Patterns of avian malaria in tropical and temperate environments : testing the “The enemy release hypothesis”.
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Date
2019
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Abstract
According to the enemy release hypothesis (ERH) the spread of invasive species will be facilitated by
release from their enemies as they occupy new areas. However, the ERH has rarely been tested by comparing
populations of native (non-invasive, long established) species with expanding or shifting ranges, to the same species
as invasive in another area. We tested the ERH with respect to blood parasite levels (prevalence and intensity of
Plasmodium spp. and Haemoproteus spp.) of (a) two closely related, widely distributed species of thrush (Turdus
leucomelas and T. merula), and (b) an invasive sparrow (Passer domesticus) whose range has expanded from the
Old World to the New World since the 18th century. A total of 158 birds were sampled in Portugal and 99 in Brazil.
All bird species were parasitized, and 55% of the individuals collected were parasitized, and the mean intensity
of infection was of 28 parasites per 10,000 erythrocytes. We assessed whether differences in levels of infection
(prevalence and intensity) were due to site (tropical/New World and temperate/Old World) or host species. The
ERH was supported: Passer domesticus and Turdus merula had higher levels of parasitism in the Old World than
in the New World. Thus, P. domesticus seems to be benefitting from its “recent” range expansion, compared to
T. leucomelas, through ecological release from its native parasites and because the parasites of the recently invaded
area seem to be infesting native species instead.
Description
Keywords
Portugal, Brazil, Turdus, Invasive bird, Range expansion
Citation
ITABAIANA, Y. A. et al. Patterns of avian malaria in tropical and temperate environments: testing the “The enemy release hypothesis”. Biota Neotropica, Campinas, v. 19, n. 4, p. 1-7, 2019. Disponível em: <http://www.scielo.br/scielo.php?pid=S1676-06032019000400204&script=sci_abstract>. Acesso em: 10 mar. 2020.