The timing and duration of flowering contributes to the reproduction of plant species. Echinacea angustifolia is a long-lived, self-incompatible species, pollinated by generalist pollinators, making it a good model for studying the consequences of habitat fragmentation on plant reproduction. The 104 paternal and 78 maternal plants in this project were part of an open pollination experiment conducted between 8 and 9-year-old plants grown from seeds, collected from local remnant populations and planted in an experimental plot that resembles local fragmented habitat. The resulting seeds were planted in 1m x 1m grid within a nearby prairie plot containing native and naturalized co-flowering species. Because an E. angustifoliaindividual takes several years of growth before flowering, 2015 was the first year where adequate numbers of the individuals flowered allowing for these analyses. We monitored flowering phenology of 197 flowering plants beginning in early July and ending in late August, collecting data from each individual every third day. We recorded flowering stage of every plant to determine the first day and last day of flowering. To estimate heritability, we compared the flowering time and duration of the parental plants observed in 2005 to their progeny observed in 2015. To account for variations in factors such as rainfall and temperature between years we standardized these data around each year’s peak flowering day (the day most plants were in flower). We then set the start date to a number that describes the number of days before peak flowering.
Using quantitative genetic regression models to determine narrow-sense heritability we found that both flowering time and duration are heritable h2 = 0.15 (p = 0.02) and h2 = 0.157 (p = 0.008). Single parent regression analysis showed that maternal flowering time contributed to the offspring with a heritability estimate of h2 = 0.175 (p = 0.02), while we found little evidence for a paternal contribution (p = 0.22). We found a similar pattern for single parent duration with maternal heritability estimated as h2 = 0.241 (p = 0.0006) and no paternal contribution (p = 0.56). Previous results demonstrate that E. angustifolia individuals assortative mate by flowering time. These results indicate that plants with similar flowering times are more likely to be related. Therefore the phenological assortative mating can increase inbreeding and subsequent inbreeding depression in fragmented E. angustifolia populations.