Ecology and Evolution最新文献

Mechanisms driving the spatial and temporal patterns of species distribution in the Earth's largest habitat, the deep ocean, remain largely enigmatic. The late Miocene to the Pliocene (~23–2.58 Ma) is a period that was marked by significant geological, climatic, and oceanographic changes. This transitional period spurred widespread species diversification, particularly among widely distributed benthic scavengers, such as amphipods. Here, we take step toward understanding the long-term evolutionary processes of amphipod colonization and diversification in the deep ocean by focusing on the model genus Eurythenes S. I. Smith in Scudder, 1882. These large-bodied scavengers play key roles in benthic communities. We constructed a time-calibrated phylogeny using two mitochondrial DNA genes by analyzing publicly available data on 14 species of Eurythenes across a global depth range from 839 to 8081 m. The resulting phylogenetic tree reveals a diverse clade, with a common ancestor originating around 11.81 Ma. A gradual increase in the effective population size of Eurythenes was observed, particularly during the Pliocene (~4 Ma). The net diversification rate remained almost constant, with slight increases between the Miocene and Pliocene (~8–4 Ma), and most new species appeared during the latter period. Additionally, reconstruction of the ancestral area suggested that the common ancestor of Eurythenes had a global distribution. A combination of dispersal and sympatric processes, along with environmental factors, such as changes in ocean temperature and sea level, contributed to the present biogeographic distribution of these species. Our findings highlight the importance of historical events, such as plate tectonics and changes in deep-water circulation, in driving the rapid speciation of Eurythenes and underscore their essential role in shaping deep-ocean biodiversity.

In recent years, DNA metabarcoding has been used for a more efficient assessment of bulk samples. However, there remains a paucity of studies examining potential disparities in species identification methodologies. Here, we explore the outcomes of diverse clustering and filtering techniques on data from a non-destructive metabarcoding approach, compared to species-level morphological identification of Brachycera (Diptera) and Hymenoptera of two bulk samples collected with Malaise traps. The study evaluated four distinct approaches, namely clustering to Amplicon Sequence Variants (ASVs) or ASVs clustered to Operational Taxonomic Units (OTUs) coupled with subsequent filtering using the LULU algorithm at 84% and 96% minimum match. In total, 114 species of Brachycera (35 families) and 85 species of Hymenoptera (27 families) were identified morphologically. Depending on the selected approach, DNA metabarcoding results strongly varied in terms of detected molecular units blasted to brachyceran and hymenopteran species. For Brachycera, ASVs clustered into OTUs followed by LULU using a 96% minimum match (OTU96) inferred the number of molecular units closest to the number of morphologically identified species. Using Syrphidae as an exemplary family, we found an overlap ranging from 9% to 81% between the morphological identification and the different clustering and filtering approaches, OTU96 being also here the closest one. For Hymenoptera, while OTU96 also yielded the highest number of molecular units, it was still considerably low compared to the number of morphologically identified species. Our results show that metabarcoding methodology needs to be significantly improved to be applied to Hymenoptera. Conversely, for Brachycera, we acknowledge the promise of employing a non-destructive metabarcoding approach, incorporating ASV clustering into OTUs and filtering with LULU, to derive dependable species lists. Such lists hold significant potential for applications in biomonitoring, conservation efforts, and other related fields.

Opportunistic nectarivory occurs in many avian lineages around the world. In order to understand the implications of this behavior to plant reproduction via pollination and to other nectarivores via competition, more thorough descriptions of opportunistic nectar-feeding behavior are necessary. We observed nectar feeding of the mallee ringneck, Barnardius zonarius barnardi, on flowers of the spotted emu bush, Eremophila maculata, in the temperate mallee of South Australia. Here, we describe the nectar-feeding behavior of B. zonarius barnardi and discuss the implications for competition with honeyeaters and the reproduction of E. maculata. We also compare the morphology of the feeding apparatus of B. zonarius barnardi with that of nectarivorous parrots, lorikeets and lories, to determine whether they share convergent morphological features to facilitate the consumption of nectar. Finally, we suggest avenues for future natural history work to better document opportunistic avian nectarivory in Australian ecosystems.

For long-lived species with biparental care, coordination and compatibility in the foraging behavior of breeding mates may be crucial to successfully raise offspring. While high foraging success is clearly important to reproductive success, it might be equally important that the mate has a complementary foraging strategy. We test whether breeding partners have similar or dissimilar foraging strategies in a species where both partners share breeding responsibilities and exhibit high mate fidelity (thick-billed murre; Uria lomvia). To examine whether thick-billed murres showed complementary in foraging strategies, we attached GPS accelerometers to both partners within 40 thick-billed murre chick-rearing pairs. Individuals within a breeding pair were dissimilar in their foraging trip distance and in their number of dives during foraging trips compared to randomized pairs. Breeding partners were also more similar in wing length than randomized pairs. This result could be related to individual quality as individuals select similar sized partners or select sites that lead to similar sized partners. We conclude that foraging strategy diversity could be maintained in this population either because individuals prefer partners with foraging strategies complementary to their own, or because partners diverge in foraging strategies over multiple breeding season together.

