Tom Masters Within Species Variation of Sceptridium biternatum Assessed by ISSR-PCR Division Sciences Department Biology Year 2004 Advisor Warren Hauk

The grapefern Sceptridum biternatum is common in the forests, swamps, fields, and knolls of the southeastern United States.  Although well known throughout its geographic range, populations from central Florida exhibit morphological traits not seen in more northern and western states. To examine genetic variation within S. biternatum, ISSR-PCR was utilized.  F-statistics documented a low amount of genetic structuring among populations and a high degree of inbreeding.  For some populations, Neighbor Joining, Maximum Parsimony, and UPGMA analyses revealed moderate to low correlation between genotype and geographic origin.  The Florida populations were not genetically different from more northern populations, suggesting the unique morphology is not a reflection of underlying genetic difference.  High spore dispersal may explain the lack of clustering among individuals from the same population. Given the putative inbreeding nature of S. biternatum, these results indicate that dispersal may trump breeding system in determining the overall genetic structure of S. biternatum.