Both intrinsic and extrinsic forces work together to shape connectivity and genetic variation in populations across the landscape. Here we explored how geography, breeding system traits, and environmental factors influence the population genetic patterns of Triodanis perfoliata, a widespread mix‐mating annual plant in the contiguous US. By integrating population genomic data with spatial analyses and modeling the relationship between a breeding system and genetic diversity, we illustrate the complex ways in which these forces shape genetic variation. Specifically, we used 4705 single nucleotide polymorphisms to assess genetic diversity, structure, and evolutionary history among 18 populations. Populations with more obligately selfing flowers harbored less genetic diversity (π: R2 = .63, p = .01, n = 9 populations), and we found significant population structuring (FST = 0.48). Both geographic isolation and environmental factors played significant roles in predicting the observed genetic diversity: we found that corridors of suitable environments appear to facilitate gene flow between populations, and that environmental resistance is correlated with increased genetic distance between populations. Last, we integrated our genetic results with species distribution modeling to assess likely patterns of connectivity among our study populations. Our landscape and evolutionary genetic results suggest that T. perfoliata experienced a complex demographic and evolutionary history, particularly in the center of its distribution. As such, there is no singular mechanism driving this species' evolution. Together, our analyses support the hypothesis that the breeding system, geography, and environmental variables shape the patterns of diversity and connectivity of T. perfoliata in the US.

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THE following observations are humbly offered to the Linnean Society, but with sincere regret that they are not either more numerous or important. They were made during a voyage in which I had the honour to accompany Mr. Robert Stevenson, civil engineer, of Edinburgh, on his annual inspection of the northern lighthouses. PHALAROPUS WILLIAMSII. Ph. orbitis albis, capite fusco vel cinereo. Bill + inch, tapering, slender, acute, bending downwards at the point. Feet black, compressed. Toes united as fdr as the first, second, and third joints of the inner, middle, and outermost toes respectively; the remaining part of the toes webbed ; the margins of the web scolloped, and somewhat of a pectinated appearance. Claws black. Eyelids white. Length 7 inches.