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The Levinson Emerging Scholars Program

Jeffrey Benca - Plant Biology

Jeffrey BencaSpurred by a lifelong passion for prehistoric life, Jeff Benca’s research uses modern and fossil representatives of ancient plant lineages to study ecosystem dynamics and environmental changes in deep time. Joining the lab of paleobotanist Dr. Caroline Stromberg in the UW Department of Biology his sophomore year, Jeff began implementing extant plants from teaching and research collections he built at the UW Botany Greenhouse to study evolutionary trends in early vascular plants. With Dr. Stromberg, he studied morphological variation in modern clubmosses and later the extinct Devonian lycopsid genus Leclercqia across six continents and 12 million years, resulting in the description of a new species from Northern Washington State.

Now, Jeff is exploring whether leaf morphology in living lycopsids and ferns, plant groups that once dominated many of earth’s ecosystems ~360 million years ago, is influenced by climate. Conducting growth chamber experiments growing lycopsids and ferns under two temperature regimes he hopes to find out whether temperature can induce changes in leaf shape. If temperature does influence leaf physiognomy of these plants, it may be possible to calibrate fossil leaves of their ancestors as new tools for assessing paleotemperatures during the Late Paleozoic. Developing more accurate temperature baselines during this time period is particularly important as it could yield entirely new analogs to modern climate change. In the coming years, Jeff plans to pursue a PhD using living and fossil plants to better understand environmental changes associated with mass extinctions and climatic changes in the distant past while making paleobiology more accessable and hands-on for students and the general public through teaching and continued outreach.

Mentor: Caroline Stromberg, Biology

Project Title: Climatic Influences on lycopsid and fern leaf physiognomy

Abstract: Understanding modern climate change hinges upon our ability to assess past climates. While relatively few analogs to modern climate change are represented in recent geological history, the Paleozoic era may offer more. Investigating Paleozoic climates could allow for study of long-term impacts of dramatic environmental transitions on terrestrial ecosystems. But exploring climate shifts in the distant past will require the expansion of existing techniques. Several methods use fossil leaf morphology to infer past climatic conditions. One such approach called Leaf Margin Analysis (LMA) uses leaf margin toothiness to infer past mean annual temperature. This approach has proven successful in using modern floras to estimate regional climates but can only assess past climates as far back as 120 million years ago (Ma) since it currently only utilizes leaves of flowering plants. However, other more ancient groups of vascular plants have evolved leaves with toothed margins as well. With toothed leaves and a fossil record exceeding 350 Ma, lycopsids (clubmosses) and ferns have potential to extend LMA back to the Late Paleozoic. To determine whether climate (in particular, temperature) influences leaf morphology in living representatives of these lineages, we are growing two species of lycopsid and two species of fern under two temperature regimes; 15°C and 25°C. If tooth number or size increases under cooler temperatures, fossil relatives of these ancient vascular plant lineages could potentially be implemented for study on climate changes long-preceding the age of flowering plants.