Variation within a species can affect community and ecosystem processes, but little is known about how effects of genetic-based variation compare to effects of variation in key species traits.

In a year-long manipulative field experiment, recently published in Journal of Ecology, Assistant Professor Randall Hughes used 12 unique Spartina alterniflora plant genotypes to test the effects of genetic diversity (number of genotypes) and trait diversity (variability in stem height). When variation in stem height was low, Hughes found that the plants performed better with higher genotypic diversity. However, when there was high variation in stem height, there was no benefit of increasing genetic diversity for plant performance. Hughes also found idiosyncratic effects of genetic diversity and trait diversity on below ground responses  (infaunal abundance and sediment oxygen) that mirrored patterns in plant percent cover.

This study suggests that relatively simple measures of diversity – here, variation in plant stem height – can increase plant performance,  particularly when genetic diversity is low.