Ecology and Evolution最新文献

The risk of predation has always been a significant impact on wild birds. Birds, facing with limited energy, must balance their investment between foraging and vigilance. There were currently limited understandings of the vigilant behavior feedback of birds under different hunger pressure. Therefore, we employed the White-browed laughingthrush (Pterorhinus sannio) and White wagtail (Motacilla alba) as research subjects to carry out experiments in winter, in exploring the tolerance of birds to external stress under different hunger pressure. After a night of energy expenditure, individuals of both species faced greater hunger pressure in the morning. The results of general linear models showed that the flight initiation distance (FID) of both species in the morning (7:00–9:00) was significantly shorter than that in the evening (16:00–18:00). Additionally, when the weather was cold (daily minimum temperature ≤ 5°C), the FID of the White-browed laughingthrush and White wagtail was significantly shorter in the morning, as same as the results of general linear models. However, when the weather was warm (daily minimum temperature ≥ 10°C), there was no significant difference even though the FID average of both species was shorter in the morning than in the evening. These suggested that the consumption and supplementation of energy are very important for birds, as the higher their hunger pressure, the greater their willingness to forage and take on risk, especially in cold winter.

Effective conservation of rare species necessitates the identification of critical habitats and their specific features that influence species occurrence. This study focused on smalltooth sawfish (Pristis pectinata), a critically endangered elasmobranch, to explore how predictive spatial modeling can enhance conservation efforts. By leveraging long-term occurrence and relative abundance data from scientific gillnet surveys, along with in situ environmental data, we used boosted regression trees (BRT) to pinpoint key habitat features essential for juvenile sawfish. Our analysis revealed strong correlations between sawfish presence and environmental variables, with a preferential selection of very shallow, warm, and saline waters fringed with mangroves, particularly those with high pneumatophore density. High relative abundances were observed in warmer months, and predictions of presence were consistent around discrete mangrove-lined areas in Everglades National Park throughout all seasons. This study emphasizes the importance of high-quality environmental data in predictive modeling and informs management strategies aimed at protecting the critical habitats necessary for the recovery of this species. Preventing the loss of mangroves in vulnerable regions of the smalltooth sawfish's range—especially near anthropogenic influences such as the Charlotte Harbor Estuary—is crucial for recovery. We also highlight the need for improved data access to facilitate global abundance predictions, thereby enhancing spatial management and conservation efforts for rare species.

Predation can alter diverse ecological processes, including host–parasite interactions. Selective predation, whereby predators preferentially feed on certain prey types, can affect prey density and selective pressures. Studies on selective predation in infected populations have primarily focused on predators preferentially feeding on infected prey. However, there is substantial evidence that some predators preferentially consume uninfected individuals. Such different strategies of prey selectivity likely modulate host–parasite interactions, changing the fitness payoffs both for hosts and their parasites. Here we investigated the effects of different types of selective predation on infection dynamics and host evolution. We used a host–parasite system in the laboratory (Daphnia dentifera infected with the horizontally transmitted fungus, Metschnikowia bicuspidata) to artificially manipulate selective predation by removing infected, uninfected, or randomly selected prey over approximately 8–9 overlapping generations. We collected weekly data on population demographics and host infection and measured susceptibility from a subset of the remaining hosts in each population at the end of the experiment. After 6 weeks of selective predation pressure, we found no differences in host abundance or infection prevalence across predation treatments. Counterintuitively, populations with selective predation on infected individuals had a higher abundance of infected individuals than populations where either uninfected or randomly selected individuals were removed. Additionally, populations with selective predation for uninfected individuals had a higher proportion of individuals infected after a standardized exposure to the parasite than individuals from the two other predation treatments. These results suggest that selective predation can alter the abundance of infected hosts and host evolution.

During the evolution of parasites, co-speciation and host-range expansion are thought to play roles in establishing associations with hosts, while sorting events can lead to dissolution of those associations. To address the roles of these processes, we focus on avian haemosporidian parasites infecting hosts of the intensively studied great tit species complex. We estimated the phylogeography of lineages detected in the species complex, and quantified their transition probabilities among hosts. Lineages detected in different host species presented a strong geographical signal but did not form monophyletic groups. Yet, distributions of lineages are not merely the result of their dispersal limitations, as many lineages that infect only one focal species can be found in birds sympatric with other focal species. Besides, closely related lineages that infect the same host species reach more similar rates of infection than expected by chance. Finally, Haemoproteus and Leucocytozoon lineages infecting P. major, the most recently dispersed species, were more generalized than others, consistent with a pattern of generalist parasites expanding their host ranges by infecting newly encountered host species. Our results suggest that host–parasite associations in this system are mainly the result of sorting events and host-range expansion of parasites, rather than co-speciation.

