Null model analysis of species co-occurrence patterns has long been used to gain insight into community assembly but is often limited to identifying non-random patterns without providing clarity about underlying ecological mechanisms. This challenge is especially apparent when sampling units are spread across a heterogeneous landscape or along an environmental gradient because multiple mechanisms can produce similar co-occurrence patterns. We developed a trait-based approach for discriminating between environmental filtering and biotic interactions as the probable...

Understanding the forces that shape the distribution of biodiversity across spatial scales is central in ecology and critical to effective conservation. To assess effects of possible richness drivers, we sampled ant communities on four elevational transects across two mountain ranges in Colorado, USA, with seven or eight sites on each transect and twenty repeatedly sampled pitfall trap pairs at each site each for a total of 90 days. With a multi-scale hierarchical Bayesian community occupancy...

Biodiversity loss, an important consequence of agricultural intensification, can lead to reductions in agroecosystem functions and services. Increasing crop diversity through rotation may alleviate these negative consequences by restoring positive aboveground–belowground interactions. Positive impacts of aboveground biodiversity on belowground communities and processes have primarily been observed in natural systems. Here, we test for the effects of increased diversity in an agroecosystem, where plant diversity is increased over time through crop rotation. As crop diversity increased...

Stress is a well-known cause of reproductive dysfunction in many species, including birds, rodents, and humans, though males and females may respond differently. A powerful way to investigate how stress affects re- production is by examining its effects on a biological system essential for regulating reproduction, the hy- pothalamic-pituitary-gonadal (HPG) axis. Often this is done by observing how a stressor affects the amount of glucocorticoids, such as cortisol or corticosterone, circulating in the blood and...

1. Context. Precipitation regimes are changing in response to climate change, yet understanding of how forest ecosystems respond to extreme droughts and pluvials remains incomplete. As future precipitation extremes will likely fall outside the range of historical variability, precipitation manipulation experiments (PMEs) are critical to advancing knowledge about potential ecosystem responses. However, few PMEs have been conducted in forests compared to short-statured ecosystems, and forest PMEs have unique design requirements and constraints. Moreover, past forest...

1) Understanding if and how trees coordinate rooting depth and aboveground hydraulic traits to define drought-resistance strategies in seasonal Amazon forests is a major gap to model parametrization aimed at predicting the effects of climate change in these ecosystems. 2) We assessed the rooting depth of 12 dominant tree species (representing ~ 42% of the forest basal area) in a seasonal Amazon forest, using the stable isotope ratios (δ18O and δ²H) of water collected from...

Natural hybrid zones can be used to dissect the mechanisms driving key evolutionary processes by allowing us to identify genomic regions important for establishing reproductive isolation and that allow for transfer of adaptive variation. We leverage whole-genome data in a system where two bird species, the saltmarsh (Ammospiza caudacutus) and Nelson’s (A. nelsoni) sparrow, hybridize despite their relatively high background genetic differentiation and past ecological divergence. Adaptive introgression is plausible in this system because Nelson’s...

The biology of the extant American horseshoe crab, Limulus polyphemus, is well documented—including its dietary habits, particularly the ability to crush shell with its gnathobasic walking appendages—but virtually nothing is known about the feeding biomechanics of this iconic arthropod. This species is also considered the archetypal functional analogue for a range of extinct groups that have gnathobasic appendages, including eurypterids, trilobites, and some of the earliest arthropods, especially Sidneyia inexpectans from the middle Cambrian (508...

Comprehensive understanding of the patterns and drivers of microbial diversity at a landscape scale is in its infancy, despite the recent ease by which soil communities can be characterized using massively parallel amplicon sequencing. Here we report on a comprehensive analysis of the drivers of diversity distribution and composition of the ecologically and economically important Phytophthora genus from 414 soil samples collected across Australia. We assessed 22 environmental and seven categorical variables as potential predictors...

1. Many plant species experience large differences in soil moisture availability within a season, potentially leading to a wide range of leaf water potentials (ΨLEAF). In order to decrease the risk of leaf dehydration, among species, there is a continuum ranging from strict control (isohydry) to little control (anisohydry) of minimum ΨLEAF. 2. In central Texas USA, species are exposed to a range of soil moisture from wet springs to hot, dry summers. There are...

Twenty years ago, Kokko & Lindstrom (1996) introduced the hypothesis that kin selection may drive the evolution of leks, shifting the lek-paradigm away from a competitive framework and spurring research on the relatedness of males on leks. However, support for Kokko & Lindstrom’s kin selection hypothesis has been sparse; most studies have shown related males to occur on leks no more than expected by chance. Additionally, evidence supporting the proposed mechanism is mixed; by joining...

Estimating abundance is an essential component of monitoring and recovery of rare species and spatially explicit capture-recapture (SECR) models provide the means for robust density estimation. Previous work has elucidated principles of SECR study design for large, generalist carnivores, but less attention has been paid to study design considerations for smaller species, with less extensive home ranges. Here we integrated data from an intensive pilot study with simulation modeling to evaluate the influence of survey...

If individuals can perceive and manage risks, they may alter their behaviors based on prior experience. This expectation may apply to nest site selection of breeding birds, for which adaptive behavioral responses may enhance fitness. Birds that nest in tidal marshes have adapted to the challenges posed primarily by periodic, monthly tidal flooding and secondarily, by predation. We investigated adaptive responses in nesting behavior of the saltmarsh sparrow (Ammodramus caudacutus), an obligate tidal-marsh-breeding bird, using...

The mechanisms that determine patterns of species dispersal are important factors in the production and maintenance of biodiversity. Understanding these mechanisms helps to forecast the responses of species to environmental change. Here we used a comparative framework and genome-wide data obtained through RAD-seq to compare the patterns of connectivity among breeding colonies for five penguin species with shared ancestry, overlapping distributions, and differing ecological niches, allowing an examination of the intrinsic and extrinsic barriers governing...