BMC ecology and evolution最新文献

Background: The microbial community within the gastrointestinal tract, known as the gut microbiome (GMB), is a complex micro-ecosystem that is modulated by the life history and physiological traits of the host as well as environmental conditions experienced by the host. In addition, phylogeny can be an important driver of GMB variability across mammalian species, with closely-related species sharing more similar microbial communities than distantly-related species, an eco-evolutionary pattern known as phylosymbiosis. In this study, we examined GMB diversity across 11 species of large herbivores in Etosha National Park (ENP), Namibia, to determine whether host species exhibit phylosymbiosis and whether different herbivore families host distinct microbial communities. The large herbivore community of ENP is an excellent model system because the herbivore species represent distinct evolutionary lineages and have evolved a variety of gut morphologies, dietary niches, and habitat requirements, all of which shape gut microbial diversity.

Results: While we found no evidence of phylosymbiosis across the greater ENP herbivore community, phylosymbiosis was detected among bovid species based on a positive correlation between microbial relative abundance and host evolutionary divergence times. Our results also revealed distinct microbial membership (e.g., Bacteroides, Treponema, and Alistipes) that distinguished bovid species from elephants and giraffes.

Conclusions: Our study provides new insights into the impact of phylogeny on GMB diversity in a closely-related African herbivore community. In particular, phylosymbiosis patterns observed in bovids but not all herbivore species demonstrates that microbial communities are dynamic and respond to a mixture of host evolutionary strategies and corresponding adaptations.

Background: The terrestrial ribbon worm Geonemertes pelaensis Semper, 1863 (phylum Nemertea) is widely reported from tropical regions worldwide. In Japan, this species has been recorded from subtropical islands including the Ogasawara Islands, a UNESCO World Heritage Site south of Tokyo recognized for its unique biodiversity, where it has been implicated in the decline of native soil invertebrates. Here, we demonstrate that the nemerteans in the Ogasawara Islands are genetically and morphologically distinct from those found on Yonaguni Island (Okinawa, Japan), indicating the presence of at least two separate species in Japan.

Results: We sequenced the complete mitochondrial genomes of both populations (18,755 bp for Ogasawara; 31,745 bp for Yonaguni), revealing substantial differences in genome size and gene arrangement. The mitochondrial genome of the Yonaguni population is unusually large, exceeding typical sizes reported for metazoans. Uncorrected p-distances in cytochrome c oxidase subunit I (COX1) sequences between the two populations ranged from 6.75 to 8.59%, which is above the widely used threshold for intraspecific variation in nemerteans. Morphological comparisons also support species-level distinction: live specimens from Yonaguni have a pale body with a prominent mid-dorsal stripe (body width-to-stripe ratio: 1:0.078-0.110), whereas individuals from Ogasawara are pale to light brown with a narrower and fading stripe (ratio: 1:0.042-0.050). Moreover, accessory-stylet pouches differ between populations: Yonaguni specimens possess four to five pouches, each containing 3-5 stylets, while Ogasawara specimens have two pouches, each with two stylets. Examination of museum specimens collected in the 1980s from Chichijima showed the extremely similar external morphology as our recent Ogasawara specimens, indicating that this form has been the only Geonemertes species in the Ogasawara Islands for nearly half a century.

Conclusions: Our results indicate the presence of species-level diversity in Japanese terrestrial nemerteans and demonstrate that accurate species identification using molecular barcodes is essential in insular ecosystems. Recognizing cryptic or pseudocryptic lineages is critical for effective biodiversity monitoring and for preventing mismanagement in ecologically sensitive regions such as the Ogasawara Islands.

Background: The White-browed Crake (Pololimnas cinereus, family: Rallidae, hereafter WbC) is a climate sensitive bird with a tropical/subtropical distribution in Southeast Asia, Australasia, and the Philippines. Range expansion into higher latitudes would be predicted for this species in a warming climate. In this study, we first photographed a WbC in a park of Motuo County on the southeast Tibetan Plateau. Then we compiled geographic data from the Global Biodiversity Information Facility (GBIF) to illustrate its distribution characteristics. We also used a MaxEnt model to simulate its global suitable range under different future climate change scenarios.

Results: The results showed: (1) this observation constitutes a new distributional record of the WbC on the Tibetan Plateau. This expanded northern boundary (29°19'25.40″N) increased the latitudinal limit of the species by 171.58 km. (2) The coldest monthly minimum temperature, the wettest seasonal precipitation, and the human footprint index were the main environmental factors affecting the distribution of WbC, the rise in the coldest monthly minimum temperature has facilitated the expansion of the WbC's habitat. (3) Future climate warming will lead to a significant increase of suitable areas for WbC, with its distribution center shifting 196.11 km and 153.80 km towards northwest in 2041-2060 and 2081-2100, respectively. Under the scenarios for the 2041-2060 and 2081-2100, the globally suitable distribution range of the WbC might expand by 1,125,400 km² and 1,275,200 km², respectively. In China, the corresponding expansion was 27,500 km² and 29,200 km², respectively, mainly distributed in Guangdong, Yunnan, Taiwan, Guangxi, Hainan, Xizang, and Fujian provinces.

