Ecology and Evolution最新文献

Primary and secondary male sexual traits can influence the interspecific interactions of hybridizing populations, yielding fitness consequences and either promoting or restricting gene flow. In this study, we evaluated the relative male fitness of two species of hybridizing tidal marsh endemics: saltmarsh (Ammospiza caudacutus) and Nelson's sparrows (A. nelsoni) and assessed the effects of male condition and competitive ability on resulting patterns of paternity and gene flow. We compared reproductive success (number of offspring sired) among saltmarsh, Nelson's, and hybrid sparrow males (n = 125) and modeled male fitness in relation to measured pre-copulatory (body size, fat scores, and muscle scores) and post-copulatory (cloacal protuberance (CP) volume and sperm length) male sexual traits across two sites within the center of the hybrid zone. We found saltmarsh sparrows had higher levels of skew in fertilization success than Nelson's and greater reproductive output than both Nelson's and hybrids, suggesting interspecific competition may occur. Body size was the best predictor of reproductive success, independent of male genotypes, providing evidence for a role of pre-copulatory sexual selection. We also found evidence of post-copulatory sexual selection and sperm competition contributing to patterns of hybridization, with CP volume and sperm length increasing with number of offspring sired. Differential mean fitness by species may influence patterns of hybridization and has the potential to drive asymmetrical introgression; however, the drivers of male fitness differed between species and sites, suggesting the level of sexual selection and resulting patterns of gene flow are context dependent and not stable across a small sptatial scale within the center of this mosaic hybrid zone. Overall, few interspecific offspring and nearly equal backcrossing in both parental species within the center of the hybrid zone suggest mechanisms such as reinforcement exist to limit hybridization and minimize asymmetric introgression.

Spiders utilize an indirect method of sperm transfer via specialized male palpal structures. In entelegyne spiders, these structures exhibit a remarkable complexity, comprising various sclerites that interlock with the female genitalia to provide stability and facilitate sperm transfer. Among the four primary coupling mechanisms recognized in entelegyne spiders, one, termed self-bracing, involves interactions between structures stabilizing the expanded copulatory organ during mating. Such interactions can involve elements that are not part of the copulatory organ. The retrolateral tibial apophysis (RTA), a characteristic of the largest group of spiders (RTA clade), is the most prominent structure for this purpose. However, recent research has demonstrated that in spiders that have lost the RTA, other parts of the palp, specifically femoral apophyses, can be involved in self-bracing. The presence of a femoral palpal fapophysis is uncommon in spiders, and only a few taxa possess apophyses on multiple palpal articles, i.e., tibia and femur, the interaction and evolution of which remain to be elucidated. This study investigated the function and interaction of apophyses on different palpal structures for the first time using the funnel weaver Anatextrix monstrabilis (Agelenidae). We specifically examined the hypothesis that the various prominent femoral apophyses are involved in self-bracing despite the presence of an RTA. Micro-computed tomography data of a cryofixed mating pair revealed that at least one of these apophyses functions in self-bracing by fitting into the groove of the embolic base, representing the second documented case of this unique self-bracing mechanism in entelegyne spiders. Furthermore, scanning electron microscopy revealed previously undocumented features in the female genitalia of Anatextrix, including an epigynal fovea, an anterior hood, and well-developed epigynal lateral margins, which potentially play a role in interlocking with male palpal sclerites during copulation. In contrast to ghost spiders (Anyphaenidae), the only other known group of entelegyne spiders exhibiting self-bracing with femoral apophyses, Anatextrix species demonstrate notable differences with regard to the size and shape of these apophyses. Thus, our study indicates that male palpal femoral structures, which do not contact female genitalia during genital coupling, can be subject to strong selection pressures similar to somatic structures that function beyond basic sperm transfer.

