Abstract Detail

Conservation Biology

Thacker, James Heath [1], Krosnick, Shawn Elizabeth [2].

Analysis of reproductive biology and shade tolerance of the endangered plant Physaria globosa (Brassicaceae).

In 2002, Al-Shehbaz & O’Kane synonymized the genus Lesquerella with Physaria, resulting in 75 new species in Physaria. Of these, Physaria globosa (Desv.) O'Kane & Al-Shehbaz (= Lesquerella globosa) is the only species in North America that occurs east of the Mississippi River. Typically flowering in late spring to early summer, P. globosa has a caudex from which single or multiple erect or spreading stems (30-50 cm) emerge bearing simple entire leaves, racemes of yellow flowers, and a dense covering of trichomes. The species is known to prefer open rocky outcrops within and along the edges of sloped cedar glade type habitats, bluff faces, talus slopes, calcareous soils and disturbed areas such as roadsides, railways, and power line right-of-ways. Most populations are found near flowing water or impoundments. Commonly referred to as Short’s Bladderpod, P. globosa was federally listed as endangered in August 2014 due to loss of habitat, small fragmented populations, competition from native and nonnative plants, prolonged inundation, and erosion across Tennessee, Kentucky, and Indiana populations. Historically, 55 known populations of the endemic forb had been observed; however, it is now known to only inhabit 26 sites. By identifying the limiting factors associated with this federally listed species, further extirpation may be impeded. This research will highlight the P. globosa mode of reproduction (e.g., self-compatibility vs. outcrossing, autogamy vs. heterogamy), and its effect on seed production, viability, and pollination. In addition, the visitation frequency and effectiveness of pollinator species will be explained by invertebrate identification and subsequent assessment of P. globosa pollen loads. Shade tolerance adaptation will be explored by the monitoring of subsets of an entire population representative of varying rates of photosynthetically active radiation. This work is being conducted USACE lands along the Cumberland River near Hartsville, TN, one of the largest identified populations of P. globosa. Research strategies will facilitate a greater understanding into the little known biology P. globosa, and will aid in determination of best management practices in the future.

1 - Tennessee Tech University, Dept. of Biology, 1100 North Dixie Avenue, Pennebaker Hall #207, Cookeville, TN, 38505, USA
2 - Tennessee Tech University, Dept. of Biology, 1100 North Dixie, Cookeville, TN, 38505, USA

Keywords:
Autogamy
heterogamy
effective pollinators
shade tolerance
endangered species.

Presentation Type: Oral Paper
Session: 48, Conservation Biology II
Location: 204/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 2:45 PM
Number: 48005
Abstract ID:725
Candidate for Awards:None