The ranges of the two most abundant helminths, Spauligodon giganticus (monoxenous life cycle) and Physaloptera retusa (heteroxenous life cycle) encompass a geographic area from Oregon and Idaho, through California and Utah across to Texas and S to Veracruz, Mexico (see Baker, 1987) or roughly twice the size of the range of Sceloporus jarrovii.
That most lizard species lack a unique helminth fauna suggests that among lizard parasites, ecological conditions favoring egg survival for monoxenous helminths and the distribution of intermediate hosts for heteroxenous helminths are much more important than the presence of a particular lizard host species.
parasites Ineffective, little relation- ship to group size (Moore et al.
The infective agents of leishmaniasis are heteroxenous
unicellular organisms where a single species of parasite can survive within several different hosts.
infantum is a biphasic parasite, with heteroxenous
life cycle, or rather, completed in two hosts: the sandfly vector (L.
The parasite has heteroxenous lifecycle and reproduce both sexually and asexually.
The parasite has heteroxenous life cycle and propagates both sexually and asexually (Cleary et al.
Isospora belli and Isospora suis complete the entire life cycle in a single host, while Isospora felis and Isospora ohioenesis are facultative or heteroxenous
and need intermediate hosts to complete their life cycle (Lindsay and Blagburn, 1994; Lindsay et al., 1997; Tenter et al., 2002; Morrison et al., 2004).
The simple presence of a parasite species in a host may indicate the presence of other organisms in the environment (heteroxenous
parasite), environmental quality, or diet and biology of the host.
The cestode, pentastomid, and the two nematodes of the family Physalopteridae found here are heteroxenous
and use invertebrates as intermediate hosts (Anderson, 2000).
However, in heteroxenous
parasites, the aggregation can be explained by susceptibility and tolerance of host organisms to infections, and also by the different ways to connect the host to the parasites (ANDERSON; GORDON, 1982).
As parasites with a heteroxenous
life cycle show some degree of specificity in relation to their intermediate hosts, the occurrence of such parasites in a definitive host indicates predator-prey interactions (Marcogliese, 2004).