Abstract Detail

Biogeography

Prather, L. Alan [1], VanTill, Alex [1], Chansler, Matt [2], Fehlberg, Shannon D. [3], Ferguson, Carolyn J. [4].

Preliminary analysis of local cytotypic, morphological and ecological variation in Phlox amabilis plants at Table Top Mountain, Arizona.

Polyploidy is an important evolutionary force in angiosperms and is increasingly recognized as contributing to extant patterns of diversity in some species. Ongoing studies of polyploidy in Phlox have uncovered intraspecific cytotypic variation in many species. In most of these cases, only one cytotype occurs at a given site, as predicted by theories of competitive and minority cytotype exclusion. Phlox amabilis, Arizona phlox, follows this pattern. This species is endemic to northwestern Arizona and is a species of conservation concern because there are few documented populations. Previously published and newly added cytotypic data revealed considerable variation among sites, but only a single cytotype at 15 sites studied. Seven diploid, three tetraploid, and five hexaploid sites were documented. At the remaining site, near Table Top Mountain in the Santa Maria Mountains of west-central Arizona, diploid and tetraploid individuals co-occur. At this site, extensive studies of fine scale patterns of cytotypic, morphological and ecological variation were undertaken. Diploids were generally dispersed broadly while tetraploids occurred in a more limited portion of the site. However, the two cytotypes were found to be somewhat intermixed, with individuals of different ploidy levels sometimes found to be growing within meters of one another. Eleven of 15 morphological traits differed significantly between the cytotypes (p<0.05, t-test), including traits known to differ between polyploids such as guard cell size and pollen grain diameter, and also traits such as upper leaf length and thickness, and corolla lobe length and notch depth. Of the eleven soil attributes studied, five differed significantly between diploids and tetraploids (p<0.05, t-test). Diploids grew on soil with lower pH, lower silt content, higher concentrations of magnesium, and lower concentrations of potassium and nitrate. Distance to the nearest woody plant was significantly greater for diploids. These morphological and ecological differences observed between cytotypes suggest that they may occupy different niches at this site. Future work will explore this possibility.

1 - Michigan State University, Department of Plant Biology, 612 Wilson Road, Department of Plant Biology, East Lansing, MI, 48824, United States
2 - Michigan State University, Department of Plant Biology, 612 Wilson Road, East Lansing, MI, 48824, United States
3 - Desert Botanical Garden, 1201 N. Galvin Pkwy., Phoenix, AZ, 85008, USA
4 - Kansas State University, Division Of Biology, Ackert Hall, Manhattan, KS, 66506-4901, USA

Keywords:
Phlox
amabilis
Polyploidy
diploid
tetraploid
Arizona
Prescott.

Presentation Type: Oral Paper:Papers for Topics
Session: 72
Location: Salon 3/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 3:45 PM
Number: 72008
Abstract ID:1177
Candidate for Awards:None