Wider geographic distribution and higher diversity of hexaploids than tetraploids in Carassius species complex reveal recurrent polyploidy effects on adaptive evolution

Abstract

Polyploidy roles on adaptive evolution and ecological novelty have been extensively studied in plants but remained unclear in vertebrates owing to the rare polyploidy incidences. Here, a huge number of 3105 specimens in Carassius species complex including 2211 hexaploids and 894 tetraploids were sampled from 34 locations through mainland China. And hexaploids had wider geographic distribution than tetraploids especially in the areas with high altitude, high latitude and low annual precipitation. Then, an approximate 1050 bp transferrin (tf) fragments were amplified from all the samples, and 526 tf alleles were identified from a total of 37260 sequences at last. Intriguingly, higher nucleotide diversity of tf alleles in hexaploids than in tetraploids was revealed. Moreover, via phylogenetic analysis of tf alleles, potential origin center of Carassius species complex was deduced to be Yangtze River basin and hexaploids should undergo multiple independent polyploidy origins from sympatric tetraploids. These findings indicate that the hexaploids might possess stronger environmental adaptation and ecological novelty than the tetraploids, which provide an association paradigm of recurrent polyploidy and ecological context in polyploid vertebrates.

Numerous mitochondrial DNA haplotypes reveal multiple independent polyploidy origins of hexaploids in Carassius species complex

“…In terms of different drainage systems or geographic areas, all‐hexaploids and highly biased‐hexaploid populations are predominant in northeast of China (except SHJ), northwest of China (except DWS), Yellow River basin, upper Yangtze River, upper Pearl River, and two localities of Japan main islands, whereas tetraploid‐biased populations are mainly distributed in Middle/Lower Yangtze River basin, Jing‐Hang Grand Canal and Ryukyus. As reported recently (Liu et al., ), hexaploids have wider geographic distribution than tetraploids in Carassius species complex throughout East Asia.…”

“…Recently, an early allopolyploidy event leading to ancestral allotetraploids has been revealed, and a recurrent autopolyploidy from allotetraploids that results in allohexaploids has been elucidated in the Carassius species complex (Li, et al., ; Luo et al., ). Therefore, the wide geographic distribution, coexistence of different ploidy forms, and occurrence of repeated polyploidy events make the Carassius species complex an ideal system to investigate evolutionary trajectory and ecological adaption of polyploidy in vertebrates (Gao et al., ; Liu et al., ).…”

“…, 3,105 specimens comprising 894 tetraploids and 2,211 hexaploids are currently sampled from 34 localities throughout mainland China reported recently(Liu et al, 2017), 364 specimens including 114 tetraploids and 250 hexaploids are from seven localities of mainland China reported previously(Luo et al, 2014), and 690 individuals containing 328 tetraploids and 362 hexaploids come from eight localities of Japan main islands and Ryukyus as described(Takada et al, 2010). In the 49 populations, there are 17 all-hexaploid populations and 32 sympatric populations of both hexaploids and tetraploids, whereas there is no one all-tetraploid population (Figure 1).…”

Morphological characterization and phylogenetic relationships of Indochinese box turtles—The Cuora galbinifrons complex

“…In addition, the overlap of distribution areas between galbinifrons and bourreti provided opportunities and possibilities for their hybridization, and hybrids from the same maternal species in captive or wild populations might generate highly homologous or identical mitochondrial DNA sequences. Finally, the relationship among closely related species might be obscured by variable morphological indices or molecular markers such as different nuclear and mitochondrial markers implemented in Carassius species complex (Liu, Jiang, et al, ; Luo et al, ), Quasipaa boulengeri (Yan et al, ), and Neosalanx taihuensis (Zhao et al, ). As a consequence, multiple molecular markers or genomic DNA of populations and larger sample sizes of known provenance will help to further investigate their taxonomic status.…”

Genetic identification of a newly synthetic allopolyploid strain with 206 chromosomes in polyploid gibel carp

“…Since the discovery of gynogenesis in natural polyploid gibel carp from the last century (Cherfas, ; Golovinskaya, Romashov & Cherfas, ; Jiang, Yu, Chen & Liang, ), artificial allogynogenesis activated by heterologous sperm from red common carp had been used to propagate allogynogenetic gibel carp (Gui, ; Gui & Zhou, ; Liu et al., ; Mei & Gui, ; Zhou & Gui, ), and the resulted allogynogenetic gibel carp populations had been extensively cultured throughout China (Zhou & Gui, ). Intriguingly, a few of allopolyploid individuals (about 0.5%) with an extra chromosome set of common carp were found from the allogynogenetic populations (Fan et al., ; Gui, Liang, Zhu & Jiang, , ; Zhao, Liu, Chen, Qing & Dong, ).…”