Conclusions: The WbC photographed in Motuo County is a new distribution record of this species on the Tibetan Plateau, with Motuo County in Xizang being the northernmost boundary of the current WbC range. The wettest seasonal precipitation, and the human footprint index were the main environmental factors affecting the distribution of the WbC. Under future climate change scenarios, the WbC's range is expanding rapidly, and tends to dispersal in a northwesterly direction.

Background: Eutrophication, followed by re-oligotrophication during lake restoration, in many perialpine lakes has caused changes to the biodiversity and functioning of freshwater ecosystems. In Lake Geneva, total phosphorus (TP) concentration has reduced since the 1970-80s and the yearly average is now close to the upper value of the target range of 10-15 µg/L. For over 60 years the lake has been monitored at SHL2, the central, deepest point in the Eastern basin, complemented by data from GE3 in the Western basin. Selection of these reference points was based on a lake-wide TP analysis in the 1950s. Lake Geneva is a popular fishing destination for anglers and over 100 commercial fishers, who have expressed concerns that further TP reductions could damage the sustainability of their livelihoods. They have called for a re-evaluation of the historical sampling points to determine whether SHL2 and GE3 can still be considered representative for lake nutrient concentrations.

Results: We present the scientific and societal impacts of CoFish, a co-designed research project between scientists and fishers of Lake Geneva. To reassess the spatial variability of TP, we collected integrated water samples across the lake, using stoppered hosepipes as a collection instrument. In this article, we present four key messages: i) there was spatial variation in phosphorus levels, and in most cases the two long-term monitoring stations fall within an acceptable range of variability; ii) the concentrations of phosphorus are generally low, at levels that could impact plankton development; iii) citizen science complemented long-term monitoring for a more spatially extensive dataset; iv) the co-design process resulted in community empowerment and a willingness to further collaborate.

Conclusions: The management implications of this work are that using a single reference sampling point to represent the lake basin is practical but not straightforward. In the discussion we advocate for a re-evaluation of the TP targets, given radical changes in the lake's physical structure and food web. We further highlight the important role of engaging fishers in citizen science, which in CoFish resulted in bridging existing gaps between lake management, science and fisheries, providing a broader basis for lake conservation.

Background: Identifying significant adaptive variation within species is a key focus of efforts to preserve evolutionary potential under environmental change. We analysed genome-wide SNPs and ecomorphological traits to define units for the conservation of Aipysurus sea snakes. This group contains nine fully-marine taxa that are primarily endemic to the northern Australian region, including two critically endangered and one endangered listed species.

Results: Results show convergent patterns of genetic and morphological divergence between coastal and offshore populations in four of five co-distributed Aipysurus lineages. In A. apraefrontalis, A. duboisii, A. foliosquama, and the A. fuscus-A. tenuis complex, individuals from the WA Coast and remote Timor Sea reefs form distinct genetic clusters with gene-tree based divergence estimates of five hundred to nine hundred and fifty thousand years. Coastal populations in all four of these lineages have longer bodies, higher vertebrate counts, and lighter colour patterns compared to offshore-reef populations. In A. laevis (the fifth co-distributed lineage), body length and colour pattern variation mirrored the coastal-offshore divisions seen in the other Aipysurus, but this species showed different patterns of geographic genetic structure that are incongruent with current species boundaries.

Conclusions: This striking genetic and morphological convergence implicates shared patterns of biogeographic isolation and suggests local adaptation related to locomotory performance and crypsis in open soft-bottomed coastal habitats versus structurally complex reefs. We recommend that coastal and offshore-reef populations of A. duboisii, A. apraefrontalis and A. foliosquama be recognised as evolutionarily significant units (ESUs), while the current taxonomy of A. fuscus, A. laevis, A. pooleorum and A. tenuis be retained.

Background: Urban environments are increasingly recognized as important habitats for wildlife, yet information on how reptiles use urban environments remains scarce. The Aesculapian snake (Zamenis longissimus), a non-venomous colubrid widespread in Central Europe, is considered a habitat generalist with a frequent association with human settlements. However, data on its occurrence and ecology in metropolitan areas are limited. To address this gap, we implemented a citizen science initiative in Bratislava, Slovakia, aiming to document the distribution and habitat use of the Aesculapian snake and to evaluate the potential and limitations of citizen science for reptile monitoring in urban environments.

