Changes In Species Assemblages Research Articles

Birds of Berlin: Changes in communities and guilds in the urban park "Tiergarten" since 1850.

Urbanization has far-reaching consequences on birds, and knowledge of the impacts on taxonomic and functional diversity is necessary to make cities as compatible as possible for species. Avian diversity in parks in urban centers has been investigated multiple times, but rarely so in long-term studies due to lacking data. The Tiergarten in Berlin is a large-scale park in the city center of great value for people and many species including birds. We compiled bird species lists since 1850 and from monitoring in 2022 in one dataset to investigate how bird communities and guilds have changed over time and how these alterations were influenced by the eventful history of the park's vegetation conditions. Long-term changes in species assemblages were analyzed with an ordination analysis, and changes in guild presence and functional richness were discussed with regard to landscape transitions. A gradual development of species assemblages yet only small changes in guild composition since 1850 was detected, whereas the 1950 community stands out with a drop in species richness and replacement of forest species with an open land community, which reflects the deforestation of the park during World War II. Consideration of habitat, lifestyle, trophic, and migration guilds revealed no sign of functional homogenization over the last 172 years (1850-2022). Despite the high frequentation of the park by humans it still allows for a high bird diversity due to the Tiergarten's sheer size and heterogeneity of vegetation and habitats. We recommend that the park is maintained and managed accordingly to preserve this condition and advise other urban parks to strive for these beneficial features.

Effects of global change on bird and beetle populations in boreal forest landscape: An assemblage dissimilarity analysis

AbstractAimDespite an increasing number of studies highlighting the impacts of climate change on boreal species, the main factors that will drive changes in species assemblages remain ambiguous. We study how species community composition would change following anthropogenic and natural disturbances. We determine the main drivers of assemblage dissimilarity for bird and beetle communities.LocationCôte‐Nord, Québec, Canada.MethodsWe quantify two climate‐induced pathways based on direct and indirect effects on species occurrence under different forest harvest management scenarios. The direct climate effects illustrate the impact of climate variables while the indirect effects are reflected through habitat‐based climate change. We develop empirical models to predict the distribution of 127 and 108 species under climate‐habitat and habitat‐only models, respectively, over the next century. We analyse the regional and the latitudinal species assemblage dissimilarity by decomposing it into balanced variation in species occupancy and occurrence and occupancy and occurrence gradient.ResultsBoth pathways increased dissimilarity in species assemblage. At the regional scale, both effects have an impact on decreasing the number of winning species. Yet, responses are much larger in magnitude under mixed climate effects. Regional assemblage dissimilarity reached 0.77 and 0.69 under mixed effects versus 0.09 and 0.10 under indirect effects for beetles and birds, respectively, between RCP8.5 and baseline climate scenarios when considering forest harvesting. Latitudinally, assemblage dissimilarity increased following the climate conditions pattern.Main conclusionsThe two pathways are complementary and alter biodiversity, mainly caused by species turnover. Yet, responses are much larger in magnitude under mixed climate effects. Therefore, inclusion of climatic variables considers aspects other than just those related to forest landscapes, such as life cycles of animal species. Moreover, we expect differences in occupancy between the two studied taxa. This could indicate the potential range of change in boreal species concerning novel environmental conditions.

Effects of light and noise pollution on avian communities of European cities are correlated with the species’ diet

Urbanization affects avian community composition in European cities, increasing biotic homogenization. Anthropic pollution (such as light at night and noise) is among the most important drivers shaping bird use in urban areas, where bird species are mainly attracted by urban greenery. In this study, we collected data on 127 breeding bird species at 1349 point counts distributed along a gradient of urbanization in fourteen different European cities. The main aim was to explore the effects of anthropic pollution and city characteristics, on shaping the avian communities, regarding species’ diet composition. The green cover of urban areas increased the number of insectivorous and omnivorous bird species, while slightly decreasing the overall diet heterogeneity of the avian communities. The green heterogeneity—a measure of evenness considering the relative coverage of grass, shrubs and trees—was positively correlated with the richness of granivorous, insectivorous, and omnivorous species, increasing the level of diet heterogeneity in the assemblages. Additionally, the effects of light pollution on avian communities were associated with the species' diet. Overall, light pollution negatively affected insectivorous and omnivorous bird species while not affecting granivorous species. The noise pollution, in contrast, was not significantly associated with changes in species assemblages. Our results offer some tips to urban planners, managers, and ecologists, in the challenge of producing more eco-friendly cities for the future.

