Biology subjects

Kishino, H.

Publications and source records attributed to Kishino, H..

11 recordsLinked to original sources

bioRxiv2026

Mammalian returns to the sea reveal broad genomic slowing rather than a fixed adaptive toolkit

Marine mammals - cetaceans, pinnipeds, sirenians, sea otters and polar bears - returned to the sea independently, yet whether their genomes converged on a shared adaptive programme or shifted in a common direction without a fixed toolkit has remained unclear. Here we separate marine specialization from general aquatic dependence across 302 mammals and 17,432 protein-coding genes and show that the dominant genomic signature of marine life is widespread evolutionary slowing, not acceleration: of 1,559 marine-associated genes, nearly 88% evolved more slowly, and this slow-direction bias persisted (98%) after removing cetaceans. Compact gene fingerprints that distinguish marine identity combine fast-rate remodeling of body-surface and sensory genes with slow-rate constraint on blood, metabolic and DNA-repair genes, but these fingerprints are sharpened by cetaceans and do not preserve a fixed functional toolkit across lineages. Species-level and ancestral-branch decompositions reveal that different marine mammals assembled marine-like genomic states through distinct gene combinations. Mammalian marine convergence is therefore directional rather than modular: a broad constraint landscape resolved into clade-weighted genomic fingerprints.

evolutionary biology↗

bioRxiv2026

Climate-driven fitness decline in Japanese chum salmon reshapes North Pacific chum salmon biogeography

Japanese chum salmon supported by one of the worlds largest hatchery programs have experienced severe declines in marine survival and egg size. To investigate the underlying mechanisms, we analyzed a 21-year time series (1999-2019) of reproductive traits of age-4 chum salmon from 13 rivers together with climate and salmon abundance data using a bootstrap-supported Bayesian network. Here, we assumed that environmental variables can affect the chum salmon populations, but not vice versa, and that there could be maternal effect on reproductive traits, but not the other way around. These constraints enabled us to infer the causal links that shaped the biogeography of North Pacific chum salmon. Global warming caused a decline in Japanese chum salmon abundance, resulting in the increase of the competing Russian chum, which in turn decreased the female body size, fecundity, and egg size of Japanese chum. These findings suggest that climate-driven warming may have exposed genetic effects of hatchery practices, contributing to fitness decline in Japanese chum salmon and the ecological reorganization of chum salmon populations in the North Pacific.

evolutionary biology↗

bioRxiv2023

Effects of climate, release practices, predation, and competition on declining hatchery-enhanced chum salmon

We investigated variations in the marine survival of Japanese hatchery chum salmon (Oncorhynchus keta) during 25 years of climate change (1998-2023). Japan is the worlds largest producer of hatchery salmon, and is located near the global southern distribution limit of chum salmon. Our goal was to identify local and context-specific metrics related to the observed coastwide decline in salmon marine survival over the past two decades. We hypothesized multiple metrics in three categories of stressors: hatchery carryovers, ocean conditions, and predators and competitors. The hatchery carryovers are stressors related to hatchery rearing that affect survival at a different life stage. We collected, processed, and collated large publicly available datasets into a comprehensive open-access database encompassing the life cycle of Japanese chum salmon, from eggs to adult spawners. Multivariate regression models showed associations between stressors and adult salmon return rate (marine survival) varied by coastal management region, salmon life stage, and seasonal high-seas distribution area. In the early marine life history stage, parental egg size and fry size-at-release had the largest positive model effects on marine survival. The sea surface temperature (SST) at time of fry release and a predator of fry had significant negative effects. In the offshore and high-seas life stages, summer SST had negative effects, while winter SST had positive effects. Russian chum and/or pink salmon abundance had negative effects, while no effect was found for North American pink and chum salmon abundance. Generalized additive models (GAMs) identified a nationwide decline in egg size and fry size-at-release. Our study highlights the need for an experimental approach to hatchery practices, including monitoring and analyses with updated information, leading to effective management decisions and policies for future sustainability and conservation of salmon resources.

evolutionary biology↗

bioRxiv2021

Massive loss of transcription factors and the initial diversification of placental mammals

As one of the most successful categories of organisms, mammals occupy a variety of niches on earth as a result of macroevolution. Transcription factors (TFs), the basic regulators of gene expression, may also evolve during mammalian phenotypic diversification and macroevolution. To examine the relationship between TFs and mammalian macroevolution, we analyzed 140,821 de novo-identified TFs and their birth and death histories from 96 mammalian species. Gene tree vs. species tree reconciliation revealed that mammals experienced an upsurge in TF losses around 100 million years ago and also near the K-Pg boundary, thus implying a relationship with the divergence of placental animals. From approximately 100 million years ago to the present, losses dominated TF events without a significant change in TF gains. To quantify the effects of this TF pruning on mammalian macroevolution, we analyzed rates of molecular evolution and expression profiles of regulated target genes. Surprisingly, TF loss decelerated, rather than accelerated, molecular evolutionary rates of their target genes, suggesting increased functional constraints. Furthermore, an association study revealed that massive TF losses are significantly positively correlated with solitary behavior, nocturnality, reproductive-seasonality and insectivory life history traits, possibly through rewiring of regulatory networks.

