Ecology and Evolution最新文献

Understanding the factors behind species' range limits is a fundamental objective in ecology. Recent research in alpine plant ecology has moved beyond the classical view that distributions are chiefly shaped by climate and competition. Specifically, broader sets of factors have been taken into account, comprising both biotic factors such as facilitation and herbivory as well as additional abiotic factors such as soil properties. However, an overview of the factors that have been identified and studied as important for elevational range limits of alpine plant species is lacking. In this systematic literature review, we synthesize evidence derived from 107 empirical studies on 226 vascular plant species occurring beyond elevational and latitudinal treelines. We find a persistent research focus on the upper elevational range limit (73% of the studies) and on the role of abiotic factors (54% of the studies), particularly temperature (36% of the studies), whereas research on inter- and intraspecific factors (40% and 25%, respectively), such as herbivory or phenology, remained comparatively rare. While temperature was clearly identified as a major factor influencing the upper range limit (29% of the studies), water availability (15% of the studies) was most commonly studied at the lower range limit. Even though a broad set of factors has been investigated, many potentially important factors remain poorly researched, such as the influence of gene flow and connectivity between populations, phenology and light (each only one or two studies). Our findings highlight the need to move beyond temperature and plant-plant interactions as factors influencing the elevational range limits of alpine plants and to integrate intraspecific (such as gene flow and adaptations) and edaphic factors more fully into future research. Improved methodological standardization and transparency and increased attention on lower range limits will be essential for explaining and predicting alpine plant responses under accelerating environmental change.

In the UK, large numbers of pheasants (Phasianus colchicus) are released into woodlands annually for recreational hunting. Post-release, they are managed to keep them in areas where they can be shot from October to January. At sites with high pheasant densities, they can negatively impact local flora and fauna through predation, trampling, and altering soil nutrients via defecation. The extent of these effects beyond release pen sites is unclear. This study investigated at what distance from release sites a suite of ecological effects of released gamebirds might be detected. We surveyed along 1 km transects from release pens at 20 shoots in Ancient Semi-Natural Woodlands (ASNW) in England and Wales. We expected higher soil nutrients, fewer characteristic woodland plants, more nitrogen-tolerant species, more damage to dead wood, and fewer woody seedlings near pens, with effects decreasing with distance. We found that pheasant numbers encountered declined with distance and sites closer to pens had fewer seedlings/saplings, lower vascular plant richness and less decayed wood (although this last result may be an artefact of the study design). These effects did not extend beyond 500 m. Contrary to expectations, soil nutrients, bare ground, and ancient woodland indicator species showed no consistent change with distance, and nitrogen-loving species and weeds were more common further from pens. We conclude that, in areas beyond release pens in ASNW in lowland England and Wales, where pheasants are not deliberately enticed, any direct negative effects on plant communities, soil nutrients and ground cover do not extend further than 500 m from the point of release. The current licensing of gamebird releases in England aims to protect designated woodlands by controlling releases occurring within a 500 m buffer around protected areas. Our results suggest that this buffer size appears to be appropriate to contain these effects of released gamebirds.

Genetic variation provides the raw material for natural selection, enabling species to maintain adaptive potential, respond to environmental changes, and resist pathogens. Reduced genetic diversity can severely compromise long-term viability, particularly in small, isolated populations prone to inbreeding, genetic drift, and restricted gene flow-a vicious cycle known as the "extinction vortex". Assessing genetic diversity in threatened species is therefore critical for effective conservation strategies. The black-and-white snub-nosed monkey (Rhinopithecus bieti) is an Endangered primate that has experienced significant population decline and habitat fragmentation, raising concerns about its genetic diversity. We utilized major histocompatibility complex (MHC) class I genes, whose encoded proteins recognize antigens central to immune responses, to assess the adaptive genetic diversity of a semi-provisioned subpopulation of this species. Species-specific multi-locus primers targeting exons 2 and 3 of MHC class I genes were designed using published R. bieti whole-genome sequences. Amplicon-based next-generation sequencing was employed to genotype these exons in the studied subpopulation inhabiting Baima Snow Mountain National Nature Reserve, Yunnan, China. A total of 16 MHC class I sequences (7 exon 2 sequences and 9 exon 3 sequences) were identified from 47 individuals and assigned to 5 loci. Exon 2 exhibited low heterozygosity (H _e = 0.349) and moderate polymorphism (PIC = 0.281), whereas exon 3 showed extremely low heterozygosity (H _e = 0.147) and low polymorphism (PIC = 0.131). In addition, positive selection signatures were detected in both exons, and phylogenetic analyses indicated trans-species evolutionary patterns in class I loci. These results underscore the role of balancing selection in maintaining adaptive genetic variation. However, low genetic diversity is likely to have diminished the studied subpopulation's capacity to adapt to environmental change, thereby undermining its long-term viability. This study emphasizes the urgent need to assess adaptive genetic diversity across all R. bieti populations in order to develop targeted management strategies. The data generated in this studied subpopulation provide the baseline for comparison.

