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ABSTRACT Invasive species with native ranges spanning strong environmental gradients are well suited for examining the roles of selection and population history in rapid adaptation to new habitats, providing insight into potential evolutionary responses to climate change. The Atlantic oyster drill (Urosalpinx cinerea) is a marine snail whose native range spans the strongest coastal latitudinal temperature gradient in the world, with invasive populations established on the US Pacific coast. Here, we leverage this system using genome‐wide SNPs and environmental data to examine invasion history and identify genotype–environment associations indicative of local adaptation across the native range, and then assess evidence for allelic frequency shifts that would signal rapid adaptation within invasive populations. We demonstrate strong genetic structuring among native regions which aligns with life history expectations, identifying southern New England as the source of invasive populations. Then, we identify putatively thermally adaptive loci across the native range but find no evidence of allele frequency shifts in invasive populations that suggest rapid adaptation to new environments. Our results indicate that while these loci may underpin local thermal adaptation in their native range, selection is relaxed in invasive populations, perhaps due to complex polygenic architecture underlying thermal traits and/or standing capacity for phenotypic plasticity. Given the prolific invasion ofUrosalpinx, our study suggests population success in new environments is influenced by factors other than selection on standing genetic variation that underlies local adaptation in the native range and highlights the importance of considering population history and environmental selection pressures when evaluating adaptive capacity. 

Understanding how latitudinal temperature variation shapes local adaptation of life history strategies is crucial for predicting future responses to warming. Contrasting predictive frameworks explain how growth and other life history traits may respond to differing selective pressures across latitude. However, these frameworks have rarely been explored within the context of fluctuating environmental temperatures across longer (i.e., seasonal) time scales experienced in nature. Furthermore, consequences of growth differences for other aspects of fitness, including reproductive output, remain unclear. Here, we conducted a long-term (17-month) simulated reciprocal transplant experiment to examine local adaptation in two populations of the predatory marine snail Urosalpinx cinerea separated by 8.6 degrees latitude (1000 km). We reared F1 offspring under two seasonally fluctuating temperature regimes (warm and cold, simulating field thermal conditions experienced by low and high latitude populations, respectively), quantifying temporal patterns in growth, maturation, and reproductive output. We identified striking divergence in life-history strategies between populations in the warm regime, with offspring from the low latitude population achieving greater growth in their first year, and high reproductive output coupled with reduced growth in their second year. In contrast, the high latitude population grew slower in their first year, but eventually attained larger sizes in their second year, at the expense of reduced reproductive output. Responses were consistent with this in the cold regime, although growth and reproductive output was reduced in both populations. Our data provides support for adaptive divergence across latitude consistent with the Pace-of-Life hypothesis, with the low latitude population selected for a fast-paced life characterized by rapid development and early reproduction. In contrast, the high latitude population exhibited slower growth and delayed maturation. Our results highlight the potential limitations of short-term comparisons of growth without considering processes over longer time scales that may exhibit seasonal temperature variation and ontogenetic shifts in energy allocation and imply a radical reshaping of physiological performance and life history traits across populations under climate change. 

Sea turtles represent an ancient lineage of marine vertebrates that evolved from terrestrial ancestors over 100 Mya. The genomic basis of the unique physiological and ecological traits enabling these species to thrive in diverse marine habitats remains largely unknown. Additionally, many populations have drastically declined due to anthropogenic activities over the past two centuries, and their recovery is a high global conservation priority. We generated and analyzed high-quality reference genomes for the leatherback ( Dermochelys coriacea ) and green ( Chelonia mydas ) turtles, representing the two extant sea turtle families. These genomes are highly syntenic and homologous, but localized regions of noncollinearity were associated with higher copy numbers of immune, zinc-finger, and olfactory receptor (OR) genes in green turtles, with ORs related to waterborne odorants greatly expanded in green turtles. Our findings suggest that divergent evolution of these key gene families may underlie immunological and sensory adaptations assisting navigation, occupancy of neritic versus pelagic environments, and diet specialization. Reduced collinearity was especially prevalent in microchromosomes, with greater gene content, heterozygosity, and genetic distances between species, supporting their critical role in vertebrate evolutionary adaptation. Finally, diversity and demographic histories starkly contrasted between species, indicating that leatherback turtles have had a low yet stable effective population size, exhibit extremely low diversity compared with other reptiles, and harbor a higher genetic load compared with green turtles, reinforcing concern over their persistence under future climate scenarios. These genomes provide invaluable resources for advancing our understanding of evolution and conservation best practices in an imperiled vertebrate lineage.