50 genetic sequencing of all the birds, they announced a paper in 2016 that "Nodogirosito's chromosome 2 is evolving like a sex chromosome". I showed that the gene in the inverted part of the chromosome is mutating faster than any part of other genomes and that the pattern of this mutation mimics the evolution pattern of sex chromosomes in birds and humans. Many researchers were surprised by the way of showing the process of evolution of human sex chromosomes by revealing the process of mutation that occurred on the chromosome of the bird.

Human sex chromosomes are a pair and gender is two, but living things are not sex chromosomes,Those with seven genderAlso exists. The combination "one pair and two sexes" is the most common, but that does not mean there is no reason for "a creature can not have more than one pair of sex chromosomes". Wilson Sayres, a computational biologist at Arizona State University said, "If you are ties to each other and when meiosisTransferIf you have a gene that plays a role in determining the gender without causing waking up, it is your new sex chromosome. "

Mr. Tuttle's research left a lot of heritage in biology, but at the same time it created a new question like "When a system like No. 2 chromosome of nodogylosito disappears?" When differences such as white stripe type and brown stripe type are added in addition to sex of both sexes, it is disadvantageous from the viewpoint that choices to select mines are reduced from one half to one quarter, leaving descendants. From this, it seems that the form of "four sexes" will disappear someday, but it is unknown what kind of things will disappear at the moment at this time.

In 2016 Mr. Tuttle passed away because of breast cancer, and the project of Nodogirosito was taken over by her husband Gonser. In the future, Mr. Gonser will continue his research to understand which gene is controlling the behavior of nodo-drosito "," what characteristics are affected by the reversal of the chromosome on which the reversed trait " is.