Y Franchesco Molina-Henao1,2,3, Robin Hopkins1,2. 1. Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA. 2. The Arnold Arboretum, Harvard University, Boston, MA, 02131, USA. 3. Departamento de Biología, Universidad del Valle, Cali, Valle, 760032, Colombia.
Abstract
PREMISE OF THE STUDY: Successful establishment of neopolyploids, and therefore polyploid speciation, is thought to be contingent on environmental niche shifts from their progenitors. We explore this niche shift hypothesis in the obligate outcrosser Arabidopsis arenosa complex, which includes diploid and recently formed autotetraploid populations. METHODS: To characterize the climatic niches for both cytotypes in Arabidopsis arenosa, we first gathered climatic data from localities with known ploidy types. We then estimated the climatic niches for diploids and autotetraploids and calculated niche overlap. Using this niche overlap statistic, we tested for niche equivalency and similarity. We explored differences in niches by estimating and comparing niche optimum and breadth and then calculated indices of niche expansion and unfilling. KEY RESULTS: Climatic niche overlap between diploids and autotetraploids is substantial. Although the two niche models are not significantly divergent, they are not identical as they differ in both optimum and breadth along two environmental gradients. Autotetraploids fill nearly the entire niche space of diploids and have expanded into novel environments. CONCLUSIONS: We find climatic niche expansion but not divergence, together with a moderate change in the niche optimum, in the autotetraploid lineage of Arabidopsis arenosa. These results indicate that the climatic niche shift hypothesis alone cannot explain the coexistence of tetraploid and diploid cytotypes.
PREMISE OF THE STUDY: Successful establishment of neopolyploids, and therefore polyploid speciation, is thought to be contingent on environmental niche shifts from their progenitors. We explore this niche shift hypothesis in the obligate outcrosser Arabidopsis arenosa complex, which includes diploid and recently formed autotetraploid populations. METHODS: To characterize the climatic niches for both cytotypes in Arabidopsis arenosa, we first gathered climatic data from localities with known ploidy types. We then estimated the climatic niches for diploids and autotetraploids and calculated niche overlap. Using this niche overlap statistic, we tested for niche equivalency and similarity. We explored differences in niches by estimating and comparing niche optimum and breadth and then calculated indices of niche expansion and unfilling. KEY RESULTS: Climatic niche overlap between diploids and autotetraploids is substantial. Although the two niche models are not significantly divergent, they are not identical as they differ in both optimum and breadth along two environmental gradients. Autotetraploids fill nearly the entire niche space of diploids and have expanded into novel environments. CONCLUSIONS: We find climatic niche expansion but not divergence, together with a moderate change in the niche optimum, in the autotetraploid lineage of Arabidopsis arenosa. These results indicate that the climatic niche shift hypothesis alone cannot explain the coexistence of tetraploid and diploid cytotypes.
Authors: Guillaume Wos; Jana Mořkovská; Magdalena Bohutínská; Gabriela Šrámková; Adam Knotek; Magdalena Lučanová; Stanislav Španiel; Karol Marhold; Filip Kolář Journal: Ann Bot Date: 2019-09-24 Impact factor: 4.357
Authors: Mariana Castro; João Loureiro; Albano Figueiredo; Miguel Serrano; Brian C Husband; Sílvia Castro Journal: Front Plant Sci Date: 2020-03-19 Impact factor: 5.753