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Location: Animal Parasitic Diseases Laboratory

Title: Anthropogenics: Human influence on global and genetic homogenization of parasite populations

item Zarlenga, Dante
item Hoberg, Eric
item Rosenthal, Benjamin
item MATTIUCCI, SIMONETTA - University Of Rome Sapienza
item NASCETTI, GIUSEPPE - University Of Tuscia

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2014
Publication Date: 12/1/2014
Citation: Zarlenga, D.S., Hoberg, E.P., Rosenthal, B.M., Mattiucci, S., Nascetti, G. 2014. Anthropogenics: Human influence on global and genetic homogenization of parasite populations. Journal of Parasitology. 100(6):756-772. doi: 10.1645/14-622.1.

Interpretive Summary: Human activities have played and continue to play a major role in the globalization of parasite populations. Here we discuss the global dissemination of parasites resulting from human activities, and show that this has escalated demonstrably in the past 500 years. Human population growth, the advent of agricultural societies, migration, and key tipping points in human history, and climate change have influenced the evolution of drug resistant parasites, induced parasites to switch hosts, and resulted in the loss of biodiversity. We show that anthropogenic influence is supported in part by studies in pristine geographical localities unencumbered by human activities i.e. Antarctica and high latitude systems of the Arctic, wherein the population structure of parasites and their hosts have remained, to a great extent, well-defined. As such, not only is parasite population structure influenced through direct human intervention via translocation, but indirectly through unintentional, human-imposed changes to ecosystems in ways that affect the longevity of parasites and their hosts. This work is important to those scientists investigating human impact on their surroundings and the effects that this impact i.e. global warming, loss of genetic diversity, dissemination of undesirable pathogen characters (drug resistance), is having on the health of the ecosystem and livestock.

Technical Abstract: The distribution, abundance, and diversity of life on Earth have been greatly shaped by human activities. This is no truer than in the geographic expansion of parasites; however, measuring the extent to which humans have influenced the dissemination and population structure of parasites has been challenging. In-depth comparisons among parasite populations extending to landscape level processes effecting disease emergence, have remained elusive. New research methods have enhanced our capacity to discern human impact, where the tools of population genetics and molecular epidemiology have begun to shed light on our historical and ongoing influence. Only since the 1990’s have parasitologists coupled morphological diagnosis, long considered the basis of surveillance and biodiversity studies, with state-of- the- art tools enabling variation to be examined among and within parasite populations. Prior to this time, populations were characterized only by phenotypic attributes such as virulence, infectivity, host range and geographical location. The advent of genetic/molecular methodologies (multilocus allozyme electrophoresis, PCR-DNA fragments analysis, DNA sequencing, DNA microsatellites, single nucleotide polymorphisms, etc.) has transformed our abilities to reveal variation among and within populations at local, regional, landscape, and global scales, and thereby enhanced our understanding of the biosphere. Numerous factors can affect population structure among parasites such as evolutionary and ecological history, mode of reproduction and transmission, host dispersal, and life-cycle complexity. Although such influences can vary considerably among parasite taxa, anthropogenic factors are demonstrably perturbing parasite fauna. Minimal genetic structure among many geographically distinct (isolated) populations is a hallmark of human activity, hastened by geographic introductions, environmental perturbation, and global warming. Accelerating environmental change now plays a primary role in defining where hosts, parasites and other pathogens occur. This work examines how anthropogenic factors have and continue to serve as drivers of globalization and genetic homogenization of parasite populations.