Abstract Detail


Cousins, Elsa A [1], Stinson, Kristina [1].

Variation in herbivory and defensive chemical production of Thlaspi arvense in subalpine meadows of the Rocky Mountains, CO.

Biotic interactions in subalpine meadows are largely influenced by rapidly changing snowmelt timing and localized population phenology. Thlaspi arvense is a widespread Eurasian member of the Brassicaceae that is expanding into subalpine habitats in North America. Generalist herbivores may play a role in limiting its expansion into high altitude ecosystems, especially in sites with late snowmelt where food sources are more scarce and tissue loss from herbivory pressure could prevent plants from reaching reproductive size. Sinigrin, the main phytochemical in T. arvense, deters generalist herbivores but also attracts oviposition by specialist butterflies that mistake it for their native hosts, but the plant is toxic to the larvae and thus creates an ecological “trap”. T. arvense produces varying levels of sinigrin in different environments. Here we documented herbivory rates and sinigrin levels of T. arvense in subalpine meadows at the edge of its invaded range. We investigated how herbivory rates varied among 10 populations of T. arvense grouped into early, medium and late snowmelt populations. We found significantly higher herbivory rates and smaller plants in later snowmelt populations, and significantly higher fruit counts and larger plants in earlier snowmelt populations. Additionally, we saw greater variation in sinigrin content and overall higher concentrations at the early snowmelt sites. Our findings suggest that small plants in late snowmelt sites may be under stronger selection to maintain higher sinigrin concentrations in order to defend against herbivory in order to reach reproductive size within a shorter growing season. As a result, plants in later melting sites may be more toxic to native butterflies but less likely to spread. However, as the climate warms and snowmelt advances to earlier dates, T. arvense may become more fecund and widespread across subalpine habitats, while losing some of its toxicity.

1 - University of Massachusetts Amherst, Environmental Conservation

Range expansion

Presentation Type: Oral Paper
Number: EC09004
Abstract ID:825
Candidate for Awards:None

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