Community size structure varies with predator–prey size relationships and temperature across Australian reefs

Climate change and fisheries exploitation are dramatically changing the abundances, species composition, and size spectra of fish communities. We explore whether variation in ‘abundance size spectra’, a widely studied ecosystem feature, is influenced by a parameter theorized to govern the shape of size‐structured ecosystems—the relationship between the sizes of predators and their prey (predator–prey mass ratios, or PPMRs). PPMR estimates are lacking for avast number of fish species, including at the scale of trophic guilds. Using measurements of 8128 prey items in gut contents of 97 reef fish species, we established predator–prey mass ratios (PPMRs) for four major trophic guilds (piscivores, invertivores, planktivores, and herbivores) using linear mixed effects models. To assess the theoretical predictions that higher community‐level PPMRs leads to shallower size spectrum slopes, we compared observations of both ecosystem metrics for ~15,000 coastal reef sites distributed around Australia. PPMRs of individual fishes were remarkably high (median ~71,000), with significant variation between different trophic guilds (~890 for piscivores; ~83,000 for planktivores), and ~8700 for whole communities. Community‐level PPMRs were positively related to size spectrum slopes, broadly consistent with theory, however, this pattern was also influenced by the latitudinal temperature gradient. Tropical reefs showed a stronger relationship between community‐level PPMRs and community size spectrum slopes than temperate reefs. The extent that these patterns apply outside Australia and consequences for community structure and dynamics are key areas for future investigation.     

Pollinator guilds respond contrastingly at different scales to landscape parameters of land‐use intensity

Land‐use intensification is the main factor for the catastrophic decline of insect pollinators. However, land‐use intensification includes multiple processes that act across various scales and should affect pollinator guilds differently depending on their ecology. We aimed to reveal how two main pollinator guilds, wild bees and hoverflies, respond to different land‐use intensification measures, that is, arable field cover (AFC), landscape heterogeneity (LH), and functional flower composition of local plant communities as a measure of habitat quality. We sampled wild bees and hoverflies on 22 dry grassland sites within a highly intensified landscape (NE Germany) within three campaigns using pan traps. We estimated AFC and LH on consecutive radii (60–3000 m) around the dry grassland sites and estimated the local functional flower composition. Wild bee species richness and abundance was positively affected by LH and negatively by AFC at small scales (140–400 m). In contrast, hoverflies were positively affected by AFC and negatively by LH at larger scales (500–3000 m), where both landscape parameters were negatively correlated to each other. At small spatial scales, though, LH had a positive effect on hoverfly abundance. Functional flower diversity had no positive effect on pollinators, but conspicuous flowers seem to attract abundance of hoverflies. In conclusion, landscape parameters contrarily affect two pollinator guilds at different scales. The correlation of landscape parameters may influence the observed relationships between landscape parameters and pollinators. Hence, effects of land‐use intensification seem to be highly landscape‐specific.     

Improved coarse‐grained model for studying sequence dependent phase separation of disordered proteins

We present improvements to the hydropathy scale (HPS) coarse‐grained (CG) model for simulating sequence‐specific behavior of intrinsically disordered proteins (IDPs), including their liquid–liquid phase separation (LLPS). The previous model based on an atomistic hydropathy scale by Kapcha and Rossky (KR scale) is not able to capture some well‐known LLPS trends such as reduced phase separation propensity upon mutations (R‐to‐K and Y‐to‐F). Here, we propose to use the Urry hydropathy scale instead, which was derived from the inverse temperature transitions in a model polypeptide with guest residues X. We introduce two free parameters to shift (Δ) and scale (µ) the overall interaction strengths for the new model (HPS‐Urry) and use the experimental radius of gyration for a diverse group of IDPs to find their optimal values. Interestingly, many possible (Δ, µ) combinations can be used for typical IDPs, but the phase behavior of a low‐complexity (LC) sequence FUS is only well described by one of these models, which highlights the need for a careful validation strategy based on multiple proteins. The CG HPS‐Urry model should enable accurate simulations of protein LLPS and provide a microscopically detailed view of molecular interactions.     

