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Abstract Identifying the specific environmental features and associated density‐dependent processes that limit population growth is central to both ecology and conservation. Comparative assessments of sympatric species allow for inference about how ecologically similar species differentially respond to their shared environment, which can be used to inform community‐level conservation strategies. Comparative assessments can nevertheless be complicated by interactions and feedback loops among the species in question. We developed an integrated population model based on 61 years of ecological data describing the demographic histories of Canvasbacks (Aythya valisineria) and Redheads (Aythya americana), two species of migratory diving ducks that utilize similar breeding habitats and affect each other's demography through interspecific nest parasitism. We combined this model with a transient life table response experiment to determine the extent that demographic rates, and their contributions to population growth, were similar between these two species. We found that demographic rates and, to a lesser extent, their contributions to population growth covaried between Canvasbacks and Redheads, but the trajectories of population abundances widely diverged between the two species during the end of the twentieth century due to inherent differences between the species life histories and sensitivities to both environmental variation and harvest pressure. We found that annual survival of both species increased during years of restrictive harvest regulations; however, recent harvest pressure on female Canvasbacks may be contributing to population declines. Despite periodic, and often dramatic, increases in breeding abundance during wet years, the number of breeding Canvasbacks declined by 13% whereas the number of breeding Redheads has increased by 37% since 1961. Reductions in harvest pressure and improvements in submerged aquatic vegetation throughout the wintering grounds have mediated the extent to which populations of both species contracted during dry years in the Prairie Pothole Region. However, continued degradation of breeding habitats through climate‐related shifts in wetland hydrology and agricultural conversion of surrounding grassland habitats may have exceeded the capacity for demographic compensation during the nonbreeding season. 

Model systems play a crucial role in biological and biomedical research, especially in the search for new treatments for challenging diseases such as glioblastoma multiforme (GBM). Organoids are 3D in vitro multicellular “middle-ground” model systems that recapitulate highly organized and heterogeneous in vivo organ-like systems, often through stem cell differentiation. Incorporating Matrigel™ or other exogenous extracellular matrices (ECMs) that do not naturally occur in the human body is common practice for organoid generation, ignoring the role of dynamic reciprocity between the cells and the ECM in tissue development. In this study, we describe a method to develop GBM organoids (GBOs) from cells without the need for exogenous ECM encapsulation and without cell culture media changes to produce stable tissue-like organoids that reach a 4 mm diameter in as little as 6 weeks. We observed a transition from homogenous cell populations to tissue-like structures when GBOs were larger than 1 mm in diameter. Transcriptomic analysis revealed that the greatest gene expression changes occurred when GBOs were 2 mm in diameter, with collagen VI as the most upregulated ECM-related gene. Quantitative and histochemical assessments further supported native ECM synthesis with significantly higher levels of glycosaminoglycans and collagen in GBOs compared with spheroids. To our knowledge, this study presents the first reproducibly large GBOs with natively produced ECMs. Organoids with natively synthesized ECMs promise to eliminate artifacts and variability from aged, homogeneic, or xenogeneic scaffolds and to provide insights for ECM-targeted drug development. 

Abstract The estimation of demographic parameters is a key component of evolutionary demography and conservation biology. Capture–mark–recapture methods have served as a fundamental tool for estimating demographic parameters. The accurate estimation of demographic parameters in capture–mark–recapture studies depends on accurate modeling of the observation process. Classic capture–mark–recapture models typically model the observation process as a Bernoulli or categorical trial with detection probability conditional on a marked individual's availability for detection (e.g., alive, or alive and present in a study area). Alternatives to this approach are underused, but may have great utility in capture–recapture studies. In this paper, we explore a simple concept:in the same way that counts contain more information about abundance than simple detection/non‐detection data, the number of encounters of individuals during observation occasions contains more information about the observation process than detection/non‐detection data for individuals during the same occasion. Rather than using Bernoulli or categorical distributions to estimate detection probability, we demonstrate the application of zero‐inflated Poisson and gamma‐Poisson distributions. The use of count distributions allows for inference on availability for encounter, as well as a wide variety of parameterizations for heterogeneity in the observation process. We demonstrate that this approach can accurately recover demographic and observation parameters in the presence of individual heterogeneity in detection probability and discuss some potential future extensions of this method.