evolutionary biology↗

bioRxiv2020

Detecting significant components of microbiomes by random forest with forward variable selection and phylogenetics

BackgroundRandom forest (RF) captures complex feature patterns that differentiate groups of samples and is rapidly being adopted in microbiome studies. However, a major challenge is the high dimensionality of microbiome datasets. They include thousands of species or molecular functions of particular biological interest. This high dimensionality significantly reduces the power of random forest approaches for identifying true differences. The widely used Boruta algorithm iteratively removes features that are proved by a statistical test to be less relevant than random probes. ResultWe developed a massively parallel forward variable selection algorithm and coupled it with the RF classifier to maximize the predictive performance. The forward variable selection algorithm adds new variable to a set of selected variables as far as the prespecified criterion of predictive power is improved. At each step, the parameters of random forest are optimized. We demonstrated the performance of the proposed approach, which we named RF-FVS, by analyzing two published datasets from large-scale case-control studies: (i) 16S rRNA gene amplicon data for Clostridioides difficile infection (CDI) and (ii) shotgun metagenomics data for human colorectal cancer (CRC). The RF-FVS approach further screened the variables that the Boruta algorithm left and improved the accuracy of the random forest classifier from 81% to 99.01% for CDI and from 75.14% to 90.17% for CRC. ConclusionValid variable selection is essential for the analysis of high-dimensional microbiota data. By adopting the Boruta algorithm for pre-screening of the variables, our proposed RF-FVS approach improves the accuracy of random forest significantly with minimum increase of computational burden. The procedure can be used to identify the functional profiles that differentiate samples between different conditions.

bioinformatics↗

bioRxiv2020

Waves out of the Korean Peninsula and inter- and intra-species replacements in freshwater fishes in Japan

The Japanese archipelago is located at the periphery of the continent of Asia. Rivers in the Japanese archipelago, separated from the continent of Asia about 17 Ma, have experienced an intermittent exchange of freshwater fish taxa through a narrow land bridge generated by lowered sea level. As the Korean Peninsula and Japanese archipelago were not covered by an ice sheet during glacial periods, phylogeographical analyses in this region can trace the history of biota for a long time beyond the last glacial maximum. In this study, we analyzed the phylogeography of four freshwater fish taxa, Hemibarbus longirostris, dark chub Nipponocypris temminckii, Tanakia ssp. and Carassius ssp., whose distributions include both the Korean Peninsula and western Japan. We found for each taxon that a small component of diverse Korean clades of freshwater fishes migrated in waves into the Japanese archipelago to form the current phylogeographic structure of biota. Indigenous populations were replaced by succeeding migrants. We refer to this phenomenon as "waves out of the Korean Peninsula," with parallels to "out of Africa" in humans.

zoology↗

bioRxiv2020

Population-specific FST and Pairwise FST: History and Environmental Pressure

Populations are shaped by their history. It is crucial to interpret population structure in an evolutionary context. Pairwise FST measures population structure, whereas population-specific FST measures deviation from the ancestral population. To understand the current population structure and a populations history of range expansion, we propose a representation method that overlays population-specific FST estimates on a sampling location map, and on an unrooted neighbor-joining tree and a multi-dimensional scaling plot inferred from a pairwise FST distance matrix. We examined the usefulness of our procedure using simulations that mimicked population colonization from an ancestral population and by analyzing published human, Atlantic cod, and wild poplar data. Our results demonstrated that population-specific FST values identify the source population and trace the evolutionary history of its derived populations. Conversely, pairwise FST values represent the current population structure. By integrating the results of both estimators, we obtained a new picture of the population structure that incorporates evolutionary history. The generalized least squares of genome-wide population-specific FST indicated that the wild poplar population expanded its distribution to the north, where daylight hours are long in summer, to seashores with abundant rainfall, and to the south with dry summers. Genomic data highlight the power of the bias-corrected moment estimators of FST, whether global, pairwise, or population-specific, that provide unbiased estimates of FST. All FST moment estimators described in this paper have reasonable process times and are useful in population genomics studies. The R codes for our method and simulations are available in the Supplemental Material.

