Naoko Kurose

Intrageneric diversity of the cytochrome b gene and phylogeny of Eurasian species of the genus Mustela (Mustelidae, Carnivora).

Abstract To illuminate molecular phylogenetic relationships among Eurasian species of the genus Mustela (Mustelidae, Carnivora), we determined nucleotide sequences of the complete mitochondrial cytochrome b gene region (1,140 base pairs). Molecular phylogenetic trees, constructed using the neighbor-joining and the maximum likelihood methods, showed the common topology of species relationships to each other. The American mink M. vison first branched off and was positioned very remotely from the other species of Mustela. Excluding M. vison, the ermine M. erminea first split from the rest of the species. Two small body-sized weasels, the least weasel M. nivalis and the mountain weasel M. altaica, comprised one cluster (named “the small weasel group”). The other species formed another cluster, where the remarkably close relationships among the domestic ferret M. furo, the European polecat M. putorius, and the steppe polecat M. eversmanni were noticed with 87–94% bootstrap values (named “the ferret group”), supporting the history that the ferret was domesticated from M. putorius and/or M. eversmanni. The European mink M. lutreola was the closest to the ferret group. The genetic distance between the Siberian weasel M. sibirica and the Japanese weasel M. itatsi corresponded to differences of interspecific level, while the two species were relatively close to M. lutreola and the ferret group. These results provide invaluable insight for understanding the evolution of Mustela as well as for investigating the hybridization status between native and introduced species for conservation.

Intraspecific Variation of Mitochondrial Cytochrome b Gene Sequences of the Japanese Marten Martes melampus and the Sable Martes zibellina (Mustelidae, Carnivora, Mammalia) in Japan

Abstract To assess genetic variations of two Japanese species of the genus Martes, the Japanese marten M. melampus and the sable M. zibellina, the whole regions (1,140 base pairs) of the mitochondrial cytochrome b gene were sequenced. Intraspecific variable sites were different between these two species, and most substitutions were transitions resulting in synonymous mutations. Molecular phylogenetic trees exhibited genetic differentiation between the two species. Genetic variations among M. melampus from Honshu, Shikoku, and Kyushu were larger than those among M. zibellina from Hokkaido. Genetic distance between cytochrome b haplotypes did not correlate to geographic distance between sampling localities. This result suggests the introgression of mitochondrial DNA haplotypes between local populations, probably resulting from incomplete geographic isolation, and/or their recent expansion on each island during a short period.

Low Genetic Diversity in Japanese Populations of the Eurasian Badger Meles meles (Mustelidae, Carnivora) Revealed by Mitochondrial Cytochrome b Gene Sequences

Abstract To assess the level of genetic variations of the Eurasian badger Meles meles in Japan, the entire sequences (1,140 base pairs) of the mitochondrial cytochrome b gene were phylogenetically examined. Most of substitutions between haplotypes were transitions resulting in synonymous mutations. A phylo-genetic tree reconstructed by sequence differences clearly showed that Japanese populations of Meles meles were differentiated from continental populations (from the Baikal area and eastern Europe) of M. meles. By contrast, genetic distances among Japanese populations were much smaller, and their geographic structures did not reflect geographic distances between sampling localities. The results indicate that polymorphisms of the ancestral populations still remain via loss of haplotypes by population size changes. In addition, M. meles could have occupied the present habitats in Japanese main islands (Honshu, Shikoku, and Kyushu) in a short period, possibly after the last glacial age.

Genetic characteristics of endangered Japanese golden eagles (Aquila chrysaetos japonica) based on mitochondrial DNA D-loop sequences and karyotypes

Mitochondrial DNA D-loop sequences (472 bases) for endangered Japanese golden eagles (Aquila chrysaetos japonica) were investigated to evaluate-intrapopulational genetic variations. Among 23 golden eagles, including origin-known eagles caught in the wild and origin-unknown eagles, 10 variable sites were found in the 472 base-sequences. From the nucleotide substitutions, five haplotypes of D-loop sequences were identified, indicating the occurrence of at least three maternal lineages in golden eagles around Japan. Distribution patterns of D-loop haplotypes suggested a wide genetic communication between local populations around Japan prior to a recent habitat fragmentation and a decrease in the population size. In addition, cytogenetic analysis showed that a karyotype specific to the Japanese golden eagle is consistently 2n=62 including eight microchromosomes. Based on mitochondrial DNA and karyotype data, it is likely that golden eagle populations from Japan and the Korean Peninsula together form a common conservation unit. These results provide an important framework for conservation actions for Japanese golden eagle populations in zoos, and in situ reintroduction and translocation programs. Zoo Biol 17:111–121, 1998.

