Biology subjects

Haines, G. E.

Publications and source records attributed to Haines, G. E..

6 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↗

bioRxiv2022

Armor reduction and pelvic girdle loss in a population of threespine stickleback (Gasterosteus aculeatus) from western Newfoundland, Canada.

We describe the antipredator armor of a unique population of threespine stickleback (Gasterosteus aculeatus) from Narrows Pond in western Newfoundland and compare traits for this population to nearby populations from marine and freshwater systems. After standardizing for length, Narrows Pond stickleback are shallower bodied and have shorter dorsal spines than stickleback from the other populations. Also, though the number of armor plates for Narrows Pond stickleback is greater than for typical low-plate morphs, the size of the lateral plates for Narrows Pond stickleback is much smaller. Finally, most (nearly 75% of sampled individuals) Narrows Pond stickleback do not have a pelvic structure (bilateral pelvic plate, ascending process, and ventral spine) and the remaining individuals have greatly reduced pelvic girdle whereas all individuals from the other populations possessed complete pelvic structures.

evolutionary biology↗

bioRxiv2022

Variation in morphology among populations of threespine stickleback (Gasterosteus aculeatus) from western Newfoundland, Canada.

Freshwater populations of threespine stickleback (Gasterosteus aculeatus) have diverged from their marine ancestor and show extensive variation among populations throughout most of their range. However, phenotypes of freshwater populations from the east coast of North America does not appear to demonstrate extensive variability observed throughout the rest of the species range. The relative young age of east coast North American populations may explain the apparent lack of freshwater variability. On the other hand, populations in this part of the species range have not received the level of attention as have populations throughout the rest of its range and the low level of variability observed may simply reflect lack of data for this region. We examined morphological traits (including linear measurements of body armor and body shape) of stickleback from 52 locations representing marine and freshwater populations along the west coast of Newfoundland, Canada. We found that variability in morphological traits among freshwater populations was much more extensive than previously assumed and similar to patterns observed throughout the rest of the species range.

evolutionary biology↗

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↗

bioRxiv2021

The pace of modern life, revisited

Wild populations must continuously adapt to environmental changes or they risk extinction. Such adaptations can be measured as phenotypic rates of change and can allow us to predict patterns of contemporary evolutionary change. About two decades ago, a dataset of phenotypic rates of change in wild populations was compiled. Since then, researchers have used (and expanded) this dataset to look at microevolutionary processes in relation to specific types of human disturbances. Here, we have updated the dataset adding 5675 estimates of phenotypic changes and used it to revisit established patterns of contemporary evolutionary change. Using this newer version, containing 7338 estimates of phenotypic changes, we revisit the conclusions of four published articles. We then synthesize the expanded dataset to compare rates of change across different types of human disturbance. Analyses of this expanded dataset suggests that: I. a small absolute difference in rates of change exists between human disturbed and natural populations, II. harvesting by humans results in larger rates of change than other types of disturbances, III. introduced populations have increased rates of change, and IV. body size does not increase through time. Overall, findings from earlier analyses have largely held-up in analyses of our new dataset that encompass a much larger breadth of species, traits, and human disturbances. Lastly, we found that types of human disturbances affect rates of phenotypic change, and we call for this database to serve as a steppingstone for further analyses to understand patterns of contemporary evolution.

evolutionary biology↗