title: Diversity, loss, and gain of malaria parasites in a globally invasive bird.
abstract: Invasive species can displace natives, and thus identifying the traits that make aliens successful is crucial for predicting and preventing biodiversity loss. Pathogens may play an important role in the invasive process, facilitating colonization of their hosts in new continents and islands. According to the Novel Weapon Hypothesis, colonizers may out-compete local native species by bringing with them novel pathogens to which native species are not adapted. In contrast, the Enemy Release Hypothesis suggests that flourishing colonizers are successful because they have left their pathogens behind. To assess the role of avian malaria and related haemosporidian parasites in the global spread of a common invasive bird, we examined the prevalence and genetic diversity of haemosporidian parasites (order Haemosporida, genera Plasmodium and Haemoproteus) infecting house sparrows (Passer domesticus). We sampled house sparrows (N = 1820) from 58 locations on 6 continents. All the samples were tested using PCR-based methods; blood films from the PCR-positive birds were examined microscopically to identify parasite species. The results show that haemosporidian parasites in the house sparrows' native range are replaced by species from local host-generalist parasite fauna in the alien environments of North and South America. Furthermore, sparrows in colonized regions displayed a lower diversity and prevalence of parasite infections. Because the house sparrow lost its native parasites when colonizing the American continents, the release from these natural enemies may have facilitated its invasion in the last two centuries. Our findings therefore reject the Novel Weapon Hypothesis and are concordant with the Enemy Release Hypothesis.
authors.affiliation: Department of Biology, Lund University, Lund, Sweden.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Marzal
authors.forename: Robert E
authors.initials: RE
authors.lastname: Ricklefs
authors.forename: Gediminas
authors.initials: G
authors.lastname: Valkiūnas
authors.forename: Tamer
authors.initials: T
authors.lastname: Albayrak
authors.forename: Elena
authors.initials: E
authors.lastname: Arriero
authors.forename: Camille
authors.initials: C
authors.lastname: Bonneaud
authors.forename: Gábor A
authors.initials: GA
authors.lastname: Czirják
authors.forename: John
authors.initials: J
authors.lastname: Ewen
authors.forename: Olof
authors.initials: O
authors.lastname: Hellgren
authors.forename: Dita
authors.initials: D
authors.lastname: Hořáková
authors.forename: Tatjana A
authors.initials: TA
authors.lastname: Iezhova
authors.forename: Henrik
authors.initials: H
authors.lastname: Jensen
authors.forename: Asta
authors.initials: A
authors.lastname: Križanauskienė
authors.forename: Marcos R
authors.initials: MR
authors.lastname: Lima
authors.forename: Florentino
authors.initials: F
authors.lastname: de Lope
authors.forename: Eyðfinn
authors.initials: E
authors.lastname: Magnussen
authors.forename: Lynn B
authors.initials: LB
authors.lastname: Martin
authors.forename: Anders P
authors.initials: AP
authors.lastname: Møller
authors.forename: Vaidas
authors.initials: V
authors.lastname: Palinauskas
authors.forename: Péter L
authors.initials: PL
authors.lastname: Pap
authors.forename: Javier
authors.initials: J
authors.lastname: Pérez-Tris
authors.forename: Ravinder N M
authors.initials: RN
authors.lastname: Sehgal
authors.forename: Manuel
authors.initials: M
authors.lastname: Soler
authors.forename: Eszter
authors.initials: E
authors.lastname: Szöllosi
authors.forename: Helena
authors.initials: H
authors.lastname: Westerdahl
authors.forename: Pavel
authors.initials: P
authors.lastname: Zetindjiev
authors.forename: Staffan
authors.initials: S
authors.lastname: Bensch
mesh_terms: D000818:Animals; D016787:Haemosporida / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D008289:Malaria, Avian / Q000469:parasitology; D010961:Plasmodium / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D016133:Polymerase Chain Reaction; D046370:Sparrows / Q000469:parasitology