Increases in Genetic Diversity of Weedy Rice Associated with Ambient Temperatures and Limited Gene Flow.

Hua Kong,Yu-Liang Zhang,Bao-Rong Lu,Qi-Yu Xia,An-Ping Guo,Zhi Wang,Jing-Yuan Guo,Hui Zhao

doi:10.3390/biology10020071

Abstract

Simple SummaryIncreased genetic diversity in plants is probably associated with greater ambient temperatures. To test this hypothesis, we studied genetic diversity and differentiation of weedy rice populations occurring in the early- and late-season rice cultivation fields in Leizhou of southern China. Data collected from 10-year climatic records showed a higher average temperature in the late rice-cultivation seasons than in the early rice-cultivation seasons. Results obtained based on 27 SSR (simple sequence repeat) loci indicated greater genetic diversity in the late-season weedy rice populations, in addition to the considerable genetic differentiation between the early- and late-season weedy rice populations. We therefore conclude that a higher ambient temperature might be an important factor to promote the formation of genetic diversity in the late-season weedy rice populations.Hypotheses regarding the association of increased species or genetic diversity with gradually warmer regions as a global pattern have been proposed, but no direct and solid experimental data are available to approve the association between plant genetic diversity and ambient temperatures. To test the diversity-temperature hypothesis, we studied genetic diversity and genetic differentiation of weedy rice (Oryza sativa f. spontanea) populations occurring naturally in early- and late-season rice fields that share nearly the same ecological conditions but with slightly different temperatures. Data collected from 10-year historical climatic records indicated a ~2 °C higher average air temperature in the late rice-cultivation seasons than in the early seasons. Results based on molecular fingerprints of 27 SSR (simple sequence repeat) loci showed a higher level of genetic diversity in the late-season weedy rice populations than in the early-season populations. In addition, a positive correlation was detected between the increased proportion of genetic diversity (ΔHe) and genetic differentiation among the weedy rice populations, suggesting limited gene flow. Therefore, we conclude from this study that increased genetic diversity in the late-season weedy rice populations is probably caused by the higher ambient temperatures. This finding provides evidence for the possible association between genetic diversity and ambient temperatures.

Highlights

Biodiversity plays an important role in maintaining the balance of the biosphere and sustaining human livelihood [1,2]
The results indicated that the early- and late-season weedy rice populations had considerable genetic differentiation based on the fingerprints generated from 27 sequence sequence repeat repeat (SSR) loci
In the corresponding early- and populations wasofobtained on the basis of the estimated best fit K-value as 5 late-season according topopthe ulation pairs (Figureanalysis, 2B). These results probably suggestedK-values that a higher level6 of genetic

Summary

Introduction

Biodiversity plays an important role in maintaining the balance of the biosphere and sustaining human livelihood [1,2]. It is generally considered that biodiversity is distributed heterogeneously around the globe due to the tremendous differences in the ecological habitats where organisms inhabit. Such differences include temperature variation with latitudinal gradients [4,5,6,7], altitudinal gradients [8], and vertical gradients in the oceans [9]. A veritable explosion of studies has focused on the large-scale spatial patterns and species levels of biodiversity [10,11,12,13]. Only a few studies focused on the examination of associations between the temperature gradient and biodiversity at the genetic level within populations or species [14,15]

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