Results: Between April 2019 and October 2022, a citizen science initiative was implemented to monitor the distribution and ecology of the Aesculapian snake in Bratislava, Slovakia. The project relied primarily on social media, which proved to be the most effective channel for data collection, complemented by direct e-mail submissions. Altogether, volunteers provided 588 verified records of the focal species, alongside 184 misidentified observations of other native reptiles, most frequently Natrix spp. Spatial analyses showed that most observations of the Aesculapian snake in Bratislava were concentrated in natural and semi-natural areas at lower elevations below 300 m a.s.l., with a few records above 500 m. Within these areas, snakes were most often reported from built-up and forested land cover, while agricultural land yielded comparatively few sightings. Seasonal patterns indicated a pronounced peak in spring and early summer, while diurnal activity was dominated by midday and afternoon observations. Specifically, the number of reports declined with increasing urbanization intensity but was higher in more densely populated areas, reflecting both ecological patterns and the availability of observers.

Conclusion: This study delivers one of the most comprehensive datasets on the Aesculapian snake in an urban setting, highlighting its synanthropic behavior and frequent use of anthropogenic habitats. At the same time, the results underscore both the opportunities and inherent biases of citizen science, confirming its value as a complementary tool for monitoring reptile populations in metropolitan environments.

Background: The distribution of intra-specific genetic diversity in tropical African forest tree species often reveals discontinuities in the form of genetic clusters distributed in parapatry or allopatry. To date, most population genetic studies have focused on canopy trees, while few studies have examined lower canopy tree species, which might differ in gene dispersal capacities. In this study, we used nuclear microsatellites (SSRs) to characterize the genetic structure of populations of Coula edulis Baill., commonly known as "African walnut", a lower canopy species exploited for its edible seeds, showing short-distance seed and pollen dispersal.

Results: Across its distribution range, we detected one genetic cluster in Upper Guinea (UG) and six in Lower Guinea (LG). High levels of genetic differentiation (F_ST = 0.39 to 0.59) were found between UG and LG, while differentiation within LG varied widely (F_ST = 0.08 to 0.50). Genetic discontinuities associated to high differentiation and a phylogeographic signal (R_ST > F_ST) suggest ancient divergence, possibly driven by population fragmentation during historical climatic fluctuations, while those associated with limited differentiation may reflect more recent divergence and/or genetic homogenization effect due to ongoing gene flow. Genetic diversity within LG clusters was highly variable (H_e = 0.40-0.71), with evidence of a founder or bottleneck effect observed in the southeastern Cameroon cluster, resulting in reduced diversity of a relict population. The UG population also showed low diversity (H_e = 0.38), likely attributable to a historical bottleneck. Morphometric analyses of herbarium specimens revealed some differentiation between LG and UG populations, questioning the taxonomic status of the taxon.

Conclusions: Our results suggest that, given the limited gene dispersal observed in C. edulis, the observed genetic discontinuities are expected to persist over extended timescales and provide baseline information for the potential domestication of the species and the conservation of its genetic resources.

Background: Polyandry is widespread in nature and, in polygynandrous species, can lead to multiple paternity when a litter is sired by more than one male. Such multiply-sired litters have been suggested to produce benefits in low-quality environments that may be masked in higher-quality environments. So far, however, the effect of environmental quality has only been tested in birds with equivocal evidence. Here, we use 202 female house mice (Mus musculus domesticus) from 5 generations (4 years; N_observations=255) that lived in semi-natural enclosures. We provided different enclosures with a different food quality to test the environment dependency of multiply-sired litters as well as its fitness consequences for females.

Results: As the operational sex ratio became male-skewed, the incidence of multiple paternity increased, indicating that under high male-male competition males might coerce females or females might mate multiply to reduce infanticide risk. We also found that the advantages of polyandry depended on environmental quality: only in poorer quality environments females that produced offspring with multiple males weaned significantly larger litters. Variation in lifetime reproductive success was significantly predicted by the female tendency towards multiple paternity, with this relationship showing a complex non-linear pattern in both environments. Importantly, our results suggested that polyandry provides greater lifetime fitness benefits when resources are of poorer quality. In other words, polyandry potentially yields its greatest advantages when resources are a limiting factor, but contributes little when conditions are already favourable.

Conclusions: Our study shows that ecological and social conditions interact to shape the fitness consequences of polyandry, with resource quality emerging as a key factor. These context-dependent benefits highlight how resource availability may influence the evolutionary maintenance of polyandrous mating in multi-male, multi-female systems.