Urban-driven decrease in arthropod richness and diversity associated with group-specific changes in arthropod abundance

Habitat loss and fragmentation caused by land-use changes in urbanised landscapes are main drivers of biodiversity loss and changes in species assemblages. While the effects of urbanisation on arthropods has received increasing attention in the last decade, most of the studies were taxon-specific, limited in time and/or covering only part of the habitats along the rural-urban gradient. To comprehensively assess the effects of urbanisation on arthropod communities, here, we sampled arthropods at 180 sites within an urban mosaic in the city of Innsbruck (Austria) using a systematic grid. At each site, arthropods were collected in three micro-habitats: the canopy, the bush layer and tree bark. They were identified to the family, infra-order or order level, depending on the taxonomic group. Urbanisation level was estimated by five different proxies extracted from land use/land cover data (e.g., impervious surface cover), all of them calculated in a 100, 500, and 1,000 m radius around the sampling points, and three indexes based on distance to settlements. We tested for the effects of different levels of urbanisation on (i) overall arthropod abundance, richness and diversity and (ii) community composition using redundancy analyses. In the canopy and the bush layer, arthropod richness and diversity decreased with increasing urbanisation level, suggesting that urbanisation acts as a filter on taxonomic groups. Our data on arthropod abundance further support this hypothesis and suggest that urbanisation disfavours wingless groups, particularly so on trees. Indeed, urbanisation was correlated to lower abundances of spiders and springtails, but higher abundances of aphids, barklice and flies. Arthropod community composition was better explained by a set of urbanisation proxies, especially impervious surface cover measured in a 100, 500, and 1,000 m radius. Arthropods are key elements of food webs and their availability in urban environments is expected to have bottom-up effects, thus shaping foraging behaviour, distribution, and/or success of species at higher trophic levels. Studying ecological networks in urban ecosystems is the next step that will allow to understand how urbanisation alters biodiversity.

Decadal-scale variation in coral calcification on coral-depleted Caribbean reefs

Over recent decades, many Caribbean reefs have transitioned to states where stony corals are no longer spatially dominant. The community dynamics culminating in this outcome are well known, but its functional implications remain incompletely understood. Here we used annual surveys from 1992 to 2019 to describe coral communities at 6 sites off St. John, US Virgin Islands, and explored how their ecological dynamics interact with their capacity to sustain estimated coral community calcification (G, kg CaCO3 m-2 yr-1). These communities had low coral cover (≤4.4%), but they changed through small and incremental events that summed to a slight decline in coral cover and changes in species assemblages favoring biotic homogenization and weedy species. Estimated coral G remained low, between 0.3 and 1.3 kg CaCO3 m-2 yr-1 (8.2-35.6 mmol CaCO3 m-2 d-1), but it differed among sites and years. The dominant contributors to G were Siderastrea siderea (1 site), Porites astreoides (1 site), and Orbicella spp. (4 sites), but higher G only occurred where Orbicella spp. remained relatively common; G dramatically declined at 1 site when the abundance of this genus decreased. These results suggest that some coral-depleted reefs may maintain low G that could be sufficient to avoid transitions into net negative budget states, provided that biological and physical erosion and dissolution of CaCO3 (not recorded here) are minimal. Further mortalities of the few coral species remaining on these reefs through disturbances like stony coral tissue loss disease would compromise this delicate production-erosion balance, and likely see transitions of such reefs into negative carbonate budget states.

