Abstract Detail

Conservation Biology

Motley, M'Kayla [1], Amos, Bonnie B. [2].

Seed Dispersal in the Threatened Tobusch Fishhook Cactus (Sclerocactus brevihamatus spp. tobuschii).

Sclerocactus brevihamatus ssp. tobuschii, a small, spherical cactus restricted to the western Edwards Plateau of Texas, is currently federally listed as threatened. We investigated the Texas fishhook cactus (TFC) seed dispersal during the taxon's fruiting period, May through June of 2017 and 2018. Time-lapse cameras were used to take single images every five minutes from 0700 to 1900 hrs in 2017 and 2018. This methodology resulted in a total of 38,968 images in 2017 and 106,344 images in 2018. In 2017 a total of 3,339 10-second long videos were taken every 5 minutes for the same period of the day. The videos and images were used to capture photographic evidence of fruit dehiscence and seed visitors; additional data were collected from field observations. Images showing fruit visitors were used to identify species and to document their behavior. Within the Kerr County study site, we found no evidence of zoonotic dispersal. Two species of ants, the fire ant (Solenopsis invicta or a hybrid S. invicta X S. geminata) and a smaller ant, Forelius pruinosus, were frugivores. Both removed the fleshy pulp and the funiculus; however, neither were observed harvesting seeds. After ant activity, the fruits rapidly collapsed and dried; seeds from eviscerated fruits fell onto or next to the mother plant. Short distance seed dispersal may have adverse consequences on fecundity because of the close proximity of closely related TFC plants. TFC is strongly self-incompatible and is visited primarily by honey bees who display nearest-neighbor flight patterns. No other fruit visitors were observed and no fruit damage other than that by the ants occurred. TFC may lack a seed disperser or ant activity may be preventing visitation by a disperser. Additional research is being conducted on TFC greenhouse specimens to gain a better understanding of the plant's fruit-ant attractant. Using a penetrometer, glucose/fructose refractometers, and a sugar assay test, we will compare fruit hardness with sugar content, which we will use to construct a model of fruit attractiveness. We hypothesize that the fruit becomes "discoverable" to ants when the fruit hits peak ripeness and sugar content is highest.

1 - Angelo State University, Biology, ASU Station #10890, San Angelo, Texas, 76909, United States
2 - Angelo State University, Biology, ASU Station #10890, San Angelo, TX, 76909, USA

Keywords:
rare plant conservation
threatened species
Seed dispersal
Sclerocactus
Cactaceae.

Presentation Type: Poster
Session: P, Conservation Biology Posters
Location: Arizona Ballroom/Starr Pass
Date: Monday, July 29th, 2019
Time: 5:30 PM This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PCB013
Abstract ID:928
Candidate for Awards:None