Morphological versus molecular identification of avian Haemosporidia: an exploration of three species concepts

Abstract

S U M M A R YMore than 200 species of avian Haemosporidia (genera Plasmodium, Haemoproteus, and Leucocytozoon) have been described based primarily on morphological characters seen in blood smears. Recent molecular studies, however, suggest that such methods may mask a substantial cryptic diversity of avian haemosporidians. We surveyed the haemosporidians of birds sampled at 1 site in Israel. Parasites were identified to species based on morphology, and a segment of the parasite's cytochrome b gene was sequenced. We compared 3 species concepts : morphological, genetic, and phylogenetic. Fifteen morphological species were present. Morphological species that occurred once within our dataset were associated with a unique gene sequence, displayed large genetic divergence from other morphological species, and were not contained within clades of morphological species that occurred more than once. With only 1 exception, morphological species that were identified from multiple bird hosts presented identical sequences for all infections, or differed by few synonymous substitutions, and were monophyletic for all phylogenetic analyses. Only the morphological species Haemoproteus belopolskyi did not follow this trend, falling instead into at least 2 genetically distant clades. Thus, except for H. belopolskyi, parasites identified to species by morphology were supported by both the genetic and phylogenetic species concepts.

Recent advances in the study of avian malaria: an overview with an emphasis on the distribution of Plasmodium spp in Brazil

“…Species of avian haemosporidian parasites have traditionally been described based on the morphology of their blood stages and limited experimental information on their vertebrate host specificity. Their identification based on microscopic observation is based mainly on characteristics of the asexual and sexual intracellular blood stages, morphometric analyses, such as length, width, area, number and size of pigment granules (Garnham 1966, Valkiūnas 2005, Martinsen et al 2006). Importantly, blood films, which are used for microscopic examinations, should be well-prepared and should be examined properly by skilled investigators (Valkiūnas et al 2008a).…”

“…Importantly, blood films, which are used for microscopic examinations, should be well-prepared and should be examined properly by skilled investigators (Valkiūnas et al 2008a). Recent molecular studies using gene sequence analysis have supported the classification of the majority of genera and many subgenera of avian haemosporidian parasites and have provided additional information Financial support: CNPq, FAPEMIG, UFMGabout the phylogenetic relationships between currently recognized genera (Martinsen et al 2006). Phylogenetic reconstruction of cytochrome b (cytb) lineages from readily distinguishable morphospecies has shown that many lineages form monophyletic clusters that match morphospecies.…”

“…Classification of avian malaria parasites into subgenera facilitates species identification when using optical microscopy to perform morphological analysis in blood films. The validity of some subgenera of avian Plasmodium remains unclear based on limited molecular analysis (Martinsen et al 2006) and some recently established subgenera (Landau et al 2010) also need to be validated. Clearly more genetic analysis is needed before the subgeneric classification of these parasites can be reconstructed (Palinauskas et al 2007).…”

New species of haematozoa from the avian families Campephagidae and Apodidae

“…New insights are being gained from the rapidly increasing volume of DNA sequencing work which provides genetic information such as cytochrome b gene sequences for classically named parasites. The question of how this new information reinforces or refutes the old taxonomic order is the focus of current stimulating research (Fallon et al, 2003Martinsen et al, 2006;Krizanauskiene et al, 2006;Hellgren et al, 2007). It is impossible to predict the ultimate conclusions, yet some trends are emerging.…”

“…Firstly, the classical morphology is generally reinforced; for example even slight character differences such as the shape of hemozoin crystals do differentiate P. cathemerium and P. relictum (Laird, 1998;Noland et al, 2003). Secondly, the distribution of parasite species across hosts is often differentiated at taxonomic level lower or equal to host family (Martinsen et al, 2006;Hellgren et al, 2007). Although instances of intra-order, but inter-family hostswitching by Haemoproteus has been observed (e.g.…”