European mushroom assemblages are phylogenetically structured by temperature

Recent global warming affects species compositions at an unprecedented rate. To predict climate‐induced changes in species assemblages, a better understanding of the link between species occurrence and climate is needed. Macrofungal fruit body assemblages are correlated with the thermal environment at the European scale. However, it is still unknown whether macrofungal communities are also phylogenetically structured by thermal environments. Thermal environments are characterized by annual temperature means but also by intra‐annual temperature variability (hereafter termed temperature seasonality), which are both considered in this study. Here, we used distribution data of 2882 species based on fruit body records across Europe to address two main questions: 1) are mushroom assemblages at the extremes of the mean (warm and cold) and seasonal (high intra‐annual variability, i.e. continental) climate gradient phylogenetically more similar than expected (phylogenetic alpha diversity); 2) are mushroom assemblages, that are subject to different mean and seasonal temperature conditions, composed of different lineages (phylogenetic beta diversity). Our phylogenetic alpha diversity analysis shows that mushroom assemblages are phylogenetically structured by warm and cold environments, indicating that phylogenetically related species with similar traits thrive under more extreme conditions. In contrast, assemblages are phylogenetically more dissimilar (overdispersed) in temperature seasonal environments, indicating limiting similarity. Phylogenetic beta diversity was significantly correlated with mean and seasonal temperature differences, a response mainly driven by a few genera. Our results show that macrofungal assemblages are phylogenetically structured by temperature across Europe, suggesting phylogenetically constrained specialization towards temperature extremes. Predicted anthropogenic warming is likely to affect species composition and phylogenetic diversity with additional consequences for the carbon‐ and nutrient cycles.

Antipredator behaviors in urban settings: Ecological experimentation powered by citizen science.

Animal behaviors are often modified in urban settings due to changes in species assemblages and interactions. The ability of prey to respond to a predator is a critical behavior, but urban populations may experience altered predation pressure, food supplementation, and other human‐mediated disturbances that modify their responsiveness to predation risk and promote habituation.Citizen‐science programs generally focus on the collection and analysis of observational data (e.g., bird checklists), but there has been increasing interest in the engagement of citizen scientists for ecological experimentation.Our goal was to implement a behavioral experiment in which citizen scientists recorded antipredator behaviors in wild birds occupying urban areas. In North America, increasing populations of Accipiter hawks have colonized suburban and urban areas and regularly prey upon birds that frequent backyard bird feeders. This scenario, of an increasingly common avian predator hunting birds near human dwellings, offers a unique opportunity to characterize antipredator behaviors within urban passerines.For two winters, we engaged citizen scientists in Chicago, IL, USA to deploy a playback experiment and record antipredator behaviors in backyard birds. If backyard birds maintained their antipredator behaviors, we hypothesized that birds would decrease foraging behaviors and increase vigilance in response to a predator cue (hawk playback) but that these responses would be mediated by flock size, presence of sentinel species, body size, tree cover, and amount of surrounding urban area.Using a randomized control–treatment design, citizen scientists at 15 sites recorded behaviors from 3891 individual birds representing 22 species. Birds were more vigilant and foraged less during the playback of a hawk call, and these responses were strongest for individuals within larger flocks and weakest in larger‐bodied birds. We did not find effects of sentinel species, tree cover, or urbanization.By deploying a behavioral experiment, we found that backyard birds inhabiting urban landscapes largely maintained antipredator behaviors of increased vigilance and decreased foraging in response to predator cues. Experimentation in citizen science poses challenges (e.g., observation bias, sample size limitations, and reduced complexity in protocol design), but unlike programs focused solely on observational data, experimentation allows researchers to disentangle the complex factors underlying animal behavior and species interactions.

The effect of natural disturbances on forest biodiversity: an ecological synthesis.

