Houston Museum of Natural Science

Abstract Biotic dispersal between regions is mediated by a suite of geographical, environmental, and biotic factors. Australia and Melanesia—with the latter centred on New Guinea—are geographically proximate regions that show differing abiotic environments and geological histories, providing an opportunity to document how environmental variation may interact with geographical proximity in shaping dispersal and evolution. Here, we present a phylogenomic framework and analysis of dispersal history for geckos in the genus Gehyra, a radiation of ∼70 species that occur across Australia, Melanesia, and nearby regions. Despite an evident history of numerous overwater dispersals in species groups occurring in Melanesia, we find very low rates of historical dispersal between Australia and Melanesia and no evidence of an increase in dispersal rate as land bridges formed between Australia and New Guinea from the late Miocene onwards. Analyses of body-size evolution suggest that ‘giant’ large-bodied forms have evolved on islands, but rather than evolving repeatedly on different islands, these are mostly members of a single old clade that dispersed across multiple islands. In contrast to some other Australasian vertebrate radiations, for Gehyra geckos, environmental differences appear to have strongly impeded dispersal between Australia and Melanesia, while also favouring differing trajectories of body size evolution.

ABSTRACT Aim The isolated nature of islands makes them particularly vulnerable to climate change. The freshwater fishes of the Greater Antilles remain understudied and are further threatened by habitat fragmentation and the introduction of exotic invasive species. A practical solution to protect this diversity is to develop a spatially explicit framework to inform conservation actions. We test whether biogeographically significant subregions can be identified within the Greater Antilles. Location The Greater Antilles, Caribbean Basin. Taxa Freshwater Fishes (Atheriniformes, Cichliformes, Cyprinodontiformes, Lepisosteiformes, and Ophidiiformes). Methods We compiled a dataset of 1704 occurrence records across the Greater Antilles based on museum vouchers and the authors' fieldwork. River basins were used as analytical units for hierarchical agglomerative clustering both among and within islands. We also combined genetic data to examine phylogeographic patterns and uncover potential substructure within islands. Results Ninety‐two per cent of the freshwater fish fauna of the Greater Antilles is endemic. Although diversity is unevenly distributed among and within islands, patterns of species richness and weighted endemism partially align across islands. The region is not a single biogeographic unit but consists of multiple subregions of biogeographic significance, where river basins from the same island are more similar to each other than to basins from other islands, with Hispaniola as the only exception. Main Conclusions The Greater Antilles comprise a mosaic of biogeographically meaningful subregions, each harbouring unique, highly vulnerable, and often range‐restricted species assemblages. The patterns recovered reflect a complex interplay among the region's geological history, multiple colonization events, and diversification processes. Our proposed areas of endemism represent testable hypotheses for investigating the evolutionary history of freshwater taxa in the region. These areas also provide natural management units that can serve as geographical targets for conservation prioritisation and policymaking for freshwater ecosystems across the Greater Antilles.

The trunks of forest trees store massive amounts of carbon, but fungi actively and invisibly decay wood inside even seemingly healthy trees. Wood-decay fungi are responsible for the loss of stored carbon in living trees, and they make trees susceptible to snapping and uprooting in storms. We used sonic tomography to measure the prevalence and severity of decay in 1744 live trees (≥20 cm diameter) of 171 species on the 50-ha Forest Dynamics Plot on Barro Colorado Island, Panama. A median of <2% of the cross-sectional trunk area showed decay, but 15% of trees had >20% decay. Twenty percent of the combined basal area showed decay, representing a loss of approximately 1% of aboveground biomass. Larger trees more often showed internal decay, with one quarter of trees showing decay before reaching canopy height. Decay severity varied by species; 23% of species showed <2% decay while 9% of species lost over half their basal area. Rare species were more affected than locally abundant species, and species with traits associated with a fast life history were more susceptible to decay. These results suggest that hidden wood decay affects a large proportion of living tropical forest trees.

台湾南西部にある菜寮とその周辺地域は，台湾の陸上で最も重要な第四紀哺乳類化石産地である．そこからは，かつて台湾の中では特に古いものとされ「左鎮人」と呼ばれた人類化石も報告されている．哺乳類化石は，主に崎頂層と呼ばれる海成の泥岩・砂岩層から産出し，この層の時代は前期更新世後期～中期更新世である（主に中期更新世）．本論文では，この地域の化石や化石産出層についての研究史を総括するとともに，これまでの研究で得られた成果を筆者らによる野外調査の結果や化石の観察，他地域の動物群との比較にもとづいて，筆者ら独自の視点でまとめる．また，この地域における化石の産状とその収集・保管，産出層の層序・年代，他地域の動物群との比較について問題点を指摘し，さらに各問題点について今後の展望を述べる．

Sexual dichromatism in plumage is common in hummingbirds (Trochilidae). However, female-limited polymorphism and anomalies, where females exhibit male plumage, also occur. The mechanisms behind these morphs, however, remain unclear. This note presents the first record of a male-like female in Anthracothorax nigricollis (Black-throated Mango) west of the Andes, confirming that this phenomenon is not exclusive to specific populations or subspecies. Moreover, we compile previously known records of male-like females in the genus Anthracothorax and highlight some best practices to avoid false positives in the sexual determination of specimens.

