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Submitted to: Insects
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/21/2018 Publication Date: 8/22/2018 Citation: Srygley, R.B. 2018. Experimental manipulation of dispersal ability in Neotropical butterfly Anartia fatima (Lepidoptera: Nymphalidae). Insects. https://doi.org/10.3390/insects9030107. DOI: https://doi.org/10.3390/insects9030107 Interpretive Summary: Experimental manipulation of flight-related morphology affects the ability of insects to disperse The ability to disperse can define a species range, allow persistence in fragmented habitats, or allow species to track changes in climate. Previously endanged species and more common ones expanding their range were found to allocate more mass to the thorax and less to reproduction, features that were assumed to be related to the ability to disperse. ARS Researchers at Sidney Montana conducted an experimental study to show that weight loading, which reduced the flight muscle ratio, affected the ability of insects to disperse whereas altering the position of center of body mass did not affect dispersal beyond the associated increase in weight loading. This study supports the hypothesis that endangered species and those colonizing new habitat have greater thoracic mass to enhance dispersal at the expense of reproductive and other non-flight-related tissues. Technical Abstract: Research on endangered British butterflies found that butterfly populations in small refuges evolve to allocate more mass to the thorax (flight muscle) and less to the abdomen than populations in large refuges. The observed change in mass allocation affects two morphological features relevant to flight: flight muscle ratio (FMR) and the position of center of body mass (cmbody). I tested whether a decrease in FMR or a change in cmbody reduce the ability to disperse by experimentally weight-loading Neotropical Anartia fatima butterflies. In one treatment group, FMR was decreased but cmbody was not altered, whereas in the second group FMR was decreased and cmbody was repositioned further posterior. In one mark-release-recapture experiment, butterflies dispersed relatively slowly, and treatment groups did not differ significantly. In a second experiment, butterflies dispersed more quickly, and control butterflies dispersed more rapidly than either treatment group. Differences in dispersal were consistent with a causal relationship between FMR and movement. A more posterior cmbody had little effect on dispersal beyond that due to the change in FMR. These results support the hypothesis that an increase in mass allocation to the thorax in small, dispersed refugia is due to selection on the ability to disperse. |
