Continental‐scale patterns of pathogen prevalence: a case study on the corncrake

Abstract

Pathogen infections can represent a substantial threat to wild populations, especially those already limited in size. To determine how much variation in the pathogens observed among fragmented populations is caused by ecological factors, one needs to examine systems where host genetic diversity is consistent among the populations, thus controlling for any potentially confounding genetic effects. Here, we report geographic variation in haemosporidian infection among European populations of corncrake. This species now occurs in fragmented populations, but there is little genetic structure and equally high levels of genetic diversity among these populations. We observed a longitudinal gradient of prevalence from western to Eastern Europe negatively correlated with national agricultural yield, but positively correlated with corncrake census population sizes when only the most widespread lineage is considered. This likely reveals a possible impact of local agriculture intensity, which reduced host population densities in Western Europe and, potentially, insect vector abundance, thus reducing the transmission of pathogens. We conclude that in the corncrake system, where metapopulation dynamics resulted in variations in local census population sizes, but not in the genetic impoverishment of these populations, anthropogenic activity has led to a reduction in host populations and pathogen prevalence.

Ecological determinants of avian malaria infections: An integrative analysis at landscape, mosquito and vertebrate community levels

“…Thus, environmental factors such as the distance to water sources and NDVI, reflecting characteristics such as vegetation cover and phenology, have been shown to be good predictors in the transmission dynamics of pathogens (Foley et al., ; Omumbo, Hay, Snow, Tatem, & Rogers, ; Sehgal, ). Strong relationships between landscape use and the prevalence of blood parasites infecting birds have previously been shown (Fourcade et al., ; Patz et al., ), which may be due to the effect of landscape features on the vector community (Norris, ). For instance, the scarcity of suitable vectors has been identified as the most likely reason of the low prevalence or absence of Plasmodium in birds from marine and saline environments (Figuerola, ; Gutiérrez‐López et al., b; Martínez‐de la Puente et al., ; Mendes, Piersma, Lecoq, Spaans, & Ricklefs, ) and deserts (Merino, Barbosa, Moreno, & Potti, ).…”

“…Environmental characteristics may also determine the dynamics of parasite transmission (Higgs & Beaty, ; Sehgal, ) and incidence of vector‐borne pathogens (Estrada‐Peña, Ostfeld, Peterson, Poulin, & de la Fuente, ; Fourcade, Keišs, Richardson, & Secondi, ; Patz, Graczyk, Geller, & Vittor, ; Sehgal, ), probably through their effects on vector and host populations (Estrada‐Peña et al., ; Roche et al., ). A number of studies have highlighted the importance of factors such as vegetation cover (Lillesand, Kiefer, & Chipman, ; Reisen, Meyer, Tempelis, & Spoehel, ; Roiz, Ruiz, Soriguer, & Figuerola, ) and water sources (Ferraguti et al., ; Ishtiaq et al., ; Krams et al., ; Njabo et al., ) on both vector and host communities.…”

“…Also, the high trace of metals concentrations is linked to the prevalence of avian malaria parasites and affects body condition of urban birds (Bichet et al., ), and a higher parasite virulence has been found in birds feeding on poor quantity and quality food from urban areas (Cornet et al., ). Finally, animal husbandry or agriculture intensification can also affect the transmission of vector‐borne pathogens, including avian malaria parasites (Fourcade et al., ; Gonzalez‐Quevedo, Davies, & Richardson, ; Patz et al., ). Thus, anthropogenic changes in landscapes and their subsequent effects on host communities can affect disease emergence in different situations (Jones et al., ).…”

Investigation of avian haemosporidian parasites from raptor birds in Turkey, with molecular characterisation and microscopic confirmation

“…However, the studies which claimed that L-CIAE02 was found in different avian orders were generally unpublished, according to the available data on L-CIAE02 haplotypes. Moreover, Fourcade et al (2014) found the L-CIAE02 haplotype in two infected corncrakes (Crex crex Linnaeus) using PCR-based methods in Poland and Russia, though no microscopy was included. However, in order to determine the true host specificity of this species of Leucocytozoon, it was necessary to make blood films and to do morphological analyses for detection of sexual development stages.…”

Environmental determinants of haemosporidian parasite prevalence in a declining population of Tree swallows

“…the rate of parasite development in vectors, allowing them to reach their infectious stage before the mosquitoes' next blood meals, which should promote parasite transmission (Paaijmans et al 2009;Garamszegi, 2011). Other studies have shown that high vector-host encounter rates are generally associated with a higher host density (Fourcade et al 2014;Ellis et al 2017).Characteristics of landscape composition, such as proximity to water bodies, also can be important factors affecting the development of some vectors because of habitat-specific phases of their lifecycles (Wood et al 2007;Lachish et al 2011;Okanga et al 2013).…”