evolutionary biology↗

bioRxiv2019

Rates of molecular evolution predict intraspecies genetic diversity

What determines genetic diversity and how it connects to the various biological traits is unknown. In this work, we offer answers to these questions. By comparing genetic variation of 14,671 mammalian gene trees with thousands of individual genomes of human, chimpanzee, gorilla, mouse and dog/wolf, we found that intraspecific genetic diversity is determined by long-term molecular evolutionary rates, rather than de novo mutation rates. This relationship was established during the early stage of mammalian evolution. Expanding this new finding, we developed a method to detect fluctuations of species-specific selection on genes as the deviations of intra-species genetic diversity predicted from long-term rates. We show that the evolution of epithelial cells, rather than of connective tissue, mainly contributes to morphological evolution of different species. For humans, evolution of the immune system and selective sweeps subjected by infectious diseases are most representative of adaptive evolution.

evolutionary biology↗

bioRxiv2019

Fitness decline in hatchery-enhanced salmon populations is manifested by global warming

Genetic stock identification (GSI) is a major management tool of Pacific salmon (Oncorhynchus Spp.) that has provided rich genetic baseline data of allozymes, microsatellites, and single nucleotide polymorphisms (SNPs) across the Pacific Rim. Here, we analyzed published data sets for adult chum salmon (Oncorhynchus keta), namely 10 microsatellites, 53 SNPs, and a mitochondrial DNA locus (mtDNA3, control region and NADH-3 combined) from 495 locations in the same distribution range (n = 61,813). TreeMix analysis of the microsatellite loci identified the highest level of genetic drift towards Japanese/Korean populations and suggested two admixture events from Japan/Korea to Russia and the Alaskan Peninsula. The SNPs had been purposively collected from rapidly evolving genes to increase the power of GSI. The highest expected heterozygosity was observed in Japanese/Korean populations for microsatellites, whereas it was highest in Western Alaskan populations for SNPs, reflecting the SNP discovery process. By regressing the SNP population structures on those of the microsatellites, we estimated the selection on the SNP loci according to deviations from the predicted structures. Specifically, we matched the sampling locations of the SNPs with those of the microsatellites according to geographical information and performed regression analyses of SNP allele frequencies on the two coordinates of multi-dimensional scaling (MDS) of matched locations obtained from microsatellite pairwise FST values. The MDS first axis indicated a latitudinal cline in American and Russian populations, whereas the second axis found a differentiation of Japanese/Korean populations. The top five outlier SNPs were mtDNA3 (combined locus of the control region and NADH-3), U502241 (unknown), GnRH373, ras1362, and TCP178, which were consistently identified by principal component analysis. We summarized the functions of the 53 nuclear SNPs and mtDNA3 locus by referring to a gene database system and discussed the functions of the outlier SNPs and fitness of chum salmon.

evolutionary biology↗

bioRxiv2018

Comprehensive understanding of population structure and adaptation through graphical representation of gene-environment-trait associations

During the history of range expansion, the populations encounter with variety of environments. They respond to the local environments by modifying the mutually interacting traits. Therefore, to understand the whole life history of the populations, it is ideal to capture the history of their range expansion with reference to the series of surrounding environments and to infer the coadaptation of the multiple traits. Toward this end, we provide an exploratory analysis based on the features of populations: site frequency spectra of populations, population-specific FST, association between genes and environments, positive selections on traits mapped on the admixture graph, and GWAS results. Correspondence analysis of genes, environments, and traits provides a birds-eye view of the history of population differentiation and range expansion and various types of environmental selections at the times. Principal component analysis of the estimated trait-specific polygenic adaptations mapped on the admixture graph enables to understand the coadaptation of multiple traits. The potential usefulness was confirmed by analyzing a public dataset of wild poplar in northwestern America. In response to the northern cold temperature and longer daylength, the populations increased the photosynthetic activity and nutrient use efficiency at the expense of the risk of pathogen invasion, and in response to warm temperature, they increased the growth. At higher altitude, they shifted the maximum activity to earlier period in spring to reduce the activity in dry summer. The R codes for our representation method and simulations of population colonization used in this study are available as supplementary script.

bioinformatics↗

bioRxiv2018

Stochastic Variational Inference of Mixture Models inPhylogenetics

The pattern of molecular evolution varies among gene sites and genes in a genome. By taking into account the complex heterogeneity of evolutionary processes among sites in a genome, Bayesian infinite mixture models of genomic evolution enable robust phylogenetic inference. With large modern data sets, however, the computational burden of Markov chain Monte Carlo sampling techniques becomes prohibitive. Here, we have developed a variational Bayesian procedure to speed up the widely used PhyloBayes MPI program, which deals with the heterogeneity of amino acid profiles. Rather than sampling from the posterior distribution, the procedure approximates the (unknown) posterior distribution using a manageable distribution called the variational distribution. The parameters in the variational distribution are estimated by minimizing Kullback-Leibler divergence. To examine performance, we analyzed three empirical data sets consisting of mitochondrial, plastid-encoded, and nuclear proteins. Our variational method accurately approximated the Bayesian phylogenetic tree, mixture proportions, and the amino acid propensity of each component of the mixture while using orders of magnitude less computational time.

bioinformatics↗