Titmice are a better indicator of bird density in Northern European than in Western European forests

Population sizes of many birds are declining alarmingly and methods for estimating fluctuations in species’ abundances at a large spatial scale are needed. The possibility to derive indicators from the tendency of specific species to co‐occur with others has been overlooked. Here, we tested whether the abundance of resident titmice can act as a general ecological indicator of forest bird density in European forests. Titmice species are easily identifiable and have a wide distribution, which makes them potentially useful ecological indicators. Migratory birds often use information on the density of resident birds, such as titmice, as a cue for habitat selection. Thus, the density of residents may potentially affect community dynamics. We examined spatio‐temporal variation in titmouse abundance and total bird abundance, each measured as biomass, by using long‐term citizen science data on breeding forest birds in Finland and France. We analyzed the variation in observed forest bird density (excluding titmice) in relation to titmouse abundance. In Finland, forest bird density linearly increased with titmouse abundance. In France, forest bird density nonlinearly increased with titmouse abundance, the association weakening toward high titmouse abundance. We then analyzed whether the abundance (measured as biomass) of random species sets could predict forest bird density better than titmouse abundance. Random species sets outperformed titmice as an indicator of forest bird density only in 4.4% and 24.2% of the random draws, in Finland and France, respectively. Overall, the results suggest that titmice could act as an indicator of bird density in Northern European forest bird communities, encouraging the use of titmice observations by even less‐experienced observers in citizen science monitoring of general forest bird density.     

Functional assembly of tropical montane tree islands in the Atlantic Forest is shaped by stress tolerance,bamboo presence,and facilitation

AimsAmidst the Campos de Altitude (Highland Grasslands) in the Brazilian Atlantic Forest, woody communities grow either clustered in tree islands or interspersed within the herbaceous matrix. The functional ecology, diversity, and biotic processes shaping these plant communities are largely unstudied. We characterized the functional assembly and diversity of these tropical montane woody communities and investigated how they fit within Grime''s CSR (C—competitor, S—stress‐tolerant, R—ruderal) scheme, what functional trade‐offs they exhibit, and how traits and functional diversity vary in response to bamboo presence/absence.MethodsTo characterize the functional composition of the community, we sampled five leaf traits and wood density along transects covering the woody communities both inside tree islands and outside (i.e., isolated woody plants in the grasslands community). Then, we used Mann–Whitney test, t test, and variation partitioning to determine the effects of inside versus outside tree island and bamboo presence on community‐weighted means, woody species diversity, and functional diversity.ResultsWe found a general SC/S strategy with drought‐related functional trade‐offs. Woody plants in tree islands had more acquisitive traits than those within the grasslands. Trait variation was mostly taxonomically than spatially driven, and species composition varied between inside and outside tree islands. Leaf thickness, wood density, and foliar water uptake were unrelated to CSR strategies, suggesting independent trait dimensions and multiple drought‐coping strategies within the predominant S strategy. Islands with bamboo presence showed lower Simpson diversity, lower functional dispersion, lower foliar water uptake, and greater leaf thickness than in tree islands without bamboo.ConclusionsThe observed functional assembly hints toward large‐scale environmental abiotic filtering shaping a stress‐tolerant community strategy, and small‐scale biotic interactions driving small‐scale trait variation. We recommend experimental studies with fire, facilitation treatments, ecophysiological and recruitment traits to elucidate on future tree island expansion and community response to climate change.     

Trait means or variance—What determines plant species' local and regional occurrence in fragmented dry grasslands?

One of the few laws in ecology is that communities consist of few common and many rare taxa. Functional traits may help to identify the underlying mechanisms of this community pattern, since they correlate with different niche dimensions. However, comprehensive studies are missing that investigate the effects of species mean traits (niche position) and intraspecific trait variability (ITV, niche width) on species abundance. In this study, we investigated fragmented dry grasslands to reveal trait‐occurrence relationships in plants at local and regional scales. We predicted that (a) at the local scale, species occurrence is highest for species with intermediate traits, (b) at the regional scale, habitat specialists have a lower species occurrence than generalists, and thus, traits associated with stress‐tolerance have a negative effect on species occurrence, and (c) ITV increases species occurrence irrespective of the scale. We measured three plant functional traits (SLA = specific leaf area, LDMC = leaf dry matter content, plant height) at 21 local dry grassland communities (10 m × 10 m) and analyzed the effect of these traits and their variation on species occurrence. At the local scale, mean LDMC had a positive effect on species occurrence, indicating that stress‐tolerant species are the most abundant rather than species with intermediate traits (hypothesis 1). We found limited support for lower specialist occurrence at the regional scale (hypothesis 2). Further, ITV of LDMC and plant height had a positive effect on local occurrence supporting hypothesis 3. In contrast, at the regional scale, plants with a higher ITV of plant height were less frequent. We found no evidence that the consideration of phylogenetic relationships in our analyses influenced our findings. In conclusion, both species mean traits (in particular LDMC) and ITV were differently related to species occurrence with respect to spatial scale. Therefore, our study underlines the strong scale‐dependency of trait‐abundance relationships.     

