TL;DR: The results indicate that host-defence-mediated competition can influence the structure of parasite communities and may play a part in the evolution of parasite diversity.
Abstract: 1. Interspecific competition influences which, how many and where species coexist in biological communities. Interactions between species in different trophic levels can mediate interspecific competition; e.g. predators are known to reduce competition between prey species by suppressing their population sizes. A parallel phenomenon may take place in host-parasite systems, with host defence mediating competition between parasite species. 2. We experimentally investigated the impact of host defence (preening) on competitive interactions between two species of feather-feeding lice: 'wing' lice Columbicola columbae and 'body' lice Campanulotes compar. Both species are host-specific parasites that co-occur on rock pigeons Columba livia. 3. We show that wing lice and body lice compete and that host defence mediates the magnitude of this competitive interaction. 4. Competition is asymmetrical; wing louse populations are negatively impacted by body lice, but not vice versa. This competitive asymmetry is consistent with the fact that body lice predominate in microhabitats on the host's body that offer the most food and the most space. 5. Our results indicate that host-defence-mediated competition can influence the structure of parasite communities and may play a part in the evolution of parasite diversity.
TL;DR: Wing lice use fly activity as a cue in orientation and locomotion, whereas body lice do not, and it is shown that wing lice are more capable of remaining attached to active flies that are walking, grooming or flying.
TL;DR: Investigating how differences in phoretic dispersal influence the population genetic structure of two different parasites of the same host species finds higher levels of genetic differentiation in body lice compared to wing lice at two spatial scales, consistent with macroevolutionary differences in the degree of host–parasite cospeciation.
Abstract: Dispersal is a fundamental component of the life history of most species. Dispersal influences fitness, population dynamics, gene flow, genetic drift and population genetic structure. Even small differences in dispersal can alter ecological interactions and trigger an evolutionary cascade. Linking such ecological processes with evolutionary patterns is difficult, but can be carried out in the proper comparative context. Here, we investigate how differences in phoretic dispersal influence the population genetic structure of two different parasites of the same host species. We focus on two species of host-specific feather lice (Phthiraptera: Ischnocera) that co-occur on feral rock pigeons (Columba livia). Although these lice are ecologically very similar, "wing lice" (Columbicola columbae) disperse phoretically by "hitchhiking" on pigeon flies (Diptera: Hippoboscidae), while "body lice" (Campanulotes compar) do not. Differences in the phoretic dispersal of these species are thought to underlie observed differences in host specificity, as well as the degree of host-parasite cospeciation. These ecological and macroevolutionary patterns suggest that body lice should exhibit more genetic differentiation than wing lice. We tested this prediction among lice on individual birds and among lice on birds from three pigeon flocks. We found higher levels of genetic differentiation in body lice compared to wing lice at two spatial scales. Our results indicate that differences in phoretic dispersal can explain microevolutionary differences in population genetic structure and are consistent with macroevolutionary differences in the degree of host-parasite cospeciation.
TL;DR: An extensive survey of chewing lice from rock pigeon and mourning dove, carried out from 1994 to 2000 and from 2003 to 2006 in Manitoba, Canada, produced the following new records: Colocerastovornikae Tendeiro for North America, and Columbicola macrourae, Hohorstiellalata, H. paladinella Hill and Tuff, and Physconelloides zenaidurae (McGregor) for Canada.
Abstract: An extensive survey of chewing lice from rock pigeon, Columba livia Gmelin, and mourning dove, Zenaida macroura (L.), carried out from 1994 to 2000 and from 2003 to 2006 in Manitoba, Canada, produced the following new records: Coloceras tovornikae Tendeiro for North America; Columbicola macrourae (Wilson), Hohorstiella lata (Piaget), H. paladinella Hill and Tuff, and Physconelloides zenaidurae (McGregor) for Canada; and Bonomiella columbae Emerson, Campanulotes compar (Burmeister), Columbicola baculoides (Paine), and C. columbae (L.) for Manitoba. We collected 25 418 lice of four species (C. compar, C. columbae, H. lata, and C. tovornikae) from 322 rock pigeons. The overall prevalence of infestation was 78.9%, 52.5%, and 23.3% for C. compar, C. columbae, and H. lata, respectively. Coloceras tovornikae was not discovered until 2003, after which its prevalence was 39.9% on 114 pigeons. We collected 1116 lice of five species (P. zenaidurae, C. baculoides, C. macrourae, H. paladinella, and B. columbae) from 1...
TL;DR: The level of stability of these populations was relatively high compared with many other organisms, and in particular higher than for plant ectoparasites (Hemiptera: Aphididae).
Abstract: Population parameters of ectoparasites on feral pigeons, Columba livia Gmelin (Aves: Columbiformes: Columbidae), were estimated from 1995–2012 in southern Manitoba, Canada. The ectoparasites are chewing lice (Phthiraptera): Philopteridae – Campanulotes compar (Burmeister), Columbicola columbae (Linnaeus), and Coloceras tovornikae Tendeiro; Menoponidae – Hohorstiella lata (Piaget). We tested the hypotheses that both abundance and population stability are species-specific traits. Over 10 years, the four species of lice had distinct population dynamics. Campanulotes compar and C. columbae were more abundant than C. tovornikae and H. lata, had higher male to female sex ratios and higher ratios of nymphs to females, different levels of aggregation, and more stable populations. Campanulotes compar was more prevalent than C. columbae and its prevalence was more stable, and the two species also showed differences in the levels and stabilities of male and nymph to female ratios. Coloceras tovornikae had a higher prevalence and male to female sex ratio than H. lata, but the two species showed similar levels of stability for these parameters. The level of stability of these populations was relatively high compared with many other organisms, and in particular higher than for plant ectoparasites (Hemiptera: Aphididae). Although the four species occupy similar habitats, often on the same bird, and three of the four feed in a similar way, the population biology of each species is distinct. The life history traits that lead to these differences have yet to be determined.