Roche, Bernadette , Lloyd, Michael , McIntyre, Meaghan .
Local adaptation in diverse populations of the lyre-leaved rock cress, Arabidopsis lyrata.
The lyre-leaved rock cress, Arabidopsis lyrata, occurs in a diversity of habitats across the eastern portion of North America. Our study includes populations of this perennial herb from serpentine barrens in Maryland (Pilot Serpentine Barren and Soldiers Delight), rocky outcrops along the Shenandoah River in Virginia (Calmes Neck), and limestone sand plains in New York (Perry Nature Preserve). The plants exhibit different morphological characteristics in the three habitat types (serpentine barren, rocky outcrop, and sand). The purpose of our study was to determine if these differences were due to phenotypic plasticity or genetic differentiation. We conducted a common garden experiment, using 4 populations planted in a randomized block design in three flats (up to 72 plants per block), measuring time to cotyledon emergence (days), rate of leaf bud emergence (leaf buds/day), and, for 3rd and 5th leaves on days 5 and 10 since emergence: leaf length, width, and height, and petiole length (mm). For most of the parameters measured, we found strong evidence for genetic differentiation among populations from different habitat types (significant population effect), with the suggestion that the traits were heritable (significant family within population effect). By creating soil-agar amalgamations with pulverized rock collected from 4 sites, we also assessed whether populations exhibited home soil advantage for early life history traits: germination success (%), days to germination, and early root growth (mm). Seeds from each site were placed on the different soil-agars (8 replicates/soil type, 2 seeds/population/replicate), and assessed daily for germination and subsequent root elongation using digital photography. We found strong evidence for home soil advantage for root elongation (significant effects of soil, population, and soil by population interaction in repeated measures MANOVA). Thus it appears that these populations are genetically differentiated for early shoot and leaf characteristics, and are locally adapted in their root elongation.
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1 - Loyola College, Biology, 4501 N. Charles Street, Baltimore, Maryland, 21210, USA
Presentation Type: Oral Paper
Location: Salon A - Gov Ballroom/Hilton
Date: Monday, August 15th, 2005
Time: 11:00 AM