Disturbances alter biodiversity via their specific characteristics, including severity and extent in the landscape, which act at different temporal and spatial scales. Biodiversity response to disturbance also depends on the community characteristics and habitat requirements of species. Untangling the mechanistic interplay of these factors has guided disturbance ecology for decades, generating mixed scientific evidence of biodiversity responses to disturbance. Understanding the impact of natural disturbances on biodiversity is increasingly important due to human-induced changes in natural disturbance regimes. In many areas, major natural forest disturbances, such as wildfires, windstorms, and insect outbreaks, are becoming more frequent, intense, severe, and widespread due to climate change and land-use change. Conversely, the suppression of natural disturbances threatens disturbance-dependent biota. Using a meta-analytic approach, we analysed a global data set (with most sampling concentrated in temperate and boreal secondary forests) of species assemblages of 26 taxonomic groups, including plants, animals, and fungi collected from forests affected by wildfires, windstorms, and insect outbreaks. The overall effect of natural disturbances on α-diversity did not differ significantly from zero, but some taxonomic groups responded positively to disturbance, while others tended to respond negatively. Disturbance was beneficial for taxonomic groups preferring conditions associated with open canopies (e.g. hymenopterans and hoverflies), whereas ground-dwelling groups and/or groups typically associated with shady conditions (e.g. epigeic lichens and mycorrhizal fungi) were more likely to be negatively impacted by disturbance. Across all taxonomic groups, the highest α-diversity in disturbed forest patches occurred under moderate disturbance severity, i.e. with approximately 55% of trees killed by disturbance. We further extended our meta-analysis by applying a unified diversity concept based on Hill numbers to estimate α-diversity changes in different taxonomic groups across a gradient of disturbance severity measured at the stand scale and incorporating other disturbance features. We found that disturbance severity negatively affected diversity for Hill number q= 0 but not for q= 1 and q= 2, indicating that diversity-disturbance relationships are shaped by species relative abundances. Our synthesis of α-diversity was extended by a synthesis of disturbance-induced change in species assemblages, and revealed that disturbance changes the β-diversity of multiple taxonomic groups, including some groups that were not affected at the α-diversity level (birds and woody plants). Finally, we used mixed rarefaction/extrapolation to estimate biodiversity change as a function of the proportion of forests that were disturbed, i.e. the disturbance extent measured at the landscape scale. The comparison of intact and naturally disturbed forests revealed that both types of forests provide habitat for unique species assemblages, whereas species diversity in the mixture of disturbed and undisturbed forests peaked at intermediate values of disturbance extent in the simulated landscape. Hence, the relationship between α-diversity and disturbance severity in disturbed forest stands was strikingly similar to the relationship between species richness and disturbance extent in a landscape consisting of both disturbed and undisturbed forest habitats. This result suggests that both moderate disturbance severity and moderate disturbance extent support the highest levels of biodiversity in contemporary forest landscapes.

Impacts of piscicide-induced fish removal on resource use and trophic diversity of lake invertebrates

Chemical eradication of non-native species has become a widely used method to mitigate the potential negative impacts of altered competitive or predatory dynamics on biodiversity and natural ecosystem processes. However, the responses of non-target species can vary from rapid full recovery to delayed or absent recolonization, and little is known about the potential shifts in resource use and trophic diversity of native species following chemical treatments. We used a before-after-control-impact approach to study the effects of rotenone piscicide treatment on abundance and trophic niche of benthic invertebrates in three untreated and three treated lakes in central Norway, the latter group hosting non-native roach (Rutilus rutilus) and pike (Esox lucius) prior to rotenone treatment. Based on community composition data, the relative abundance of invertebrate grazers and collectors decreased while that of predators increased following fish removal in the treated lakes. The stable isotope data indicated minor shifts in resource use of, and trophic diversity among, benthic invertebrate communities. While the predatory dragonfly larvae (Odonata) and grazer snails (Lymnaeidae) showed increased δ13C values indicating increased reliance on littoral benthic algae, the collector mayfly larvae (Leptophlebia) showed decreased δ13C values following fish removal in treated lakes. Grazer snails also showed a shift to a lower trophic position, while the predatory dragonflies and collector mayflies showed no changes in δ15N values following fish removal. The community-level isotopic niches of benthic invertebrates showed no consistent changes, although the sample-size corrected and Bayesian estimates of standard ellipse areas (SEAC and SEAB) slightly increased in two of the three treated lakes due to an increased range in δ15N. In conclusion, our study findings indicate some changes in species assemblages but minor shifts in the resource use and trophic diversity of benthic invertebrate communities following fish removal in rotenone treated lakes.

