title: Linking morphometric and genetic divergence with host use in the tick complex, Ornithodoros capensis sensu lato.
abstract: Host specific adaptations in parasites can lead to the divergence of conspecific populations. However, this divergence can be difficult to measure because morphological changes may not be expressed or because obvious changes may simply reflect phenotypic plasticity. Combining both genetic and phenotypic information can enable a better understanding of the divergence process and help identify the underlying selective forces, particularly in closely-related species groups. Here, we link genetic and morphometric data to understand divergence patterns within the Ornithodoros (Carios) capensis complex, a group of soft ticks (Argasidae) exploiting colonial seabirds across the globe. Species designations in this complex were historically based on larval morphology and geographic location. However, recent work has suggested that divergence within the group may be at least partially linked to host specificity. We therefore first examined population genetic structure of ticks in relation to host use and geography. These analyses revealed strong structure in relation to host use, both when populations were sympatric and widely allopatric, with a secondary effect of geography. They also demonstrated the presence of several novel and presumably undescribed species exploiting these seabird hosts. We then used geometric morphometrics (landmark and outline analyses) to test whether host-associated genetic divergence is always accompanied by the same phenotypic changes. We found that morphological variation (size and shape) correlated well with genetic structure; tick size and shape varied strongly in relation to host type, and weakly with geography. These results support the hypothesis that speciation in this tick group has been more strongly shaped by host use than by geographic barriers per se. The revealed phenetic patterns now require detailed investigation to link them with host-specific selective forces.
authors.affiliation: MIVEGEC UMR 5290 CNRS-IRD-UM, Centre IRD, 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France. Electronic address: marlene.dupraz@ird.fr.
authors.forename: Marlène
authors.initials: M
authors.lastname: Dupraz
authors.affiliation: MIVEGEC UMR 5290 CNRS-IRD-UM, Centre IRD, 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Toty
authors.affiliation: MIVEGEC UMR 5290 CNRS-IRD-UM, Centre IRD, 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Noël
authors.affiliation: Universidad de Zaragoza, Facultad de Veterinaria, Miguel Servet 177, 50013 Zaragoza, Spain.
authors.forename: Agustin
authors.initials: A
authors.lastname: Estrada-Peňa
authors.affiliation: Institut de Recerca de la Biodiversitat (IRBio), Departament de Biologia Animal, Universitat de Barcelona, Av Diagonal 643, 08028 Barcelona, Spain.
authors.forename: Jacob
authors.initials: J
authors.lastname: González-Solís
authors.affiliation: CEFE, CNRS UMR 5175, 1919 Route de Mende, 34293 Montpellier, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Boulinier
authors.affiliation: IRD, UMR IRD-CIRAD INTERTRYP, Campus international de Baillarguet, Montpellier, France.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Dujardin
authors.affiliation: MIVEGEC UMR 5290 CNRS-IRD-UM, Centre IRD, 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France.
authors.forename: Karen D
authors.initials: KD
authors.lastname: McCoy
mesh_terms: D000818:Animals; D001717:Birds / Q000469:parasitology; D016000:Cluster Analysis; D005260:Female; D005828:Genetics, Population; D007303:Insect Vectors / Q000033:anatomy & histology* / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D008297:Male; D026861:Ornithodoros / Q000033:anatomy & histology* / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D010802:Phylogeny; D017282:Tick-Borne Diseases / Q000635:transmission
keywords: Adaptation; Ectoparasite; Host specificity; Morphometry; Population genetic structure; Tropical seabirds