Abstract Detail

Population Genetics/Genomics

Spalink, Daniel [1], Karimi, Nisa [2], Richards, Jeannine [3], Thein, Tom [3], Eifler, Evan [4], DiNicola, Alexa [5], Schomaker, Lisa [6], Givnish, Thomas [7].

Passive seed dispersal, strong genetic structure, and small spatial scale of gene flow associated with morphological divergence in the desert winter annual, Eschscholtzia parishii: potential implications for rapid small-scale speciati.

Herbaceous annuals make up a large proportion of floristic diversity in the American deserts. While this striking diversity is clearly evident in episodic super blooms, as seen this year in the Sonoran Desert, the underlying historical drivers of this diversity are generally unknown. Several factors – such as spatiotemporal patchiness of flowering, among-year variation in rainfall and favored ecophysiological traits, almost exclusive zoophily, and the open physiognomy of deserts – have all been proposed as potential causes of desert annual diversity. One factor has generally been overlooked: the lack of obvious means of long-distance seed dispersal in most desert annual lineages, with potential consequences for genetic differentiation at small spatial scales which could lead ultimately to rapid speciation and endemism at small spatial scales. If this hypothesis is correct, we would expect that individual species of desert annuals would have populations with strong genetic structure and a short distance of average gene flow. To test this hypothesis, we sampled six populations of Eschscholtzia parishii (Papaveraceae) across a 17-mile radius in Anza Borrego Desert State Park in southern California. We measured genetic diversity, structure, and the spatial distance of gene flow in and across these populations using SNPs derived from genotyping-by-sequencing (GBS). We also measured floral shapes and sizes from dozens of individuals per population. We found that all populations were genetically distinct despite their close geographic proximity. Two distinct floral morphological types were observed, restricted to the northernmost or southernmost populations. On average, the spatial distance of gene flow s was only 8 meters. These findings offer support to the hypothesis that the high diversity of desert winter annuals may result, in part, from reproductive isolation across small spatial scales, which may in turn be related to limited gene flow distances via seeds.

1 - Texas A&M University, Ecosystem Science And Management, 2138 TAMU, College Station, TX, 77802, United States
2 - University Of Wisconsin - Madison, Department Of Botany, 430 Lincoln Drive, Madison, WI, 53706, United States
3 - University of Wisconsin-Madison, 430 Lincoln Drive, Madison, Wi, 53706
4 - UW Madison, Botany, 430 Lincoln Dr., Madison, WI, 53706, United States
5 - University Of Wisconsin-Madison, Botany Department, 132 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, United States
6 - Institute for Applied Ecology, Corvalis, Oregon
7 - University Of Wisconsin-Madison, Department Of Botany, 430 Lincoln Drive, Madison, WI, 53706.0, United States

Keywords:
gene flow
desert annual
population genetics
spatial scale of gene flow
speciation
morphometrics.

Presentation Type: Oral Paper
Session: POPGEN1, Population Genetics/Genomics I
Location: Tucson H/Starr Pass
Date: Monday, July 29th, 2019
Time: 9:30 AM
Number: POPGEN1007
Abstract ID:941
Candidate for Awards:None