QCBS Students

Malie Lessard-Therrien

McGill University
M.Sc. candidate

Supervisor: Jonathan Davies
Start: 2011-09-01
End: 2013-08-15

A phylogenetic study of flowering phenology in tundra plants of the Canadian Subarctic
The study of plant phenology has gained new importance in the context of climate change. Tundra plant species are of particular interest as they strongly cue on climatic variables to trigger their phenology and the tundra is experiencing the highest warming trend globally. In this thesis, I describe patterns of flowering phenology in a subarctic plant community using a phylogenetic comparative approach. My research addresses two primary goals: (i) clarifying the relative roles of environmental constraints and evolution history on flowering phenology in tundra communities, and (ii) establishing the connection between key abiotic and biotic factors and the onset of flowering phenology while controlling for phylogenetic relationships between species. A field survey conducted on Mount Irony (856 m), North-East Canada (54°90′N, 67°16′W) during summer 2012 revealed that flowering patterns differed substantially between communities at different elevational bands. First, flowering day was phylogenetically conserved only for communities found at lower elevational bands where environmental conditions are less harsh. Snowmelt date, elevation and thawing degree days were the dominant abiotic controls on phenology. Early flowering species showed less variability in their first flowering dates than late flowering species during the growing season, reflecting higher sensitivity to climatic cues early in the spring. By establishing a link between phenological responses and evolutionary relationships, we can evaluate how constrained or variable phenology may be across species, communities, sites and time, allowing us to work forward to predict adaptive potential in response to future climate change.

1- A phylogenetic comparative study of flowering phenology along an elevational gradient in the Canadian subarctic
Lessard-Therrien, Malie, T. Jonathan Davies, Kjell Bolmgren
2013 International Journal of Biometeorology