Drought has an effect on hydrologic conditions and water quality under climate change. Small water retention in forests is one of the priority investment programs implemented in recent years, supported by the European Union. This study aimed to assess the ecological conditions of forest lakes using macrophytes and benthos organisms diversity as an ecological indicator of ecosystem conditions under climatic changes. The study was carried out in forest artificial lakes serving as surface water retention in the context of biodiversity in climatic changes and its role in the retention of water. Despite systematic maintenance activities, a long period of lake existence significantly determines the natural biological processes occurring in lakes and riparian habitats. The analysis showed low values of salinity indicators and the concentration of nitrogen and phosphorus. The pH ranged from 6.2 to 7.6; showing slightly acidic conditions or within the limits of neutral. The model of plant associations showed the occurrence of 24 species of plants within nine plant assemblages in the Phragmitetea and Potametea classes of associations (Biocenotic index 1.007–1.692). Despite human activities, lake condition, as assessed by the ESMI index or the biocenotic diversity indices, is good (0.416–0.648). Climate change, expressed by an increase in the frequency of dry years, creates a situation of changes in filling lakes with water, which, taking into account their small depth, results in dynamically changing conditions for the development of phytolittoral. Along with the phytolittoral changes, benthos communities change, their density and the number of taxa also fluctuate. It should be assumed that with ongoing climate change, these phenomena will probably intensify, which will lead to changes in entire ecosystems at plant and animal levels.

For birds breeding in the Arctic, nest success is affected by the timing of nest initiation, which is partially determined by local conditions such as snow cover. However, conditions during the non-breeding season can carry over to affect the timing of breeding. We used tracking and breeding data from 248 individuals of 8 species and subspecies of Arctic-breeding shorebirds to estimate how the timing of nest initiation is related to local conditions like snowmelt phenology versus prior conditions, measured by the timing and speed of migration. Using path analysis, our global model showed that local and prior conditions have similar effect sizes (Standardised Path Coefficients ± SE of 0.44 ± 0.07 and 0.43 ± 0.07 for snowmelt and arrival timing, respectively), suggesting that both influence the timing of breeding and therefore potentially reproductive output. However, the importance of each variable varied across species. Individuals that arrived later to the breeding grounds did not leave the wintering grounds later, but instead took longer to migrate, potentially reflecting differences in flight speed or time spent at stopover sites. We hypothesise that this may be due to reduced habitat quality at some stopover sites or an inability to adjust their departure timing or migration speed to match the advancing spring phenology in the North. Individuals that migrated longer distances also arrived and nested later. Our results highlight the benefits and potential conservation implications of using a full annual cycle approach to assess the factors influencing reproductive timing of birds.

A species' distribution depends on its tolerance to environmental conditions. These conditions are defined by a minimum, maximum, and optimal ranges of single and combined factors. Forays into environmental conditions outside the minimum or maximum tolerance of a species (i.e., thresholds) are predicted to have large effects on a species' population and may help predict population resilience in the face of changing conditions. Here, we explore ecological thresholds for an important fisheries species and ecosystem engineer, Crassostrea virginica (eastern oyster). In coastal Louisiana, extreme freshwater inputs from rivers and precipitation events impact estuarine salinity, which is a key driver of oyster population dynamics. Using daily salinity and monthly oyster abundance monitoring data across Louisiana estuaries, we explore low salinity exposure threshold levels for oysters. Two statistical approaches were applied, with each model highlighting a different operational definition of a threshold: random forest models identified a threshold as an abrupt change in the oyster abundance- salinity relationship, while Bayesian models identified an increased probability of oyster abundance dropping below a critical threshold, defined here as less than 50% of the 5-year mean. All model results indicate oysters in coastal Louisiana experience low salinity exposure thresholds, defined as the number of consecutive summer days of salinity levels less than 5. However, actual number of days and salinity threshold differed by statistical approach, oyster life stage, and estuary highlighting the multiple dimensions defining ecological thresholds. While thresholds are considered important benchmarks to inform management and assess population or ecosystem vulnerability, our results reveal the need to carefully relate threshold definition to management goals and to acknowledge that thresholds may be highly context dependent.

