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Hardy P.B.,81 Winstanley Road | Dennis R.L.H.,4 Fairfax Drive
Entomologist's Gazette | Year: 2010

An outstanding issue in butterfly ecology is the extent to which resources are used in the matrix (non-habitat). Observations are recorded of Pieris napi (Linnaeus, 1758) locating concealed host plants and egg-laying in long-standing, regularly mown, urban parkland.


Dennis R.L.H.,Staffordshire University | Dennis M.P.,4 Fairfax Drive | Hardy P.B.,81 Winstanley Road | Kinder P.M.,11 Westover
Entomologist's Gazette | Year: 2011

Colonisation of isolated biotopes suggests that many butterflies have the capacity to migrate over large distances. This raises questions about some of the factors involved in range extensions, both concerning dispersal, female investments, site resource quality and mass effects, important in understanding population persistence. It is suggested that butterfly dispersal is underestimated.


Hardy P.B.,81 Winstanley Road | Kinder P.M.,11 Westover | Sparks T.H.,UK Institute of Zoology | Dennis R.L.H.,Staffordshire University | Dennis R.L.H.,UK Center for Ecology and Hydrology
Journal of Insect Conservation | Year: 2010

Uplands are expected to provide refuges for species subject to lowland habitat loss and projected climate changes. Here, we argue that upland populations also provide refuges when lowland sites are subject to climatic fluctuations and extreme events and that species with populations dispersed over adjoining uplands and lowlands spread their risk of extinction. A proviso is that development is sufficiently lagged with altitude but that development rates are compatible. Emergence patterns and development of the butterfly Anthocharis cardamines and its larval host plant Cardamine pratensis show these characteristics, and coupled with the butterfly's capacity to migrate between isolated populations present a case where upland and lowland populations can act as sources when one or the other area is adversely affected by extreme events. © 2009 Springer Science+Business Media B.V.


Dennis R.L.H.,Oxford Brookes University | Dennis R.L.H.,Staffordshire University | Hardy P.B.,81 Winstanley Road | Dapporto L.,Instituto Comprensivo Materna Elementere Media Convenevole da Prato
Journal of Biogeography | Year: 2012

Aim To relate variation in the migration capacity and colonization ability of island communities to island geography and species island occupancy. Location Islands off mainland Britain and Ireland. Methods Mean migration (transfer) capacity and colonization (establishment) ability (ecological indices), indexed from 12 ecological variables for 56 butterfly species living on 103 islands, were related to species nestedness, island and mainland source geography and indices using linear regression models, RLQ analysis and fourth-corner analysis. Random creation of faunas from source species, rank correlation and rank regression were used to examine differences between island and source ecological indices, and relationships to island geography. Results Island butterfly faunas are highly nested. The two ecological indices related closely to island occupancy, nestedness rank of species, island richness and geography. The key variables related to migration capacity were island area and isolation; for colonization ability they were area, isolation and longitude. Compared with colonization ability, migration capacity was found to correlate more strongly with island species occupancy and species richness. For island faunas, the means for both ecological indices decreased, and variation increased, with increasing island species richness. Mean colonization ability and migration capacity values were significantly higher for island faunas than for mainland source faunas, but these differences decreased with island latitude. Main conclusions The nested pattern of butterfly species on islands off mainland Britain and Ireland relates strongly to colonization ability but especially to migration capacity. Differences in colonization ability among species are most obvious for large, topographically varied islands. Generalists with abundant multiple resources and greater migration capacity are found on all islands, whereas specialists are restricted to large islands with varied and long-lived biotopes, and islands close to shore. The inference is that source-sink dynamics dominate butterfly distributions on British and Irish islands; species are capable of dispersing to new areas, but, with the exception of large and northern islands, facilities (resources) for permanent colonization are limited. The pattern of colonization ability and migration capacity is likely to be repeated for mainland areas, where such indices should provide useful independent measures for assessing the conservation status of faunas within spatial units. © 2012 Blackwell Publishing Ltd.


Dennis R.L.H.,Oxford Brookes University | Dennis R.L.H.,Staffordshire University | Hodgson J.G.,University of Sheffield | Hardy P.B.,81 Winstanley Road | Dapporto L.,Instituto Comprensivo Materna Elementere Media Convenevole da Prato
Journal of Natural History | Year: 2012

Larger organisms are expected to take longer to develop, depressing overall growth rates. An examination of relationships between size, development times and growth rates in British and northwest European butterflies has revealed a reversal of this relationship with large species developing rapidly and small species developing slowly, especially in subsets of species that complete their development in a single season and have multiple broods. Distinctive life history associations are found to be linked to rapid development (daytime and gregarious feeding) and enhanced defence (larval spines, aposematism) from the resulting increased exposure to enemies. Taxonomic bias is evident in development-size patterns linked to overwintering strategy and voltinism. Different strategies exist for faster growth in the larger Pieridae and non-satyrine Nymphalidae. Larval host plant contrasts for food quantity and quality underlie distinctions for size and development times. © 2012 Copyright Taylor and Francis Group, LLC.

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