Abstract
Several North American trees are hypothesized to have lost their co‐evolved seed disperser during the late‐Pleistocene extinction and are therefore considered anachronistic. We tested this hypothesis for the American persimmon (Diospyros virginiana) by studying the effects of gut passage of proposed seed dispersers on seedling survival and growth, natural fruiting characteristics, and modern animal consumption patterns. We tested gut passage effects on persimmon seeds using three native living species, the raccoon (Procyon lotor), Virginia opossum (Didelphis virginiana), and coyote (Canis latrans), and two Pleistocene analogs; the Asian elephant (Elephas maximus) and alpaca (Vicugna pacos). Persimmon seeds excreted by raccoons, coyotes, and elephants survived gut transit. Gut passage did not affect sprouting success, but did tend to decrease time to sprout and increase seedling quality. Under field conditions, persimmon fruits were palatable on the parent tree and on the ground for an equal duration, but most fruits were consumed on the ground. Seven vertebrate species fed upon persimmon fruits, with the white‐tailed deer (Odocoileus virginianus)—a species not capable of dispersing persimmon seeds—comprising over 90% of detections. Conversely, potential living seed dispersers were rarely detected. Our results suggest the American persimmon evolved to attract a variety of seed dispersers and thus is not anachronistic. However, human‐induced changes in mammal communities could be affecting successful seed dispersal. We argue that changes in the relative abundance of mammals during the Anthropocene may be modifying seed dispersal patterns, leading to potential changes in forest community composition.
Highlights
Several North American plants are hypothesized to be anachronistic (Barlow, 2001), in that they lack living seed dispersers (Janzen, 1982; Janzen & Martin, 1982)
The survivorship and plant quality field experiments demonstrated that a variety of mammals are potential seed dispersers for the Species Mean (±1 SD) Proportion
Seeds that had passed through the digestive system of raccoons and coyotes, as well as seeds that were manually dissected from the fruits, generally produced higher quality plants compared to those that sprouted from whole fruits
Summary
Several North American plants are hypothesized to be anachronistic (Barlow, 2001), in that they lack living seed dispersers (Janzen, 1982; Janzen & Martin, 1982). Experimental studies indicate that the seeds of some proposed anachronistic fruits sprout and produce higher quality seedlings after passing through the guts of Pleistocene ecological analogs (e.g., Asian Elephant, Elephas maximus L., Boone et al, 2015), while others have shown that native extant mammals could be effective seed dispersers for these plants (Cypher & Cypher, 1999; Roehm & Moran, 2013). To test the hypothesis that the American persimmon is anachronistic, we performed replicated controlled field experiments where we measured the sprouting success and quality of plants produced from persimmon seeds that had passed through the digestive system of a variety of hypothesized past and current dispersers These species included native extant small/medium sized mammals and large mammals that represented analogs of extinct Pleistocene species. If D. virginiana has anachronistic fruit, we predict higher sprouting success, higher seedling survival, and/or higher seedling quality for those seeds that passed through the guts of our Pleistocene analogs while field observations would indicate poor dispersal rates
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