Home | Business News | Browse by Publication | J | Journal of the Mississippi Academy of Sciences

Ecology and evolutionary biology.

Article Excerpt
Chair: Robert Hamilton, Mississippi College

THURSDAY MORNING

Chesnut

O4.01

9:00 PHYLOGENY, CLASSIFICATION, AND IDENTIFICATION OF THE TROPICAL PLANT FAMILY SAMYDACEAE

Mac Alford, Angela Dement

University of Southern Mississippi

The flowering plant family Samydaceae consists of 14 genera and about 240 species of tropical trees and shrubs. Although closely related to willows, cottonwoods, violets, and passion flowers, the family has received less attention because its species are exclusively tropical and have minute flowers, making collection and identification difficult. In order to facilitate identification, an interactive, electronic key was created for all of the species in the family and will be demonstrated. The key was then used to check identifications of material collected for a study of relationships within the family. A previous study indicated that the largest genus in the family, Casearia, is not monophyletic, but the support values were generally low. In this study, we sampled the same species for different genetic regions to determine if additional variation would affirm or refute the previous hypothesis. DNA sequences from more variable plastid regions and from the nucleus proved useful, but DNA sequences from two mitochondrial regions was almost invariable (5 differences / 2000 base-pairs). Phylogenetic analyses of the DNA data affirm the previous hypothesis that Casearia is not monophyletic and that changes in classification are needed.

O4.02

9:15 RESPONSES OF LOWER MISSISSIPPI RIVER PHYTOPLANKTON BIOMASS AND COMPOSITION DUE TO NUTRIENT ADDITIONS

Heath E. Capello, Clifford Ochs

University of Mississippi

In large rivers like the Lower Mississippi River (LMR), abiotic features, such as discharge and light, are usually considered the major factors influencing the biomass and composition of potamoplankton. Because large rivers are often turbid, nutrient limitation is thought rarely to be an issue. However, as the light regimes change in rivers due to human alterations of lotic systems, nutrients may alter phytoplankton community dynamics. This research seeks to understand how nitrogen, phosphorus, and silica inputs can change LMR phytoplankton. Samples were taken in the main channel of the LMR at two different locations over the course of a year. After being returned to the laboratory, phytoplankton were cultured at in situ temperatures and treated with nutrients in a factorial design. Chlorophyll fluorescence and high-performance liquid chromatography were employed to track changes in biomass and community...

View this article FREE - Now for a Limited Time, try Goliath Business News
Free for 3 Days!