By definition, mating between individuals is infrequent in highly selfing organisms, and so too, therefore, hybridization should be rare between genetically divergent lineages in predominantly self-fertilizing species. Notwithstanding these expectations, here we report a remarkable case of natural hybridization between highly diverged phylogeographic lineages of the mangrove rivulus, a small killifish that reproduces predominantly by self-fertilization and typically is found as highly homozygous lines in most parts of its extensive geographic range. Two distinctive genetic...

Herbaria contain a cumulative sample of the world’s flora, assembled by thousands of people over several hundred years. Recent advances in computation, DNA sequencing, and image manipulation have allowed us to capitalize on this resource. Using herbarium material, we conducted a species-level analysis of a major clade in the grass tribe Andropogoneae, which includes the dominant species of the world’s grasslands, from the genera Andropogon, Schizachyrium, Hyparrhenia, and other groups. We imaged 188 of the...

Heritable variation in, and genetic correlations among, traits determine the response of multivariate phenotypes to natural selection. However, as traits develop over ontogeny, patterns of genetic (co)variation and integration captured by the G matrix may also change. Despite this, few studies have investigated how genetic parameters underpinning multivariate phenotypes change as animals pass through major life history stages. Here, using a self-fertilizing hermaphroditic fish species, mangrove rivulus (Kryptolebias marmoratus), we test the hypothesis that G...

With fossil representatives from the Silurian capable of respiring atmospheric oxygen, millipedes are among the oldest terrestrial animals, and likely the first to acquire diverse and complex chemical defenses against predators. Exploring the origin of complex adaptive traits is critical for understanding the evolution of Earth’s biological complexity, and chemical defense evolution serves as an ideal study system. The classic explanation for the evolution of complexity is by gradual increase from simple to complex, passing...

To survive, animals must respond appropriately to stress. Stress responses are costly, so early-life experiences with potential stressors could adaptively tailor adult stress responses to local conditions. However, how multiple stressors influence the development of the stress response remains unclear, as is the role of sex. Trinidadian guppies (Poecilia reticulata) are small fish with extensive life history differences between the sexes and population variation in predation pressure and social density. We investigated how sex and...

Identifying drivers of dispersal limitation and genetic differentiation is a key goal in biogeography. We examine patterns of population connectivity and genetic diversity using Restriction-site Associated DNA sequencing (RADseq) in two bumble bee species, Bombus vosnesenskii and Bombus bifarius across latitude and altitude in mountain ranges from California, Oregon, and Washington, U.S.A. Bombus vosnesenskii, which occurs across a broader elevational range at most latitudes, exhibits little population structure while B. bifarius, which occupies a relatively...

Understanding how the brain processes social information and generates adaptive behavioural responses is a major goal in neuroscience. We examined behaviour and neural activity patterns in socially relevant brain nuclei of hermaphroditic mangrove rivulus fish (Kryptolebias marmoratus) provided with different types of social stimuli: stationary model opponent, regular mirror, non-reversing mirror and live opponent. We found that: i) individuals faced with a regular mirror were less willing to interact with, delivered fewer attacks towards, and...

The life histories of ammonites and the life strategies they employed are difficult to assess without robust modern analogues but placing constraints on ammonite growth rates provides a fundamental first step to understanding this abundant, but poorly understood, fossil group. Here we interpret periodic variations in carbon and oxygen stable isotope profiles from Campanian and Maastrichtian ammonites (Baculites) as seasonally driven and use these records to determine their rate of shell precipitation. Several of these...

Speciation is the result of an accumulation of reproductive barriers between populations, pinpointing these factors is often difficult. However, hybrid zones can form when these barriers are not complete, especially when lineages come into contact in intermediate or modified habitats. We examine a hybrid zone between two closely related riverine turtle species, Sternotherus depressus and S. peltifer, and use ddRAD sequencing to to understand how this hybrid zone formed and elucidate genomic patterns of reproductive...