Testing the hypothesis of recent population expansions in nematode parasites of human-associated hosts

Abstract

It has been predicted that parasites of human-associated organisms (eg humans, domestic pets, farm animals, agricultural and silvicultural plants) are more likely to show rapid recent population expansions than are parasites of other hosts. Here, we directly test the generality of this demographic prediction for species of parasitic nematodes that currently have mitochondrial sequence data available in the literature or the public-access genetic databases. Of the 23 host/parasite combinations analysed, there are seven human-associated parasite species with expanding populations and three without, and there are three non-humanassociated parasite species with expanding populations and 10 without. This statistically significant pattern confirms the prediction. However, it is likely that the situation is more complicated than the simple hypothesis test suggests, and those species that do not fit the predicted general pattern provide interesting insights into other evolutionary processes that influence the historical population genetics of hostparasite relationships. These processes include the effects of postglacial migrations, evolutionary relationships and possibly life-history characteristics. Furthermore, the analysis highlights the limitations of this form of bioinformatic datamining, in comparison to controlled experimental hypothesis tests. Heredity (2005) 94, 426-434.

Life history determines genetic structure and evolutionary potential of host–parasite interactions

“…a recent host shift) are likely to be inaccurate, and might lead to a failure to detect the predicted pattern or to false detection of a nonexistent pattern [59]. For example, some wild species, even ones with nearly cosmopolitan distributions, possess little variation at neutral marker loci [60,61].…”

Genetic diversity and population genetics of large lungworms (Dictyocaulus, Nematoda) in wild deer in Hungary

“…Our results suggest that D. eckerti has not experienced a severe recent population bottleneck and that there was a population expansion ∼11,500 years ago (although these results should be interpreted with caution, e.g. see Morrison and Höglund 2005 ). Our estimate for a relatively recent D. eckerti population expansion is likely to be driven by the population expansion of its hosts.…”

Nematode infection: A rare mimic of acute appendicitis

“…Often stool culture results take time to produce, and waiting for these results may put the patient at a high risk of appendiceal perforation 5 . Despite the high false-positive rate, surgery is often justified due to the morbidity and mortality associated with appendiceal perforation 6 .…”