Comparative phylogeography between the ermine Mustela erminea and the least weasel M. nivalis of Palaearctic and Nearctic regions, based on analysis of mitochondrial DNA control region sequences.

Abstract Phylogeography of the ermine Mustela erminea and the least weasel M. nivalis from Palae-arctic and Nearctic regions were investigated based on mitochondrial DNA control region sequences. Mustela erminea exhibited a very low level of genetic variation, and geographic structures among populations were unclear. This may indicate that M. erminea recently reoccupied a wide territory in Eurasia following the last glacial retreat. In comparison with M. erminea, genetic variations within and among populations of M. nivalis were much greater. Molecular phylogenetic relationships showed that two lineages of M. nivalis occurred in the Holarctic region: one spread from the Eurasian region to North America, and the other occurred in south-eastern Europe, the Caucasus and Central Asia. The results suggest either mitochondrial DNA introgression among populations of south-eastern Europe, the Caucasus and Central Asia, or ancestral polymorphisms remaining in those populations. Contrastive phylogeographic patterns between the two mustelid species could reflect differences of their migration histories in Eurasia after the last glacial age.

Genetic Diversity in Domestic Cats Felis catus of the Tsushima Islands, Based on Mitochondrial DNA Cytochrome b and Control Region Nucleotide Sequences

Abstract Nucleotide sequences of mitochondrial DNA (mtDNA) of 50 domestic cats (Felis catus) obtained from the Tsushima Islands were determined and the genetic diversity was analyzed. In the cats, six haplotypes of the complete cytochrome b sequences (1,140 base-pairs, bp) and ten haplotypes of the partial control region sequences (350 bp) were identified. Haplotypes obtained from both genes showed existence of at least 11 maternal lineages of domestic cats in Tsushima. Mean values of polymorphic site numbers and sequences differences in the control region were 2.4 times and 1.8 times higher than those in the cytochrome b gene, respectively. Our results support the idea that the evolutionary rate of the control region was faster than that of the cytochrome b as reported in other mammals. Molecular phylogenetic trees showed the similar clustering of haplotypes for both genes. Meanwhile, no individual variations within the Tsushima leopard cat (Felis bengalensis euptilura), which is native to Tsushima, were observed, possibly as a result of genetic drift in the small ancestral population by geographical isolation. In contrast, the diversity of the domestic cat population was higher than that of the leopard cats, because the genetic variability of the formers founders, which were repeatedly brought to Tsushima in the past, still remains. In addition, no sequences of the leopard cat mtDNA were detected in any domestic cats. However, because the possibility that the domestic cat would crossbreed with the leopard cat cannot be denied, genetic monitoring of two species is necessary to biological conservation in Tsushima.

Phylogeographic Variation in Two Mustelines, the Least Weasel Mustela nivalis and the Ermine M. erminea of Japan, Based on Mitochondrial DNA Control Region Sequences

Abstract The least weasel Mustela nivalis and the ermine M. erminea of Japan are considered relicts of the last glacial period. To study phylogeographic variation in these mustelines, fragments of the mitochondrial DNA control region were sequenced. In both species, the control region included tandem repeats of 10base motifs at the 3′ portion specific to the genus Mustela. Phylogenetic trees of the 5′ portion (581–584 bases) of M. nivalis indicated that haplotypes in the Hokkaido population clearly diverged from those in the Honshu population. Geographic pattern of intraspecific variations illustrated by this result is concordant with that by the result of a previous cytogenetic study, which revealed the karyotypic differentiation between the two populations. These findings might suggest that the Hokkaido and Honshu populations of M. nivalis were geographically isolated in advance of the formation of the Tsugaru strait between Hokkaido and Honshu. Distribution pattern of the mitochondrial DNA haplotypes within Hokkaido suggests that M. nivalis experienced the repeated changes of environments during glacial and inter-glacial periods of the Quaternary, or that this species immigrated from Sakhalin/Siberia into Hokkaido so recently. On the other hand, M. erminea exhibited a smaller sequence divergence between the Hokkaido and Honshu populations, suggesting a shorter geographic isolation than in M. nivalis.

Karyological differentiation between two closely related mustelids, the Japanese weasel Mustela itatsi and the Si- berian weasel M. sibirica

Abstract Chromosomes of the Japanese weasel Mustela itatsi endemic to Japanese main islands except Hokkaido were examined by conventional, G-, and C-stainings,and compared with those of the Siberian weasel M. sibirica which is widespread ineastern Asia and Siberia. The two species shared the same diploid chromosome number (2n=38). However, their fundamental numbers and G- and C-banding patterns were largely differentiated from each other. Judging from the karyological features as well as mitochondrial DNA data and morphological characters previously reported, M itatsi should be regarde as an independent species from M. sibirica, in agreement with the first description