Parasites with low host specificity (e.g. infecting a large diversity of host species) are of special interest in disease ecology, as they are likely more capable of circumventing ecological or evolutionary barriers to infect new hosts than are specialist parasites. Yet for many parasites, host specificity is not fixed and can vary in response to environmental conditions. Using data on host associations for avian malaria parasites (Apicomplexa: Haemosporida), we develop a hierarchical model that quantifies this environmental dependency by partitioning host specificity variation into region- and parasite-level effects. Parasites were generally phylogenetic host specialists, infecting phylogenetically clustered subsets of available avian hosts. However, the magnitude of this specialisation varied biogeographically, with parasites exhibiting higher host specificity in regions with more pronounced rainfall seasonality and wetter dry seasons. Recognising the environmental dependency of parasite specialisation can provide useful leverage for improving predictions of infection risk in response to global climate change.
1.Univ Fed Bahia, Lab Evolucao & Biogeog, Rua Barao de Jeremoabo 147, BR-40170115 Salvador, BA, Brazil 2.Swansea Univ, Dept Biosci, Swansea SA2 8PP, W Glam, Wales 3.Univ North Dakota, Dept Biol, 1 Campus Dr & Cornell St, Grand Forks, ND 58202 USA 4.Univ North Dakota, Dept Biol, 10 Cornell St, Grand Forks, ND 58202 USA 5.Univ Chicago, Dept Surg, 5812 S Ellis Ave, Chicago, IL USA 6.Field Museum Nat Hist, Integrat Res Ctr, 1400 S Lake Shore Dr, Chicago, IL 60605 USA 7.Drexel Univ, Acad Nat Sci, Dept Ornithol, 1900 Benjamin Franklin Pkwy, Philadelphia, PA 19103 USA 8.Drexel Univ, Dept Biodivers Earth & Environm Sci, 1900 Benjamin Franklin Pkwy, Philadelphia, PA 19103 USA 9.Univ Oxford, Dept Zool, Edward Grey Inst Field Ornithol, Oxford OX1 3PS, England 10.Univ Queensland, Sch Vet Sci, Gatton, Qld, Australia