Ecology, Not Distance, Explains Community Composition in Parasites of Sky-Island Audubon's Warblers

Abstract

23 1. Haemosporidian parasites of birds are ubiquitous in terrestrial ecosystems, but their 24 coevolutionary dynamics remain poorly understood. If species turnover in parasites occurs at a 25 finer scale than species turnover in hosts, widespread hosts would encounter diverse parasites 26 and potentially diversify as a result. Previous studies have shown that some wide-ranging hosts 27 encounter varied haemosporidian communities throughout their range, and vice-versa. However, 28it remains difficult to test spatial patterns of diversity in this complex multi-host multi-parasite 29 system because it remains inadequately surveyed. 30 2. We sought to understand how and why a community of avian haemosporidian parasites varies 31 in abundance and composition across an array of eight sky islands in southwestern North 32America. We tested whether bird community composition, aspects of the environment, or 33 geographic distance explain parasite species turnover in a widespread, generalist host. 34 3. We sampled 178 Audubon's Warblers (Setophaga auduboni) along elevational transects in 35 eight mountain ranges and screened them for haemosporidian mtDNA. We tested predictors of 36 infection using generalized linear models (GLMs) and we tested predictors of bird-and parasite-37 community dissimilarity using generalized dissimilarity modeling (GDM). 38 4. Predictors of infection differed by genus: Parahaemoproteus was predicted by elevation and 39 climate, Leucocytozoon varied idiosyncratically among mountain ranges, and Plasmodium was 40 unpredictable, but rare. Parasite species turnover was nearly three-fold higher than bird species 41 turnover and was predicted by elevation, climate, and bird community composition, but not by 42 geographic distance. 43 5. Haemosporidian communities vary strikingly at spatial scales of hundreds of kilometers, 44 across which the bird community varies only subtly. The finer spatial scale of turnover among 45 Ecology explains sky-island parasite communities 3 parasites species implies that their ranges tend to be smaller than those of their hosts. Avian host 46 species should encounter different parasite species in different parts of their ranges, resulting in 47

Prevalence and diversity of haemosporidian parasites in the yellow‐rumped warbler hybrid zone

“…This is consistent with Williamson et al. () who found that probability of infection by Parahaemoproteus decreased with elevation in New Mexico sky‐island Audubon's warblers. One possibility could be that S. c. coronata do not cope as well in high elevation environments.…”

“…This means these young birds were infected on the breeding ground, as opposed to their wintering grounds, suggesting that infection occurs in the nest or soon after fledging. This is supported by a recent study on Setophaga coronata auduboni in New Mexico (US) sky islands that found a high diversity of haemosporidian lineages but no bird infected by hDENPEN02 (Williamson et al., ).…”

Abundance data applied to a novel model invertebrate host shed new light on parasite community assembly in nature

“…Fournier et al., 2016) and parasite communities (e.g. Williamson et al., 2019). Our models support this idea by suggesting that the regional species pool, and ecological selection in terms of both habitat suitability and biotic interactions are important for structuring communities.…”

Contrasting drivers of diversity in hosts and parasites across the tropical Andes

“…These parasites can reduce the fitness of their hosts, even in low-level chronic infections (42), and are thought to have the potential to shape avian biogeographic patterns (40,43). Hemosporidian communities in turn are thought to be influenced to varying degrees by host community, climate, and barriers to dispersal (44)(45)(46)(47)(48)(49)(50)(51), but improved modeling frameworks with new data are needed to reciprocally test the causes of host and parasite turnover across biodiverse, tropical landscapes.…”