Selection acting across environmental gradients, such as latitudes, can cause spatial structuring of genomic variants even within panmictic populations. In this study, we focused on the ...within‐generation latitudinal selection between northernmost and southernmost individuals of the North Pacific population of a tropical eel Anguilla marmorata, which shares its northernmost distribution with a temperate eel Anguilla japonica. Whole‐genome sequencing data indicated that the northernmost and southernmost individuals of A. marmorata belong to a single panmictic population, as suggested by previous studies. On the contrary, parts of genomic regions across multiple chromosomes exhibited significant genetic differentiation between the northernmost and southernmost individuals, and in these genomic regions, the genotypes of the northernmost individuals were similar to those of A. japonica. These findings suggested within‐generation latitudinal selection of A. marmorata, which might have led to genetic closeness between northernmost A. marmorata and A. japonica.
Parts of genomic regions (outlier SNP loci) exhibited significant genetic differentiation between the northernmost and southernmost individuals of Anguilla marmorata, and in these genomic regions, the genotypes of the northernmost individuals of A. marmorata were similar to those of A. japonica. This finding suggests latitudinal selection in the tropical eel A. marmorata.
Abstract
Extinct lineages can leave legacies in the genomes of extant lineages through ancient introgressive hybridization. The patterns of genomic survival of these extinct lineages provide insight ...into the role of extinct lineages in current biodiversity. However, our understanding on the genomic landscape of introgression from extinct lineages remains limited due to challenges associated with locating the traces of unsampled ‘ghost’ extinct lineages without ancient genomes. Herein, we conducted population genomic analyses on the East China Sea (ECS) lineage of
Chaenogobius annularis
, which was suspected to have originated from ghost introgression, with the aim of elucidating its genomic origins and characterizing its landscape of introgression. By combining phylogeographic analysis and demographic modelling, we demonstrated that the ECS lineage originated from ancient hybridization with an extinct ghost lineage. Forward simulations based on the estimated demography indicated that the statistic
γ
of the HyDe analysis can be used to distinguish the differences in local introgression rates in our data. Consistent with introgression between extant organisms, we found reduced introgression from extinct lineage in regions with low recombination rates and with functional importance, thereby suggesting a role of linked selection that has eliminated the extinct lineage in shaping the hybrid genome. Moreover, we identified enrichment of repetitive elements in regions associated with ghost introgression, which was hitherto little known but was also observed in the re‐analysis of published data on introgression between extant organisms. Overall, our findings underscore the unexpected similarities in the characteristics of introgression landscapes across different taxa, even in cases of ghost introgression.
We conducted field surveys of aquatic animals in seven rivers on the Pacific coast of Atsumi Peninsula, Aichi Prefecture, Japan and collected 30 species of fish, 21 species of decapod crustaceans, ...and 5 species of gastropods. Fourteen species of them were described in detail based on the specimens, of which two fishes (Kuhlia marginata and Eleotris melanosoma), five freshwater caridean shrimps (Macrobrachium formosense, M. lar, M. latimanus, Caridina typus and C. multidentata), a brackish-water crab (Ptychognathus ishii) and a freshwater snail (Septaria porcellana) represented the first records from Aichi Prefecture. Since all of these species had already been recorded from adjacent areas, lack of surveys and/or reports from small streams in the prefecture may explain why there were so many first-time records. On the other hand, some of them were diadromous species which mainly inhabit more southerly areas, and therefore these species might have come to appear in Aichi Prefecture in recent years due to the effects of global warming.
Specimens of nine crab species that are mainly distributed in the south of the Japanese archipelago (Cycloachelous granulatus, Ilyograpsus nodulosus, Macrophthalmus banzai, Metopograpsus thukuhar, ...Parapyxidognathus deianira, Ptychognathus capillidigitatus, Ptychognathus ishii, Scylla serrata, Varuna litterata) and two rare crab species (Camptandrium sexdentatum, Sestrostoma toriumii) were collected from rivers flowing into the Sagami Bay and adjacent waters to improve their records for this region. For some species, the specimens included ovigerous females or were collected in autumn and the following spring, suggesting overwintering and range extension in this region, possibly due to increasing water temperatures as a result of global warming.
Sixteen tropical and two temperate fish species whose distributions are biased to the south of the Japanese Archipelago were collected from the rivers and coastal areas of Sagami Bay and adjacent ...waters. Oligolepis stomias was newly reported from the Kanto area representing the northernmost record for the species. Eleotris fusca, Ophieleotris sp. 1, Taenioides sp. B, Oxyurichthys lonchotus, Callogobius tanegasimae, Bathygobius hongkongensis, Drombus sp., Favonigobius reichei and Scatophagus argus were recorded for the first time from Chiba Prefecture and these are the easternmost specimen-based records for the species. The occurrence of Plectorhinchus gibbosus in Zushi represents a new specimen-based record from Kanagawa Prefecture. Lutjanus argentimaculatus, Lutjanus rivulatus, Lutjanus fulvus, Kuhlia marginata, Oligolepis acutipennis, Redigobius bikolanus and Bathygobius peterophilus were also noted. These specimens and research of other specimens, pictures and literature surveys show that, in Sagami Bay and adjacent waters, the numbers of stations where each fish species were recorded has increased in recent years. In addition, the total numbers of recorded or settling species are increasing over time in not only the collecting area but also in other areas north of Kyushu along the Kuroshio Current. These results indicate northward range extensions along the Kuroshio Current for these warm water fishes, and can be explained by a rising trend in sea surface temperature caused by global warming.