Climate-induced forest dieback drives compositional changes in insect communities that are more pronounced for rare species

Species richness, abundance and biomass of insects have recently undergone marked declines in Europe. We metabarcoded 211 Malaise-trap samples to investigate whether drought-induced forest dieback and subsequent salvage logging had an impact on ca. 3000 species of flying insects in silver fir Pyrenean forests. While forest dieback had no measurable impact on species richness, there were significant changes in community composition that were consistent with those observed during natural forest succession. Importantly, most observed changes were driven by rare species. Variation was explained primarily by canopy openness at the local scale, and the tree-related microhabitat diversity and deadwood amount at landscape scales. The levels of salvage logging in our study did not explain compositional changes. We conclude that forest dieback drives changes in species assemblages that mimic natural forest succession, and markedly increases the risk of catastrophic loss of rare species through homogenization of environmental conditions.

Calling Phenology in Rana sylvatica (Wood Frog) at High-Elevation Ponds in the White Mountains, New Hampshire

Permanent, fishless, alpine and subalpine ponds are extremely rare in New England, and amphibians occupying these ponds are unique bioindicators of environmental change because they are subject to different ecological pressures compared with lowland populations. Further, alpine and montane ecosystems are expected to undergo rapid change in the coming decades. Therefore, uncoupling the interacting effects of temperature, precipitation, and ice-out on breeding efforts may identify specific ecological mechanisms driving reproduction of amphibians. The reproductive phenology of amphibians in climatically extreme alpine environments in the eastern United States is historically under-reported and remains poorly understood. To evaluate the reproductive phenology of amphibians near the upper extreme of their vertical distribution in the White Mountains, NH, we digitally recorded amphibian calls between 2010 and 2020 at 3 permanent, fishless ponds: Hermit Lake (1180 m), Eagle Lake (1278 m), and Lakes of the Clouds (1546 m). Our study revealed dynamic changes in species assemblages and provides the first report of Hyla versicolor (Gray Tree Frog) in a subalpine context (at Hermit Lake). We analyzed the calling phenology of the earliest breeding North American anuran, Rana sylvatica (Wood Frog), and found differences in calling phenology among the 3 ponds and temporary changes in calling phenology correlated with interpolated daily weather parameters. We stress the need for further research to understand both short- and long-term, weather-driven reproductive dynamics in amphibian phenology in high mountains and their corresponding demographic effects.

Climate change in the Bay of Biscay: Changes in spatial biodiversity patterns could be driven by the arrivals of southern species

Under climate change, future species assemblages will be driven by the movements and poleward shift of local species and the arrival of more thermophilic species from lower latitudes. To evaluate the impacts of climate change on marine communities in the Bay of Biscay, we used the hierarchical filters modelling approach. Models integrated 3 vertical depth layers and considered 2 Intergovernmental Panel on Climate Change (IPCC) scenarios (Representative Concentration Pathway, RCP2.6 and RCP8.5) and 2 periods (2041-2050 and 2091-2100) to simulate potential future species distributions. Results predicted potentially suitable future ranges for 163 species as well as future arrivals of non-indigenous southern species. We aggregated these results to map changes in species assemblages. Results revealed that coastal areas would undergo the highest species loss among the Bay of Biscay species, depending on their vertical habitat (benthic, demersal, benthopelagic or pelagic). Benthic and demersal species were projected to experience a westward shift, which would induce a deepening of those species. In contrast, pelagic species were projected to shift northward. The potential ecological niche for half of the studied species, mostly benthic and demersal, was projected to decrease under climate change. In addition, a high rate of southern species arrivals is expected (+28%). Assessment of community composition showed high species replacement within the 0-50 m isobath, driven by the replacement of native species by southern ones. This could lead to a major reorganization of trophic networks and have socio-economic impacts.

