Canadian Forest Service Publications
Developmental costs of biological invasion: the exotic wood borer Tetropium fuscum is more asymmetric and smaller in invaded area. 2018. Goczal, J.; Rossa, R.; Nawrocka, A.; Sweeney, J.D.; Tofilski, A. Environmental Entomology 47(4):982-989.
Issued by: Atlantic Forestry Centre
Catalog ID: 39422
CFS Availability: PDF (download)
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Biological invasions provide a unique opportunity to gain insight into basic biological processes occurring under new circumstances. During the process of establishment, exotic species are exposed to various stressors which may affect their development. Presence of the stressors is often detected by measurements of left-right body asymmetry, which consists of two main components: fluctuating asymmetry and directional asymmetry. Fluctuating asymmetry constitutes random differences between the two body sides, whereas directional asymmetry occurs when a particular trait is bigger on one of the sides. The relation between these two asymmetry components is still not fully understood. Our goal was to investigate the potential differences in asymmetry patterns between native and invasive populations of Tetropium fuscum (Fabr. 1787) (Coleoptera: Cerambycidae), a harmful forest pest native to Europe and introduced to North America. Wing asymmetry assessment was based on the geometric morphometrics of hind wings. We found that specimens from invaded area were markedly smaller and have more asymmetric wings than individuals from native population, suggesting some unfavorable conditions in the invaded area. Moreover, we found significant directional asymmetry in the native but not in the invasive population. On the other hand, differences between left and right hind wings were similar in the native and invasive populations, in terms of direction. This suggests that a high level of fluctuating asymmetry in the invasive population may blur the intrinsic directional asymmetry and hinder its detection. Our data show that fluctuating asymmetry has a potential as an indicator of developmental stress in invasive species.
Plain Language Summary
Insects, like people, have bilateral symmetry, that is, the left side of the body is pretty much a mirror image of the right. However, in some insect populations there can be differences between the right- and left-hand sides of the body (e.g., longer left wing than right wing), known as asymmetry, and the degree of asymmetry may indicate developmental stress in the population. We compared the level of asymmetry between two populations of the brown spruce longhorn beetle, Tetropium fuscum: the native European population and the invasive population that has been established in Nova Scotia since at least 1990. The T. fuscum in Nova Scotia were smaller and had greater wing asymmetry than those from Europe, but it was unclear whether these differences are due to developmental stress, adaptation to a new environment, or were inherited from the founder population of T. fuscum introduced to Nova Scotia from Europe.