Color is one of the most pronounced axes of floral variation, and interactions between plants and pollinators are crucial for color diversification. Non-pollinator agents of selection also play a pivotal role in the evolution of floral pigmentation. Our research assesses how spatial heterogeneity in multiple selective agents shapes large-scale geographic and temporal patterns of phenotypic diversity among populations and species using systems with petal and pollen color variation. 

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Representative publications:

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Koski et al. Evolution, 2022

Finnell & Koski 2021

Koski et al. Journal of Evolutionary Biology, 2020

Koski & Galloway, New Phytologist, 2018​

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A rapidly changing climate, transformation of natural landscapes, and pollinator declines directly and indirectly influence plant reproduction and evolution. Understanding responses of plant reproduction to such environmental changes is crucial for the conservation of plant diversity. We are interested in how plant reproductive strategies and floral phenotypes have responded to rapid environmental change, and how plant reproductive traits will impact the capacity for range shifts. 

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Representative publications:

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Heiling & Koski, Evolution 2024

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Sullivan & Koski Proceedings B 2021

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Koski, MacQueen and Ashman, Current Biology 2020

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Our best examples of pollinator-mediated floral evolution are in plants that are pollination specialists-stark shifts in the dominant pollinator often corresponds with shifts in floral morphology. But many flowering plants, are generalist-pollinated by a variety of taxa with unique sensory systems, behaviors and dietary requirements. Our research addresses how different flower-visiting taxa affect plant reproduction in generalized pollination systems, and how they may promote floral diversity through unique sensory systems, preferences, and pollen-transfer efficiencies.

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Representative publications:

Koski 2022, American Journal of Botany

Koski, 2020, New Phytologist

Ison et al. 2018, Annals of Botany

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Flowering plants have evolved tremendous diversity in modes of reproduction. Self-fertilization can be costly due to inbreeding depression, so why has it evolved so frequently in flowering plants? We study how contemporary ecology (pollinator and mate availability), and genetic signatures of historical range expansion shape variation in the capacity to self-fertilize. Beyond the drivers of mating system variation, we assess the ecological and evolutionary outcomes of mating system variation among populations. 

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Representative publications:

Cisternas-Fuentes & Koski, Proceedings B

Koski et al., Evolution Letters, 2019

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