Published In

Ecology and Evolution

Document Type

Article

Publication Date

11-2015

Subjects

Insect-plant relationships, Insects -- Evolution, Insects -- Behavior

Abstract

Host shifts of phytophagous insect specialists to novel plants can result in divergent ecological adaptation, generating reproductive isolation and potentially new species. Rhagoletis pomonellafruit flies in eastern North America underwent a host shift ~160 ya from native downy hawthorn (Crataegus mollis) to introduced, domesticated apple (Malus domestica). Divergent selection on diapause phenology related to the earlier fruiting time of apples versus downy hawthorns resulted in partial allochronic reproductive isolation between the fly races. Here, we test for how rapid and repeatable shifts in life-history timing are driving ecological divergence of R. pomonella in the Pacific Northwestern USA. The fly was introduced into the region via larval-infested apples 40–65 ya and now attacks native black hawthorn (Crataegus douglasii) and introduced ornamental hawthorn (Crataegus monogyna), in addition to early- and late-maturing apple varieties in the region. To investigate the life-history timing hypothesis, we used a field-based experiment to characterize the host-associated eclosion and flight activity patterns of adults, and the feeding times of larvae at a field site in Vancouver, Washington. We also assessed the degree to which differences in host-fruiting time generate allochronic isolation among apple-, black hawthorn-, and ornamental hawthorn-associated fly populations. We conclude that host-associated fly populations are temporally offset 24.4% to 92.6% in their seasonal distributions. Our results imply that R. pomonella possesses the capacity for rapid and repeatable shifts in diapause life history to match host-fruiting phenology, which can generate ecologically based reproductive isolation, and potentially biodiversity in the process.

Description

The article was published under the terms of the Creative Commons Attribution License (CC BY) which allows users to copy, distribute and transmit an article, adapt the article and make commercial use of the article. The CC BY license permits commercial and non-commercial re-use of an open access article, as long as the author is properly attributed.

Copyright 2015 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

DOI

10.1002/ece3.1826

Persistent Identifier

http://archives.pdx.edu/ds/psu/16504

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