Distribution anomalies in avian haemosporidian parasites in the southern Lesser Antilles

Abstract

We compared the haemosporidian parasite faunas (Plasmodium and Haemoproteus) of small land birds on the islands of St Lucia, St Vincent and Grenada in the southern Lesser Antilles. The islands differ in distance from the South American source of colonists, proximity to each other, and similarity of their avifaunas. On each island, we obtained 419–572 blood samples from 22–25 of the 34–41 resident species. We detected parasite infection by PCR and identified parasite lineages by sequencing a portion of the mitochondrial cytochrome b gene. Parasite prevalence varied from 31% on St Lucia to 22% on St Vincent and 18% on Grenada. Abundant parasite lineages differed between the three islands in spite of the similarity in host species. As in other studies, the geographic distributions of the individual parasite lineages varied widely between local endemism and broad distribution within the West Indies, including cases of long‐distance disjunction. St Vincent was unusual in the near absence of Plasmodium parasites, which accorded with low numbers of suitable mosquito vectors reported from the island. Parasites on St Vincent also tended to be host specialists compared to those on St Lucia and Grenada. Similarity in parasite assemblages among the three islands varied in parallel with host assemblage similarity (but not similarity of infected hosts) and with geographic proximity. Parasite prevalence increased with host abundance on both St Lucia and St Vincent, but not on Grenada; prevalence did not vary between endemic and more widespread host species. In addition, the endemic host species harbored parasites that were recovered from a variety of non‐endemic species as well. These results support the individualistic nature of haemosporidian parasite assemblages in evolutionarily independent host populations.

Dynamics of avian haemosporidian assemblages through millennial time scales inferred from insular biotas of the West Indies

“…This result mirrors the observation that the hosts of related parasites (i.e., sister lineages) are not more closely related than pairs of species drawn at random from the host taxonomic hierarchy (13). In the West Indies, we frequently observe locally prevalent and geographically widespread lineages replacing one another across islands of the archipelago (12,14) (Fig. 3).…”

Prevalence of haemosporidians in a Neotropical endemic bird area

“…We found an overall prevalence of haemosporidians of 32.1%. This result concurs with prevalence reported for the Neotropics (Latta and Ricklefs 2010, Ricklefs et al 2011, Lacorte et al 2013, Marzal et al 2015. In contrast, a previous large-scale study (1487 birds screened) across Neotropical highlands in Colombia (González et al 2015) found an overall prevalence of 10%, although this study did not screen for Leucocytozoon infections and this genus was the most common in our study (see below).…”

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

“…Traits that influence host compatibility, and its constituent properties of host susceptibility, parasite infectivity, and the virulence of infection, evolve over time [68,69]. In the West Indies, the same suite of avian hosts and malaria parasites assemble into different patterns of relationships across island replicates [27,28,41], and there is some evidence that these differences can arise over short time periods [42]. If host compatibility issues outweigh heterogeneity in the encounter rate in structuring these parasite-host relationships, such idiosyncratic patterns observed in the West Indies and elsewhere may suggest that compatibility mechanisms are highly labile, even when parasites with complex life cycles are involved.…”

“…Some avian Plasmodium taxa are nearly restricted to a single host species [29,32]. 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].…”

“…Patterns of avian Plasmodium host range are highly idiosyncratic [26][27][28][29]38,41]. Plasmodium parasites are non-randomly distributed across host species, typically infecting only a subset of available hosts [26,28].…”