Habitat selection and movement are key mechanisms by which animals can respond to and potentially cope with highly variable environmental conditions. Optimal responses likely vary, however, depending on the severity and scope of conditions. We tested this hypothesis using a facultative migrant species, the Great Gray Owl (Strix nebulosa), which exhibits high inter- and intra-individual variation in the timing, direction, and distance of winter movements. Specifically, we evaluated whether episodic, spatiotemporally variable “locked-pasture” snow conditions, which restrict access to subnivean food, prompted shifts in habitat selection or long-distance movements by owls. We quantified the movement of 42 owls using global positioning system (GPS) data within the Greater Yellowstone Ecosystem, USA, during 2017–2022. We used a novel ecological application of SnowModel, a snow evolution modeling system, to estimate fine-scale, physical snow properties likely to influence access to prey. Variables included snow depth, snow crusts produced by wind, and ice crusts produced by melt-freeze and rain-on-snow events. Owls avoided heterogeneously distributed wind crusts via local shifts in habitat selection. More homogenous ice crusts elicited long-distance movements away from affected home ranges. Finally, owls employed both proximate shifts in habitat selection and long-distance movements to avoid deeper snow. Ultimately, owls exhibited behavioral flexibility in response to limiting snow conditions that can vary in terms of severity, spatial extent, and duration. Such behavioral responses determine species distribution, with implications for population and community dynamics in spatiotemporally variable systems. Understanding the effects of, and responses to, environmental controls is increasingly important given the scope of on-going global change.

The overwhelming majority of research on wild bumble bees has focused on the social colony stage. Nest-founding queens in the early season are difficult to study because incipient nests are challenging to find in the wild and the foundress queen flight period is very short relative to the entire nesting period. As a result, natural history information on foundress queens is exceedingly rare. New methodological approaches are needed to adequately study this elusive life stage. We trap-nested wild queen bumble bees in artificial nest boxes in Gothic, Colorado and used a custom-built radio frequency identification (RFID) system to continuously record queen foraging activity (inferred from entering and exiting the nest) for the majority of their spring flight periods. Foundress queens made frequent, short foraging trips, which tended to increase in duration over the course of the flight period. All queens who produced adult workers ceased foraging within approximately 1 week after workers emerged in the nest. We observed frequent nest failure among foundress queens: Fewer than one quarter of queens who laid eggs in nest boxes went on to produce reproductive gynes at the end of the season. We also report nest characteristics and curious phenomena we observed, including conspecific nest invasion and queens remaining outside the nest overnight. We present this trap-nesting and subsequent RFID tracking method as a valuable, albeit resource-intensive, path forward for uncovering new information about the elusive, incipient life stage of wild bumble bees.

Understanding the drivers influencing ungulate population dynamics is crucial for developing conservation and management strategies to support wildlife health. Trace and macro elements are vital for ungulate growth, reproduction and survival. Thus, the trajectory of wildlife populations may be associated with element imbalances. Element concentrations can be measured in hair, an increasingly recognised bio-monitoring tool. However, a better understanding of the relevance for wild ungulate population dynamics is needed. This study aimed to assess if element profiles in hair reflected the population trajectory of a keystone Arctic ungulate, muskox Ovibos moschatus, and whether benchmarks could be defined for element concentrations to assess population status. We measured qiviut (hair) element concentrations of 11 muskox populations ranging across northern America, including Greenland, and evaluated the association between element concentrations and different population trajectories. Seven trace and macro elements differentiated increasing populations from declining and stable populations using linear discriminant analysis. In general, copper, selenium, iron, manganese and cobalt tended to be at higher concentrations in increasing populations, whereas zinc and calcium were generally at lower concentrations in these populations, though variations were observed among populations. Benchmarks were defined for copper, selenium and iron, indicating populations were more likely to decline below a threshold concentration of these elements (‘limit’) and increase above a threshold concentration (‘target’). ‘Limit’ benchmarks were defined for zinc and calcium where populations were more likely to be increasing below this threshold value. Hair element profiles are a useful indicator of population trajectory in wild ungulate populations. Identified benchmarks can be used to assess population status, complementing ongoing but irregular and expensive monitoring efforts like population surveys, while trace element concentrations can provide insights into the mechanisms driving population change. Hair samples can easily be collected non-invasively or alongside other monitoring activities, enhancing proactive wildlife management and conservation.

