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Dispersal Ecology (dispersal + ecology)
Selected AbstractsDispersal ecology versus host specialization as determinants of ectoparasite distribution in brood parasitic indigobirds and their estrildid finch hostsMOLECULAR ECOLOGY, Issue 1 2007CHRISTOPHER N. BALAKRISHNAN Abstract Brood parasitic birds offer a unique opportunity to examine the ecological and evolutionary determinants of host associations in avian feather lice (Phthiraptera). Brood parasitic behaviour effectively eliminates vertical transfer of lice between parasitic parents and offspring at the nest, while at the same time providing an opportunity for lice associated with the hosts of brood parasites to colonize the brood parasites as well. Thus, the biology of brood parasitism allows a test of the relative roles of host specialization and dispersal ecology in determining the host,parasite associations of birds and lice. If the opportunity for dispersal is the primary determinant of louse distributions, then brood parasites and their hosts should have similar louse faunas. In contrast, if host-specific adaptations limit colonization ability, lice associated with the hosts of brood parasites may be unable to persist on the brood parasites despite having an opportunity for colonization. We surveyed lice on four brood parasitic finch species (genus Vidua), their estrildid finch host species, and a few ploceid finches. While Brueelia lice were found on both parasitic and estrildid finches, a molecular phylogeny showed that lice infesting the two avian groups belong to two distinct clades within Brueelia. Likewise, distinct louse lineages within the amblyceran genus Myrsidea were found on estrildid finches and the parasitic pin-tailed whydah (Vidua macroura), respectively. Although common on estrildid finches, Myrsidea lice were entirely absent from the brood parasitic indigobirds. The distribution and relationships of louse species on brood parasitic finches and their hosts suggest that host-specific adaptations constrain the ability of lice to colonize new hosts, at least those that are distantly related. [source] Linking movement behaviour, dispersal and population processes: is individual variation a key?JOURNAL OF ANIMAL ECOLOGY, Issue 5 2009Colin Hawkes Summary 1Movement behaviour has become increasingly important in dispersal ecology and dispersal is central to the development of spatially explicit population ecology. The ways in which the elements have been brought together are reviewed with particular emphasis on dispersal distance distributions and the value of mechanistic models. 2There is a continuous range of movement behaviours and in some species, dispersal is a clearly delineated event but not in others. The biological complexities restrict conclusions to high-level generalizations but there may be principles that are common to dispersal and other movements. 3Random walk and diffusion models when appropriately elaborated can provide an understanding of dispersal distance relationships on spatial and temporal scales relevant to dispersal. Leptokurtosis in the relationships may be the result of a combination of factors including population heterogeneity, correlation, landscape features, time integration and density dependence. The inclusion in diffusion models of individual variation appears to be a useful elaboration. The limitations of the negative exponential and other phenomenological models are discussed. 4The dynamics of metapopulation models are sensitive to what appears to be small differences in the assumptions about dispersal. In order to represent dispersal realistically in population models, it is suggested that phenomenological models should be replaced by those based on movement behaviour incorporating individual variation. 5The conclusions are presented as a set of candidate principles for evaluation. The main features of the principles are that uncorrelated or correlated random walk, not linear movement, is expected where the directions of habitat patches are unpredictable and more complex behaviour when organisms have the ability to orientate or navigate. Individuals within populations vary in their movement behaviour and dispersal; part of this variation is a product of random elements in movement behaviour and some of it is heritable. Local and metapopulation dynamics are influenced by population heterogeneity in dispersal characteristics and heritable changes in dispersal propensity occur on time-scales short enough to impact population dynamics. [source] Nest-to-nest dispersal of Chaetodactylus krombeini (Acari, Chaetodactylidae) associated with Osmia cornifrons (Hym., Megachilidae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 3 2009Y.