Author
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Hoberg, Eric |
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Submitted to: Office of International Epizootics Scientific and Technical Review
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/1/2010 Publication Date: 8/1/2010 Citation: Hoberg, E.P. 2010. Invasive Processes, Mosaics and the Structure of Helminth Parasite Faunas. Office of International Epizootics Scientific and Technical Review. 29:255-272. Interpretive Summary: Invasive and exotic species including many parasitic organisms result in substantial socio-economic impact globally and in North America. Human-related factors are currently most important in determining the patterns of introduction and dissemination for a variety of parasites and pathogens that infect domestic and free-ranging livestock and humans. The process of invasion has accelerated over time and now interacts of environmental perturbations associated with climate change on local to regional geographic scales. This review explores patterns for introduction of helminths among ungulates and other vertebrates and addresses the primary mechanisms and implications for continued invasion of managed and wild ecosystems. The biosphere in evolutionary and ecological time has been structured by episodes of geographic and host colonization that have determined distributions for complex assemblages of microparasites and macroparasites including helminths circulating among vertebrates. Biological invasion is an intricate phenomenon often involving “extra-range dispersal” and establishment of exotic (non-indigenous) species and populations substantially beyond their native range. Invasion may also involve expansion or shifting host and geographic distributions for an endemic (indigenous) species or fauna under changing environmental conditions. Invasions result in faunal interchange occurring under influences from both natural and anthropogenic forces where expansion on spatial/temporal continua bridges continents, regions and landscapes. Drivers for invasion are idiosyncratic, multifactorial, interactive, and opportunistic with a powerful role for historical contingency. Life history patterns for helminths interact with invasion pathways to determine the potential for introduction. Human-mediated events, such as the global expansion of pathogens linked to development of agriculture, domestication of food animals, and European exploration have had a pervasive influence on the distribution of helminths. Globalization, broad transport-networks and environmental perturbation linked to climate change along with other drivers have accelerated these processes. Powerful tools are available and support the exploration of invasive species, with a cornerstone residing in systematics and our capacity to accurately identify parasites and to define evolutionary and biogeographic history. Faunal baselines linked to archival collections and informatics are a permanent record for the biosphere when archived in museum collections. Absence of comprehensive taxonomic inventories for parasites, including molecular-genetic data, influences our ability to recognize the introduction of non-indigenous parasites, or to document patterns of expansion for local faunas under a regime of environmental perturbation. Technical Abstract: The biosphere in evolutionary and ecological time has been structured by episodes of geographic and host colonization that have determined distributions for complex assemblages of microparasites and macroparasites including helminths circulating among vertebrates. Biological invasion is an intricate phenomenon often involving “extra-range dispersal” and establishment of exotic (non-indigenous) species and populations substantially beyond their native range. Invasion may also involve expansion or shifting host and geographic distributions for an endemic (indigenous) species or fauna under changing environmental conditions. Invasions result in faunal interchange occurring under influences from both natural and anthropogenic forces where expansion on spatial/temporal continua bridges continents, regions and landscapes. Drivers for invasion are idiosyncratic, multifactorial, interactive, and opportunistic with a powerful role for historical contingency. Life history patterns for helminths interact with invasion pathways to determine the potential for introduction. Human-mediated events, such as the global expansion of pathogens linked to development of agriculture, domestication of food animals, and European exploration have had a pervasive influence on the distribution of helminths. Globalization, broad transport-networks and environmental perturbation linked to climate change along with other drivers have accelerated these processes. A consequence of invasion and establishment of exotic species is that faunal structure will be a mosaic representing admixtures of indigenous and non-indigenous species and populations; exemplified by helminth faunas among domestic and free-ranging ungulates and a diversity of host-parasites systems among vertebrates. Contemporary mosaics are evident where human-mediated events have brought assemblages of new invaders and relatively old endemics into sympatry, emphasizing interactions at ecotones, particularly those at borderlands between managed and natural ecosystems. Understanding the historical origins and complex components of mosaics is essential in formulating predictions about future responses to environmental change. Powerful tools are available and support the exploration of invasive species, with a cornerstone residing in systematics and our capacity to accurately identify parasites and to define evolutionary and biogeographic history. Faunal baselines linked to archival collections and informatics are a permanent record for the biosphere when archived in museum collections. Absence of comprehensive taxonomic inventories for parasites, including molecular-genetic data, influences our ability to recognize the introduction of non-indigenous parasites, or to document patterns of expansion for local faunas under a regime of environmental perturbation. |
