Remnants of the past: Ecology of relict Anticlea populations in Missouri

In the northern hemisphere, many plant species contracted their ranges during the last glacial period to southern refugia from which they rapidly expanded northward after deglaciation. Some relict populations still persist in these paleorefugia, far from the core of the contemporary range. Paleoendemic populations, in addition to being isolated, are frequently small in size relative to conspecifics in the contemporary core range. Relict plant populations are often protected by conservation agencies because they contribute to regional biodiversity and because they may contain genetic diversity absent in core populations. Usually, localized microclimates are presumed to facilitate population persistence, but few studies have investigated this, or the dynamics of relict populations. I monitored microclimate and population characteristics from 1999-2002 in three Missouri sites supporting relict Anticlea elegans populations. I also used intersimple sequence repeat markers to assess genetic relationships between study populations and nine other relict and non-relict Anticlea elegans populations. Results showed that microclimate in relict sites is moderated year-round relative to surrounding climate, and that higher daily minimum temperatures rather than lower daily maximum temperatures best differentiates relict Anticlea habitat in southern Missouri from surrounding climate. Within study sites, Anticlea populations demonstrated long survival of genets, stage class stability, and absence of recruitment, fitting a model of remnant population dynamics. I also found that five Missouri relict populations, which occur within a 50 km radius, are more differentiated from each other than twelve relict and non-relict populations across an area of more than 2000 km. My data emphasize the importance of Missouri as a glacial refuge and the importance of Missouri sites in maintaining relict populations through time.