Cetaceans are negatively affected by anthropogenic activities, including acoustic and physical disturbance from boat traffic. Behavioural responses to such disturbances are context-dependent, and site-specific insights are needed for effective local management plans. In this study, the impact of speed and proximity of recreational boats on the swimming speed and surfacing interval of one of the most common coastal cetacean species, the harbour porpoise (Phocoena phocoena), is investigated using data collected by unmanned aerial vehicles (UAVs) within a key habitat for the vulnerable Belt Sea population. In August 2024, two UAVs were flown simultaneously on predefined routes within the area. One UAV searched for and followed detected porpoises, while the other monitored recreational boats. All data was captured as UAV video and used to determine surfacing intervals of individual porpoises, measure speed of porpoises and boats and calculate the closest distance between porpoises and boats for each simultaneous sighting. A total of 91 synchronous flights were conducted, resulting in 28 porpoise observational events. GLM analyses showed that an interaction between mean boat speed and distance to the boat influenced the mean speed of the porpoises. In the presence of boats with high mean speeds, porpoises at close range reduced their swimming speed, while porpoises at greater distances instead increased their swimming speed. Also, porpoise surfacing intervals decreased (i.e., porpoises surfaced more frequently) with decreasing distance to boats. This study demonstrates that recreational boats influence the behaviour of porpoises, which could lead to potential negative individual- and population-level effects.

Muskrat (Ondatra zibethicus) populations have been declining in North America for decades. The precise cause of these widespread declines has not yet been identified. Over a similar timeframe, wetlands across large regions of North America have been experiencing an invasion of hybrid cattail Typha x glauca. This invasion is associated with many negative consequences for wetlands, including a reduction in biodiversity, open water habitat, and interspersion of water and vegetation. Muskrats are strongly tied to wetlands, especially where there is a high degree of interspersion of water and emergent vegetation. Therefore, a widespread reduction in interspersion caused by T. x glauca invasions may be contributing to widespread muskrat population declines. We sought to better understand the impact of marsh interspersion on fine-scale muskrat habitat use in light of widespread invasions of T. x glauca. We measured intensity of habitat use by muskrats in a large, Typha-dominated marsh in south-central Ontario using camera traps, stratifying camera placement along a gradient of interspersion. We found no correlation between interspersion and intensity of use. The ubiquity of T. x glauca and low overall interspersion at our study site may have prevented a robust test of our hypothesis. Further research is needed to determine precisely how interspersion affects muskrat habitat use at a fine scale, and how potential changes in habitat quality and use may be contributing to widespread muskrat population declines.

Cuticular hydrocarbons (CHCs) are a ubiquitous component of insect cuticles that are used for a wide range of chemical signaling functions, especially recognition. Recognition and other signals are vital for the maintenance of insularity and cooperation in social insect colonies. Therefore, we expect natural selection on the composition and variability of social insect CHC profiles. Selection on these signals may result in the evolution of genetic polymorphism affecting variation in CHC profiles. Here we tested for a genetic basis of CHC variation in the desert ant Cataglyphis niger. We applied a genomic mapping approach to a cohort of brothers from the same nest to reduce noise from environmental effects and achieve a clear statistical signal for association between the variation of CHCs and quantitative trait loci (QTL). This analysis identified 19 QTLs associated with 8 out of the 31 CHCs identified, and one QTL associated with total CHC quantity. These QTLs are located on 11 different chromosomes, including two cases where QTLs of different CHCs overlap. Each QTL explains between 13%-25% of the variation in a specific CHC. We highlight several candidate genes in the QTLs identified, including fatty acid elongase and reductase genes. Our results reveal a polygenic genomic architecture underlying CHC variation in a population of the desert ant and open new research avenues into the genetic basis and evolution of chemical signaling in social insects.