The toughest animals of the Earth versus global warming: Effects of long‐term experimental warming on tardigrade community structure of a temperate deciduous forest

Understanding how different taxa respond to global warming is essential for predicting future changes and elaborating strategies to buffer them. Tardigrades are well known for their ability to survive environmental stressors, such as drying and freezing, by undergoing cryptobiosis and rapidly recovering their metabolic function after stressors cease. Determining the extent to which animals that undergo cryptobiosis are affected by environmental warming will help to understand the real magnitude climate change will have on these organisms. Here, we report on the responses of tardigrades within a five‐year‐long, field‐based artificial warming experiment, which consisted of 12 open‐top chambers heated to simulate the projected effects of global warming (ranging from 0 to 5.5°C above ambient temperature) in a temperate deciduous forest of North Carolina (USA). To elucidate the effects of warming on the tardigrade community inhabiting the soil litter, three community diversity indices (abundance, species richness, and Shannon diversity) and the abundance of the three most abundant species (Diphascon pingue, Adropion scoticum, and Mesobiotus sp.) were determined. Their relationships with air temperature, soil moisture, and the interaction between air temperature and soil moisture were tested using Bayesian generalized linear mixed models. Despite observed negative effects of warming on other ground invertebrates in previous studies at this site, long‐term warming did not affect the abundance, richness, or diversity of tardigrades in this experiment. These results are in line with previous experimental studies, indicating that tardigrades may not be directly affected by ongoing global warming, possibly due to their thermotolerance and cryptobiotic abilities to avoid negative effects of stressful temperatures, and the buffering effect on temperature of the soil litter substrate.     

The influence of phylogeny and life history on telomere lengths and telomere rate of change among bird species: A meta‐analysis

Longevity is highly variable among animal species and has coevolved with other life‐history traits, such as body size and rates of reproduction. Telomeres, through their erosion over time, are one of the cell mechanisms that produce senescence at the cell level and might even have an influence on the rate of aging in whole organisms. However, uneroded telomeres are also risk factors of cell immortalization. The associations of telomere lengths, their rate of change, and life‐history traits independent of body size are largely underexplored for birds. To test associations of life‐history traits and telomere dynamics, we conducted a phylogenetic meta‐analysis using studies of 53 species of birds. We restricted analyses to studies that applied the telomere restriction fragment length (TRF) method, and examined relationships between mean telomere length at the chick (Chick TL) and adult (Adult TL) stages, the mean rate of change in telomere length during life (TROC), and life‐history traits. We examined 3 principal components of 12 life‐history variables that represented: body size (PC1), the slow–fast continuum of pace of life (PC2), and postfledging parental care (PC3). Phylogeny had at best a small‐to‐medium influence on Adult and Chick TL (r ² = .190 and .138, respectively), but a substantial influence on TROC (r ² = .688). Phylogeny strongly influenced life histories: PC1 (r ² = .828), PC2 (.838), and PC3 (.613). Adult TL and Chick TL were poorly associated with the life‐history variables. TROC, however, was negatively and moderate‐to‐strongly associated with PC2 (unadjusted r = −.340; with phylogenetic correction, r = −.490). Independent of body size, long‐lived species with smaller clutches, and slower embryonic rate of growth may exhibit less change in telomere length over their lifetimes. We suggest that telomere lengths may have diverged, even among closely avian‐related species, yet telomere dynamics are strongly linked to the pace of life.     

