Biology subjects

Derry, A. M.

Publications and source records attributed to Derry, A. M..

7 recordsLinked to original sources

bioRxiv2026

Intrinsic fitness differences outweigh environmental matching in shaping introduction outcomes in nature

Species introductions and transplants offer powerful contexts to understand evolutionary patterns and processes, and they are increasingly critical for conservation. However, introduction success varies widely, and predicting outcomes remains challenging. Introducing multiple source populations should increase the chance of success, while also providing an opportunity to explore the factors that predict success of individual source populations in the same environment. We used replicated, mixed-population introductions of >12,000 threespine stickleback (Gasterosteus aculeatus) to test whether source population success could be predicted by environmental matching between source and recipient environments and/or by intrinsic source population characteristics. We introduced four to eight source populations of stickleback into each of nine natural lakes and tracked their relative success over the following two years (up to two generations). Source population success was largely consistent across lakes, despite divergent environmental conditions. These results point to the importance of intrinsic source population characteristics rather than environmental matching in predicting introduction success in natural settings. Source populations that were consistently successful tended to have greater stress tolerance (mortality rate during translocation) and higher genetic diversity, though these relationships were not conclusive. Our study highlights the value of considering factors that generate fitness differences independent of environmental contexts in predicting ecological and evolutionary dynamics and planning conservation programs. Significance StatementPredicting which populations will succeed when introduced to new environments is a central challenge in ecology, evolution, and conservation. Environmental conditions are often assumed to be crucial in determining which populations succeed, given the expectation that populations preadapted to local conditions should perform best. We test this assumption by introducing >12,000 threespine stickleback fish from up to eight source populations into nine natural lakes spanning diverse environmental conditions. We show that the relative success of individual source populations was remarkably consistent across lakes and environmental conditions, indicating that some populations are intrinsically better suited to introductions. Our findings underscore the importance of considering intrinsic population characteristics alongside environmental conditions when predicting ecological and evolutionary outcomes and guiding conservation efforts.

evolutionary biology↗

bioRxiv2025

Lake size shapes the relationship between body mass and gut microbiota in threespine stickleback (Gasterosteus aculeatus)

Host-microbe interactions are shaped by both host and environmental factors. However, little is known about how host-microbe interactions vary across populations within a species. Here, we characterized the gut microbiota of 191 wild threespine stickleback fish (Gasterosteus aculeatus) from six populations from Alaskan lakes spanning a gradient of surface area. We tested how environmental context (lake size and ecotype) and host traits (sex, body mass, gravidity, Schistocephalus solidus (S. solidus) infection, and fibrosis) influence stickleback gut microbial composition using 16S rRNA gene sequencing. We found that the lake surface area strongly predicted fish gut microbial alpha diversity. Fish from intermediate-sized lakes harbored significantly more diverse microbiota than those from small and large lakes, independent of ecotype. Body mass was associated with gut microbial diversity. Model-predicted marginal effects from the mass and lake surface area interaction analysis showed that the association between fish mass and microbial alpha diversity was strongly negative in the smallest lakes, weakest in intermediate-sized lakes, and strongly positive in the largest lakes. In addition, sex and S. solidus infection were significantly associated with gut microbiota alpha and beta diversity, whereas fibrosis and gravidity showed minimal effects. Differential abundance analysis revealed lake size-dependent associations between body mass and individual taxa. Together, these results demonstrate that both habitat context and host variation interactively shape stickleback gut microbial communities in the wild. Integrating lake-level and individual-level analyses reveals how ecological setting modulates host-microbe associations, offering insights into the role of the gut microbiota in host adaptation and population divergence.

microbiology↗

bioRxiv2025

Evolutionary rescue and adaptive reversal allowed the persistence of freshwater copepods during historical lake acidification and pH recovery

The persistence of populations facing severe environmental disturbance can be enabled by natural selection on heritable phenotypic variation - a process known as evolutionary rescue. Few studies have documented this process in complex natural settings and the long-term outcome of evolutionary rescue. Here, we used copepod resting eggs of Leptodiaptomus minutus from three time periods of lake ecological history, spanning {approx} 200 generations (100 years) in two populations impacted by historical acidification. Whole genome sequencing of the resting eggs revealed significant allele frequency shifts associated with the acidification followed by pH recovery. We used a resurrection ecology approach to retrace adaptive shifts concomitant with environmental transitions. Copepods from the pre-acidification period showed sensitivity to acidity, while individuals from the acidification period were adapted to acidic pH. This tolerance was subsequently lost during pH recovery, implying an adaptive reversal. Demographic models indicated a decline during the acidification process followed by population recovery based on historical data, suggesting that selection led to evolutionary rescue. This study fills a critical knowledge gap about the long-term implications of evolutionary rescue in the wild.

evolutionary biology↗

bioRxiv2024

eDNA provides accurate and precise estimates of abundance by integrating bioenergetics and particle mass-balance

