[PCA] ARTICLE: Seed Consumption by Gopher Tortoises (Gopherus polyphemus) in the Globally Imperiled Pine Rockland Ecosystem of Southern Florida, USA

Park, Margaret E margaret_park at fws.gov
Fri Jul 2 13:56:48 CDT 2021


Additional information from the author of an article that I shared earlier today. My apologies for not consolidating.

Question:
I am curious whether you determined whether/which of the consumed plant species were still viable upon 'deposition' and which of these species may also depend on scarification to germinate?

Adrian Figueroa responded:
I did not attempt to germinate seeds consumed by the tortoises in my undergrad study because we had frozen the scats, which likely killed the seed embryo.

However, now that I'm back at Zoo Miami and preparing for my own graduate research, my plan is to perform germination trials on ingested vs. uningested seeds as well as testoing for the influence of fire stimuli on seed germination (since this plant community is fire-reliant, requiring burns ever 3-5 years). My idea is to perform a two factor crossed design where I examine (1) the effect of ingestion by gopher tortoises vs. depulped seeds that aren't ingested and (2) mimicking the effect of fire by irrigating seeds with tap water vs. smoke-infused water to see if there are any synergistic effects of ingestion and then exposure to smoke-treated water. I chose to use smoke-treated water because some studies have shown that it's a stronger catalyst for seed germination for fire-dependent plant species than exposing the seeds to heat shock.

On another note, I was able to dissect fresh scat samples that a wild gopher tortoise provided me with while I was putting a new radio transmitter on her. By the time I finished dissecting the scat, she had pooped out 348 seeds of locustberry (Byrsonima lucida)! That plant is the host for the Florida duskywing butterfly (Ephyriades brunneus floridensis) which is an imperiled species in Florida. I have since planted the seeds in different substrates to see which would work best for feeding/germination trials in my official dissertation research.

________________________________
From: Park, Margaret E
Sent: Friday, July 2, 2021 1:55 PM
To: PCA Listserve <native-plants at lists.plantconservation.org>; apwg at lists.plantconservation.org <apwg at lists.plantconservation.org>
Subject: ARTICLE: Seed Consumption by Gopher Tortoises (Gopherus polyphemus) in the Globally Imperiled Pine Rockland Ecosystem of Southern Florida, USA


 Adrian Figueroa, James Lange, Stephen M. Whitfield, Chelonian Conservation and Biology, May 24, 2021



Abstract

Turtles have been identified as key dispersers of seeds in many ecosystems; however, seed dispersal by turtles (chelonochory) has received far less attention than seed dispersal by birds or mammals. We assessed the role of gopher tortoises (Gopherus polyphemus)—a keystone species—as potential seed dispersers by analyzing the seed composition of their diet in a globally imperiled ecosystem: the pine rockland ecosystem of South Florida. The pine rocklands contain high numbers of both endemic and invasive plant species that may be dispersed by tortoises. We collected scat samples from wild gopher tortoises living in the pine rockland habitats in the Richmond Tract (Miami-Dade County, Florida, USA) and examined the samples to identify seeds consumed. We extracted 2484 seeds from 53 samples from at least 10 individual tortoises. Of the 2484 individual seeds, we distinguished 33 morphospecies and identified 23 to the species taxonomic level. The 14 most abundant seed species in the scat constituted > 90% of all seeds eaten by the tortoises. Three of the 14 most abundant seeds were from nonnative plants, but none were among the most disruptive invasive species. Tortoises consumed mostly herbaceous ground cover and fibrous grasses. Given that the tortoises were consuming several ground cover plants and contained a high density of those seeds in their scats, they seemed to be consuming the seeds as bycatch rather than selectively feeding on them, therefore supporting Janzen's “foliage is the fruit” hypothesis. The prevalence of many seeds and a variety of seed species in the tortoise scat suggests that gopher tortoises may be serving the ecological role of a seed dispersal agent for some of the plants they consume within the pine rocklands.



Link to article: https://meridian.allenpress.com/ccb/article-abstract/20/1/27/465473/Seed-Consumption-by-Gopher-Tortoises-Gopherus
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.plantconservation.org/pipermail/native-plants_lists.plantconservation.org/attachments/20210702/be3c394c/attachment.html>


More information about the native-plants mailing list