Globally, freshwater ecosystems are threatened. Research progress concerning African freshwater snails was reviewed using a systematic review process. Since 1757, the number of publications produced has increased, particularly in the last decade. In the first 50 years (1757–1800), 0.1% of publications on freshwater snails in Africa were conducted, followed by 0% (1801–1850), 3.3% (1851–1900), 3.5% (1901–1950) and 48.7% (1951–2000). The last 23 years (2001–2024) exhibited a large increase (44.3%) in publications of the total conducted. Studies on freshwater snails varied in number across the 10 major African water basins, with the majority of studies in the Nile (21.7%), followed by the Congo Basin (17.6%) and Niger (12.4%). The Orange Basin and Lake Tanganyika also received a high number of studies (10.9%) and (7.2%), respectively. Most freshwater snail study objectives related to conservation and taxonomy (70%), followed by disease vector (20.5%), with genetics/genomic/DNA barcoding/eDNA receiving significant focus as well (5.2%). Studies focusing on geology and palaeontology (2.5%), followed by climate change (1.5%) and machine learning (0.4%). The modern phase in the study of African freshwater snails came around the early 20th century with the discovery of Bulinus truncatus and Biomphalaria alexandrina as intermediate hosts for the parasites causing human schistosomiasis. African freshwater malacology has since then benefited from African and overseas malacologists based at universities and medical laboratories across Africa and overseas. In addition to taxonomic studies, there was a steady rise in contributions relating to ecology, disease vectors, palaeontology and genetics. These contributed knowledge on local endemism and speciation, invasive species, species origins and distribution across African water basins, as well as the spread of infectious diseases and impacts of climate change. In the last decade, there have been shifts in methods with the application of DNA barcoding, genomics, environmental DNA and, most recently, machine learning approaches.

Chronic wasting disease (CWD) is a prion disease that infects cervid species by direct and environmental transmission and is invariably fatal. CWD spread can be promoted by the attraction of animals to “hotspots” such as hay bales and grain bags stored in fields and at farm sites. The density and location of hotspots may impact contact rates. We used an individual-based movement model of mule deer (Odocoileus hemionus) to investigate the effects of density and configuration of hotspots (hereafter artificial attractants, AA) on contact rates at a constant density of 1 deer/km² during winter. The model tracks when two deer from the same or different groups come into contact under 6 AA densities (0–1 AA/km²) and 6 AA configurations. We compared placing AA randomly versus clustered around farms, and removing them randomly versus biased by proximity to preferred habitat. Overall, the number of unique contacts per individual and the number of unique deer visiting an AA increased, and the number of AAs used by each deer decreased as AA density declined. Selectively removing field attractants near preferred habitat resulted in a larger increase in contacts per deer, with deer contacting more and different individuals, fewer deer using the remaining AA, and fewer visits per AA than random removal. There was a greater increase in contact rates when reducing AA density at farms by randomly removing all AA at a farm compared to randomly removing individual AA across farms. Deer responses to AA removal may not be as straightforward as originally believed. Deer contacts may increase, not decrease, with AA removal because deer are attracted to the remaining AA. Under moderate deer densities, AA removal may require a broad-scale, “all or nothing” approach to prevent deer from concentrating at remaining AA, but concomitantly lowering deer density needs further assessment.