Anthropogenic activities have led to an unprecedented crisis in freshwater biodiversity loss. The capacity to monitor the abundance of wild populations is critical to conserving biodiversity, but conventional physical specimen collection methods are invasive, costly, and labour-intensive. Environmental DNA (eDNA) offers a promising alternative, being easy to sample, with studies under controlled laboratory conditions showing consistent correlations between eDNA concentration and abundance. However, applying eDNA to monitor abundance remains contentious, as eDNA particle dynamics and the ecology of eDNA production can decouple this relationship in natural ecosystems. To address this, we provide a novel modeling method to produce population estimates from eDNA. We integrated bioenergetics and mass-balance frameworks to relate eDNA concentrations to freshwater fish population abundance estimated through conventional mark-recapture in Brook Trout (Salvelinus fontinalis) across nine Rocky Mountains lakes, five of which underwent size-selective harvesting over two years. Our integrated framework improved the variance explained in eDNA concentrations from 24% to 71%. The integrated model accurately distinguished most (94%) abundance estimates across populations and sampling periods, detecting both natural and harvest-induced reductions in abundance within several populations. This study is the first to empirically integrate the DNA production mechanism and particle dynamics and provide a new methodological approach enabling rapid and accurate abundance quantification. We also discuss how this new tool can be integrated in existing monitoring programs.

ecology↗

bioRxiv2022

Environmental determinants of invasion hotspots and refugia at a river scale: implications for conservation of native biodiversity

Introductions of exotic invasive species are a global disturbance for natural habitats. The severity of invasions can greatly vary from local to global scales, as observed in invasion refuges, exhibiting lower-than-expected invasion intensity. In this study, we analyzed the effects of water conductivity and wetland presence on the density of the round goby (Neogobius melanostomus) in a large-scale study (> 1300 sites), spanning a 400 km stretch of the St. Lawrence River (Canada). Our results showed that round goby density was null in sites with water conductivity under 100 {micro}S/cm and increased toward a probable biological optimum at 300 {micro}S/cm. The presence of wetlands appeared to also decrease round goby density along the conductivity continuum. Similarly, fish community diversity was maximal outside of the round goby water conductivity optimum. Hence, low water conductivity (<100 {micro}S/cm), in interaction with the presence of wetlands, can provide a refuge for native aquatic species, establishing a simple risk assessment tool for managers. Our results also highlighted the high value of wetland conservation for conservation of native species biodiversity.

ecology↗

bioRxiv2021

Dimensionality and modularity of adaptive variation: Divergence in threespine stickleback from diverse environments

In nature, populations are subjected to a wide variety of environmental conditions that affect fitness and induce adaptive or plastic responses in traits, resulting in phenotypic divergence between populations. The dimensionality of that divergence, however, remains contentious. At the extremes, some contend that populations diverge along a single axis of trait covariance with greatest availability of heritable variation, even if this does not lead a population directly to its fitness optimum. Those at the other extreme argue that selection can push populations towards their fitness optima along multiple phenotype axes simultaneously, resulting in divergence in numerous dimensions. Here, we address this debate using populations of threespine stickleback (Gasterosteus aculeatus) in the Cook Inlet region of southern Alaska from lakes with contrasting ecological conditions. We calculated effective dimensionality of divergence in several trait suites (defensive, swimming, and trophic) thought to be under correlated selection pressures, as well as across all traits. We also tested for integration among the trait suites and between each trait suite and the environment. We found that populations in the Cook Inlet radiation exhibit dimensionality of phenotype high enough to preclude a single axis of divergence.

evolutionary biology↗

bioRxiv2020

Allometric scaling strengthens the relationship between eDNA particle concentration and organism abundance in nature

Organism abundance is a critical parameter in ecology, but its estimation is often challenging. Approaches utilizing eDNA to indirectly estimate abundance have recently generated substantial interest. However, preliminary correlations observed between eDNA concentration and abundance in nature are typically moderate in strength with significant unexplained variation. Here we apply a novel approach to integrate allometric scaling coefficients into models of eDNA concentration and organism abundance. We hypothesize that eDNA particle production scales non-linearly with mass, with scaling coefficients < 1. Wild populations often exhibit substantial variation in individual body size distributions; we therefore predict that the distribution of mass across individuals within a population will influence population-level eDNA production rates. To test our hypothesis, we collected standardized body size distribution and mark-recapture abundance data using whole-lake experiments involving nine populations of brook trout. We correlated eDNA concentration with three metrics of abundance: density (individuals/ha), biomass (kg/ha), and allometrically scaled mass (ASM) ({sum}(individual mass0.73)/ha). Density and biomass were both significantly positively correlated with eDNA concentration (adj. R2 = 0.59 and 0.63, respectively), but ASM exhibited improved model fit (adj. R2 = 0.78). We also demonstrate how estimates of ASM derived from eDNA samples in unknown systems can be converted to biomass or density estimates with additional size structure data. Future experiments should empirically validate allometric scaling coefficients for eDNA production, particularly where substantial intraspecific size distribution variation exists. Incorporating allometric scaling may improve predictive models to the extent that eDNA concentration may become a reliable indicator of abundance in nature.

ecology↗