Data for Evolutionary responses of a dominant plant along a successional gradient in a salt-marsh system

The
ecological responses of plant populations along a successional gradient have
been intensively examined; however, the evolutionary responses received much
less attention. Here, I explored genetic changes of key phenotypic traits of a
dominant clonal plant (Elytrigia atherica) along a saltmarsh successional
gradient by collecting samples along the successional gradient in the high and
low marsh and growing them in a common environment (greenhouse). Additionally, to
explore whether changes in traits are driven by abiotic (e.g. clay thickness) and
biotic (e.g. grazing intensity) variables along the successional gradient, I
measured these two variables in the field. I found that clay thickness (a proxy
of total nitrogen) increased along the successional gradient both in the high
and low marsh; grazing intensity from hares (the most important herbivores)
decreased along the successional gradient in the high marsh but did not change
in the low marsh. Meanwhile, I found that growth in number of leaves and ramets
decreased, while rhizome length increased, along the successional gradient for E.
atherica collected from the high marsh. Opposite trends were found for E. atherica
collected from the low marsh. Results suggest that, in the high marsh,
herbivores may overrule nutrients to drive trait changes. That is, at the early
successional stages, E. atherica had higher growth in number of leaves and
ramets to compensate for high-intensity grazing. In the low marsh, nutrients may
be the dominant driver for trait changes. That is, at the late successional
stages, E. atherica had higher growth in number of leaves and ramets but
shorter rhizomes to maximize its expansion under the favorable conditions (high
nutrient availability). Results suggest that ecologically important abiotic and
biotic variables such as nutrients and herbivores may
also have a substantial evolutionary impact on plant populations.

Data
include traits, clay thickness, droppings.