Phylogeography and genetic structure of the endemic cyprinid fish Microphysogobio brevirostris in northern Taiwan

Population genetic diversity and structure of Rhinogobius candidianus (Gobiidae) in Taiwan: Translocation and release

Rhinogobius candidianus is a freshwater goby distributed in north, northwest, west, and south Taiwan, but this species has been introduced to east Taiwan and became dominant. To investigate its native population genetic diversity and structure and evaluate the sources and diversity of translocated populations, the mitochondrial DNA control region and cytochrome b gene (1981 bp) from 220 specimens were analyzed. These results indicated that (1) the east populations originated from two sources in west Taiwan; (2) translocated populations exist in east Taiwan and south Taiwan; (3) many populations have likely been moved secondarily by human intervention; (4) the effective size of the populations had declined greatly; (5) within the native populations, the ancestral populations colonized Taiwan during the land bridge phase in the Pleistocene through north Taiwan; (6) the landform changes in Taiwan shaped the population structure; and (7) the landforms of the coastline during glaciation also shaped the native range. The low-level genetic diversity, high population differentiation, and population decline greatly suggest the need for resource management and conservation interventions. Four clades (α-δ) should be managed as four distinct evolutionarily significant units, while the translocated populations should be managed as separate management units. Moreover, the translocated populations in east Taiwan should be evaluated and monitored carefully.

Genetic diversity of Rhinogobius delicatus (Perciformes: Gobiidae): origins of the freshwater fish in East Taiwan

Mitochondrial DNA cytochrome b and d-loop sequences (1,984 bp) from 92 specimens of the freshwater goby Rhinogobius delicatus from seven drainages in East Taiwan were identified as two major lineages exhibiting a southern or northern distribution. The existence of low genetic diversity, a pattern of population decline and high population differentiation (F _ST=0.711) support the need for the development of management strategies for the conservation of localized populations. The results of a statistical dispersal-vicariance analysis suggested that the ancestral populations of R. delicatus were widely distributed in East Taiwan. Compared with the phylogeographic patterns of the other endemic eastern Taiwan freshwater fishes, Onychostoma alticorpus, Aphyocypris kikuckii and Hemimyzon taitungensis, our study suggests that the freshwater fishes colonized East Taiwan through northeastern and southwestern Taiwan, although the ancestral populations colonized the island before it reached its present shape.

Geographical and temporal origins of Neocaridina species (Decapoda: Caridea: Atyidae) in Taiwan

BACKGROUND

The freshwater species on Taiwan Island have been documented to have originated from mainland China and the Japanese islands from multiple events and by multiple colonization routes. Moreover, the sequences from the mitochondrial DNA cytochrome c oxidase subunit I (COI) have been used for DNA barcoding to identify the species. This study used the COI sequences to identify Neocaridina species in Taiwan and to examine their geographical and temporal origins.

RESULTS

In total, 479 specimens were collected from 35 localities, which covered almost all rivers in Taiwan. In addition, some sequences were downloaded from GenBank. The maximum likelihood (ML) tree displayed that all sequences were sorted into 13 taxa (clades), and all sequences in Taiwan were sorted into four clades. The Bayesian skyline plots revealed that these four Neocaridina species have declined recently in Taiwan.

CONCLUSIONS

All results support that (1) there are four Neocaridina species in Taiwan, which are N. davidi, N. saccam, N. ketagalan and an undescribed Neocaridina species (N. sp.); (2) these four species colonized Taiwan Island in four colonization events; (3) N. sp. colonized Taiwan first; (4) after the island reached its shape, N. ketagalan and N. saccam colonized Taiwan from the Japanese islands and mainland China, respectively; (5) N. davidi colonized northern Taiwan last; and (6) the cyclic glacial and landform changes in East Asia shaped the colonization events and population structures of the Neocaridina species.

Genetic variation of the land-locked freshwater shrimp Caridina pseudodenticulata (Decapoda: Atyidae: Caridina) in Taiwan

Caridina pseudodenticulata is a land-locked freshwater shrimp, which is endemic to North and West Taiwan. It is listed as Vulnerable under criteria A1ce in the IUCN Red List. Our study used mitochondrial DNA fragment sequences of the cytochrome oxidase subunit I (COI) gene to examine its genetic structure. In total, 204 sequences were analyzed from 22 populations, and all 39 haplotypes were identified. Our study (1) found that the genetic diversity within population of this species was similar to that of other land-locked freshwater prawn in Taiwan; (2) displayed that during glaciation, the Taiwan Strait was largely above water, an event which created opportunities for colonization Taiwan and dispersal widely; (3) showed that although the phylogenetic analysis showed the lack of a population genetic structure, the AMOVA and haplotypes distribution pattern revealed geographically divided; (4) indicated that C. pseudodenticulata could across to neighbor rivers through the mouths of rivers, which confluent with each other during floods.