Host species, locations, and diet can significantly impact microbial diversity and community in insects. Several ladybird beetles are known as key predators and potential biological control agents for aphids. However, there is limited understanding of how host species, locations, and aphid prey influence the microbial diversity and community of aphidophagous ladybird beetles in natural environments. In this study, we collected 74 samples of ladybirds and their aphid prey from various locations in Guangxi, China, and sequenced the 16S amplicons to investigate differences in their microbiomes. The dominant genera in the ladybird samples, Bacteroides and Alistipes, were rarely reported as predominant in other ladybird populations, indicating a unique genus-level microbial community pattern in Guangxi. Alpha diversity indices and Bray–Curtis distances varied significantly among ladybird species. Abundance analysis revealed that the relative abundance of dominant bacteria in aphidophagous ladybirds differed significantly among different ladybird species and locations. Although the primary and facultative aphid symbionts differed among aphid samples from various populations and locations, they had minimal direct impact on the microbial community of the aphidophagous ladybirds, being sporadically detected in the corresponding predator samples. Our findings provide insights into the microbial communities of ladybirds and aphids in sympatric and distinct field environments, highlighting the plasticity of microbial abundance in aphidophagous ladybirds across different ladybird species and locations, as well as the low retention rate of specific aphid symbionts in ladybird predators.

Sea turtles are large reptiles that inhabit the world's oceans and include seven extant species within two families: Cheloniidae and Dermochelyidae. These species are threatened globally, with several subpopulations listed as Endangered or Critically Endangered by the IUCN. Thailand hosts five sea turtle species, including leatherback turtles (Dermochelys coriacea ), which are significant for their nesting sites along the Andaman Sea coast. Conservation efforts in Thailand include beach patrols, hatcheries, and community education to mitigate threats such as poaching and habitat destruction. Leatherback turtles, classified as “Vulnerable” by the IUCN and listed in CITES Appendix I, face challenges in estimating global population size due to their highly migratory nature. They are the largest sea turtles, with distinct physical characteristics such as leathery skin, lack of scales, a hard shell, and backward-pointing spines in the throat that aid the passage of food. Leatherbacks reach sexual maturity at around 13–14 years of age and exhibit natal homing behavior for nesting. These turtles have low hatching rates; only 50% of eggs hatch, and just 2% of those hatchlings survive. Population genetic studies of leatherback turtles have been key to better understanding threats to survival, revealing low global mtDNA haplotype diversity, with notable recent radiation originating from the Indo-Pacific region. Despite this low diversity, there is significant population structuring, which hints at hidden nesting populations and foraging grounds that may contribute to genetic variability. For that reason, relocating nests to favorable locations is one possible conservation measure. Other strategies must address habitat loss, pollution, bycatch, and climate change in protection efforts for this species, as well as ensuring global population connectivity to maintain the genetic diversity of these highly migratory turtles.

Logistical, environmental and temporal considerations can limit the effectiveness of long-term live trapping for small mammals in remote environments. Owl pellet content analysis offers a low-cost, non-invasive alternative to live trapping, as it is generally reflective of prey abundance within the broader small mammal community. One species to which this detection technique could be readily applied is the threatened Australian dasyurid, the Julia Creek dunnart, Sminthopsis douglasi. Most population information is outdated, and the species is notoriously difficult to monitor. Here, we aimed to monitor S. douglasi and other small terrestrial vertebrates over time and in relation to a native long-haired rat (Rattus villosissimus) plague, assessing their occurrence as dietary items in eastern barn owl (Tyto javanica delicatula) pellets collected at Toorak, north-west Queensland, Australia. A total of 1007 individual vertebrates were identified from 706 barn owl pellets spanning 3 present-day collections (2023–2024), with further analysis incorporating a prior published historical dataset (1994–2001, 210 pellets). We demonstrated a shift in Toorak small mammal community structure both over time and in response to an active R. villosissimus plague. Despite declines across present-day pellet collections, S. douglasi was always detected in high abundance, peaking at 30.75% of all individuals. Cumulative probability of detection indicated that analysis of owl pellets was highly effective at detecting S. douglasi (within 20 pellets) despite the ongoing rodent plague, which has undermined the effectiveness of parallel live trapping efforts across the region. Owl pellet analysis is thus an effective methodology for rapidly assessing S. douglasi populations and should be incorporated into both S. douglasi and other small mammal species monitoring regimes.