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DISCORDANT LONGITUDINAL CLINES IN FLOWERING TIME AND PHYTOCHROME C IN ARABIDOPSIS THALIANA
Author(s) -
Samis Karen E.,
Heath Katy D.,
Stinchcombe John R.
Publication year - 2008
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.2008.00484.x
Subject(s) - biology , photoperiodism , epistasis , adaptation (eye) , cline (biology) , population , evolutionary biology , ecology , botany , genetics , gene , demography , neuroscience , sociology
Using seasonal cues to time reproduction appropriately is crucial for many organisms. Plants in particular often use photoperiod to signal the time to transition to flowering. Because seasonality varies latitudinally, adaptation to local climate is expected to result in corresponding clines in photoperiod‐related traits. By experimentally manipulating photoperiod cues and measuring the flowering responses and photoperiod plasticity of 138 Eurasian accessions of Arabidopsis thaliana, we detected strong longitudinal but not latitudinal clines in flowering responses. The presence of longitudinal clines suggests that critical photoperiod cues vary among populations occurring at similar latitudes. Haplotypes at PHYC, a locus hypothesized to play a role in adaptation to light cues, were also longitudinally differentiated. Controlling for neutral population structure revealed that PHYC haplotype influenced flowering time; however, the distribution of PHYC haplotypes occurred in the opposite direction to the phenotypic cline, suggesting that loci other than PHYC are responsible for the longitudinal pattern in photoperiod response. Our results provide previously missing empirical support for the importance of PHYC in mediating photoperiod sensitivity in natural populations of A. thaliana . However, they also suggest that other loci and epistatic interactions likely play a role in the determination of flowering time and that the environmental factors influencing photoperiod in plants vary longitudinally as well as latitudinally.