Habitat Use by Waterbirds in Relation to Pond Size,Water Depth,and Isolation: Lessons from a Restoration in Southern Spain

Wetland restoration is increasingly important to reverse habitat degradation, recover ecosystem services, and maintain biodiversity. To aid project design, more information is required on the influence of wetland size, depth of water, and isolation on the waterbird communities that become established. During a restoration project in Doñana, one of the Europe's most important wetland complexes, an experimental network of 96 temporary ponds with standard shape but variable size, water depth, and isolation was created. We surveyed the waterbird community in spring from 2006 to 2008 and related species abundance and richness to abiotic pond characteristics. We also performed analyses pooling species by foraging guilds or body size. Waterbird abundance and species richness were highest in 2007, the wettest year when the ponds had longer hydroperiods. Larger ponds had consistently higher abundance and species richness for the entire community and for different guilds and body sizes. Moreover, the density of birds per hectare was higher in large ponds than in the smaller ones. Pond isolation and excavated depth did not affect overall abundance and richness, although opposing effects of depth were observed on some size classes, and ducks and large birds preferred isolated ponds. Some bird groups preferred ponds at a particular location. This is the first waterbird study to address the importance of pond size, depth, and isolation independently of confounding variables such as pond shape. It illustrates the varied responses from different bird groups and demonstrates the importance of varying depth, location, and isolation to enhance community abundance and diversity .     

The drivers of avian‐haemosporidian prevalence in tropical lowland forests of New Guinea in three dimensions

Haemosporidians are among the most common parasites of birds and often negatively impact host fitness. A multitude of biotic and abiotic factors influence these associations, but the magnitude of these factors can differ by spatial scales (i.e., local, regional and global). Consequently, to better understand global and regional drivers of avian‐haemosporidian associations, it is key to investigate these associations at smaller (local) spatial scales. Thus, here, we explore the effect of abiotic variables (e.g., temperature, forest structure, and anthropogenic disturbances) on haemosporidian prevalence and host–parasite networks on a horizontal spatial scale, comparing four fragmented forests and five localities within a continuous forest in Papua New Guinea. Additionally, we investigate if prevalence and host–parasite networks differ between the canopy and the understory (vertical stratification) in one forest patch. We found that the majority of Haemosporidian infections were caused by the genus Haemoproteus and that avian‐haemosporidian networks were more specialized in continuous forests. At the community level, only forest greenness was negatively associated with Haemoproteus infections, while the effects of abiotic variables on parasite prevalence differed between bird species. Haemoproteus prevalence levels were significantly higher in the canopy, and an opposite trend was observed for Plasmodium. This implies that birds experience distinct parasite pressures depending on the stratum they inhabit, likely driven by vector community differences. These three‐dimensional spatial analyses of avian‐haemosporidians at horizontal and vertical scales suggest that the effect of abiotic variables on haemosporidian infections are species specific, so that factors influencing community‐level infections are primarily driven by host community composition.     

Selection of O‐negative induced pluripotent stem cell clones for high‐density red blood cell production in a scalable perfusion bioreactor system

ObjectivesLarge‐scale generation of universal red blood cells (RBCs) from O‐negative (O‐ve) human induced pluripotent stem cells (hiPSCs) holds the potential to alleviate worldwide shortages of blood and provide a safe and secure year‐round supply. Mature RBCs and reticulocytes, the immature counterparts of RBCs generated during erythropoiesis, could also find important applications in research, for example in malaria parasite infection studies. However, one major challenge is the lack of a high‐density culture platform for large‐scale generation of RBCs in vitro.Materials and MethodsWe generated 10 O‐ve hiPSC clones and evaluated their potential for mesoderm formation and erythroid differentiation. We then used a perfusion bioreactor system to perform studies with high‐density cultures of erythroblasts in vitro.ResultsBased on their tri‐lineage (and specifically mesoderm) differentiation potential, we isolated six hiPSC clones capable of producing functional erythroblasts. Using the best performing clone, we demonstrated the small‐scale generation of high‐density cultures of erythroblasts in a perfusion bioreactor system. After process optimization, we were able to achieve a peak cell density of 34.7 million cells/ml with 92.2% viability in the stirred bioreactor. The cells expressed high levels of erythroblast markers, showed oxygen carrying capacity, and were able to undergo enucleation.ConclusionsThis study demonstrated a scalable platform for the production of functional RBCs from hiPSCs. The perfusion culture platform we describe here could pave the way for large volume‐controlled bioreactor culture for the industrial generation of high cell density erythroblasts and RBCs.

Human pluripotent stem cell‐derived red blood cells could help alleviate worldwide blood shortages and provide a secure year‐round supply. However, current generation methods lack the necessary scalability. Here, we present the selection of O‐negative hiPSC clones and demonstrate the small‐scale generation of functional erythroblasts in a high‐density perfusion bioreactor system.     

