Separating myth and reality is essential for evaluating the effectiveness of laws. Section 7 of the US Endangered Species Act (Act) directs federal agencies to help conserve threatened and endangered species, including by consulting with the US Fish and Wildlife Service (FWS) or National Marine Fisheries Service on actions the agencies authorize, fund, or carry out. Consultations ensure that actions do not violate the Act's prohibitions on "jeopardizing" listed species or "destroying or adversely modifying" these species' critical habitat. Because these prohibitions are broad, many people consider section 7 the primary tool for protecting species under the Act, whereas others believe section 7 severely impedes economic development. This decades-old controversy is driven primarily by the lack of data on implementation: past analyses are either over 25 y old or taxonomically restricted. We analyze data on all 88,290 consultations recorded by FWS from January 2008 through April 2015. In contrast to conventional wisdom about section 7 implementation, no project was stopped or extensively altered as a result of FWS finding jeopardy or adverse modification during this period. We also show that median consultation duration is far lower than the maximum allowed by the Act, and several factors drive variation in consultation duration. The results discredit many of the claims about the onerous nature of section 7 but also raise questions as to how federal agencies could apply this tool more effectively to conserve species. We build on the results to identify ways to improve the effectiveness of consultations for imperiled species conservation and increase the efficiency of consultations.Endangered Species Act | section 7 consultation | imperiled species |

Heteromorphic sex chromosomes have evolved repeatedly among vertebrate lineages despite largely deleterious reductions in gene dose. Understanding how this gene dose problem is overcome is hampered by the lack of genomic information at the base of tetrapods and comparisons across the evolutionary history of vertebrates. To address this problem, we produced a chromosome-level genome assembly for the African Bullfrog (Pyxicephalus adspersus)-an amphibian with heteromorphic ZW sex chromosomes-and discovered that the Bullfrog Z is surprisingly homologous to substantial portions of the human X. Using this new reference genome, we identified ancestral synteny among the sex chromosomes of major vertebrate lineages, showing that non-mammalian sex chromosomes are strongly associated with a single vertebrate ancestral chromosome, while mammals are associated with another that displays increased haploinsufficiency. The sex chromosomes of the African Bullfrog however, share genomic blocks with both humans and non-mammalian vertebrates, connecting the two ancestral chromosome sequences that repeatedly characterize vertebrate sex chromosomes. Our results highlight the consistency of sex-linked sequences despite sex determination system lability and reveal the repeated use of two major genomic sequence blocks during vertebrate sex chromosome evolution. MAIN TEXTSexual reproduction is the dominant mode of creating offspring among vertebrates 1 , but the fundamental genetic mechanisms that produce two sexes are-in contrast-staggeringly diverse 2,3 . This diversity of genetic sex determination systems is what dictates the formation of sex chromosomes, which differ widely from autosomal chromosomes in their lability, gene content, and structural organization 4,5 . A particular departure from autosomal characteristics is the phenomenon of heteromorphic sex chromosomes which differ in size and gene content. As sex chromosomes evolve, the sex chromosome associated with the heterogametic sex (either Y or W) can experience gene loss, rearrangements, and gains of heterochromatin that change chromosome size and reduce gene dosage on the gametologous X or Z chromosome, respectively 6-12 .At the same time, reductions in gene dosage are largely deleterious [13][14][15][16][17] . Mechanisms of dosage compensation, such as X-inactivation in eutherian mammals 18-20 and X-linked hyperexpression in lizards 21,22 are thought to help solve this problem. However, sex-linked genes are expressed at levels proportional to their copy number in birds, snakes, and liver flukes-all species with ZW sex determination-suggesting a lack of dosage compensation 6,23-27 . The ability to compensate gene dose reductions during sex chromosome evolution in some lineages but tolerate gene dose reductions in others remains poorly understood 24,28 . One hypothesis that addresses this phenomenon is that certain genomic regions are more dose tolerant than others, and shuffling of these syntenic blocks has contributed to the repeated evolution of heteromorphic sex chromoso...

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SummaryVariation is essential to ecological and evolutionary dynamics, but genetic variation of quantitative traits may be concentrated in a limited number of dimensions, constraining ecoevolutionary dynamics. We describe high-dimension variation in natural accessions of the model alga, Chlamydomonas reinhardtii, and test the hypothesis that extensive fitness variation across 30 environments is constrained to a small number of axes.We used high-throughput phenotyping to investigate morphological, fitness, and genotype 9 environment (G 9 E) variation in 18 natural C. reinhardtii accessions in 30 environments.The organismal phenotypes of cell cycle, cell size, and phototactic behavior exhibited substantial genetic variation between lines, and we found up to 74-fold fitness variation across accessions and environments. Approximately 47% of the extensive G 9 E variation is accounted for by the first two principal components (PCs) of the G-matrix corresponding to covariation in metals response, nitrogen availability, or salt and nutrient response.The natural variation of C. reinhardtii accessions supports the hypothesis that, despite abundant genetic variation across single environments, the species' adaptive response should be constrained along few major axes of selection. These results highlight the utility of natural accessions for integrating ecoevolutionary and genetic research.

Achieving ambitious goals to conserve at least 30% of U.S. lands and waters by 2030 (“30 × 30”) will require a multiscale baseline understanding of current protections, key decisionmakers, and policy tools for moving forward. To help conservationists and decisionmakers support the science‐based call to address the biodiversity and climate crises, we analyze the current spatial patterns of biodiversity and carbon in the United States relative to protected areas and present a typology for classifying land contributions toward the 30 × 30 goals. Analyses demonstrate that 30% is achievable nationally, but spatial heterogeneity highlights the need for tailored approaches from a mix of authorities at federal, regional, and state scales. Current land protections rarely overlap with areas essential for conserving imperiled species biodiversity and mitigating climate change. One‐fifth of unprotected biodiversity hotspots and over 8% carbon‐rich areas face a higher risk of land conversion by 2050. In contrast, 3.6% of key biodiversity areas and 15.6% of carbon‐rich areas may experience higher climate exposure. Policy considerations for making practical, substantive progress toward ecologically meaningful achievement of 30 × 30 goal include the need for significant investments in public and private lands conservation.

Frog sex chromosomes offer an ideal system for advancing our understanding of genome evolution and function because of the variety of sex determination systems in the group, the diversity of sex chromosome maturation states, the ease of experimental manipulation during early development. After briefly reviewing sex chromosome biology generally, we focus on what is known about frog sex determination, sex chromosome evolution, and recent, genomics-facilitated advances in the field. In closing we highlight gaps in our current knowledge of frog sex chromosomes, and suggest priorities for future research that can advance broad knowledge of gene dose and sex chromosome evolution.

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To stem the ongoing loss of biodiversity, conservation practitioners must distinguish between effective and ineffective approaches for protecting species habitats. Using Google Earth Engine and 31 years of Landsat images, we quantified changes in the habitats of 24 vertebrates listed under the US Endangered Species Act (ESA) and on the International Union for Conservation of Nature (IUCN) Red List across categories of land ownership (eg federal, state, private) in the continental US that are subject to different conservation‐focused legal restrictions. These estimates exclude changes attributable to agricultural conversion and burned areas. The imperiled species we evaluated lost the least amount of habitat (3.6%) on federal lands, whereas losses on private lands without conservation easements were more than twice as high (8.1%). Differences in annual percent loss before and after ESA listing, and between ESA‐listed and Red List species, indicate that the ESA limited habitat loss and was most effective on federal lands. These results underscore the importance of federal lands in protecting habitat for imperiled species and highlight the need to improve habitat protection on private lands for long‐term conservation.