Biology subjects

Janecka, M. J.

Publications and source records attributed to Janecka, M. J..

3 recordsLinked to original sources

bioRxiv2025

Interplay between purging and admixture shapes genetic load in an invasive guppy population

Demographic history can shape the genetic load of populations by influencing the efficacy of selection, levels of heterozygosity, and the incorporation of new variants via gene flow. Understanding these dynamics is crucial for identifying threats to population viability and predicting evolutionary trajectories of invasive populations translocated by humans into non-native environments. We investigate these processes in Trinidadian guppies (Poecilia reticulata) by estimating genetic loads across multiple populations, with a particular focus on a single expanding population in which translocated individuals have rapidly spread and replaced native individuals. Overall, we observe the expected negative relationship between neutral genetic diversity and relative genetic load. In the translocated population, patterns differ between strongly and weakly deleterious mutations. Strongly deleterious alleles are purged at the isolated translocation site but tend to accumulate along the expansion front. In contrast, the genetic load estimated based on weakly deleterious variants declines along the expansion gradient. These differing patterns can be explained by admixture with native populations (which carried fewer weakly deleterious mutations) reducing the overall genetic load of the population at the expansion front. However, admixture has also increased genetic diversity and introduced new strongly deleterious alleles, thereby reversing the purging effect. Together, our findings illustrate the complex interactions determining genetic load in subdivided populations, offering important insights into the evolutionary aspects of biological invasions.

evolutionary biology↗

bioRxiv2022

Parasite gene flow in riverine habitats: ascertaining the roles of stream drift, river bifurcations and host dispersal.

Determining the factors that shape parasite gene flow across complex landscapes is central to understanding the coevolutionary process. In rivers, unidirectional currents, stream drift, may facilitate downstream parasite dispersal, while bifurcating branches may cause population subdivision among branches. The generative habitat processes in rivers can potentially interact with host dispersal to determine gene flow within the aquatic ecosystem. We examined the population genetic structure and gene flow of a trematode infecting semi-aquatic snakes to determine the relative contributions of stream drift, river bifurcations and host dispersal in shaping parasite gene flow in three connected riverine ecosystems. We found the strongest population structure immediately below a recently constructed reservoir at the confluence of the two rivers, with mild structure between one out the the three reaches of the river. Patterns of isolation by distance along linear pathways were not uniform, despite similar path network path lengths. We found the strongest evidence for isolation by distance associated with the river bifurcation. The comparison of terrestrial versus within river network dispersal indicates that parasite transmission between branches occurs along river networks. Short-distance terrestrial dispersal however may be important along some linear networks. Our results highlight the complexity of host-habitat interactions shaping parasite gene flow and the need for empirical data from natural systems to develop accurate models of parasite transmission in rivers.

ecology↗

bioRxiv2021

Social hosts evade predation but have deadlier parasites

Parasites exploit hosts to replicate and transmit, but overexploitation kills host and parasite (1): predators may shift this cost-benefit balance by consuming hosts (2-4) or changing host behavior, but the strength of these effects remains unclear. Modeling both, we find a primary, strong effect: hosts group to defend against predators (5), increasing parasite transmission, thus multiple infections, and therefore favoring more exploitative, virulent, parasites (6). Indeed, among 18 Trinidadian Gyrodactyus spp. parasite lines, those collected from high predation guppy populations were more virulent in common garden than those from low predation populations. Our model accurately predicted this result when parametrized with our experimentally demonstrated virulence-transmission trade-off, implicating the behavioral effects of predation. Broadly, our results indicate that reduced social contact selects against parasite virulence. One-Sentence SummaryOur theory and data show predators cause increased host social grouping; the resulting transmission favors parasite virulence.

ecology↗