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Abstract Sexual dichromatism is thought to evolve primarily as a function of sexual selection, especially female choice. However, other forces, from sex-specific environmental conditions to social signaling in females, can also generate color differences between sexes. We studied dewlap dichromatism across 292 species of Anolis lizards. Dewlaps are colorful throat ornaments found on males of most anole species but are also present in females in many species. Although male and female dewlaps often have similar coloration, in some species, they are strikingly dichromatic. We found that ornament color is labile and that dichromatism results from the loss of costly pigments in females. This pattern could indicate a shift towards signal loss in females; however, the secondary gains of female dewlaps across the phylogeny suggest a potential advantageous function. Possible mechanisms for female dewlap coloration include social selection, nonsexual signaling, or detectability in different microhabitats (e.g., sensory drive). Female dewlap color overlap between co-occurring species is both less than expected by chance overall and reduced in species-rich communities, suggesting that dichromatism could be driven by competition. Our results highlight that selection on females drives the observed pattern of dichromatism, suggesting a potentially adaptive role for female ornaments and emphasizing the need for additional work to understand female ornament evolution. 

Abstract Spiny lizards (genus Sceloporus) have long served as important systems for studies of behavior, thermal physiology, dietary ecology, vector biology, speciation, and biogeography. The western fence lizard, Sceloporus occidentalis, is found across most of the major biogeographical regions in the western United States and northern Baja California, Mexico, inhabiting a wide range of habitats, from grassland to chaparral to open woodlands. As small ectotherms, Sceloporus lizards are particularly vulnerable to climate change, and S. occidentalis has also become an important system for studying the impacts of land use change and urbanization on small vertebrates. Here, we report a new reference genome assembly for S. occidentalis, as part of the California Conservation Genomics Project (CCGP). Consistent with the reference genomics strategy of the CCGP, we used Pacific Biosciences HiFi long reads and Hi-C chromatin-proximity sequencing technology to produce a de novo assembled genome. The assembly comprises a total of 608 scaffolds spanning 2,856 Mb, has a contig N50 of 18.9 Mb, a scaffold N50 of 98.4 Mb, and BUSCO completeness score of 98.1% based on the tetrapod gene set. This reference genome will be valuable for understanding ecological and evolutionary dynamics in S. occidentalis, the species status of the California endemic island fence lizard (S. becki), and the spectacular radiation of Sceloporus lizards. 

Field biology is an area of research that involves working directly with living organisms in situ through a practice known as “fieldwork.” Conducting fieldwork often requires complex logistical planning within multiregional or multinational teams, interacting with local communities at field sites, and collaborative research led by one or a few of the core team members. However, existing power imbalances stemming from geopolitical history, discrimination, and professional position, among other factors, perpetuate inequities when conducting these research endeavors. After reflecting on our own research programs, we propose four general principles to guide equitable, inclusive, ethical, and safe practices in field biology: be collaborative, be respectful, be legal, and be safe. Although many biologists already structure their field programs around these principles or similar values, executing equitable research practices can prove challenging and requires careful consideration, especially by those in positions with relatively greater privilege. Based on experiences and input from a diverse group of global collaborators, we provide suggestions for action-oriented approaches to make field biology more equitable, with particular attention to how those with greater privilege can contribute. While we acknowledge that not all suggestions will be applicable to every institution or program, we hope that they will generate discussions and provide a baseline for training in proactive, equitable fieldwork practices.