REU Supplement: Collaborative Research: Linking Abiotic Stress to Gender Specific Fitness in a Desert Bryophyte

Morphological and physiological differences along an environment gradient in a desert moss. Phenotypic variation within species across habitats can result from plasticity or genetic variation. The desert moss Syntrichia caninervis grows along a light and temperature gradient: in the understory, light and temperature are low relative to the inter-story between shrubs. Syntrichia caninervis appears morphologically distinct between these environments. The ultimate goal of this study is to determine if differences are plastic or genetic. An initial study was preformed to quantify morphological and physiological differences. Shoots were collected in the Mojave Desert from 16 pairs (understory and interstory patches). Shoots were measured for shoot and leaf morphological traits. A subset of pairs (9) was rehydrated for 72hr hours in both a high light and low light conditions. Flourescence (Fv/Fm) readings were taken before, immediately after, 24hr after, and 48hr after a heat shock treatment of 40°C for one hour. Leaf length and shoot length and width were all found to be significantly larger in understory shoots. There was no statistical difference in the initial Fv/Fm between plants from the interstory and understory. However compared to plants in high light conditions, plants from both habitats showed faster recovery in low light 48hr after the heat shock. These results demonstrate that understory shoots are larger than interstory shoots. The Fv/Fm data suggests that the ideal environment for shoot recovery from high heat is low light and the understory is the more favorable habitat. We are currently collecting data from a common garden to determine if morphological differences are genetic or environmental.