The evolution of parasites from their hosts: intra– and interspecific parasitism and Emery's rule

Abstract

In some taxa of Hymenoptera, fungi, red algae and mistletoe, parasites and their hosts are either sibling species or at least closely related (Emery's rule). Three evolutionary mechanisms have been proposed for this phenomenon: (i) intraspeci c parasitism is followed by sympatric speciation; (ii) allopatric speciation is followed by secondary sympatry and the subsequent parasitism of one sibling species by the other; and (iii) allopatric speciation of a species with intraspeci c parasitism is followed by secondary sympatry, in which one species becomes an obligate parasite of the other. Mechanisms (i) and (ii) are problematic, while mechanism (iii) has not, to our knowledge, been analysed quantitatively. In this paper, we develop a model for single-and two-species evolutionary stable strategies (ESSs) to examine the basis for Emery's rule and to determine whether mechanism (iii) is consistent with ESS reasoning. In secondary sympatry after allopatric speciation, the system's evolution depends on the relative abundances of the two sibling species and on the proportional damage wrought by parasites of each species on non-parasitic members of the other. Depending on these interspeci c effects, either the rarer or the commoner species may become the parasite and the levels of within-species parasitism need not determine which evolves to obligate parasitism.

Bumblebee inquilinism in Bombus�(Fernaldaepsithyrus) sylvestris (Hymenoptera, Apidae): behavioural and chemical analyses of host-parasite interactions

“…This is typically in accordance with the Emery's rule (Emery, 1909), which proposes speciation patterns to explain how the 60 S. Dronnet et al parasites and their hosts would have evolved jointly (Schmid-Hempel, 1998;Lowe et al, 2002). If Emery's rule was applied for bumblebees, one species of inquiline should be phylogenetically close to its host species.…”

Biological Notes On Three Species of Giant Australian Mason Wasps, Abispa (Hymenoptera: Vespidae: Eumeninae)

“…Among those who study socially parasitic eusocial Hymenoptera, there has been much discussion concerning whether they follow Emery's Rule, which posits that social parasites and their hosts are closely related (Lowe et al 2002;Huang and Dornhaus 2008). In many ants Emery's Rule does seem to apply, but in other eusocial Hymenoptera, such as vespine wasps, studies have shown that social parasites are not closely related (Carpenter and Perera 2006).…”

Chemical mimicry in an incipient leaf-cutting ant social parasite

“…These are normally derived from ancestral host traits (Emery 1909) because social parasites are sister clades (the "loose" version of Emery's rule) or even sister species (the "strict" version of Emery's rule). Emery's rule has been hypothesized to be consistent with sympatric speciation (Elmes 1978;Buschinger 1986), but allopatric explanations for the evolution of social parasitism cannot be excluded (Wilson 1971;Lowe et al 2002). A recently discovered example of the strict version of Emery's rule is the Panamanian leafcutting ant Acromyrmex insinuator, which is an inquiline social parasite of its host and sister species Acromyrmex echinatior (Schultz et al 1998;Sumner et al 2004a).…”