The Arctic Ocean supports a unique and dynamic microbial community, yet its composition, structure, and response to environmental shifts remain incompletely understood. In this study, 16S rRNA gene metabarcoding (targeting the V3-V4 and V4-V5 hypervariable regions) was used to assess surface water microbial diversity across 20 stations in the Barents Sea, focusing on latitudinal variations within two contrasting current systems: the West Spitsbergen Current (WSC) and the East Spitsbergen Current (ESC). Our results showed that the microbial community is dominated by three primary families—Pseudoalteromonadaceae, Moraxellaceae, and Flavobacteriaceae (14.20%). Comparative analysis of the V3-V4 and V4-V5 regions reveals that each region captures different aspects of microbial diversity, with V4-V5 detecting a higher number of unique families. Analysis through Nonmetric Multidimensional Scaling (NMDS) reveals distinct community separations between the WSC and ESC, though ANOSIM results indicate no significant within-system differences. Environmental parameters, including pH and temperature, appear closely linked with community composition, reflecting the influence of climatic and oceanographic processes on microbial structure. As global climate change continues to reshape Arctic environments, monitoring microbial diversity is essential to understand and predict shifts in the Arctic Ocean`s ecosystem functions.

ABSTRACTLamprologine cichlids are a diverse group of fishes distributed in Lake Tanganyika and the Congo River. Nine species ofLamprologusoccur in the Congo River basin including the only blind cichlidLamprologus lethops, but little is known about the natural history and evolution of this enigmatic species. To alleviate this knowledge gap, we characterized the complete mitochondrial genomes ofL. lethopsand its riverine congeners and provided a phylogenetic hypothesis based on these data. We recovered complete mitochondrial genomes from eleven specimens of eight species ofLamprologus. Mitogenomes were identical in the number and order of genes and similar in size (16,579-16,587 bp). In contrast to previous phylogenomic studies, riverineLamprologuswere recovered in two non-sister mitochondrial lineages that were more closely related to other genera of Lake Tanganyika lamprologines than to each other. In the first lineage, most relationships were not highly supported. In the second lineage,L. lethopswas recovered as the sister species ofL. markerti, L. mocquardiandL. tigripictilis. Interestingly, sequences fromL. mocquardiwere found in the two mitochondrial lineages. Our results hint at multiple events of past introgression and highlight the importance of increasing taxonomic and genomic sampling to study complex evolutionary histories.

Animal culture evolves alongside genomes, and the two modes of inheritance-culture and genes-interact in myriad ways. For example, stable geographic variation in culture can act as a reproductive barrier, thereby facilitating genetic divergence between "cultural populations." White-crowned sparrows (Zonotrichia leucophrys) are a well-established model species for bird song learning and cultural evolution, as they have distinct, geographically discrete, and culturally transmitted song types (i.e., song dialects). In this study, we tested the hypothesis that divergence between culturally transmitted songs drives genetic divergence within Nuttall's white-crowned sparrows (Z. l. nuttalli). In accordance with sexual selection theory, we hypothesized that cultural divergence between mating signals both preceded and generated genetic divergence. We characterized the population structure and song variation in the subspecies and found two genetically differentiated populations whose boundary coincides with a major song boundary at Monterey Bay, California. We then conducted a song playback experiment that demonstrated males discriminate between songs based on their degree of divergence from their local dialect. These results support the idea that discrimination against non-local songs is driving genetic divergence between the northern and southern populations. Altogether, this study provides evidence that culturally transmitted bird songs can act as the foundation for speciation by sexual selection.

A single species of seahorse, Hippocampus kuda, has been reported from the Arabian/Persian Gulf. Anatomical and DNA analyses of specimens from Kuwait indicate a second species occurs in the northern Gulf, and based on available specimens, may be the most prevalent species in the region. Evidence indicates the species to be H. trimaculatus and represents a range extension from India’s Gulf of Kutch of 2,600 km. DNA analysis of additional specimens is encouraged, particularly of H. trimaculatus specimens from outside the Gulf.