Drosophila lacertosa is widely distributed from northern India to Far East of Russia throughout China.We have studied geographical distributions of three kinds of chromosomal karyotypes,type D(2n=10,4 pairs of V-shape...Drosophila lacertosa is widely distributed from northern India to Far East of Russia throughout China.We have studied geographical distributions of three kinds of chromosomal karyotypes,type D(2n=10,4 pairs of V-shaped metacentric chromosomes and a pair of micro-chromosomes),type L(2n= 10,5V with a pair of large-sized heterochromatic autosomes)and type M(2n=10,5V with middle-sized ones).Type D was found exclusively in local populations of D.lacertosa distributed in Yun-Gui Plateau,southwestern China.Both type L and M have a wide range of distribution,and the former occurred in subtropical regions of China including Taiwan Island,whereas the latter in cool temperate regions of East Asia covering Far East of Russia,Korea and the Japan Islands.A strong premating isolation was detected between flies with type D and those with type L or M.These data demonstrate that genetic differentiation leading to cryptic speciation might have occurred in natural populations of Drosophila lacertosa.展开更多
Oryza sativa and Oryza latifolia belong to the AA and CCDD genomes of Oryza, respectively. In this study, amphiploids were obtained from the tube seedlings of O. sativa × O. latifolia F1 hybrids by treatment with...Oryza sativa and Oryza latifolia belong to the AA and CCDD genomes of Oryza, respectively. In this study, amphiploids were obtained from the tube seedlings of O. sativa × O. latifolia F1 hybrids by treatment with colchicine, an agent for chromosome doubling. Subse- quently, amphiploids were investigated using the methods of morphology, genomic in situ hybridization, and molec- ular markers. Amphiploids were characterized by a shorter plant height, larger diameter of stem, longer and wider leaves, darker leaf color, decreased spikelets per panicle and panicle length, and larger spikelets and anthers than the original F1 hybrid. Based on the mitotic metaphase chro- mosome number of the investigated root tips, the somatic chromosome number of the amphiploid is 2n = 72. Additionally, the amphiploid is an allohexaploid, and its genomic constitution is AACCDD by genomic in situ hybridization analysis. Finally, the amphiploids were identified to be true using 37 polymorphic markers at the DNA level.展开更多
Homoploid hybrid speciation （HHS） involves the recombination of two differentiated genomes into a novel, func- tional one without a change in chromosome number. Theoretically, there are numerous ways for two parenta...Homoploid hybrid speciation （HHS） involves the recombination of two differentiated genomes into a novel, func- tional one without a change in chromosome number. Theoretically, there are numerous ways for two parental genomes to recom- bine. Hence, chance may play a large role in the formation of a hybrid species. If these genome combinations can evolve rapidly following hybridization and sympatric situations are numerous, recurrent homoploid hybrid speciation is a possibility. We argue that three different, but not mutually exclusive, types of contingencies could influence this process. First, many of these ＂hopeful monsters＂ of recombinant parent genotypes would likely have low fitness. Only specific combinations of parental genomic con- tributions may produce viable, intra-fertile hybrid species able to accommodate potential constraints arising from intragenomic conflict. Second, ecological conditions （competition, geography of the contact zones or the initial frequency of both parent spe- cies） might favor different outcomes ranging from sympatric coexistence to the formation of hybrid swarms and ultimately hybrid speciation. Finally, history may also play an important role in promoting or constraining recurrent HHS if multiple hybridization events occur sequentially and parental divergence or isolation differs along this continuum. We discuss under which conditions HHS may occur multiple times in parallel and to what extent recombination and selection may fuse the parent genomes in the same or different ways. We conclude by examining different approaches that might help to solve this intriguing evolutionary puz- zle [Current Zoology 59 （5）： 667-674, 2013].展开更多
基金supported by National Natural Science Foudation of China,(No.39930100,30024004)Chinese Academy of Science(No.KSCX2-1-05)Japan Society for the Promotion of Science(No.12375002)
文摘Drosophila lacertosa is widely distributed from northern India to Far East of Russia throughout China.We have studied geographical distributions of three kinds of chromosomal karyotypes,type D(2n=10,4 pairs of V-shaped metacentric chromosomes and a pair of micro-chromosomes),type L(2n= 10,5V with a pair of large-sized heterochromatic autosomes)and type M(2n=10,5V with middle-sized ones).Type D was found exclusively in local populations of D.lacertosa distributed in Yun-Gui Plateau,southwestern China.Both type L and M have a wide range of distribution,and the former occurred in subtropical regions of China including Taiwan Island,whereas the latter in cool temperate regions of East Asia covering Far East of Russia,Korea and the Japan Islands.A strong premating isolation was detected between flies with type D and those with type L or M.These data demonstrate that genetic differentiation leading to cryptic speciation might have occurred in natural populations of Drosophila lacertosa.
基金supported by the National Natural Science Foundation of China (31571624, 31071382)the National Basic Research Program of China (2010CB125904, 2013CBA01405)+1 种基金the key Natural Science Project in University of Jiangsu Province (15KJA210004)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Oryza sativa and Oryza latifolia belong to the AA and CCDD genomes of Oryza, respectively. In this study, amphiploids were obtained from the tube seedlings of O. sativa × O. latifolia F1 hybrids by treatment with colchicine, an agent for chromosome doubling. Subse- quently, amphiploids were investigated using the methods of morphology, genomic in situ hybridization, and molec- ular markers. Amphiploids were characterized by a shorter plant height, larger diameter of stem, longer and wider leaves, darker leaf color, decreased spikelets per panicle and panicle length, and larger spikelets and anthers than the original F1 hybrid. Based on the mitotic metaphase chro- mosome number of the investigated root tips, the somatic chromosome number of the amphiploid is 2n = 72. Additionally, the amphiploid is an allohexaploid, and its genomic constitution is AACCDD by genomic in situ hybridization analysis. Finally, the amphiploids were identified to be true using 37 polymorphic markers at the DNA level.
文摘Homoploid hybrid speciation （HHS） involves the recombination of two differentiated genomes into a novel, func- tional one without a change in chromosome number. Theoretically, there are numerous ways for two parental genomes to recom- bine. Hence, chance may play a large role in the formation of a hybrid species. If these genome combinations can evolve rapidly following hybridization and sympatric situations are numerous, recurrent homoploid hybrid speciation is a possibility. We argue that three different, but not mutually exclusive, types of contingencies could influence this process. First, many of these ＂hopeful monsters＂ of recombinant parent genotypes would likely have low fitness. Only specific combinations of parental genomic con- tributions may produce viable, intra-fertile hybrid species able to accommodate potential constraints arising from intragenomic conflict. Second, ecological conditions （competition, geography of the contact zones or the initial frequency of both parent spe- cies） might favor different outcomes ranging from sympatric coexistence to the formation of hybrid swarms and ultimately hybrid speciation. Finally, history may also play an important role in promoting or constraining recurrent HHS if multiple hybridization events occur sequentially and parental divergence or isolation differs along this continuum. We discuss under which conditions HHS may occur multiple times in parallel and to what extent recombination and selection may fuse the parent genomes in the same or different ways. We conclude by examining different approaches that might help to solve this intriguing evolutionary puz- zle [Current Zoology 59 （5）： 667-674, 2013].
