Phenotypic and Genomic Signatures of Latitudinal Local Adaptation Along With Prevailing Ocean Current in a Coastal Goby.

In the marine realm, unidirectional ocean currents often lead to high migration rates of marine organisms and, therefore, inhibit the formation of their latitudinal genetic structure. In contrast, cryptic latitudinal structures associated with local adaptation may frequently exist in widespread species generally exposed to a strong environmental heterogeneity. However, our understanding of the evolvability of locally adapted populations in open marine environments still needs to be completed.

Plate reduction in southern Japanese freshwater populations of threespine stickleback ().

Adaptation to similar environments can lead to the evolution of similar phenotypes in phylogenetically independent lineages. However, the extent of parallel evolution often varies. Because such variations can be due to environmental heterogeneity among seemingly similar habitats, identification of the environmental factors that cause non-parallel patterns can provide valuable insight into the ecological factors associated with phenotypic diversification.

Gudgeon fish with and without genetically determined countershading coexist in heterogeneous littoral environments of an ancient lake.

Countershading, characterized by a darker dorsal surface and lighter ventral surface, is common among many animals. This dorsoventral pigment polarity is often thought to be adaptive coloration for camouflage. By contrast, noncountershaded (melanistic) morphs often occur within a species due to genetic color polymorphism in terrestrial animals.

Multiple waves of freshwater colonization of the three-spined stickleback in the Japanese Archipelago.

Background: The three-spined stickleback (Gasterosteus aculeatus) is a remarkable system to study the genetic mechanisms underlying parallel evolution during the transition from marine to freshwater habitats. Although the majority of previous studies on the parallel evolution of sticklebacks have mainly focused on postglacial freshwater populations in the Pacific Northwest of North America and northern Europe, we recently use Japanese stickleback populations for investigating shared and unique features of adaptation and speciation between geographically distant populations. However, we currently lack a comprehensive phylogeny of the Japanese three-spined sticklebacks, despite the fact that a good phylogeny is essential for any evolutionary and ecological studies.

Accumulation of Deleterious Mutations in Landlocked Threespine Stickleback Populations.

Colonization of new habitats often reduces population sizes and may result in the accumulation of deleterious mutations by genetic drift. Compared with the genomic basis for adaptation to new environments, genome-wide analysis of deleterious mutations in isolated populations remains limited. In the present study, we investigated the accumulation of deleterious mutations in five endangered freshwater populations of threespine stickleback (Gasterosteus aculeatus) in the central part of the mainland of Japan.

Genomic and phenotypic consequences of two independent secondary contact zones between allopatric lineages of the anadromous ice goby Leucopsarion petersii.

Genetic and phenotypic analyses of independent secondary contact zones between certain pairs of divergent populations offer powerful opportunities to assess whether the consequences vary with different environmental backgrounds. Populations of the ice goby Leucopsarion petersii are distributed throughout the Japanese archipelago and comprise genetically and phenotypically divergent groups in the Japan Sea and the Pacific Ocean. In particular, populations in the Japan Sea have a larger body size and numbers of vertebrae than those in the Pacific Ocean.

A key metabolic gene for recurrent freshwater colonization and radiation in fishes.

Colonization of new ecological niches has triggered large adaptive radiations. Although some lineages have made use of such opportunities, not all do so. The factors causing this variation among lineages are largely unknown.

Genomic architecture of habitat-related divergence and signature of directional selection in the body shapes of Gnathopogon fishes.

Evolution of ecomorphologically relevant traits such as body shapes is important to colonize and persist in a novel environment. Habitat-related adaptive divergence of these traits is therefore common among animals. We studied the genomic architecture of habitat-related divergence in the body shape of Gnathopogon fishes, a novel example of lake-stream ecomorphological divergence, and tested for the action of directional selection on body shape differentiation.

A RAD-based linkage map and comparative genomics in the gudgeons (genus Gnathopogon, Cyprinidae).

Background: The construction of linkage maps is a first step in exploring the genetic basis for adaptive phenotypic divergence in closely related species by quantitative trait locus (QTL) analysis. Linkage maps are also useful for comparative genomics in non-model organisms. Advances in genomics technologies make it more feasible than ever to study the genetics of adaptation in natural populations.

Molecular signatures of lineage-specific adaptive evolution in a unique sea basin: the example of an anadromous goby Leucopsarion petersii.

Climate changes on various time scales often shape genetic novelty and adaptive variation in many biotas. We explored molecular signatures of directional selection in populations of the ice goby Leucopsarion petersii inhabiting a unique sea basin, the Sea of Japan, where a wide variety of environments existed in the Pleistocene in relation to shifts in sea level by repeated glaciations. This species consisted of two historically allopatric lineages, the Japan Sea (JS) and Pacific Ocean (PO) lineages, and these have lived under contrasting marine environments that are expected to have imposed different selection regimes caused by past climatic and current oceanographic factors.

Phylogeography and historical demography of the anadromous fish Leucopsarion petersii in relation to geological history and oceanography around the Japanese Archipelago.

Phylogeographical patterns of marine and diadromous organisms are often influenced by dynamic ocean histories. For example, the marine realm around the Japanese Archipelago is an interesting area for phylogeographical research because of the wide variation in the environments driven by repeated shifts in sea level in the Quaternary. We analysed mitochondrial cyt b gene and nuclear myh6 gene sequences for individuals collected from throughout the range of the anadromous fish Leucopsarion petersii to assess the lineage divergence, phylogeographical pattern and historical demography in relation to geological history and oceanographic features around the archipelago.

PERMANENT GENETIC RESOURCES: Isolation and characterization of polymorphic trinucleotide and dinucleotide microsatellite loci for the ice goby, Leucopsarison petersii.

Eleven microsatellite markers were isolated and characterized for the ice goby, Leucopsarion petersii, from genomic libraries enriched for (ATG)(9) and (CA)(16) . Twenty individuals from a single population were used to screen polymorphism in these loci. The number of alleles per locus and observed heterozygosity ranged from four to 22 and from 0.