Abstract Detail

Biogeography

Saghatelyan, Anna [1].

Geographical relationships and comparative analysis of three natural floras in South Texas.

Southernmost tip of Texas is a part of Tamaulipan Province which some authors consider in the Madrean Subkingdom of Holarctic Kingdom, while others in the “Xerofitica Mexicana” of Neotropical Kingdom. To shed more light on this question a natural flora of fourteen counties in S TX Plains ecoregion, South Texas Plains flora (STX), was studied from a biogeographical perspective and compared with two adjacent southern Texas floras: Edwards Plateau (EP) and Big Bend (BB). I will present the final analysis, which was based on the species and genera distribution outlines and phylogenetic literature searches to find relationships and patterns of migration of species of major clades. STX with 1250 species of 554 genera, being on the crossroads of migration routes, has multiple connections with adjacent floristic centers. Tamaulipan endemism is not particularly high in comparison with twice higher Chihuahuan endemism in BB. Largest families show much higher numbers of tropical-subtropical, Tamaulipan, Gulf Coast, and Mesoamerican species in STX in comparison with those in EP. To the contrary, North temperate, EN American, and Chihuahuan species are much more numerous in EP than in STX. Majority of the BB differential species are in Chihuahuan, SW N American, Sonoran/Apachian, and Madrean geoelements. Geographical spectra of all genera in the three floras show prevalence of species of tropic-subtropical genera: 51.5% in STX; 40% in EP and BB. Temperate genera have 25.4% in EP, 20.4% in BB, and only 16.5% in STX. Western/southwestern N American genera have 21% in BB, 13.4% in EP, and 11.5% in STX. The geographical spectra of species show higher numbers of Neotropical, Gulf Coast-Caribbean, and other tropical/subtropical geoelements in STX. The species of Holarctic Subkingdom/N American Atlantic Region comprise 36% in STX, which is four times more than those in BB. They show closer affinity of STX to EP, which has 47% of its species in this group. Many differential among the three floras genera, especially of the largest family Asteraceae, underscore importance of Mexican centers of diversity in the assembly of the STX flora. The generic and specific geographical spectra of STX illustrate its transitional position-an ecotone between the Western (Madrean) and Eastern (Atlantic and Gulf Coast) N American Regions, with a very high influence of various tropical elements and a higher affinity to the EP flora than to that of BB.

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

Keywords:
Texas
floristics
geographical connections
Tamaulipas.

Presentation Type: Oral Paper
Session: 13, Biogeography
Location: Sundance 3/Omni Hotel
Date: Monday, June 26th, 2017
Time: 4:45 PM
Number: 13012
Abstract ID:487
Candidate for Awards:None