Effects of heatwave events on the seagrass-dwelling crustacean Pandalus latirostris in a subarctic lagoon.

Heatwaves often cause mass mortality of organisms in seagrass areas, and they eventually alter some ecological functions of seagrass ecosystems. In subarctic regions, however, the effects of heatwaves on seagrass areas are still unclear. In a subarctic lagoon of northern Japan, we examined the effects of heatwaves on the Hokkai shrimp, Pandalus latirostris, a commercially exploited species distributed in seagrass areas of northern Japan and eastern Russia.

Geographic patterns in colonial reproductive strategy in Myrmecina nipponica: Links between biogeography and a key polymorphism in ants.

The ability to express different phenotypes can help define species distributions by allowing access to, and exploitation of, new environments. Social insects employ two markedly different reproductive strategies with contrasting cost/benefit characteristics: independent colony foundation (ICF), which is associated with high dispersal range and high risk, and dependent colony foundation (DCF), characterized by low risk but low dispersal. The ant Myrmecina nipponica employs both of these strategies, with the frequency of each apparently varying between populations.

Phylogeographic insights into the invasion history and secondary spread of the signal crayfish in Japan.

Successful invasion by nonindigenous species is often attributed to high propagule pressure, yet some foreign species become widespread despite showing reduced genetic variation due to founder effects. The signal crayfish (Pacifastacus leniusculus) is one such example, where rapid spread across Japan in recent decades is believed to be the result of only three founding populations. To infer the history and explore the success of this remarkable crayfish invasion, we combined detailed phylogeographical and morphological analyses conducted in both the introduced and native ranges.

Classification of the spermatogenic cycle, seasonal changes of seminiferous tubule morphology and estimation of the breeding season of the large Japanese field mouse (Apodemus speciosus) in Toyama and Aomori prefectures, Japan.

The large Japanese field mouse, Apodemus speciosus, is a potential indicator of environmental stress, but this function has not been confirmed by histological studies. Since environmental stress affects the reproductive function of mice, we determined the reproductive characteristics of this species at two locations: Toyama (36°35'N, 137°24'E) and Aomori (40°35'N, 140°57'E). Mice were captured during May-November (n=119) and July-November (n=146) at these locations, respectively.

Loss of genetic diversity means loss of geological information: the endangered Japanese crayfish exhibits remarkable historical footprints.

Intra-specific genetic diversity is important not only because it influences population persistence and evolutionary potential, but also because it contains past geological, climatic and environmental information. In this paper, we show unusually clear genetic structure of the endangered Japanese crayfish that, as a sedentary species, provides many insights into lesser-known past environments in northern Japan. Over the native range, most populations consisted of unique 16S mtDNA haplotypes, resulting in significant genetic divergence (overall F(ST) = 0.

Expression profiling without genome sequence information in a non-model species, Pandalid shrimp (Pandalus latirostris), by next-generation sequencing.

While the study of phenotypic variation is a central theme in evolutionary biology, the genetic approaches available to understanding this variation are usually limited because of a lack of genomic information in non-model organisms. This study explored the utility of next-generation sequencing (NGS) technologies for studying phenotypic variations between 2 populations of a non-model species, the Hokkai shrimp (Pandalus latirostris; Decapoda, Pandalidae). Before we performed transcriptome analyses using NGS, we examined the genetic and phenotypic differentiation between the populations.

Molecular phylogeny of a red-snow-crab species complex using mitochondrial and nuclear DNA markers.

Nucleotide sequence variation of mitochondrial DNA COI and nuclear rRNA gene regions was used to reconstruct phylogenetic relationships for the red-snow-crab species complex, including the red snow crab, Chionoecetes japonicus, its nominal subspecies, C. japonicus pacificus, and the triangle tanner crab, C. angulatus.

Ergatoid queen development in the ant Myrmecina nipponica: modular and heterochronic regulation of caste differentiation.

Caste polyphenism in social insects provides us with excellent opportunities to examine the plasticity and robustness underlying developmental pathways. Several ant species have evolved unusual castes showing intermediate morphologies between alate queens and wingless workers. In some low-temperature habitats, the ant Myrmecina nipponica produces such intermediate reproductives (i.

Phylogenetic relationships within parrots (Psittacidae) inferred from mitochondrial cytochrome-b gene sequences.

Blood and tissue samples of 40 individuals including 27 parrot species (15 genera; 3 subfamilies) were collected in Indonesia. Their phylogenetic relationships were inferred from 907 bp of the mitochondrial cytochrome-b gene, using the maximum-parsimony method, the maximum-likelihood method and the neighbor-joining method with Kimura two-parameter distance. The phylogenetic analysis revealed that (1) cockatoos (subfamily Cacatuinae) form a monophyletic sister group to other parrot groups; (2) within the genus Cacatua, C.

Molecular phylogeny among local populations of weaver ant Oecophylla smaragdina.

The molecular phylogeny of 24 Oecophylla smaragdina populations and two O. longinoda populations was studied using 647 bp of the mitochondrial cyt b gene. The phylogenetic analysis suggested that O.