Assessing the relationship between flowering time and fitness in Leavenworthia stylosa

Abstract

Recent research has shown a trend towards early flowering time in a variety of species around the world. Leavenworthia stylosa, a cedar glade species endemic to the Central Basin of Tennessee, appeared to also follow this pattern. Herbarium specimens showed a trend towards earlier flowering in L. stylosa over the last century. In two years of research, there was no overall fitness cost or benefit to flowering earlier than the population average within years, but there was a fitness cost for individuals that flowered later than average. Between years, higher fruit set was found during a year with unusually early flowering compared to a year with more typical flowering time. Based on analyses of historical climate data, earlier flowering did not appear to be due to warmer spring temperatures. Early flowering was also not the result of earlier fall germination time.