-L. Park Abstract A cleptoparasitic mite, the Krombein's hairy-footed mite, Chaetodactylus krombeini Baker (Acari, Chaetodactylidae) became a key pest that affects the maintenance and propagation of Osmia spp. (Hym., Megachilidae), thus disrupting orchard pollination in the United States. Although hypopi, the dispersal stages of C. krombeini, are known to disperse from nest to nest by hitchhiking on Osmia cornifrons adults, we observed that they might disperse in other ways too in commercial orchards. This study was conducted to elucidate the nest-to-nest dispersal mechanisms of C. krombeini hypopi. We tested three potential dispersal mechanisms of C. krombeini other than phoresy by O. cornifrons: (1) dispersal by walking from nest to entrances of nearby nests, (2) dispersal by walking from nest to nest through emergence holes made by parasitic wasps on nests, and (3) dispersal by being unloaded and uptaken to and from flowers by O. cornifrons. Results of this study showed that C. krombeini hypopi could disperse from a nest to nearby nests by walking through nest entrances and holes made by parasitic wasps of O. cornifrons. Although 0.06% of C. krombeini hypopi on blueberry flowers were picked up by O. cornifrons, they were not able to be unloaded to flowers from O. cornifrons and no hypopi could inhabit or survive on blueberry flowers. This indicated no or very low chance of C. krombeini hypopi dispersal via blueberry flowers. Based on our findings of C. krombeini dispersal ecology, development of C. krombeini control strategies are discussed in this article. [source] Dispersal ecology versus host specialization as determinants of ectoparasite distribution in brood parasitic indigobirds and their estrildid finch hostsMOLECULAR ECOLOGY, Issue 1 2007CHRISTOPHER N. BALAKRISHNAN Abstract Brood parasitic birds offer a unique opportunity to examine the ecological and evolutionary determinants of host associations in avian feather lice (Phthiraptera). Brood parasitic behaviour effectively eliminates vertical transfer of lice between parasitic parents and offspring at the nest, while at the same time providing an opportunity for lice associated with the hosts of brood parasites to colonize the brood parasites as well. Thus, the biology of brood parasitism allows a test of the relative roles of host specialization and dispersal ecology in determining the host,parasite associations of birds and lice. If the opportunity for dispersal is the primary determinant of louse distributions, then brood parasites and their hosts should have similar louse faunas. In contrast, if host-specific adaptations limit colonization ability, lice associated with the hosts of brood parasites may be unable to persist on the brood parasites despite having an opportunity for colonization. We surveyed lice on four brood parasitic finch species (genus Vidua), their estrildid finch host species, and a few ploceid finches. While Brueelia lice were found on both parasitic and estrildid finches, a molecular phylogeny showed that lice infesting the two avian groups belong to two distinct clades within Brueelia. Likewise, distinct louse lineages within the amblyceran genus Myrsidea were found on estrildid finches and the parasitic pin-tailed whydah (Vidua macroura), respectively. Although common on estrildid finches, Myrsidea lice were entirely absent from the brood parasitic indigobirds. The distribution and relationships of louse species on brood parasitic finches and their hosts suggest that host-specific adaptations constrain the ability of lice to colonize new hosts, at least those that are distantly related. [source] Species-specific detection of Lobaria pulmonaria (lichenized ascomycete) diaspores in litter samples trapped in snow coverMOLECULAR ECOLOGY, Issue 9 2001J.-C. Walser Abstract The foliose lichen Lobaria pulmonaria has suffered a substantial decline in central and northern Europe during the twentieth century and is now considered to be critically endangered in many European lowland regions. Based on demographic studies, it has been proposed that under the present environmental conditions and forest management regimes, dispersal of diaspores and subsequent establishment of new thalli are insufficient to maintain the remnant small lowland populations. Chances of long-term survival may therefore be reduced. The data and analytical power of these demographic studies are limited. Since lichen diaspores show very few species-specific morphological characteristics, and are therefore almost indistinguishable, the accurate assessment of diaspore flux would be a fundamental first step in better understanding the life cycle of L. pulmonaria. Here we present a new molecular approach to investigate the dispersal of L. pulmonaria diaspores in its natural environment by specifically identifying small amounts of DNA in snow litter samples at varying distances from known sources. We used a species-specific polymerase chain reaction (PCR) primer pair to amplify the ribosomal internal transcribed spacer region (ITS rDNA) and a sensitive automated PCR product detection system using fluorescent labelled primers. We detected considerable amounts of naturally dispersed diaspores, deposited as far as 50 m away from the closest potential source. Diaspores were only found in the direction of the prevailing wind. Diaspore deposition varied from 1.2 diaspores per m2 per day at 50 m distance from the source to 15 diaspores per m2 per day at 1 m distance. The method described in this paper opens up perspectives for studies of population dynamics and dispersal ecology mainly in lichenized ascomycetes but also in other organisms with small, wind-dispersed diaspores. [source] | ||||||||||