Diversification and host switching in avian malaria parasites

Abstract

The switching of parasitic organisms to novel hosts, in which they may cause the emergence of new diseases, is of great concern to human health and the management of wild and domesticated populations of animals. We used a phylogenetic approach to develop a better statistical assessment of host switching in a large sample of vector-borne malaria parasites of birds (Plasmodium and Haemoproteus) over their history of parasite-host relations. Even with sparse sampling, the number of parasite lineages was almost equal to the number of avian hosts. We found that strongly supported sister lineages of parasites, averaging 1.2% sequence divergence, exhibited highly significant host and geographical fidelity. Event-based matching of host and parasite phylogenetic trees revealed significant cospeciation. However, the accumulated effects of host switching and long distance dispersal cause these signals to disappear before 4% sequence divergence is achieved. Mitochondrial DNA nucleotide substitution appears to occur about three times faster in hosts than in parasites, contrary to findings on other parasite-host systems. Using this mutual calibration, the phylogenies of the parasites and their hosts appear to be similar in age, suggesting that avian malaria parasites diversified along with their modern avian hosts. Although host switching has been a prominent feature over the evolutionary history of avian malaria parasites, it is infrequent and unpredictable on time scales germane to public health and wildlife management.

Host compatibility rather than vector–host-encounter rate determines the host range of avian Plasmodium parasites

“…In addition, these relationships can vary geographically, and Plasmodium parasites may occur on different hosts across their range [28,41]. These host-parasite relationships are not well preserved through time [42], and co-phylogenetic analyses of parasites and hosts reveal that host switching over evolutionary time-scales is pervasive [43,44]. These geographically variable relationships and host-switching events suggest that avian Plasmodium parasites have the ability to evolve the necessary machinery to exploit a broad range of hosts, despite their restricted host ranges at any given point in space and time.…”

Associations between malaria and MHC genes in a migratory songbird

“…Avian malaria parasites, comprising species in the genera Plasmodium and Haemoproteus, have achieved considerable attention Ricklefs & Fallon 2002;Waldenström et al 2002;Bensch & Å kesson 2003;Fallon et al 2003). This species-rich group of vector-borne blood parasites is taxonomically related to the parasites causing malaria in humans, but are restricted to bird hosts.…”

Low Haemosporidian Diversity and One Key-Host Species in a Bird Malaria Community on a Mid-Atlantic Island (São Miguel, Azores)

“…These parasites are vector borne and show a wide range of host specificity. Some are exclusive to specific bird species (Reullier et al, 2006;Pé rez-Tris et al, 2007), whereas others infect a wide range of species (Beadell et al, 2004;Hellgren et al, 2007;Krizanaskiene et al, 2006;Ricklefs and Fallon, 2002).…”