It is likely that at school they will teach us that the human being has, as a general rule, 23 pairs of chromosomes. We know that there are complex organisms, such as animals, that survive with just a couple of chromosomes, such as species ants Myrmecia pilosula.
The question is then what are the species with the highest number of chromosomes.
A new record. A recent study has indicated a kind of butterfly, the so -called Atlas girl (Polyommatus atlantica), As the animal with the greatest number of chromosomes known: 229 pairs. The number is even more striking if we consider that many of the species closest to this in the taxonomic tree have 23 or 24 pairs.
The Atlas girl. The Atlas girl is an elusive butterfly that inhabits the Northwest Cordillera of Africa, extending their habitat in parts of Morocco and Algeria. We had long known that this animal had a high number of chromosomes, but the new study of the animal’s genome opens the doors to have a precise measure of the number, while also allowing us to know more about why this surprising figure.
“I have been investigating this butterfly for many years and I am one of the few people who have been able to observe it in nature. Unfortunately, P. Atlantic is seriously threatened by the destruction of their habitat. SINC Roger Vila, co -author of the study.
Investigating the chromosome. The strange future of this butterfly genome began about three million years ago, explains the team responsible for sequencing this genome. And everything would have begun with 24 chromosomes, a number similar to that of other species in his family.
The analysis allowed to discover that the chromosomes of the Atlas girl had been fragmenting in the areas where DNA accumulated with less density. This, the equipment adds, implies that, despite the growth of the number of chromosomes, the genetic information contained in them did not grow proportionally.
Three million years of fragmentation. The team observed that all chromosomes except sexual experienced this fragmentation, carrying the total number of cormosomes from 24 to 229 throughout the last three million years. A “relatively short” interval of time in evolutionary terms, highlights the team responsible for the study.
The details of the study have been published in an article in the magazine Current Biology.
Evolutionary advantage? The study raises new unknowns, admits the team. An example is to know to what extent the fragmentation of chromosomes or having an abundant number of these, can help or harm the species that travel this evolutionary path.
More than counting chromosomes. Beyond establishing this “new record”, the study can help us better understand the evolutionary and genetic history of this and other species. Knowing this evolutionary past can also give us clues about the future of this evolution, the team maintains.
We could, for example, better understand how species can respond to changes in their environment, such as the increase in the temperature we are observing in some regions of the globe.
Chromosomatic changes also occur at the non-evolutive level, for example in some cancer cells. That is why knowing the fragmentation mechanisms of chromosomes can help us investigate the changes when they happen in medical contexts.
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Image | Roger Vila
