Thread by @MSBbirds

Why do tropical bird & avian-malaria communities vary from place to place?

In PNAS, @SabrinaMcnew et al. answered this by modeling diversity across Peru, based on years of field, lab, & museum work.

(📸:@UrSchmittinMe et al.)

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pnas.org/content/118/12…

We explained 'species turnover' among communities as having resulted from environmental differences and/or hosts/parasites.

Generalized dissimilarity modeling (GDM) was key.

For both birds & avian malaria, *rainfall* had the strongest influence on species turnover.

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Temperature, net primary productivity, and elevation were also important drivers of bird species turnover...

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Was bird community composition driven by avian malaria community composition?

No!

Bird turnover predicted avian malaria turnover, but not vice versa.

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These findings from birds & malaria were similar to previous findings in rodents & fleas onlinelibrary.wiley.com/doi/abs/10.111…

It seems that parasite communities tend to change in response to host species composition, but the parasites do not drive host biogeographic patterns.

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Drivers of phylogenetic turnover (change in phylo composition from place to place) were similar to species turnover for birds, but not malaria -> processes that structure malaria communities shifted during evolution. Malaria phlyo turnover was strongly driven by *elevation*

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We used models of turnover to project faunal dissimilarity onto the landscape, resulting in detailed maps that depict community differences as contrasting colors.

We think such maps could be used to help set conservation priorities by identifying hotspots of turnover.

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Accordingly, McNew made the high resolution pdf’s and raster files from this study freely available on her Github site.

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github.com/smcnew/Peru_GD…

The non-linear GDM models revealed the scale-dependence of various effects that we uncovered. Contrary to expectations, climatic effects on parasite turnover occurred on relatively small, local scales, while host-community effects manifested on broad, regional scales.

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Bird species richness was predicted by elevation & net primary productivity alone (~80% of variation explained).

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Parasite richness, however, was explained only by the diversity of birds screened. As with turnover, it appears that parasites follow hosts, while host diversity patterns are driven by other aspects of the environment.

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A short story of how this study came about is provided in this press release from the University of New Mexico.

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news.unm.edu/news/why-biodi…

The paper is dedicated to the memory of Paloma Ordoñez — a dear friend, dedicated field biologist, and our co-author, who passed away tragically in 2020.

This study was a collaboration among 3 institutions: @UNM's Museum of Southwestern Biology, Centro de Ornitología y Biodiversidad (@CORBIDIteam), & @FieldMuseum (Field Museum of Natural History). Many people pitched in with fieldwork, including the ones pictured, & more.

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Collections & databases (arctosdb.org) were critical infrastructure for this work. From here on, samples of each of the 400 malaria species that we uncovered will be permanently available for study from the cryo-collections of MSB & FMNH.

#collectionsareessential

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Due credit & thanks to all the authors of this study 🙏👏
@SabrinaMcnew @barrowevobio @jl_williamson @JMBFMNH @SpencerGalen @ariel_gaffney @UrSchmittinMe Paloma Ordoñez, Ashley Smiley, Andy Johnson, Shane DuBay, Heather Skeen, Emil Bautista, Thomas Valqui, & Shannon Hackett

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Message @SabrinaMcnew or me for a pdf reprint if you would like to read more 😊

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