Island biogeography of avian haemosporidians in the neotropical region

Abstract

Islands have provided numerous examples of unique biological patterns and also have been fundamental in the development of the theory of island biogeography and the identification of putative processes to explain the presence and numbers of species on islands. The equilibrium model explaining species richness on islands has been at the center of this theory. We conducted exploratory analyses of avian blood parasites (Haemosporida) in three Neotropical insular regions (West Indies, Galapagos, and the Revillagigedo Archipelago), aiming to contribute to the development of the theory of island biogeography for this group of parasites. To explore and synthesize current knowledge, we compiled published mtDNA cyt b sequences and geographical information. We discarded short sequences with less than 300 bp and those that did not coincide with the MalAvi reference sequences. We generated two matrices, the first with sequences of the genus Haemoproteus (n = 366, 346 bp) and the second with Plasmodium (n = 228, 443 bp) sequences, including sequences from the continental Americas as reference. We used lineages representing unique sequence haplotypes with at least one different base pair. We found a positive nonsignificant trend between the number of lineages and island size when including all islands in the study; it was significant only for the Haemoproteus genus in the West Indies. Taxon cycles are recognizable patterns resulting from processes by which taxa adapt to local and specialized conditions leading to restricted distribution and specialization of older taxa. Although Haemoproteus and Plasmodium in the West Indies showed a trend consistent with a taxon cycle-older lineages in a reduced number of islands-general linear model analyses were not significant. The small island effect (SIE) must be revised to understand what factors allow islands, such as Montserrat, Nevis or Socorro, to host disproportionately more lineages than expected from their size. The opposite pattern, where larger islands such as Santa Cruz and Fernandina host fewer lineages than expected also deserves study. Microorganisms, such as haemosporidian parasites, require comprehensive sampling on islands in a wider geographical range.