Document Type
Peer-Review Article
Abstract
We analyzed the relative abundance of the large fritillaries Euptoieta claudia (Cramer) (immigrant), Speyeria cybele (Fabricius) and S. atlantis (Edwards) (generalists), S. aphrodite (Fabricius) (grassland species), and S. idalia (Drury) (prairie specialist) in transect surveys at grasslands and pine barrens during 1990-2006 for variation and correlation over time (measured both as chronological year and as years since last management treatment) among six subregions in central and northern Wisconsin. Population trends (correlations of abundance with chronological year) were few and not significantly skewed toward either negative or positive trends. Spatial synchrony between pairs of subregions was significantly different among species, and these differences ordinated by ecological classification, with the strongest positive correlations for the immigrant species and lowest for the grassland species, with the only analyzable generalist (S. cybele) in between. The specialist was represented by only one correlation that fell between the generalist and grassland species. Little variation in this spatial synchrony was apparent across the range of distances in this study (19-388 km), but the relationship to distance was negative, as expected. Immigrants (non-resident vagrants) appear more affected by landscape scale factors, and so are more spatially synchronized, while less vagile species appear more affected by local conditions and less spatially synchronized by population exchange. Covariance in abundance between the subset of localities surveyed every year and all localities in the subregion surveyed per year suggests that results for a large sample of all surveyed areas, although varying from year to year, approximates the results of more rigorous methods of population monitoring. Differences in abundance by management type showed a pattern of more statistical differentiation with increasing specialization of the species, consistent with previous analyses of these species in other midwestern regions. Results at Buena Vista Grassland were more divergent from previous studies. For both S. idalia and S. aphrodite, mow+burn and burn were relatively more favorable and graze less favorable than elsewhere; the highest abundances of both species were found in graze+burn. Furthermore, years since burning and years since grazing were remarkably similar to each other for both S. aphrodite and S. idalia, and these were similar between the two species, especially for years 0-3. But in both this study and previous analyses, year 0 after burning (and relatively heavy season-long cattle-grazing at Buena Vista) had very low abundances. Contrasts of management results at Buena Vista with results at prairies and barrens may be due to differences in vegetation (old field at Buena Vista vs. native vegetation) and/or due to lower treatment frequency and size (relative to site size) at Buena Vista than elsewhere. Thus, degree of habitat specificity and dispersal tendency both strongly affect patterns of fritillary population abundance.
Recommended Citation
Swengel, Ann B. and Swengel, Scott R.
2009.
"Spatiotemporal Variation of Violet-Feeding Large Fritillaries (Euptoieta, Speyeria) (Lepidoptera: Nymphalidae) in Central and Northern Wisconsin,"
The Great Lakes Entomologist, vol 42
(3)
: 121-138
DOI: https://doi.org/10.22543/0090-0222.2557
Available at:
https://scholar.valpo.edu/tgle/vol42/iss3/2