Shielded environments reduce stress in alien Asteraceae species during hot and dry summers along urban‐to‐rural gradients

Urban environments often host a greater abundance and diversity of alien plant species than rural areas. This is frequently linked to higher disturbance and propagule pressure, but could also be related to the additional establishment of species from warmer native ranges in cities, facilitated by the latter''s higher air temperatures and drier soils. A hitherto unresolved question is how stressful the urban environments become during climate extremes such as heatwaves and droughts. Do such episodes still favor alien plant species, or set them back? We used in situ measured phenotypic leaf and development trait responses of the six most widespread alien Asteraceae species from various native climates along Belgian urban‐to‐rural gradients, measured during two unusually warm and dry summers. Urbanization was characterized by three factors: the percentage of artificially sealed surfaces (urbanity, measured at three spatial scales from in situ to satellite‐based), the vegetation cover and the sky view factor (SVF, fraction of the hemisphere not blocked by buildings or vegetation). Across species, either from colder or warmer native climates, we found a predominant protective effect of shielded environments that block solar radiation (low SVF) along the entire urban‐to‐rural gradient. Such environments induced lower leaf anthocyanins and flavonols indices, indicating heat stress mitigation. Shielded environments also increased specific leaf area (SLA), a typical shade response. We found that vegetated areas had a secondary importance, increasing the chlorophyll content and decreasing the flavonols index, but these effects were not consistent across species. Finally, urbanity at the organism spatial scale decreased plant height, while broader‐scale urbanity had no significant influence. Our results suggest that sealed surfaces constrain alien Asteraceae during unusually warm and dry summers, while shielded environments protect them, possibly canceling out the lack of light. These findings shed new light on alien plant species success along urban‐to‐rural gradients in a changing climate.     

Small mammal responses to fire severity mediated by vegetation characteristics and species traits

The frequency of large, high‐severity “mega‐fires” has increased in recent decades, with numerous consequences for forest ecosystems. In particular, small mammal communities are vulnerable to post‐fire shifts in resource availability and play critical roles in forest ecosystems. Inconsistencies in previous observations of small mammal community responses to fire severity underscore the importance of examining mechanisms regulating the effects of fire severity on post‐fire recovery of small mammal communities. We compared small mammal abundance, diversity, and community structure among habitats that burned at different severities, and used vegetation characteristics and small mammal functional traits to predict community responses to fire severity three years after one mega‐fire in the Sierra Nevada, California. Using a model‐based fourth‐corner analysis, we examined how interactions between vegetation variables and small mammal traits associated with their resource use were associated with post‐fire small mammal community structure among fire severity categories. Small mammal abundance was similar across fire severity categories, but diversity decreased and community structure shifted as fire severity increased. Differences in small mammal communities were large only between unburned and high‐severity sites. Three highly correlated fire‐dependent vegetation variables affected by fire and the volume of soft coarse woody debris were associated with small mammal community structures. Furthermore, we found that interactions between vegetation variables and three small mammal traits (feeding guild, primary foraging mode, and primary nesting habit) predicted community structure across fire severity categories. We concluded that resource use was important in regulating small mammal recovery after the fire because vegetation provided required resources to small mammals as determined by their functional traits. Given the mechanistic nature of our analyses, these results may be applicable to other fire‐prone forest systems, although it will be important to conduct studies across large biogeographic regions and over long post‐fire time periods to assess generality.     

Camera‐trap data do not indicate scaling of diel activity and cathemerality with body mass in an East African mammal assemblage

Diel activity patterns of animal species reflect constraints imposed by morphological, physiological, and behavioral trade‐offs, but these trade‐offs are rarely quantified for multispecies assemblages. Based on a systematic year‐long camera‐trap study in the species‐rich mammal assemblage of Lake Manyara National Park (Tanzania), we estimated activity levels (hours active per day) and circadian rhythms of 17 herbivore and 11 faunivore species to determine the effects of body mass and trophic level on activity levels and cathemerality (the degree to which species are active throughout the day and night). Using generalized least squares and phylogenetic generalized least squares analyses, we found no support for the hypothesis that trophic level is positively associated with activity levels. We found no support for activity levels to scale positively with body mass in herbivores or to differ between ruminants and nonruminants; in faunivores, we also did not detect relationships between body mass and activity levels. Cathemerality was positively associated with activity levels but did not scale significantly with body mass. Overall, our findings caution against trophic level or body mass‐associated generalized conclusions with regard to diel activity patterns.     

