Abstract Detail

Population Genetics/Genomics

Zumwalde, Bethany A. [1], Prather, L. Alan [2], Ferguson, Carolyn J. [3], Fehlberg, SHANNON D [1].

Fine-scale population genetic, morphological and ecological segregation of Phlox amabilis diploid and tetraploid cytotypes in a contact zone.

Studies of polyploidy and cytotype variation in Phlox have revealed widespread genome duplication between and within species. Our recent work has focused on the morphological, evolutionary, population genetic, and environmental niche differentiation of cytotypes in three diploid-polyploid complexes from the southwestern United States: Phlox amabilis, P. nana, and P. woodhousei. In P. amabilis, environmental niche modeling at a broad spatial scale indicates clear differentiation of habitat suitability and climatic variables for hexaploid cytotypes but considerable overlap between diploid and tetraploid cytotypes. Here we report on local cytotype distribution at a diploid-tetraploid contact zone in P. amabilis and on correlation of this distribution with genetic variation, morphology, and fine-scale ecological properties. Our overarching goal is to identify factors that contribute to environmental niche differentiation of ploidy levels. We documented broad-scale cytotype variation in P. amabilis across 28 sites using flow cytometry. At 27 of these sites, only a single cytotype was observed (with the exception of rare triploids found at three diploid sites) resulting in 16 diploid, six tetraploid, and five hexaploid sites. At the remaining site in Prescott National Forest in Arizona, diploids and tetraploids were found to co-occur. At this site, we gathered detailed information for 65 representative plants, including cytotype, genetic diversity at six microsatellite loci, morphological diversity, carbon and nitrogen isotope composition of leaves, and vegetation and soil attributes. In general, all analyses indicated fine-scale differentiation of diploid and tetraploid plants. Diploids and tetraploids were genetically distinct, with nearly one third of observed alleles unique to each cytotype, supporting the hypothesis of secondary contact. Morphological characters differed across cytotypes for both vegetative and reproductive traits, potentially correlating with other observed differences. Carbon and nitrogen isotope concentrations were similar between cytotypes; however, the percentage of nitrogen was higher and the carbon to nitrogen ratio was lower for tetraploids, suggesting higher photosynthetic capacity. Four soil attributes differed between diploids and tetraploids, including nitrates, calcium, potassium, and pH. We interpret these results in the context of broader, regional cytotype distributions, genetic variation, soil attributes, and environmental niche modeling. The results presented here suggest that identification of genetic and ecological factors contributing to the spatial distribution of cytotypes at fine scales can improve our knowledge of the contributions of polyploidy to different aspects of diversity, evolution, and speciation.

1 - Desert Botanical Garden, 1201 N. Galvin Pkwy., Phoenix, AZ, 85008, USA
2 - Michigan State University, PLANT BIOLOGY, Plant Biology Laboratories, 612 Wilson Rd, Rm 48, East Lansing, MI, 48824-1312, USA
3 - Kansas State University, Herbarium and Division of Biology, Ackert Hall, Manhattan, KS, 66506, USA

Keywords:
cytotype
Polyploidy
ecological niche modeling
microsatellites
Morphology
ecophysiology
Polemoniaceae
Phlox.

Presentation Type: Oral Paper
Session: 40, Population Genetics/Genomics
Location: Sundance 5/Omni Hotel
Date: Wednesday, June 28th, 2017
Time: 2:30 PM
Number: 40005
Abstract ID:401
Candidate for Awards:None