Report on my visit to Kyoto University as an Advanced Futures Fellow: Evolution of cyanogenesis in Trifolium repens in response to spatial and temporal environmental variation in Japan

Abstract

Here I report on my activity from April to June 2018 as an Advanced Futures Fellow at Kyoto University. During this time, I examined how the plant white clover (Trifolium repens), adapts to spatial variation at large and small spatial scales associated with environmental variation in temperature. At a large spatial scale, I sampled 25 T. repens populations from the South to the North of Japan, and assayed the frequency of plants that produce hydrogen cyanide (HCN), an antiherbivore defence trait that also reduces tolerance to freezing and varies due to Mendelian inheritance at two loci. I further tested for genetic clines in HCN along urban-rural gradients across three cities (Sapporo, Kyoto and Hiroshima). Trifolium repens exhibited a a decrease in the frequency of HCN genotypes with increasing latitude and lower temperatures. The strength of these clines were stronger than clines sampled seven decades ago, suggesting that T. repens has continued to adapt to large scale climatic gradients in Japan since its introduction in the 1800s. I detected a cline in HCN along the urban-rural gradient of Kyoto, whereas there were no clear genetic clines in either Sapporo or Hiroshima. My results show that T. repens adapts to large scale environmental gradients but seldom adapts to small scaleenvironmental variation in Japan.