Reading(s)
The Anomalous Kentucky Coffeetree: Megafaunal Fruit Sinking to Extinction?
Seed source impacts germination and early establishment of dominant grasses in prairie restorations
Lab Goals and Objectives
Identify the life-history traits that place the Kentucky coffeetree (Gymnocladus dioicus) within the "megafaunal fruit" syndrome, including large indehiscent pods, thick seed coats requiring scarification, sweet pulp, and chemical defenses toxic to modern ungulates. Explain how the extinction of Pleistocene megaherbivores eliminated both the primary seed dispersers and the disturbed "megafaunal disclimax" habitats this shade-intolerant, dioecious species evolved to exploit. Evaluate why reliance on inefficient water dispersal (hydrochory) and clonal root sprouting leaves modern populations vulnerable to pollen limitation and local extirpation without human-mediated dispersal.
Evaluate genetic and phytogeographic evidence showing that post-Last Glacial Maximum (LGM) range expansion of pawpaw (Asimina triloba) into formerly glaciated northern regions was driven by Indigenous cultivation and trade rather than wildlife vectors. Connect human-mediated founder events with rare alleles shared with distant southern source populations.
Apply principles of local adaptation when harvesting little bluestem (Schizachyrium scoparium) from a specialized marl prairie remnant for a nearby restoration site. Contrast the ecological advantages of sourcing seed from local remnants such as preserving locally adapted genotypes, matching edaphic conditions, and preventing genetic swamping against potential challenges including lower seed mass, reduced first-season germination compared to nursery-propagated seed, and inbreeding depression in small, isolated populations.
Demonstrate field techniques for assessing seed maturity and collecting across a representative sample to capture local genetic variation and minimize artificial selection or genetic drift during harvest.
Reflection Prompt
Ecological restoration often operates under the assumption that we are returning a degraded landscape to a "natural," pre-human baseline. Yet every stop on today's field lab, from a relict tree grove to an understory fruit tree and a specialized marl prairie, reveals a landscape where plant distributions, genetics, and survival are deeply entangled with missing animals and human hands. Is planting Kentucky coffeetree in upland restorations an "artificial" intervention, or are restorationists acting as necessary ecological surrogates for extinct megafauna? How does the post-LGM dispersal of pawpaw by Indigenous peoples challenge the "pristine myth" of North American forests? When we manage or restore eastern woodlands today, how should we view species whose northern ranges are cultural artifacts as much as ecological ones? If commercial nursery seeds establish so vigorously, why did we spend the afternoon hand-harvesting seed from a local marl prairie instead of ordering bulk seed from a regional nursery? Across all three species, dispersal is a limiting bottleneck, whether due to extinct mammoths, shifting Indigenous land-use patterns, or modern habitat fragmentation. Based on today's lab, how would you redefine the role of humans in seed dispersal and ecosystem assembly? Can restoration ecology succeed if it treats humans strictly as external disturbers rather than active participants in evolutionary and biogeographic processes?
Materials, Links, Logistics, & General Itinerary (subject to change as needed)
We will meet at Reith Village at 1:00 PM. We will visit a couple of sites to understand aspects of seeds and restoration. We will end the lab by harvesting seeds at Merry Lea for another restoration project across the property at Merry Lea.