Breaking ecological barriers: Anthropogenic disturbance leads to habitat transitions, hybridization, and high genetic diversity

Genetic diversity is expected to erode in disturbed habitats through strong selection, local extinctions, and recolonization associated with genetic bottlenecks and restricted gene flow. Despite this general prediction and over three decades of population genetics studies, our understanding of the long-term effect of environmental disturbance on local and regional genetic diversity remains limited. We conducted a population genetic survey of the microcrustacean Daphnia across a landscape subject to anthropogenic stressors from a century of industrial mining. At the local scale we found moderate genetic diversity (i.e., low clonal diversity), characteristic of habitat-specific selective sweeps and local extinctions, but high diversity and strong genetic structure at the regional scale despite the shared watershed of many lakes and exceptional dispersal ability of daphniids. Many habitats experienced changes in species assemblages, with the obligate asexual Daphnia pulex lineages—known only to inhabit ponds—dominating disrupted urban lakes. This habitat transition (pond to lake) was likely facilitated by the disruption of ecological barriers maintaining the genomic separation of these young species. Thus, disrupted habitats can exhibit complex and unexpected genetic patterns of local extinctions and recolonizations, followed by habitat transitions, hybridization and potential speciation events that are difficult to predict and should not be underestimated.

Rapid assessment of avian species richness and abundance using acoustic indices

• Monitoring environmental sound presents an opportunity for rapid biodiversity assessment. • Environmental sound can be readily described using acoustic indices. • Higher bird species-richness and abundance associated with patterns in indices values. • Patterns were coherent across multiple acoustic indices, and across habitat types. • We solve methodological issues and provide conceptual clarity for using indices. Accelerating global shifts in climate and land use change are altering natural habitats and species assemblages, making management interventions crucial to halt the biodiversity crisis. Management decisions must be informed by accurate biodiversity assessments. However, such assessments are often time consuming, expensive, and require specialist knowledge. Monitoring environmental sound may offer a novel method for rapid biodiversity assessment. Changes in species assemblages at a given location are reflected in the site’s acoustic energy, termed the soundscape. Soundscapes can be readily described using acoustic indices; metrics based on objective features of recordings such as pitch and amplitude. Changes in acoustic indices values may therefore reflect changes in species assemblages, alerting land managers to shifts in wildlife populations. However, thus far, evidence supporting the use of acoustic indices in biodiversity monitoring has been equivocal. Here, we test the practical application of acoustic indices for biodiversity monitoring while solving methodological issues and providing conceptual clarity. Using 84 h of audio recordings covering 315 dawns from 43 sites, coupled with bird assemblage and vegetation data collected in the field, we demonstrate strong relationships between acoustic indices and avian species richness and abundance. In contrast with many previous studies, we found that sites with high bird species-richness and abundance had less even soundscapes (i.e. acoustic energy was less evenly distributed among frequencies) compared with sites with low species richness and abundance. Crucially, these patterns were coherent across multiple acoustic indices, and across habitat types, emphasising their utility for monitoring. Acoustic indices sensitive to the frequencies at which birds sing are most useful for monitoring avian communities; the Acoustic Evenness Index, Biophony Index, and the biophony component of the Normalised Difference Soundscape Index exhibited the strongest relationship with species richness. Land managers can use acoustic indices for biodiversity monitoring, complementing other, more established, assessment methods.

Fine-scale temporal turnover of jarrah forest understory vegetation assemblages is independent of fire regime