The living heart: Climate gradients predict desert mountain endemism

Mountain regions are centers of biodiversity endemism at a global scale but the role of arid‐zone mountain ranges in shaping biodiversity patterns is poorly understood. Focusing on three guilds of taxa from a desert upland refugium in Australia, we sought to determine: (a) the relative extent to which climate, terrain or geological substrate predict endemism, and (b) whether patterns of endemism are complimentary across broad taxonomic guilds. We mapped regional endemism for plants, land snails, and vertebrates using combined Species Distribution Models (SDMs) for all endemic taxa (n = 82). We then modelled predictors of endemism using Generalised Additive Models (GAMs) and geology, terrain, and climate variables. We tested for the presence of inter‐ and intraguild hotspots of endemism. Many individual plant and land snail taxa were tightly linked with geology, corresponding to small distributions. Conversely, most vertebrate taxa were not constrained to specific geological substrates and occurred over larger areas. However, across all three guilds climate was the strongest predictor of regional endemism, particularly for plants wherein discrete hotspots of endemism were buffered from extreme summer temperatures. Land snail and vertebrate endemism peaked in areas with highest precipitation in the driest times of the year. Hotspots of endemism within each guild poorly predicted endemism in other guilds. We found an overarching signal that climatic gradients play a dominant role in the persistence of endemic taxa in an arid‐zone mountain range system. An association with higher rainfall and cooler temperatures indicates that continuing trends toward hotter and drier climates may lead to range contractions in this, and potentially other, arid‐zone mountain biotas. Contrasting patterns of endemism across guilds highlight the need to couple comprehensive regional planning for the protection of climate refugia, with targeted management of more localized and habitat specialist taxa.     

Both landscape and local factors influence plant and hexapod communities of industrial water‐abstraction sites

1. At the landscape level, intensification of agriculture, fragmentation, and destruction of natural habitats are major causes of biodiversity loss that can be mitigated at small spatial scales. However, the complex relationships between human activities, landscapes, and biodiversity are poorly known. Yet, this knowledge could help private stakeholders managing seminatural areas to play a positive role in biodiversity conservation.
2. We investigated how water‐abstraction sites could sustain species diversity in vascular‐plant communities and two taxonomic groups of insect communities in a fragmented agricultural landscape.
3. Landscape‐scale variables (connectivity indices and surrounding levels of herbicide use), as well as site‐specific variables (soil type for vascular plants, floral availability for Rhopalocera, and low herbaceous cover for Orthoptera), were correlated to structural and functional metrics of species community diversity for these taxonomic groups, measured on 35 industrial sites in the Ile‐de‐France region in 2018–2019.
4. Rhopalocera and Orthoptera consisted essentially of species with a high degree of dispersal and low specialization, able to reach the habitat patches of the fragmented landscape of the study area. Sandy soil harbored more diverse vascular‐plant communities. Plant diversity was correlated to a greater abundance of Rhopalocera and a lower richness of Orthoptera.
5. Increasing landscape connectivity was related to higher abundance of plants and Rhopalocera, and a higher evenness index for Orthoptera communities. Higher levels of herbicide use were related to a decrease in the biodiversity of plants and Rhopalocera abundance. High levels of herbicide favored high‐dispersal generalist plants, while high levels of connectivity favored low‐dispersal plants. Specialist Orthoptera species were associated with low herbaceous cover and connectivity.
6. Water‐abstraction sites are valuable seminatural habitats for biodiversity. Changing intensive agricultural practices in surrounding areas would better contribute to conserving and restoring biodiversity on these sites.

     

Identifying mismatches between conservation area networks and vulnerable populations using spatial randomization

