Parasites lost?

Ribosomal DNA and Phylogeny of the Ascaridoidea (Nemata: Secernentea): Implications for Morphological Evolution and Classification

“…Among the Ascaridoidea, trees inferred from the SSU or combined SSU plus LSU data uniformly depicted the heterocheilid as basal among the Ascaridoidea. This observation is consistent with previous results (Nadler, 1992(Nadler, , 1995 and the hypothesis of Sprent (1982Sprent ( , 1983Sprent ( , 1992, who considered heterocheilids as the basal ascaridoid lineage based on structural features he interpreted as plesiomorphic (features of the excretory system, labia, and arrangement of esophageal gland nuclei). Neither the SSU tree or combined SSU plus LSU trees yielded robust support for relationships among families and subfamilies as revealed by bootstrap resampling.…”

“…Differences in the organization and ranking of groups above the genus level have also been common. For example, two of the four family groupings recognized by Hartwich (1974) and Gibson (1983) were considered to be either of questionable affinity or nonnatural by Sprent (1983Sprent ( , 1992 and were excluded from the classification of Fagerholm (1991). Instability of ascaridoid classifications is one consequence of the absence of a robust phylogenetic hypothesis.…”

Australian spiny mountain crayfish and their temnocephalan ectosymbionts: an ancient association on the edge of coextinction?

“…However, very few studies have reconstructed the shared histories of associated clades through deep time, during which extensive environmental change may have profoundly affected their evolution, both separately and jointly [3]. Furthermore, there is an urgent need for information on the specificity of interspecies associations in cases where the host is of conservation concern [4], because the extinction risk for symbionts (non-free-living organisms [5]) may be closely linked to that of their hosts [6][7][8]. Adaptation to new host species (host switches) may reduce the risk of symbiont coextinction (in this case, defined as the extinction of a symbiont species owing to the extinction of its hosts [9,10]).…”

Infectious Diseases, Biodiversity and Global Changes: How the Biodiversity Sciences May Help

“…This may not be seen as a positive consequence as parasites should not only be thought of as harmful, however. Parasites have their own intrinsic value (Sprent, 1992). They contribute to maintain high diversity as ecological engineers (Thomas et al, 1999), they may control biotic invaders, and they stabilize ecosystems (Marcogliese & Cone, 1997;Mouritsen et al, 2005;Arias-González & Morand, 2006;Pedersen & Fenton, 2006).…”