BackgroundPrescribed burning is an important management tool in jarrah (Eucalyptus marginata Sm.) forests of southwest Western Australia to reduce the risk of damaging bushfires. In 1986 to 1987, we established long-term study sites in dry (mean annual rainfall ~700 mm) and moist (mean annual rainfall ~1000 mm) jarrah forests to assess the effects of prescribed burning, as well as other fire treatments including fire exclusion, on the composition, richness, and relative abundance of forest understory vegetation.ResultsOver almost 30 years, species assemblages within all fire treatments changed significantly through time, but the changes were independent of treatment. The pattern of change in composition of fire response types over elapsed time was different between sites. At the dry site, changes in species assemblages were initially relatively large in the first decade or so of the study, but slowed thereafter. At the moist site, compositional change driven by obligate seeding shrubs occurred faster and more uniformly with time across all treatments. Species richness was also independent of fire treatment at both sites. Species richness decreased with elapsed time on the moist site but increased with elapsed time on the dry site. The stronger elapsed-time effect rendered the time since fire effect on loss of species richness on the moist site to be insignificant, but there was an inverse relationship with time since fire at the dry site. Within each site, there were clear patterns of changing abundance based on life form and fire response groups, but this was not consistent between sites.ConclusionsAt the scale of the current study, jarrah forest plant communities displayed resilience to imposed experimental fire regimes. Over time, either elapsed time or time since fire, species assemblages across all treatments changed regardless of fire treatment, but changes were mostly associated with specific plant life forms and fire response traits, suggesting that the process is both deterministic and stochastic. While many species changed in abundance over time, no species were lost as a result of the fire treatments. Within the fire frequency and intensity ranges investigated in this study, there was flexibility in the application of prescribed fire to achieve management objectives without loss of plant diversity.

Extreme genetic structure and dynamic range evolution in a montane passerine bird: implications for tropical diversification

Aim: Employ phylogeographic analyses of a widespread species complex to examine the role of historical and evolutionary processes in the origin and maintenance of high species diversity in the Neotropical montane region. Location: Neotropical highlands. Taxon: Henicorhina wood-wrens (Aves, Troglodytidae). Methods: We collected mtDNA sequence data for 288 individuals thoroughly covering the range of the Henicorhina leucophrys complex from Mexico to Bolivia. Sequences were employed to characterize population structure, infer phylogenetic relationships among populations and their divergence times, examine lineage accumulation through time, and identify presumptive species using coalescent methods. We also explored the origin of elevational and latitudinal replacements involved in spatial changes in species assemblages in the Andes. Results: We found remarkable genetic structure within the complex, which consists of numerous lineages reaching >12% sequence divergence; most divergent populations occur in areas separated by topographic barriers but several of them, typically not sister to each other, co-occur with elevational segregation on mountain slopes or replace each other with latitude along the Andes. Some close relatives occur in areas separated by thousands of kilometers, with more distant relatives occupying intervening areas. The complex likely originated in the Mexican highlands and expanded extensively in South America while diverging rapidly at a constant rate into many different lineages which have persisted for millions of years. Coalescent analyses consistently revealed that the complex may comprise more than 30 species; while we do not suggest these presumptive species should be recognized by taxonomists in the absence of additional data, H. leucophrys is a distant outlier among New World birds in terms of high lineage diversity within a single recognized species. Main Conclusions: Our study captured wood-wren lineages in the act of building up diversity via divergence and persistence in allopatry, achievement of secondary sympatry, and coexistence at the landscape scale mediated by ecological and evolutionary divergence. Although dispersal by wood-wrens is restricted at present and this likely accounts for strong population structure across topographic barriers, their ranges have been dynamic, managing to disperse over much of the montane Neotropics. Phases of expansion and contraction of ranges and localized extinctions of populations likely account for phylogeographic patterns which are precursors to the origin of new species and the accumulation of diversity in tropical mountains.

Body size structure of oribatid mite communities in different microhabitats

ABSTRACTSize scaling phenomena occur on different levels, from organisms to ecosystems. In predictive ecology, empirical data on body size relation have been used for decades to explain large-scale temporal and spatial patterns. More recently, community ecologists have started to use abundance-weighted mean body sizes as a tool to predict changes in species assemblages along gradients in above-ground systems. In soil and litter systems, however, body size of individuals or the body size structure of communities have rarely been addressed in this way. Here we use community data of oribatid mites from different forest ground microhabitats (dead wood, moss, and litter) in combination with body size measurements to describe some basic body-size relationships for decomposer mites. Generally, we found that the community body size (measured as an abundance-weighted mean of all species) as well as size distribution of sexual and parthenogenetic oribatids differed across microhabitats. Furthermore, our results showed that the abundance of oribatid mites in fragmented (moss), but not in continuous (dead wood, litter) microhabitats, can be predicted by the community body size. All these differences might be explained by specific microhabitat conditions like pore size and food resource quality, but also by the dominance and competitive or facultative interactions among certain species in a particular sample or habitat. Additionally, our results bring renewed attention to body size as an important predictor for patterns, structure, and energy translocation in terrestrial forest soil food webs.

