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Abstract Mimulus laciniatus (syn. Erythranthe lacinata) is an annual plant endemic to the Sierra Nevada region of California. Mimulus laciniatus is notable for its specialized ecological niche, thriving in granite outcrops of alpine environments characterized by shallow soils that dry out rapidly as the snowpack is exhausted during season-ending droughts. Due to its narrow habitat range and sensitivity to environmental change, this species serves as an important model for studying adaptation and survival in marginal habitats. As part of the California Conservation Genomics Project, here we report the sequencing and assembly of a high-quality nuclear genome and chloroplast genome of M. laciniatus. The primary assembly is 309.96 Mb and consists of 104 scaffolds with a scaffold N50 of 20.99 Mb, a largest contig size of 24.29 Mb and a contig N50 of 11.09 Mb, The alternate haplotype assembly consists of 194 scaffolds spanning 213.84 Mb. BUSCO completeness of the primary assembly is 98.6%. This high quality genome adds a valuable resource to the expanding collection of sequenced genomes of the monkeyflowers (Mimulus sensu lato), which have become a model clade for studying ecological adaptation, speciation, and evolutionary genetics. 

Abstract In a rapidly changing environment, predicting changes in the growth and survival of local populations can inform conservation and management. Plastic responses vary as a result of genetic differentiation within and among species, so accurate rangewide predictions require characterization of genotype-specific reaction norms across the continuum of historic and future climate conditions comprising a species’ range. Natural hybrid zones can give rise to novel recombinant genotypes associated with high phenotypic variability, further increasing the variance of plastic responses within the ranges of the hybridizing species. Experiments that plant replicated genotypes across a range of environments can characterize genotype-specific reaction norms; identify genetic, geographic, and climatic factors affecting variation in climate responses; and make predictions of climate responses across complex genetic and geographic landscapes. The North American hybrid zone ofPopulus trichocarpaandP. balsamiferarepresents a natural system in which reaction norms are likely to vary with underlying genetic variation that has been shaped by climate, geography, and introgression. Here, we leverage a dataset containing 45 clonal genotypes of varying ancestry from this natural hybrid zone, planted across 17 replicated common garden experiments spanning a broad climatic range, including sites warmer than the natural species ranges. Growth and mortality were measured over two years, enabling us to model reaction norms for each genotype across these tested environments. Genomic variation associated with species ancestry and northern/southern regions significantly influenced growth across environments, with genotypic variation in reaction norms reflecting a trade-off between cold tolerance and growth. Using modeled reaction norms for each genotype, we predicted that genotypes with moreP. trichocarpaancestry may gain an advantage under warmer climates. Spatial shifts of the hybrid zone could facilitate the spread of beneficial alleles into novel climates. These results highlight that genotypic variation in responses to temperature will have landscape-level effects.