Skip to main content
Dryad

A cline within an ecotype of the yellow monkeyflower, Mimulus guttatus

Zambiasi, Thomas1; Lowry, David B.2

Published Aug 08, 2024 on Dryad. https://doi.org/10.5061/dryad.4tmpg4fkh

Data files

Aug 08, 2024 version files 172.87 KB

Abstract

A key goal of evolutionary biologists is to understand how and why adaptive genetic variation is partitioned within species. In the yellow monkeyflower, Mimulus guttatus (syn. Erythranthe guttata), coastal perennial populations collectively constitute a single genetically and morphologically differentiated ecotype. While the distinctiveness of the coastal ecotype has now been well documented, there is also variation in environmental factors across the range of the coastal ecotype that could drive differentiation among its component populations in a more continuous way. Based on previous observations of a potential cline within this ecotype, we quantified plant height across coastal perennial accessions from 69 total populations in two greenhouse common garden experiments. To evaluate possible environmental factors driving the relationship between plant height and latitude, we regressed height against multiple climatic factors, including temperature, precipitation, and coastal wind speeds. In both experiments, plant height was negatively correlated with latitude. Mimulus height correlated positively with annual precipitation and with mean wind speed, to a lesser degree, and negatively with annual mean temperature. We hypothesize that one or more of these factors drove clinal variation within the coastal ecotype. Overall, our study illustrates the complexity of how the distribution of environmental variation can simultaneously drive the evolution of distinct ecotypes as well as continuous clines within those ecotypes. These results are discussed in the context of the classic criticisms of ecotypes being intermediates in the process of speciation.