Examining the impacts of natural and anthropogenic influences on aquatic macrophytes in shallow lakes is crucial for their effective restoration and management. However, there is a lack of direct evidence regarding past species composition or detailed and continuous evidence of recent changes in aquatic macrophyte communities. This study utilized plant macrofossil remains deposited in the sediment, combined with macrophyte surveys from 1983 to 2010, to reconstruct the historical changes in the macrophyte community over approximately 160 years in Lake Weishan, a sub-lake of Lake Nansi located in the lower Yellow River (Huanghe River) Basin, northern China. Approximately 54.3% of the species historically recorded at the core site were identified through macro-remains analysis, including five previously unrecorded submerged taxa (Myriophyllum verticillatum, Ranunculus trichophyllus, Chara sp., Nitella sp., and Vallisneria spinulosa) discovered during monitoring surveys. The findings revealed four major shifts in the macrophyte community: A transition from a swampy environment dominated by emergent/wetland plants (ca. 1855–1875) to an expanded water body characterized by a rapid proliferation of submerged macrophytes (ca. 1875–1910), followed by mass disappearance of macrophytes (ca. 1910–2005) and subsequent significant resurgence (after 2005). Multiple factor analysis was employed to investigate the correlation between these shifts and changes in paleolimnological indicators (invertebrates, geochemistry, and grain size), as well as documented records related to hydrology, climate changes, and human activities. The results confirmed our hypothesis that climatically and anthropogenically induced hydrological alterations were likely the primary drivers influencing macrophyte composition alteration and succession dynamics in the lake. This study highlights the potential use of plant macrofossils for reconstructing long-term changes in macrophyte community components, abundance assessment, and ecosystem health evaluation within the lower Yellow River region. To effectively address persistent challenges such as water diversion and climate change, we propose integrating paleoecological methods into standard ecological monitoring protocols employed for water ecological quality assessment.

Assessments of genetic diversity, structure, history, and effective population size (N_e) are critical for the conservation of imperiled populations. The lesser prairie-chicken (Tympanuchus pallidicinctus) has experienced declines due to habitat loss, degradation, and fragmentation in addition to substantial population fluctuations with unknown effects on genetic diversity. Our objectives were to: (i) compare genetic diversity across three temporally discrete sampling periods (2002, 2007–2010, and 2013–2014) that are characterized by low or high population abundance; (ii) examine genetic diversity at lek and lek cluster spatial scales; (ii) identify potential bottlenecks and characterize genetic structure and relatedness; and (iii) estimate the regional N_e. We analyzed 194 samples across the shinnery oak prairie region of eastern New Mexico and western Texas using 13 microsatellite loci. Mean heterozygosity, allelic richness, and inbreeding coefficient were not significantly different between discrete sampling periods, suggesting that this population has maintained its genetic diversity across the sampled population fluctuations. We did not detect genetic structure using multiple Bayesian clustering approaches. Furthermore, there was no support for recent genetic bottlenecks, and we estimated that the N_e ranged from 229.5 (p_crit = 0.05, 95% CIs = 121.2–1023.1) to 349.1 (p_crit = 0.02, 95% CIs = 176.4–2895.2) during our final sampling period (2013–2014). Although we provide evidence for gene flow within this region, continued habitat loss and fragmentation that leads to population declines and isolation could increase the risk of genetic consequences. Continued monitoring of genetic diversity and increasing available habitat that supports robust populations of lesser prairie-chickens may improve the likelihood of the species' persistence.

Native animals worldwide are experiencing long-term coexistence with invasive plants, leading to diverse behavioral changes. Invasive plants may create new habitat structures that affect the distribution or behavior of prey, which in turn might attract predators to these novel habitats, thereby altering predator–prey dynamics within the ecosystem. However, this phenomenon is rarely reported. Our previous research found that in the Yellow Sea wetlands of China, the native bird species, the vinous-throated parrotbill (Sinosuthora webbiana), has adapted to breeding in the invasive smooth cordgrass (Spartina alterniflora) by increasing its nesting height. Here, our observations indicate that in cordgrass habitats, the main nest predator of parrotbills was the Eurasian magpie (Pica pica), accounting for 75% of predation events. In contrast, in native habitats, the primary predators were mammals and snakes, accounting for 83% of predation events, with no nests being predated by magpies. We believe that changes in the breeding and nesting behavior of parrotbills may have attracted magpie predation in cordgrass habitats. Our findings may provide an empirical case of how behavioral changes induced by invasive plants can lead to dynamic shifts in predation relationships. We advocate for further research into this intriguing phenomenon, as it could enhance our understanding of changes in interspecific relationships and their ecological consequences within the context of biological invasions.

