Zoological Science最新文献

Copy number variation (CNV) in gene loci in animals can be driven by adaption to the environment. The relationship between CNV in genes for amylase (AMY), which hydrolyzes starch, and dietary adaptation has been well studied. Copy number (CN) of AMY is higher in human populations with high-starch diets, compared with those with low-starch diets. Although CNV in AMY has been reported in humans and some domestic animals, there have been few studies of animals in the wild. The brown bear (Ursus arctos), widespread in the Northern Hemisphere, shows large dietary variation among individuals and groups. Brown bear population genetic structures are associated with the dispersal history due to climate change over the past few tens of thousands of years, and this together with dietary variation should have led to CNV in AMY. In this study, we investigated CNV in AMY in brown bears worldwide by using whole genome sequencing data. We detected AMY CNV among regional groups. AMY CN was similar among brown bears in geographically proximate populations, such as between Hokkaido (Japan) and East Asia, and between the North America mainland and the ABC islands. CNs were smaller in bears from East Asia, including Hokkaido, compared to those from other regions across brown bears' distribution. Our results suggest that CNs of AMY reflect the population demographic history of brown bears after the Last Glacial Maximum.

Snails of the family Eulimidae are parasites of echinoderms in all five extant classes. Despite long years of taxonomic research on Eulimidae in Japan, their local species richness remains to be investigated, and few studies have focused on a eulimid fauna of a certain echinoderm taxon, even if it is a common species. Here, we conducted a comprehensive sampling of Melanella species parasitizing the black sea cucumber Holothuria leucospilota in Shirahama, Wakayama, central Japan. The data used in this study were partly obtained during a summer education program of the Seto Marine Biological Laboratory, Kyoto University. Melanella kuronamako and M. spina parasitized the external surface, and two unidentified species were found inside the host's body cavity. This study represents the first record of M. spina in Japanese waters and eulimids exploiting the internal habitat of H. leucospilota. Morphological and molecular comparisons between the present four species and other Japanese Melanella specimens suggested that they generally exhibit wide geographic distributions and low host specificity. Additionally, the two species from the body cavity were probably seldom observed in central Japan, as inferred from the accumulated results of the dissection of H. leucospilota through a long-running, annual education program at Shirahama.

Oxytocin (OT)/vasopressin (VP)-like peptide has been reported in invertebrates as a single peptide with various common names. This peptide was suggested to be a primitive form of the oxytocin and vasopressin present in vertebrates. In this study, the full mRNA sequence of the OT/VP-like peptide was annotated in the central nervous system (CNS) transcriptome of the mud crab Scylla olivaceathrough the National Center for Biotechnology Information (BioProject ID: PRJNA1006859). The sequence contained 607 bp corresponding to 158 amino acids. Multiple alignment and phylogenetic tree analyses suggested that the OT/VP-like peptide of S. olivacea is most similar to that of Scylla paramamosain. Reverse transcription polymerase chain reaction (RT-PCR) analysis indicated that the mRNA was expressed in the eyestalks, brain, ventral nerve cord (VNC), ovaries, and other peripheral organs. Real-time qPCR revealed that the highest expression levels of this mRNA occurred in the CNS and ovaries of the crabs bearing stage I ovaries. Using the conserved region CFITNCPPGGKRSGGLMSTLGR to produce antibody, the OT/VP-like peptide was detected in neuronal clusters 6/7, 8, 11, and 14/15 and in neuropils of the brain, as well as the neurons and neuropils of the VNC, including the subesophageal (SEG), thoracic (TG), and abdominal (AG) ganglia. In the ovaries, immunoreactivity of this peptide occurred in the ooplasm of the oocytes of immature ovaries, and it was detected near the cell membranes of oocytes of mature ovaries. This work supports the neuro-endocrine study of an economically important mud crab species and could be helpful in aquaculture management.

A new lineid heteronemertean with a branched proboscis, Polydendrorhynchus amaleshii sp. nov., is described as the second member of the genus Polydendrorhynchus Yin and Zeng, 1986, following Polydendrorhynchus zhanjiangensis (Yin and Zeng, 1984). The description is based on specimens collected from the northeastern coastal Bay of Bengal, including the Subarnarekha Estuary and Frazerganj in the Indian Sundarbans mangrove ecosystem. The new species is distinguished from its congener by having up to 56 terminal branchlets of the proboscis and the absence of rhynchocoel compartments. In a maximum-likelihood phylogenetic analysis based on COI and 16S rRNA genes, P. amaleshii and P. zhanjiangensis formed a well-supported clade. Polydendrorhynchus amaleshii represents the ninth nemertean species recorded from India.

The study concentrated on the Notocomplana Faubel, 1983 species that exist in the northern regions of the Pacific Ocean. The research utilized a comprehensive methodology that combined molecular (mitochondrial COI and nuclear 28S rRNA genes) and anatomical approaches. The primary objective of this study was to gain a thorough understanding of the diversity of the genus Notocomplana in this region. This includes all possible species and their populations. The study used various analysis tools to establish the boundaries and relationships within and between species. Bayesian inference and maximum likelihood were used for kinship analysis, while bPTP, mPTP, and ABGD were used for species delimitation. Haplotype studies were conducted using TCS and MSN. The study focused on Notocomplana hagiyai Oya and Kajihara, 2017, a well-known species of the genus from Asia found along the coasts of Vladivostok in Russia, as well as Notocomplana species from the North Pacific coast of Asia and North America. The analysis revealed the degree of diversity in Notocomplana and the relationships between different species and populations, both within and between them. The diversity of species and haplotypes found on the North Pacific coasts was very motivating, particularly concerning the relationships between the Asian and American populations. Although the 28S analysis indicated that N. septentrionalis (Kato, 1937) was a sister group to the Asian species, the COI analyses did not provide any definitive resolution regarding the kinship relationships between N. septentrionalis and the other groups.