Fish assemblage changes over half a century in the Yellow River, China.

Riverine environments have been threatened by anthropogenic perturbations worldwide, whereby their fish assemblages have been modified by habitat changes and nonendemic species invasions. We assessed changes in fish assemblages by comparing the species presence in historical and contemporary fish data in the Yellow River from 1965 to 2015. The temporal change in species assemblages was found with increased nonendemic species and fewer natives. Fish species richness of the river declined 35.4% over the past fifty years. Moreover, the decreased mean Bray–Curtis dissimilarity among reaches suggested that the fish assemblages of different reaches in the Yellow River were becoming more similar over time. However, temporal patterns of fish assemblages varied among reaches. In the upper Yellow River, higher species richness and more invasive species were found than those in the historical record, while the lower reaches experienced significant species loss. Dam constructions, exotic fish invasions, and flow reductions played the vital role in structuring the temporal fish assemblages in the Yellow River. It is suggested that river basins which experienced different types and levels of stressors by anthropogenic perturbations can produce varied effects on their temporal trends of species assemblages.

100 years on: a re-evaluation of the first discovery of microfauna from Ross Island, Antarctica

AbstractOver a century ago microfaunal diversity was first recorded by James Murray in lakes at Cape Royds, Ross Island, Antarctica. The report stands as the seminal study for today’s biodiversity investigations, and as a baseline to evaluate changes in faunal communities and introductions. In the present study, Cape Royds lakes were revisited and the mitochondrial c oxidase subunit I (COI) gene and morphology were used to compare diversity of Rotifera, Tardigrada and Nematoda with the records Murray published in the early 1900s. Cyanobacterial mats and the water column were sampled for microfauna from the five largest lakes using methods described by Murray. Across all five lakes similar patterns were observed for species distribution of all three phyla reported by Murray over 100 years ago. Some changes in species assemblages were identified within and between lakes, but there were no new introductions of named species for the Cape Royds region. Some of the species included by Murray in his monograph have been recently redescribed as Antarctic endemics, but others still retain their original name from the Northern Hemisphere holotypes and are also in need of revision to adequately determine the true endemism for these faunal groups.

An ecological climate change classification for South Australia

ABSTRACTTemperatures in South Australia have risen 0.5–1.5°C post-1950, a trend expected to drive ecological change. However, climate sensitivity, landscape resilience and management priorities vary among regions. We classified the vulnerability of South Australian plant assemblages to climate change in a framework that combines climate sensitivity and resilience. Generalised Dissimilarity Models (GDMs) of plant species composition were trained with species occurrence records from field plots. Resilience was represented by the proportional remnancy of native vegetation surrounding each location. Landscapes were classified using bivariate quantiles. Mean annual rainfall, summer maximum temperatures and spatial structure were important predictors of species turnover. GDMs (explaining 37–68% of deviance) were projected onto future climate scenarios to calculate sensitivity metrics. The Wheat Belt, mallee and Flinders Ranges were the most sensitive, representing a climatic transition characterised by rapid change in species assemblages. Southern Eyre Peninsula and western Kangaroo Island were classified as Resilient; the Mount Lofty Ranges, southern Flinders Ranges and eastern Kangaroo Island as Resistant; northern Eyre Peninsula and northern Flinders Ranges as Sensitive; and the Wheat Belt as Susceptible. The classification assists decisions on management priority and provenances or species selection for restoration and assisted migration in conjunction with other biodiversity measures.