Trypanosoma cruzi -- the vector-parasite paradox

Abstract

Trypanosoma cruzi and the majority of its insect vectors (Hemiptera, Reduviidae, Triatominae)

Triatominae (Hemiptera: Reduviidae): Systematic questions and some others

“…Although it has only been suggested that triatomines are polyor diphyletic (see brief discussion in Schaefer & Coscarón 2001), that suggestion is gradually making its way into the literature as fact. What Schofield and Dujardin (1999) present as a "working hypothesis" (p. 187) becomes for Bargues et al (2000) a "current theory" (p. 570) and as noted above, for Schofield (2000) a clear fact. Cruz-López et al (2001) state in their paper's introduction that the Triatominae are "probably" polyphyletic, a statement too strong for the weak evidence upon which it is based.…”

“…Are Triatominae polyphyletic (descended from more than two ancestors) or diphyletic (descended from two ancestors) or, as currently treated, monophyletic? These possibilities have been suggested (Schofield 1988(Schofield , 2000Schofield & Dolling 1993;Schofield & Dujardin 1999;Bargues et al 2000), and discussed by Carcavallo et al (1999Carcavallo et al ( , 2000; but the evidence is weak (see below, and Schaefer & Coscarón 2001), or controverted by other evidence (Hypša et al 2002).…”

“…What are the relationships inter se of the derivatives of the tropicopolitan T. rubrofasciata? 2a) If, as seems likely (Patterson et al 2001), the several Old World species of Triatoma are each derived from a different population of T. rubrofasciata, and if these speciations all occurred within the past 200 (Schofield 2000) or 350 years (Patterson et al 2001), why have not other populations of T. rubrofasciata also speciated? That is, selection pressures on some populations of T. rubrofasciata must have been far greater than pressures on other populations, so that the former have become sufficiently distinct as to be accorded species status.…”

“…4b) Might Linshcosteus be descended from a nontriatomine (and see 3, above)? That is, might Linshcosteus not be a triatomine at all (Schofield 1988(Schofield , 2000Schofield & Dolling 1993;Gorla et al 1997)? This possibility has been suggested by many of those who believe Triatominae to be di-or polyphyletic, and who argue that those features of Linshcosteus that link it with Triatominae are merely features any reduviid must acquire if it is to feed on vertebrate blood; Linshcosteus, by this argument, is convergent with members of Triatominae.…”

“…Molecular analyses also are difficult to analyze for phylogenetic conclusions; and of course analyses based on different molecules may (and do) yield different results (just as will analyses based on different single morphological characters). The occasional difficulty of reconciling molecular results with other types of results (e.g., geological) is exemplified in the last paragraph of Schofield (2000).…”