Octopuses have well-developed sensory organs and a large brain, which allows them to use multiple senses, such as vision, touch, and taste. Most studies on the sensory abilities of octopuses have focused on a single sensory modality, particularly vision. However, octopuses are simultaneously exposed to multiple sensory stimuli. If an octopus can transfer information about its environment between two different senses, then the flexibility of its multisensory system must provide an adaptive advantage. This type of recognition system is referred to as cross-modal recognition. Here, we describe cross-modal recognition between the vision and touch of novel objects in octopuses. Octopuses were engaged in learning three geometrically identical objects that provided different sensory information: i) a soft object transforming against touch (visual-only condition), ii) a hard object being shielded (tactile-only condition), and iii) a hard object (visuo-tactile condition). In the shape discrimination test of objects (ball vs. cross), all octopuses, except those in the visual-only condition, selected the correct object. Furthermore, octopuses that first learned about an object by touch immediately recognized it solely through vision. These observations indicate that octopuses are more likely to depend on the tactile information of objects in the process of forming representations of novel objects, and that cross-modal object recognition across tactile and visual perception exists in octopuses.

The water mite genus Hygrobates and the newt family Salamandridae are distributed widely in the northern hemisphere. However, only in Eastern and Southeastern Asia a host-parasite association developed, with several Hygrobates species, which belong to the subgenus Lurchibates, parasitizing newts of the genera Laotriton, Pachytriton, and Paramesotriton. Presently, there is no molecular study on parasitic Hygrobates, which impedes our understanding of their phylogeny and the evolutionary history of the host-parasite association between Lurchibates and their hosts. In this study, we performed comparative phylogenetic analyses on parasitic Lurchibates mites and their newt hosts based on their respective phylogenies. Our results did not support the monophyly of parasitic species of Hygrobates, but instead, group them significantly with a free-living species, H. longiporus. Among the parasitic species, H. forcipifer, H. macrochela, H. malosimilis, and H. robustipalpis are significantly grouped together, while branching patterns of the remaining species were not supported. Distance-based approaches of cophylogeny analysis between hosts and parasites found no significant link. On the other hand, among all the cost schemes constructed by event-based cophylogeny methods, four cospeciation events, two duplication and host-switching events, one loss event, and two failure to diverge events between parasitic water mites and newts were discovered. Our findings suggested that host switching events might have played an important role in the evolution of these parasitic mites, which might have led to incompletely exclusive host-parasitic relationships at species level.

We report the first record of the pallenopsid pycnogonid species Bathypallenopsis californica (Schimkewitsch, 1893) from the northwestern Pacific. Based on one male specimen collected from 1987-2007 m depth off the southeastern coast of Hokkaido, Japan, we redescribe the species and present its cytochrome c oxidase subunit I (COI) sequence for use in future DNA barcoding. We found a cystidean-stage crinoid on the leg-1 femur of the sea spider, representing the first record of a cystidean found on a sea spider. BLAST searches for COI and 28S sequences revealed that the crinoid was Florometra asperrima (Clark, 1907).

In this study, we obtain and analyze the first transcriptome data for the family Thamnocephalidae, targeting Branchinella kugenumaensis (Ishikawa, 1895), an anostracan fairy shrimp primarily found in Japan and Far Eastern Eurasia. We collected a male specimen from a rice paddy in Tochigi, Japan, and performed RNA-seq analysis, obtaining an assembled transcriptome comprising a 15,157 nucleotide sequence with an 80.75% completeness score. Because the relationships among the families within Anostraca remain unclear, using both mitochondrial and nuclear genes, we constructed phylogenetic trees employing maximum likelihood and Bayesian methods. Our results indicate that Artemiidae formed a cluster with Thamnocephalidae, and together they formed a sister group to the other Anostraca. We also demonstrated that a large number of parallel or back substitutions can hinder the estimation of phylogenetic relationships. This study not only enhances our understanding of anostracan phylogeny but also highlights the significance of transcriptome data in evolutionary biology.

While the echolocation behavior and specialized adaptive auditory system of the greater horseshoe bat (Rhinolophus ferrumequinum) are well documented, comprehensive insights into its wild ecology, especially its detailed nocturnal movements for foraging behavior, remain scarce. Therefore, our objective was to obtain information on the spatiotemporal features of the movements of the Japanese greater horseshoe bat (Rhinolophus nippon), a close relative of R. ferrumequinum, during foraging. Hence, we investigated the nightly flight paths of R. nippon using high-resolution GPS data loggers. Initially, hidden Markov modeling analysis classified bat flight paths into two behavioral patterns: commuting and area-restricted behavior, the latter primarily corresponding to foraging activities. Focusing on foraging behavior along their trajectory, we observed that R. nippon repeatedly foraged with brief stops lasting only a few minutes and an average distance of approximately 300 m between any two foraging sites. Notably, one individual covered a considerable distance (23.6 km) from its roost, possibly because of irregular social behavior during the mating season. Furthermore, for commuting, bats occasionally used forest roads, which were located along the middle of relatively steep slopes. In cases of echolocations with limited detection distances, echoes from the ground and adjacent tree lines offered crucial navigation cues, underscoring the significance of forest roads as nightly movement routes for echolocating bats. Overall, our findings highlight the importance and urgency of ongoing research on bat movement ecology in Japan.