Abstract Detail

Ecology

Melen, Miranda [1], Lustenhouwer, Nicky [1], Parker, Ingrid [2].

Eco-evolutionary drivers of native and exotic range expansion in a weedy annual plant, Dittrichia graveolens (Asteraceae).

Globally, many species are expanding ranges, either in response to climate change in their native range or after introduction to a new environment. In order to understand whether species will track climate or colonize new areas, it is critical to understand the drivers of population spread. Recent work has shown that spreading populations can evolve rapidly, greatly complicating range expansion forecasts. We studied differentiation in dispersal and reproductive rates as well as phenology in a species that is currently expanding its native range and invading a new continent. Dittrichia graveolens (stinkwort) is an annual plant in the Asteraceae family that is native to the Mediterranean Basin in Europe where it grows along roadsides and in disturbed soils. While this species is actively spreading north to higher latitudes in Europe, it is also invading east to higher altitudes in California where it is considered a noxious and invasive weed. This is a unique opportunity to assess rapid evolution in a species that is undergoing range expansion on one continent and invasion on another. We collected seeds from 18 populations in Europe and 28 populations in California and grew them in a greenhouse at the University of California, Santa Cruz. We monitored phenology and measured several plant traits that are expected to be under selection during range expansion because they promote population spread: plant height and seed weight (affecting dispersal) and number of seed heads and number of seeds per head (affecting plant fecundity). We found that the phenology of California plants closely matched the phenology of European plants from a similar Mediterranean climate. California plants and European plants showed a similar number of seed heads, but California plants generated fewer seeds per head. Height varied negatively with increasing latitude rather than along the range expansion gradients, suggesting that rather than selection for dispersal, climate factors were a more important driver of variation in plant height. Understanding how evolution shapes populations during spread will help conservation managers working with native species facing climate change, and also policymakers and practitioners assessing plant invasion risk.

1 - University of California, Santa Cruz, Department of Ecology and Evolutionary Biology, 130 McAllister Way, Santa Cruz, CA, 95060, USA
2 - University Of California Santa Cruz, Department Of Ecology And Evolutionary Biology, 130 McAllister Way, Coastal Biology Building, Santa Cruz, CA, 95060, United States

Keywords:
Dittrichia graveolens
Asteraceae
population spread
range expansion
invasion biology
dispersal
phenology
evolution
Invasive species.

Presentation Type: Oral Paper
Session: ECO3, Ecology 3: Weeds, Exotic and Invasive Plants, Restoration Ecology, and Research Natural Areas
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 4:00 PM
Number: ECO3005
Abstract ID:503
Candidate for Awards:Ecological Section Best Graduate Student Paper