Biological soil crusts (Biocrusts), which are widely distributed across arid and semi-arid surfaces, play important ecological roles. Cyanobacteria are considered key intrinsic drivers of biocrust persistence and functioning, exerting a profound influence on their ecological roles. Although the distribution patterns and environmental drivers of cyanobacteria have been extensively studied in biocrusts, their role in microbial community assembly remains insufficiently understood. This study investigated the dynamics of cyanobacterial communities during biocrust succession and their relationships with bacterial and fungal community variations. The results revealed pronounced shifts in the cyanobacterial community, explained by ASV (amplicon sequence variants) turnover and changes in dominant taxa such as Microcoleaceae, unclassified Cyanobacteriales, and Chroococcidiopsidaceae. Total phosphorus, nitrogen, and pH were identified as key environmental factors associated with changes in cyanobacterial community. The bacterial community was primarily governed by homogeneous selection within deterministic processes, whereas the fungal community appeared to be shaped by stochastic processes and variable selection within deterministic processes. Together with abiotic factors such as phosphorus, nitrogen, soil organic carbon, and pH, the cyanobacterial community significantly contributed to bacterial and fungal community structure, as supported by multiple analytical approaches. A few cyanobacterial species from Chroococcidiopsidaceae, Microcoleaceae, and Nostocaceae were identified as keystone taxa in the microbial co-occurrence network, enhancing its stability during early biocrust development. These keystone cyanobacteria also underwent succession and exhibited strong co-occurrence with specific microorganisms, including Craurococcus caldovatus, Rubellimicrobium, Rubrobacter, and Microvirga. Overall, these findings elucidate how cyanobacteria are involved in structuring microbial communities during biocrust succession and provide a theoretical basis for improving biocrust restoration in dryland ecosystems.

Anurans are profoundly affected by the ongoing biodiversity crisis. Understanding the drivers of their population decline is key to guiding management strategies and prioritize conservation efforts. Population trends have recently become a popular indicator of extinction risk, yet comprehensive global-scale assessments are still scarce, particularly those that account for phylogenetic nonindependence. In this study, we assess the ecological and environmental factors associated with population decline in the world's anurans. We conducted a phylogenetic generalized least squares analysis using large-scale datasets of population trend (as indicated by their IUCN status), morphology, geographical distribution, and climate variables across 5246 globally distributed species. Specifically, we tested whether body size (BS), range size, annual mean temperature (AMT), temperature annual range (TAR), climate moisture index (CMI), latitude, and environmental prevalence (i.e., relative availability of climate conditions in the geographical space) affect population trends. A large majority of evaluated species were in decline. Range size and TAR were negatively correlated with decline, whereas latitude was positively correlated. Climatic prevalence was not correlated with decline, although declining species often showed lower prevalence values. The findings underscore the critical state of anuran populations, which may worsen in the future due to synergistic effects with climate change. Therefore, we recommend initiatives, such as the establishment of protected areas with multiple narrowly-distributed species, and the increase of the population trend assessment coverage.

The Lord Howe Island Group (LHIG) is one of Australia's most renowned archipelagos. Although a number of studies have investigated the biogeography and genetic diversity of species on Lord Howe Island (LHI) itself, the evolutionary distinctiveness of populations across LHI's satellite islets remains poorly understood. In this study, we explored the genetic structure and health of the Endangered, endemic cockroach Panesthia lata across four islands of the LHIG, using a panel of nuclear single-nucleotide polymorphisms and complete mitochondrial genomes. Our analyses reveal that the lineage on the permanently isolated islet Ball's Pyramid is highly divergent from the remaining populations, while those on the episodically connected LHI, Roach Island, and Blackburn Island may have diverged as recently as the end of the last interglacial period. These results offer the first evidence that Pleistocene sea level lowstands allowed for historical faunal connectivity across the LHIG. Further, while P. lata was believed to have been locally extirpated by rodents on LHI, we discovered a surviving, relict population, albeit with high pairwise kinship indicative of a strong population bottleneck. We also detect relatively high levels of kinship in the other populations, suggesting potential inbreeding that could necessitate ongoing management. Finally, the combination of shallow genetic structure and low diversity suggests that genetic rescue from another island may be a viable strategy to conserve the LHI population of P. lata, as well as other species that have been similarly impacted by rodents.

The monitoring of sex ratios in wild populations of the critically endangered African penguin Spheniscus demersus is essential for conservation management but is currently limited by the inherent difficulty in acquiring blood samples required for sexing. This study optimized a noninvasive method for the DNA extraction and PCR-based genetic sexing of S. demersus using guano and molted feather samples. Two primer sets (CHD1F/R & 2550F/2718R) were used that target sex-specific length polymorphisms in the CHD1-Z and CHD1-W genes on the CHD1 sex chromosomes. Using methods optimized for the extraction of DNA from inhibitor-rich guano and difficult-to-lyse molted feather samples, this work can directly contribute to the conservation monitoring of wild S. demersus populations through sex determination using noninvasive means.