Grassland birds are among the most globally threatened bird groups due to substantial degradation of native grassland habitats. However, the current network of grassland conservation areas may not be adequate for halting population declines and biodiversity loss. Here, we evaluate a network of grassland conservation areas within Wisconsin, U.S.A., that includes both large Focal Landscapes and smaller targeted conservation areas (e.g., Grassland Bird Conservation Areas, GBCAs) established within them. To date, this conservation network has lacked baseline information to assess whether the current placement of these conservation areas aligns with population hot spots of grassland‐dependent taxa. To do so, we fitted data from thousands of avian point‐count surveys collected by citizen scientists as part of Wisconsin''s Breeding Bird Atlas II with multinomial N‐mixture models to estimate habitat–abundance relationships, develop spatially explicit predictions of abundance, and establish ecological baselines within priority conservation areas for a suite of obligate grassland songbirds. Next, we developed spatial randomization tests to evaluate the placement of this conservation network relative to randomly placed conservation networks. Overall, less than 20% of species statewide populations were found within the current grassland conservation network. Spatial tests demonstrated a high representation of this bird assemblage within the entire conservation network, but with a bias toward birds associated with moderately tallgrasses relative to those associated with shortgrasses or tallgrasses. We also found that GBCAs had higher representation at Focal Landscape rather than statewide scales. Here, we demonstrated how combining citizen science data with hierarchical modeling is a powerful tool for estimating ecological baselines and conducting large‐scale evaluations of an existing conservation network for multiple grassland birds. Our flexible spatial randomization approach offers the potential to be applied to other protected area networks and serves as a complementary tool for conservation planning efforts globally.     

Molecular approaches reveal weak sibship aggregation and a high dispersal propensity in a non‐native fish parasite

Inferring parameters related to the aggregation pattern of parasites and to their dispersal propensity are important for predicting their ecological consequences and evolutionary potential. Nonetheless, it is notoriously difficult to infer these parameters from wildlife parasites given the difficulty in tracking these organisms. Molecular‐based inferences constitute a promising approach that has yet rarely been applied in the wild. Here, we combined several population genetic analyses including sibship reconstruction to document the genetic structure, patterns of sibship aggregation, and the dispersal dynamics of a non‐native parasite of fish, the freshwater copepod ectoparasite Tracheliastes polycolpus. We collected parasites according to a hierarchical sampling design, with the sampling of all parasites from all host individuals captured in eight sites spread along an upstream–downstream river gradient. Individual multilocus genotypes were obtained from 14 microsatellite markers, and used to assign parasites to full‐sib families and to investigate the genetic structure of T. polycolpus among both hosts and sampling sites. The distribution of full‐sibs obtained among the sampling sites was used to estimate individual dispersal distances within families. Our results showed that T. polycolpus sibs tend to be aggregated within sites but not within host individuals. We detected important upstream‐to‐downstream dispersal events of T. polycolpus between sites (modal distance: 25.4 km; 95% CI [22.9, 27.7]), becoming scarcer as the geographic distance from their family core location increases. Such a dispersal pattern likely contributes to the strong isolation‐by‐distance observed at the river scale. We also detected some downstream‐to‐upstream dispersal events (modal distance: 2.6 km; 95% CI [2.2–23.3]) that likely result from movements of infected hosts. Within each site, the dispersal of free‐living infective larvae among hosts likely contributes to increasing genetic diversity on hosts, possibly fostering the evolutionary potential of T. polycolpus.     

Increases in subsistence farming due to land reform have negligible impact on bird communities in Zimbabwe

Habitat alterations resulting from land‐use change are major drivers of global biodiversity losses. In Africa, these threats are especially severe. For instance, demand to convert land into agricultural uses is leading to increasing areas of drylands in southern and central Africa being transformed for agriculture. In Zimbabwe, a land reform programme provided an opportunity to study the biodiversity response to abrupt habitat modification in part of a 91,000 ha dryland area of semi‐natural savannah used since 1930 for low‐level cattle ranching. Small‐scale subsistence farms were created during 2001–2002 in 65,000 ha of this area, with ranching continuing in the remaining unchanged area. We measured the compositions of bird communities in farmed and ranched land over 8 years, commencing one decade after subsistence farms were established. Over the study period, repeated counts were made along the same 45 transects to assess species'' population changes that may have resulted from trait‐filtering responses to habitat disturbance. In 2012, avian species'' richness was substantially higher (+8.8%) in the farmland bird community than in the unmodified ranched area. Temporal trends over the study period showed increased species'' richness in the ranched area (+12.3%) and farmland (+6.8%). There were increased abundances in birds of most sizes, and in all feeding guilds. New species did not add new functional traits, and no species with distinctive traits were lost in either area. As a result, species'' diversity reduced, and functional redundancy increased by 6.8% in ranched land. By 2020, two decades after part of the ranched savannah was converted into farmland, the compositions of the two bird communities had both changed and became more similar. The broadly benign impact on birds of land conversion into subsistence farms is attributed to the relatively low level of agricultural activity in the farmland and the large regional pool of nonspecialist bird species.