Gender gaps were observed in multiple categories of student participation in an active-learning biology course. Despite similar performance on in-class assessments, student surveys suggest that men and women experience the classroom differently. The results suggest that active learning is not a panacea for equitable participation in science, technology, engineering, and mathematics courses.

Natural hybridization events provide unique windows into the barriers that keep species apart as well as the consequences of their breakdown. Here, we characterize hybrid populations formed between the northern swordtail fish Xiphophorus cortezi and Xiphophorus birchmanni from collection sites on two rivers. We use simulations and new genetic reference panels to develop sensitive and accurate local ancestry calling in this novel system. Strikingly, we find that hybrid populations on both rivers consist of two genetically distinct subpopulations: a cluster of pure X. birchmanni individuals and one of phenotypically intermediate hybrids that derive ∼85–90% of their genome from X. cortezi. Simulations suggest that initial hybridization occurred ∼150 generations ago at both sites, with little evidence for contemporary gene flow between subpopulations. This population structure is consistent with strong assortative mating between individuals of similar ancestry. The patterns of population structure uncovered here mirror those seen in hybridization between X. birchmanni and its sister species, Xiphophorus malinche, indicating an important role for assortative mating in the evolution of hybrid populations. Future comparisons will provide a window into the shared mechanisms driving the outcomes of hybridization not only among independent hybridization events between the same species but also across distinct species pairs.

24Geographically limited dispersal can shape genetic population structure and result in a correlation between genetic and geographic distance, commonly called isolation-by-26 distance. Despite the prevalence of isolation-by-distance in nature, to date few studies have empirically demonstrated the processes that generate this pattern, largely 28 because few populations have direct measures of individual dispersal and pedigree information. Intensive, long-term demographic studies and exhaustive genomic surveys 30 in the Florida Scrub-Jay (Aphelocoma coerulescens) provide an excellent opportunity to investigate the influence of dispersal on genetic structure. Here, we used a panel of 32 genome-wide SNPs and extensive pedigree information to explore the role of limited dispersal in shaping patterns of isolation-by-distance in both sexes, and at an 34 exceedingly fine spatial scale (within ~10 km). Isolation-by-distance patterns were stronger in male-male and male-female comparisons than in female-female 36 comparisons, consistent with observed differences in dispersal propensity between the sexes. Using the pedigree, we demonstrated how various genealogical relationships 38 contribute to fine-scale isolation-by-distance. Simulations using field-observed distributions of male and female natal dispersal distances showed good agreement with 40 the distribution of geographic distances between breeding individuals of different pedigree relationship classes. Furthermore, we extended Malécot's theory of isolation-42 by-distance by building coalescent simulations parameterized by the observed dispersal curve, population density, and immigration rate, and showed how incorporating these 44 extensions allows us to accurately reconstruct observed sex-specific isolation-bydistance patterns in autosomal and Z-linked SNPs. Therefore, patterns of fine-scale 46 . CC-BY 4.0 International license It is made available under a (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/093989 doi: bioRxiv preprint first posted online Dec. 14, 2016; 3 isolation-by-distance in the Florida Scrub-Jay can be well understood as a result of limited dispersal over contemporary timescales. 48 Author Summary 50Dispersal is a fundamental component of the life history of most organisms and therefore influences many biological processes. Dispersal is particularly important in 52 creating genetic structure on the landscape. We often observe a pattern of decreased genetic relatedness between individuals as geographic distances increases, or 54 isolation-by-distance. This pattern is particularly pronounced in organisms with extremely short dispersal distances. Despite the ubiquity of isolation-by-distance 56 patterns in nature, there are few examples that explicitly demonstrate how limited dispersal influences spatial genetic structure. Here we investigate the processes that 58 result in spatial genetic structure u...

Geographically limited dispersal can shape genetic population structure and result in a correlation between genetic and geographic distance, commonly called isolation-by-distance. Despite the prevalence of isolation-by-distance in nature, to date few studies have empirically demonstrated the processes that generate this pattern, largely because few populations have direct measures of individual dispersal and pedigree information. Intensive, long-term demographic studies and exhaustive genomic surveys in the Florida Scrub-Jay (Aphelocoma coerulescens) provide an excellent opportunity to investigate the influence of dispersal on genetic structure. Here, we used a panel of genome-wide SNPs and extensive pedigree information to explore the role of limited dispersal in shaping patterns of isolation-by-distance in both sexes, and at an exceedingly fine spatial scale (within ~10 km). Isolation-by-distance patterns were stronger in male-male and male-female comparisons than in female-female comparisons, consistent with observed differences in dispersal propensity between the sexes. Using the pedigree, we demonstrated how various genealogical relationships contribute to fine-scale isolation-by-distance. Simulations using field-observed distributions of male and female natal dispersal distances showed good agreement with the distribution of geographic distances between breeding individuals of different pedigree relationship classes. Furthermore, we built coalescent simulations parameterized by the observed dispersal curve, population density, and immigration rate, and showed how incorporating these extensions to Malécot’s theory of isolation-by-distance allows us to accurately reconstruct observed sex-specific isolation-by-distance patterns in autosomal and Z-linked SNPs. Therefore, patterns of fine-scale isolation-by-distance in the Florida Scrub-Jay can be well understood as a result of limited dispersal over contemporary timescales.