vavilovВавиловский журнал генетики и селекцииVavilov Journal of Genetics and Breeding2500-3259Institute of Cytology and Genetics of Siberian Branch of the RAS10.18699/VJ16.170vavilov-693Research ArticleЭволюция и видообразование. ОБЗОРEvolution and speciation. REVIEWХромосомы и видообразование у туко-туко (Ctenomys, Hystricognathi, Rodentia)Chromosomes and speciation in tuco-tuco (Ctenomys, Hystricognathi, Rodentia)ТоргашеваА. А.TorgashevaA. A.

Новосибирск

Novosibirsk

БашеваЕ. А.BashevaE. A.

Новосибирск

Novosibirsk

Гомес ФернандесМ.Х.Gomez FernandezM. J.

Буэнос-Айрес

Buenos Aires

МирольП.MirolP.

Буэнос-Айрес

Buenos Aires

БородинП. М.BorodinP. M.

Новосибирск

Novosibirsk

borodin@bionet.nsc.ruФедеральное государственное бюджетное научное учреждение «Федеральный исследовательский центр Институт цитологии и генетики Сибирского отделения Российской академии наук»; Федеральное государственное автономное образовательное учреждение высшего образования «Новосибирский национальный исследовательский государственный университет»РоссияInstitute of Cytology and Genetics SB RAS; Novosibirsk State UniversityRussian FederationФедеральное государственное бюджетное научное учреждение «Федеральный исследовательский центр Институт цитологии и генетики Сибирского отделения Российской академии наук»РоссияInstitute of Cytology and Genetics SB RASRussian FederationАргентинский музей естественных наук им. Бернардино РивадавияАргентинаArgentine Museum of Natural Sciences “Bernardino Rivadavia”Argentina201624092016204408415Copyright © Торгашева А.А., Башева Е.А., Гомес Фернандес М.J., Мироль П., Бородин П.М., 20162016Торгашева А.А., Башева Е.А., Гомес Фернандес М., Мироль П., Бородин П.М.Torgasheva A.A., Basheva E.A., Gomez Fernandez M.J., Mirol P., Borodin P.M.This work is licensed under a Creative Commons Attribution 4.0 License.https://vavilov.elpub.ru/jour/article/view/693

Южноамериканские грызуны рода туко-туко (Ctenomys) представляют собой интересную модель видообразования. Их строгая территориальность и одиночный образ жизни под землей, сильно фрагментированные ареалы, низкая миграционная активность послужили причинами их очень быстрой радиации. В настоящее время описано около 60 видов этого рода. Его представителей обнаруживают в самых разных местообитаниях, от гор в Андах до прибрежных дюн Атлантики, от влажных степей Пампы до пустынь Чако. Туко-туко отличаются очень высоким уровнем хромосомного полиморфизма и политипизма на основе робертсоновских и полно-плечевых реципрокных транслокаций и инверсий и поэтому могут быть использованы для тестирования разных версий гипотезы хромосомного видообразования. Классическая версия этой гипотезы делает акцент на стерильности гибридов, обусловленной неправильным или неполным синапсисом хромосом у гетерозигот по перестройкам, гибелью зародышевых клеток, неправильной сегрегацией хромосом и генерацией несбалансированных гамет. В рамках современной версии хромосомного видообразования предполагается, что сокращение потока генов через хромосомные гибридные зоны обусловлено подавлением рекомбинации у гибридов вокруг точек разрыва перестроек, различающих родительские виды. Полевые исследования не выявили сильных негативных эффектов хромосомной гетерозиготности на приспособленность. Эти результаты поставили под сомнение валидность классической версии гипотезы. Анализ поведения хромосом в профазе мейоза у гетерозигот по перестройкам выявил у них значимые изменения в частоте и распределении рекомбинации: супрессию кроссинговера в районе точек разрыва и дистализацию хиазм. Эти изменения могут модулировать поток генов между хромосомными расами и усиливать дивергенцию, возникшую за счет пространственной изоляции. Эти данные подтверждают рекомбинационную модель хромосомного видообразования.

Tuco-tucos, South American rodents of the genus Ctenomys represent an interesting model of speciation. Their strict territorial and solitary life under the earth, vast but highly fragmented habitats, low migration activity were the causes of their very fast radiation. About 60 species of this genus have been described. They are found in a variety of habitats, from the mountains of the Andes to the coastal dunes of the Atlantic, from humid steppes of Pampas to dry deserts of Chaco. Tuco-tucos have a very high level of chromosomal polymorphism and polytypism based on Robertsonian and whole-arm reciprocal translocations and inversions, and can therefore be used to test different versions of chromosomal speciation hypothesis. The classic version of this hypothesis emphasizes the sterility of the hybrids, due to incorrect or incomplete chromosome synapsis in heterozygotes for rearrangements, germ cells death, chromosome nondisjunction and the generation of unbalanced gametes. The modern version of chromosomal speciation hypothesis suggests that the reduction of gene flow across chromosomal hybrid zones is due to the suppression of recombination in hybrids around the break points of rearrangements distinguishing the parental species. Field studies have not revealed strong negative effects of chromosomal heterozygosity on the fitness of the carriers. These results cast doubt on the validity of the classic version of the hypothesis. Analysis of chromosome behavior in the meiotic prophase in the chromosomal heterozygotes revealed significant changes in the frequency and distribution of recombination: crossingover suppression around the breakpoint and chiasma distalization. These changes can modulate the flow of genes between chromosomal races and amplify the divergence which has arisen due to spatial isolation. These data confirm the recombinational model of chromosomal speciation.

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The authors declare that there are no conflicts of interest present.