In much of the northern Great Basin of the western United States, rangelands, and semi-arid ecosystems invaded by exotic annual grasses such as cheatgrass (Bromus tectorum) and medusahead (Taeniatherum caput-medusae) are experiencing an increasingly short fire cycle, which is compounding and persistent. Improving and expanding ground-based field methods for measuring the above-ground biomass (AGB) may enable more sample collections across a landscape and over succession regimes and better harmonize with other remote sensing techniques. Developments and increased adoption of unoccupied aerial systems (UAS) and instrumentation for vegetation monitoring enable greater understanding of vegetation in many ecosystems. Research to understand the relationship of traditional field measurements with remotely sensed data in rangeland environments is growing rapidly, and there is increasing interest in the use of aerial platforms to quantify AGB and fine-fuel load at pasture and landscape scales. Our study uses relatively inexpensive handheld photography with custom quadrat sampling frames to collect and automatically reconstruct 3D models of the vegetation within 0.2 m² quadrats (n = 288). Next, we examine the relationship between volumetric estimates of vegetation with biomass. We found that volumes calculated with 0.5 cm voxel sizes (0.125 cm³) most closely represented the range of biomass weights. We further develop methods to classify ground points, finding a 2% reduction in predictive ability compared with validation ground surface reconstructions. This finding is significant given that our study site is characterized by a dense litter layer covering the ground surface, making reconstruction challenging. Overall, our best reconstruction workflow had an R² of 0.42, further emphasizing the importance of high-resolution imagery and reconstruction techniques. Ultimately, we conclude that more work is needed of increasing extents (such as from UAS) to better understand and constrain uncertainties in volumetric estimations of biomass in ecosystems with high amounts of invasive annual grasses and fine-fuel litter.

Mountains with complex terrain and steep environmental gradients are biodiversity hotspots such as the eastern Tibetan Plateau (TP). However, it is generally assumed that mountain terrain plays a secondary role in plant species assembly on a millennial time-scale compared to climate change. Here, we investigate plant richness and community changes during the last 18,000 years at two sites: Lake Naleng and Lake Ximen on the eastern TP with similar elevation and climatic conditions but contrasting terrain. We applied plant DNA metabarcoding to lake sediments leveraging a new regional reference database for taxa identification. Furthermore, we developed a simplified species dispersal model named SMARC. This was used to simulate species migration along river valleys in response to past climate change at the taxonomic resolution of the sedimentary ancient DNA (sedaDNA) approach. Statistical analyses, including ordination-based ecological trajectory analysis, yielded a significant match between sedaDNA and simulated results at single taxon and community levels including certain site-specific differences. Steep terrain downstream of Lake Naleng enhances connectivity to glacial lowland refugia during postglacial warming. In contrast, gentle terrain over long distances implies weak connectivity to the lowland and thus resulted in a strong migration lag at Lake Ximen. Likewise, terrain differences among our sites defined the different connectivity to alpine refugia during late-Holocene cooling. Our consistent proxy- and model-based results, for the first time, indicate that dispersal related migration lags in complex mountain terrain lead to uneven vegetation trajectories at sites with similar climatic conditions mainly because of differences in connectivity to refugia. Ultimately our results indicate that connectivity to refugia is a first-order factor for species migration in addition to elevation-related climatic conditions shaping the postglacial vegetation trajectory in mountainous terrain. This has hitherto largely been ignored when forecasting mountain vegetation responses to climate change and related risk assessment.

This study evaluates the response of ground beetle (Coleoptera: Carabidae) assemblage to forest management practices by integrating species composition, body traits, wing morphology and developmental instability. Traditional approaches that rely on averaged identity-based descriptors often overlook phenotypic plasticity and functional trait variability, potentially masking species-specific responses to environmental changes. To address this, we applied a three-layered analytical approach to address this gap, utilising ground beetle occurrence and morphological trait data from Podyjí National Park, Czech Republic. The first layer assessed assemblage composition with ecological and dietary preferences across control, ecotone and clearing treatments using multivariate techniques. Building on species-level knowledge, the second layer analysed the interaction between coarse traits, such as wing morphology and fine-scale body traits, including body size (proxied by elytron length), head width and last abdominal sternite, to assess their relationship with the different treatments. These interactions were explored as intraspecific wing plasticity can affect functional interpretations. The third layer focused on fluctuating asymmetry as an intraindividual indicator of developmental instability, examining how ground beetles respond to environmental stressors. Our findings revealed: (i) no significant impact of habitat treatments on the presence of specialist species in the assemblage analysis; (ii) analysis of morphological traits highlights the combined influence of a coarse trait, such as wing morphology, and a fine trait, such as head width, which together contribute to the partitioning of assemblages and help distinguish differences in habitat use; and (iii) FA analysis revealed a significant positive association between the second antennal segment of specialist species and litter while displaying a negative association with Collembola. This multilevel analytical framework not only confirms ecological findings but also advances our approach to habitat and species analysis, offering deeper insights into ecosystem dynamics.