The black bream (Megalobrama skolkovii) is an economically important species widely distributed in China, with its geographic populations potentially having undergone differentiations and local adaptations. In this study, we presented a chromosome-level genome assembly of this species and investigated genetic differentiations of its populations that are allopatric (the northern one) and sympatric (the Poyang Lake) to its kin species, the blunt-snout bream (M. amblycephala), using whole genome resequencing analysis. The results showed that the genome size of black bream was 1.13 Gb, very similar to its kin species but larger than its close relatives, the four Chinese major carps. By resequencing individuals from the northern and Poyang Lake populations, we found that the northern population showed lower genetic diversity, larger genetic differentiation, and two sharp historical declines in population size through demographic analysis, indicating the possible bottlenecks after the allopatric isolation. In contrast, the Poyang Lake population, with its higher genetic diversity, higher Tajima's D value, and lower levels of linkage disequilibrium, reflects the ancestral state of black bream. In addition, we also found that the northern population shared more alleles with its kin species, indicating it may retain more ancestral variations. This was further analyzed to be caused by incomplete lineage sorting and ancient introgression. Some key genes related to reproductive processes, body size development, and muscle metabolism were found under selection in the northern population, possibly responsible for its local adaptation. Our findings that the black bream allopatric population had a loss of genetic diversity but retained more ancestral variations can expand our knowledge on population genetic differentiation and give us hints for future genetic conservation.

Understanding species' dietary ecology and interspecific interactions is crucial for multi-species conservation planning. In Central Asia and the Himalayas, wolves have recolonized snow leopard habitats, raising considerable concern about resource competition between these apex predators. Using micro-histological analysis of prey species remains (e.g., hair) in their fecal samples, we determined the prey composition, dietary niche breadth, and the extent of diet overlap between these two apex predators in Shey Phoksundo National Park, Nepal. We analyzed 152 scat samples collected along 89 survey transects from April to June 2021. Our findings reveal a significant overlap in their diets (Pianka's index = 0.93), with snow leopard and wolf scats containing the remains of 11 and 10 prey species, respectively. However, the interspecific difference in prey selection was apparent, with significant deviations between observed and expected prey use indicating non-random prey selection relative to availability: Snow leopards exhibited a higher occurrence of wild prey items in their diet (55.28%), primarily blue sheep (Pseudois nayaur) (24.83%), whereas wolves relied predominantly on domestic livestock (67.89%), with goats (Capra hircus) accounting for over one-fourth of their diet (29.15%). Yaks (Bos grunniens) comprised a significant portion of the biomass consumed by both predators, with higher for wolves (43.68%) than snow leopards (36.47%). Overall, the narrow dietary niche breadth with high overlap indicates potential resource competition between snow leopards and wolves. However, a comprehensive understanding of resource competition will require further study on other axes of niche partitioning, including habitat and time. Nevertheless, the region's low prey richness means that, with increasing human influence, any reduction in wild prey or increase in livestock could intensify competition between snow leopards and wolves, which could have implications for livestock depredation.

This study aims to enhance our understanding of the temporal and spatial processes scales governing the evolutionary diversification of Neotropical birds with Trans- and Cis-Andean populations of the species Attila spadiceus from South and Central America. Through a multilocus analysis of the mitochondrial (CytB and ND2) and nuclear genes (I7BF, I5BF, and G3PDH) of 41 samples representing six subspecies, we describe the existing molecular lineages of A. spadiceus, and estimate their demographic dynamics. We used Ecological Niche Modeling (ENM) with six different algorithms to predict the potential distribution of A. spadiceus in both present-day and past scenarios, examining the overlap climatic niche between Cis- and Trans-Andean lineages. The analysis confirms a relatively recent divergence of the Trans- and Cis-Andean lineages, at approximately 0.25 million years ago (Ma). The niche modeling supports the existence of a dynamic scenario of the expansion and retraction of forest corridors in northwestern South America during the last glaciation. This suggests that the earlier orogenesis of the Andes was not a primary determinant of this dichotomy. Additionally, the analysis of population dynamics indicated a trend of increasing population size starting at 0.05 Ma for both lineages. Our findings highlight the significance of Pleistocene Forest corridors north of the Andes as the key factor maintaining communication before the separation of the lineages, likely associated with the retraction of this forest. We highlight the absence of any significant differentiation between the disjunct Amazonian and Atlantic Forest populations, at both part of the Cis-Andean lineage. The phylogeographic profile of A. spadiceus diverges from the patterns observed in other Neotropical birds, which emphasizes the need for further research on the role of the forest corridors of the northern Andes as drivers of diversification, to provide comprehensive insights into the processes that led to the formation of the region's present-day avian diversity.