Abstract Detail

Biogeography

Saghatelyan, Anna [1].

Biogeographical Connections of South Texas Flora.

With phylogenetic relationships clarified for many taxa, comparative analyses of entire floras can elucidate their geographical connections and regionalization. Local floras of south Texas, situated on the boundary of the Boreal and Madrean Subkingdoms of Takhtajan system and in proximity to the Neotropical Kingdom, show a complex pattern of geographical connections. For this study I chose southernmost Texas, which is a part of Tamaulipan Province of Morrone with somewhat controversial placement. A flora of 13 counties, S TX flora (S TX), in South Texas Plains ecoregion was compiled and all the species distribution tracks were outlined. The flora was analyzed and compared to two other Texas floras: Big Bend Region (BB) with 1587 species and Edwards Plateau (EP) with 1619 species. South TX Plains has 1259 species in the flora and is dominated by subtropical thorn scrub vegetation. The spectra of all different floristic elements of these three floras were compared to each other. Phylogenetic literature was searched to find relationships, patterns of migrations, and geographical connections of major clades. The placement of BB in the Chihuahuan Subprovince of the Madrean Subkingdom was confirmed: 58% of its flora is in the combined south-western north American/madrean geoelement, as opposed to 29% of that element in EP and only to 24% in S TX. In EP 42% of the flora belongs to the Atlantic Region, mostly the Prairie Province. In S TX 31% of the flora is in the combined tropical/gulf coast/tamaulipan element. S TX flora has 360 species which are absent from EP, almost all of them being tropical/subtropical, tamaulipan, or gulf/caribbean species. Temperate genera have two times more species in EP than in S TX. Western North American genera have three times more species in BB and two times more species in EP than in S TX. The species of tropical genera comprise 34% in BB, 29% in EP, and 43% in S TX flora. Preliminary results indicate that S TX, with 180 subendemic and 80 endemic tamaulipan species, is well placed in the Tamaulipan chorion and shows stronger tropical/subtropical connections than the other two TX floras. It has more Chihuahuan Subprovince (27% of S TX) than the Atlantic Region (22 % of S TX) species. The flora is an ecotone from the Gulf Province to the Chihuahuan Subprovince of the Madrean Region and Prairie Province of the Atlantic Region.

1 - McMurry University, McMurry Station Box 368, Abilene, TX, 79697, USA

Keywords:
species distribution
comparative floristic analysis
Texas
geoelement
flora
Tamaulipas.

Presentation Type: Oral Paper
Session: 43, Biogeography III
Location: 205/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 1:45 PM
Number: 43002
Abstract ID:863
Candidate for Awards:None