Biology subjects

Castillo, G.

Publications and source records attributed to Castillo, G..

4 recordsLinked to original sources

bioRxiv2026

Testing Thirty Years of Hypotheses: Ancient Trout-Salmon Introgression and Limited Pre-Colonial Gene Flow Between Rainbow and Cutthroat Trout Shaped Pacific Salmonid Evolution

Introgression is the transfer of genetic material between species or populations through hybridization and backcrossing. While often deleterious or neutral in nature, introgression can also have beneficial consequences for the recipient lineage. Oncorhynchus is a genus of ray-finned fish (family Salmonidae) composed of nine species of Pacific trout and eight species of Pacific salmon, in which deep introgression has long been proposed to explain patterns of gene-tree-species-tree discordance, and in which hybridization is extensively observed between introduced and endemic species. In this study, we identified well-supported introgression between the ancestral lineage of Pacific trout and the ancestor of Chinook and coho salmon, a long-posited but previously untested hypothesis. While other salmon lineages (pink, chum, sockeye, and masu salmon) have been sympatric with trout for extended periods, providing an opportunity for hybridization to occur, we found no evidence of introgression between trout and these other salmon lineages. Our findings suggest mito-nuclear incompatibilities serve as a possible barrier to gene flow between the clade comprised of pink, chum, and sockeye salmon and all other lineages in Oncorhynchus. Within Pacific trout, we detected no historical introgression between cutthroat and rainbow trout lineages, suggesting that the extensive hybridization observed between them today reflects recent, primarily human-mediated contact rather than long-term gene flow. These findings show that ancestral introgression has shaped the evolutionary history of Oncorhynchus and should be accounted for in future comparative phylogenetic studies of the genus.

evolutionary biology↗

bioRxiv2026

Sex in the City: Reproductive Behaviors of Dragonflies across an Urban Landscape

Anthropogenic cityscapes provide complex habitats that influence animal communication and movement patterns, which are generally understudied in aquatic and semi-aquatic organisms. Community science, referring to public participation in scientific research, is an important tool for recording occurrence records and behavioral observations of understudied urban species. Boise, Idaho (USA), one of the fastest-growing cities in North America, has a long-established community science program for documenting occurrences of the semi-aquatic insect order Odonata (dragonflies and damselflies), making the city an ideal study system for comparing behavioral observations from community science with observations recorded using AI driven iNaturalist. In this study, we test the accuracy of iNaturalist observations and volunteer surveys to characterize dragonfly reproductive behaviors (tandem flight and tandem perching, oviposition, and mating) in the city, and use these observations to determine which dragonflies are using the urban landscape as reproductive habitat. The total numbers of species observations by volunteers and on iNaturalist in Boise were strongly correlated, while reproductive observations showed a strong observational threshold, as reproductive behaviors were rarely identified in less-observed species. iNaturalist tended to underrepresent total occurrences of ''flyer'' species, which rarely perch, while volunteer surveys underrepresented occurrences and reproductive behaviors of a more cyclical species that did not appear to be abundant in the field season in which this study was conducted. Our findings suggest that Boise provides suitable breeding habitat for both migratory and resident dragonflies. Species distribution models of three migratory and three putatively migratory species further demonstrate that these species would be expected in southwestern Idaho regardless of the presence of a city, and have persisted through urban development. This research demonstrates the value of community science in conducting basic research on understudied urban-dwelling species, although findings must be considered alongside potential biases.

ecology↗

bioRxiv2024

The Blueprint for Survival: The Blue Dasher Dragonfly as a Model for Urban Adaptation

Human alteration of natural environments and habitats is a major driver of species decline. However, a handful of species thrive in human altered environments. The biology, distribution, population structure, and molecular adaptations enabling certain species to thrive in human-altered habitats are not well understood. Here, we evaluate the population and functional genomics, ecological niche and distributions, and geometric morphometrics of the blue dasher (Pachydiplax longipennis), one of the most ubiquitously observed insects in human altered habitats. Using resequencing data we identify a number of genes involved with the success of the blue dasher in human altered habitats, including loci contributing to immune function and response to oxidative stress. Some genes related to these functions are found in regions of strong population structure, while others are not, potentially indicating both regional and widespread adaptations to urban environments within this species. Using one of the most robust locality datasets for any species to date, we also generate habitat suitability predictions which show that P. longipennis has spread with urbanization, suggesting humans have created suitable habitat for this species. These results complement morphological and genomic data showing P. longipennis (particularly East of the Rocky Mountains) has the capacity to rapidly disperse to newly suitable habitats. Given the shared barriers to colonizing an urban habitat, we expect that many of the adaptations we have identified in P. longipennis can be used for predicting what animals might succeed in urban habitats more generally.

evolutionary biology↗

bioRxiv2024

Environmental DNA vs. Community Science: Strengths and Limitations for Urban Odonata Surveys

The study of insect decline remains a major frontier in insect biodiversity and conservation. Despite growing concern about accelerating rates of insect decline generally, relatively little data has been compiled about species of aquatic insects. Data is particularly lacking on the distribution of aquatic insects in urban ecosystems. Here, we compare environmental DNA (eDNA) metabarcoding and community science observation as means of monitoring Odonata within an urban system in Southwest Idaho. We show that the distribution of Odonata across this urban landscape is not uniform and that both monitoring methods have different strengths and weaknesses. We found that eDNA metabarcoding was very sensitive to the identification of genera from underrepresented families in the region, but was unable to distinguish between closely related genera, particularly from localities where eDNA could accumulate more damage. On the other hand, community science observations effectively identified the presence of genera from more speciose families but missed the presence of relatively rare species, and those that had a short flight season. These findings suggest that, in our study system, eDNA and community science are highly complementary of each other. In cases where only one method is employed for a monitoring or conservation project, care should be given to account for the biases of each approach.

ecology↗