Blood parasite infection and heterozygosity in pure and genetic-hybrid Golden-winged Warblers (Vermivora chrysoptera) across Canada

Abstract

We examined beterozygosity at bypervariable microsatellite loci and blood parasite presence-absence in five populations of Golden-winged Warblers {Vermivora chrysoptera) tbat span tbe species' Canadian range. All populations were predominantly composed of genetically pure individuals, witb small proportions of pbenotypic and genetic bybrids. By comparing beterozygosity and infection status in concert, we tested wbether more-heterozygous individuals bave lower parasite prevalence, perbaps because tbey possess a more robust immune system. By considering tbe genetic status (pure vs. bybrid) of individuals in relation to infection by parasites and beterozygosity, we build on existing researcb tbat examines tbe effect of Blue-winged Warbler {V. cyanoptera) hybridization on Golden-winged Warbler populations. Finally, by looking at populations across tbe east-west range of tbe species, we could bypotbesize what role geographic variation in vectors might play in population-level infection rates. We found no difference in infection probability between pure and bybrid individuals, but a greater frequency of infection in populations in the western portion of tbe range. Our results add to tbe growing evidence tbat bybrids in this system do not face postzygotic selection, and tbat Golden-winged Warblers breeding in the most northwestern extent of their range may face challenges that could impede their conservation. Ongoing work that compares reproductive success of Ontario and Manitoba populations is likely to add an important dimension to our findings and could furtber inform conservation efforts for tbe species. Infección por Parásitos Sanguineos y Heterocigosidad en Lineas Genéticamente Puras e Híbridas deVermivora chrysoptera en Canadá RESUMEN.-Examinamos la beterocigosidad en loci microsatelitales bipervariables y la presencia/ausencia de parásitos en la sangre de cinco poblaciones de Vermivora chrysoptera a lo largo del área de distribución de la especie en Canadá. Todas las poblaciones estuvieron compuestas predominantemente por individuos genéticamente puros, con pequeñas proporciones de bíbridos genotípicos y morfológicos. Mediante la comparación de la heterocigosidad con el estado de infección, evaluamos si los individuos más heterocigotos tienen menor prevalencia de parásitos, tal vez debido a que poseen un sistema inmune más robusto. Al considerar el estado genético (puro vs. bíbrido) de los individuos en relación con la infección parasitaria y la beterocigosidad, aprovecbamos las investigaciones ya existentes sobre el efecto de la bibridación con V. cyanoptera en las poblaciones de V. chrysoptera. Finalmente, mediante el análisis de poblaciones localizadas a lo largo del sector oriente-occidente de la distribución de esta especie, podemos proponer bipótesis sobre cuál es el efecto que puede tener la variación geográfica de los vectores sobre las tasas de infección especificas de cada población. No encontramos diferencias en la probabilidad de infección entre individuos puros e bibridos, pero si una mayor frecuenc...

Host dispersal and landscape conversion are associated with the composition of haemosporidian parasites of the golden-winged warbler

“…Parasite prevalence generally increases to the north-west across the range of the golden-winged warbler. More than half of the Manitoba golden-winged warblers sampled carried at least one genus of a blood parasite, a frequency ten times higher than the site with the lowest prevalence, Kentucky (see also Vallender et al ., 2012). Manitoba also has the highest number of co-infections, which can have synergistic fitness consequences resulting in poor body condition and mortality (Palinauskas et al ., 2011).…”

“…Polymerase chain reaction (PCR) protocol A followed the methods of Vallender et al . (2012), which first looked at blood parasites in golden-winged warblers. In this protocol, primers L15183 (Szymanski and Lovette, 2005) and H15725 (Ricklefs and Fallon, 2002) amplified a 550 bp region in cytochrome b , typically covering the two parasite genera Plasmodium and Parahaemoproteus .…”

“…To determine blood parasite composition, we extracted DNA from all 257 golden-winged warbler and 14 black-capped chickadee blood samples using a homemade kit (Ivanova et al, 2006). To screen for the presence of blood parasites, we used two primer sets that amplified overlapping regions of cytochrome b. Polymerase chain reaction (PCR) protocol A followed the methods of Vallender et al (2012), which first looked at blood parasites in golden-winged warblers. In this protocol, primers L15183 (Szymanski and Lovette, 2005) and H15725 (Ricklefs and Fallon, 2002) amplified a 550 bp region in cytochrome b, typically covering the two parasite genera Plasmodium and Parahaemoproteus.…”

“…Golden-winged warblers ( Vermivora chrysoptera ) are an excellent candidate species to study host–parasite biogeography. Parasite prevalence varies strongly across this species' range (Vallender et al ., 2012), and therefore provides an opportunity to investigate how changes in landscape structure across eastern North American relate to parasite prevalence. Observation and survey records of golden-winged warblers over the past 150 years indicate that the species has expanded its range in a north-northwesterly (NNW) direction, potentially driven by patterns of early successional habitat created by abandonment of cleared agricultural land, and climate change (Gill, 1980; Buehler et al ., 2007; Confer et al ., 2011; Fig.…”

Golden-winged Warbler body fat and blood parasites are associated with anthropogenic and environmental habitat metrics

“…The Golden-winged Warbler population in Manitoba is potentially valuable from a conservation perspective because it has the lowest rate of genetic introgression with the Blue-winged Warbler across the breeding range (Vallender et al 2009, Moulton et al 2018). However, this population also has a high prevalence of blood-parasite infections, relative to other populations (i.e., in Kentucky, Ontario, and Wisconsin), perhaps because of high levels of anthropogenic development in the form of agriculture on the landscape, or because this population occurs near the edge of the species' historical north-west range expansion (Vallender et al 2012, Enslow et al 2020. If anthropogenic development leads to decreased body condition, or increased parasite prevalence, in Manitoba's Golden-winged Warblers, this may pose a conservation concern to this important population.…”