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  1. Abstract

    As anthropogenic activities are increasing the frequency and severity of droughts, understanding whether and how fast populations can adapt to sudden changes in their hydric environment is critically important. Here, we capitalize on the introduction of the Cuban brown anole lizard (Anolis sagrei) in North America to assess the contemporary evolution of a widespread terrestrial vertebrate to an abrupt climatic niche shift. We characterized hydric balance in 30 populations along a large climatic gradient. We found that while evaporative and cutaneous water loss varied widely, there was no climatic cline, as would be expected under adaptation. Furthermore, the skin of lizards from more arid environments was covered with smaller scales, a condition thought to limit water conservation and thus be maladaptive. In contrast to environmental conditions, genome-averaged ancestry was a significant predictor of water loss. This was reinforced by our genome-wide association analyses, which indicated a significant ancestry-specific effect for water loss at one locus. Thus, our study indicates that the water balance of invasive brown anoles is dictated by an environment-independent introduction and hybridization history and highlights genetic interactions or genetic correlations as factors that might forestall adaptation. Alternative water conservation strategies, including behavioral mitigation, may influence the brown anole invasion success and require future examination.

     
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  3. Abstract

    Understanding the three‐dimensional (3D) surface complexity of biological systems can yield fundamental insights into how organisms interact with their environments. The wealth of current imaging technologies permits detailed 3D visualization of biological surfaces on the macro‐, micro‐ and nanoscale. Analysis of the reconstructed 3D images, however, remains a challenging proposition.

    Here, we presentQuSTo, a versatile, open‐source program developed in Python to quantify surface topography from profiles obtained from 3D scans. The program calculates metrics that quantify surface roughness and the size (i.e. height and length) and shape (i.e. convexity constant (CC), skewness (Sk) and kurtosis (Ku)) of surface structures.

    We demonstrate the applicability of our program by quantifying the surface topography of snake skin based on newly collected data from white light 3D scans of the ventrum and dorsum of 32 species. To illustrate the utility ofQuSTofor evolutionary and ecological research, we test whether snake species that occur in different habitats differ in skin surface structure using phylogenetic comparative analyses.

    TheQuSToapplication is free, open‐source, user‐friendly and easily adapted for specific analysis requirements (available in GitHub, github.com/GMLatUCDavis/QuSTo) and is compatible with 3D data obtained with different scanning techniques, for example, white light and laser scanning, photogrammetry, gel‐based stereo‐profilometry. Scientists from various disciplines can useQuSToto examine the surface properties of an array of animal and plant species for both fundamental and applied biological and bioinspired research.

     
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  4. Abstract

    Patterns of convergent evolution in head shape, combined with performance measures, provide ideal opportunities to understand the processes driving its evolution. Anole lizards represent an excellent subject to test this, as recurrent habitat specialists or ecomorphs evolved independently across different islands.

    We show that phenotypic similarity corresponds to both phylogenetic similarity and similarity in habitat, indicating that there is convergent evolution in head shape among ecomorphs. Moreover, we show that the evolution of tall, wide heads correlate with the evolution of higher bite forces, driving head shape variation among and within ecomorphs.

    In addition, the processes affecting head shape variation can differ between sexes, leading to sexual head shape dimorphism. These processes might, however, still depend on the habitat. Consequently, there could also be convergent evolution in head shape dimorphism among ecomorphs.

    We found no evidence for convergent evolution in sexual head shape dimorphism. Moreover, the sexual head shape dimorphism correlates poorly with bite force, suggesting that intersexual head shape differences are related to other functions. Different processes are thus driving the evolution of head shape and head shape dimorphism.

    A freePlain Language Summarycan be found within the Supporting Information of this article.

     
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  5. Abstract

    Sexual selection can lead to rapid evolution of sexual traits and striking morphological diversity across taxa. In populations where competition for mates is intense, males sometimes evolve distinct behavioral strategies along with morphological differences that help them secure mating opportunities. Strong postcopulatory selection and differential resource allocation across male strategy type can result in strategy‐specific differences in sexual traits, such as sperm morphology, ejaculate components, and testis size. Some polymorphic species also have strategy‐specific genital morphology. Thus far, among vertebrates, this has only been observed in fish. Here, we present the first morphological description of the intromittant copulatory organ, the hemipenis, of the three mating types of the side‐blotched lizard,Uta stansburiana, from a population that exhibits alternative mating strategies. We found that the isometrically scaling hemipenis was shortest in the nonterritorial (yellow) morph that sneaks copulations with other males' mates. Although the hemipenes were generally the same shape across morphs, the usurping territorial (orange) morph had a significantly wider apical horn than the nonterritorial sneaker morph. Sneaker males also had smaller relative body masses than both the mate‐guarding (blue) morph and the usurper morph, and shorter tibia than the usurper morph. This study using a small sample of males suggests that strong sexual selection may drive genital trait differentiation across morphs within populations of terrestrial vertebrates.

     
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