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Department of Biological Sciences

Sierra Jaeger and Dr. Eric LoPresti published a new study in Ecology

While a single, dominant pollinator species may contribute exclusively to a plant’s reproductive output, the contributions of other less-effective or less-frequent floral visitors are also occasionally noted to contribute to pollination. Yet, the extent of secondary pollinator contributions to plant reproduction and their potential influence on plant evolution are largely overlooked. In their new study titled "Secondary pollinators contribute to reproductive success of a pink-flowered sand verbena population", graduate student Sierra Jaeger and her mentor Dr. Eric LoPresti analyzed the independent contributions of nocturnal and diurnal pollinators to the reproductive success of the sweet sand verbena A. fragrans,. A. fragrans usually displays white flowers between dusk and dawn except in a small region of northern Texas and southwestern Oklahoma, where it bears pink flowers that also open in the morning. To parse diurnal and nocturnal pollination contributions, the authors excluded floral visitors during the day and/or night by covering inflorescences with small organza drawstring bags. This pollinator-exclusion study led to the discovery that secondary pollinators of the pink-flowered population contributed significantly to the plants’ overall pollination success, in stark contrast to the white-flowered populations. These results not only suggest that the atypical flower color and the floral closing and opening behavior alter this species’ plant-insect interactions, but also that diurnal pollinator interactions may be a selective force behind the evolution or maintenance of pink floral color in these populations. A fascinating study!

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