Portal de Periódicos da CAPES

Comparing spatial patterns of population density, biomass, and genetic diversity patterns of the habitat generalist mayfly Isonychia japonica Ulmer (Ephemeroptera:Isonychiidae) in the Chikuma–Shinano River basin

2016; University of Chicago Press; Volume: 35; Issue: 2 Linguagem: Inglês

10.1086/686537

2161-9565

Rie Saito, Koji Tojo,

Fish Ecology and Management Studies

Evaluating the relative connectivity of populations within and among streams in a riverine landscape is crucial to developing a better understanding of stream ecology. Molecular markers provide a reasonable approach to assess the connectivity of populations and to evaluate inherent properties of populations, such as genetic diversity. Many previous investigators of genetic differentiation within species at the regional level have focused on habitat specialists, but habitat generalists, with their continuous and broad distribution across a wide variety of habitats, have not been a focus of research. We examined a typical habitat generalist mayfly, Isonychia japonica Ulmer (Ephemeroptera:Isonychiidae) by evaluating its population density, biomass, and genetic structure at 42 study sites in the largest river system in the Japanese Archipelago, the Chikuma–Shinano-gawa River basin. We conducted genetic analysis of the mitochondrial DNA cytochrome oxidase c subunit I (COI) region (610 base pairs). We confirmed that I. japonica inhabits an extensive range of ∼300 km from its up- to downstream habitats throughout the watershed. Genetic analysis of 330 specimens showed that genetic diversity at each study site was extremely high, regardless of the respective population density or biomass. In many cases, specimens shared the same haplotypes even between distant study sites. One dominant haplotype was widely observed in the river basin. The direction and strength of the estimated gene flow supported the hypothesis that high gene flow has occurred in all directions. The pattern of gene flow does not appear to be affected by unsuitable habitat areas or areas of low population density or low biomass. We argue that I. japonica has a metapopulation genetic structure, where low-density demes are sustained by a continual influx of immigrants.