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Excited to see our new paper (with @frondley_fern and @MichaelSundue) on global fern diversity out at @JBiogeography -- it has been a lot of fun to work on and I am glad to see it published! A short 
on some of the main takeaways:
on some of the main takeaways:
Earth's biodiversity is conspicuously unevenly distributed, and mountains harbor a disproportionately high number of species, especially in the tropics. They also are home to a lot of rare and small-ranged taxa, like this Amauropelta cornuta from Colombia (with @MichaelSundue)
Although we can all appreciate how biodiverse mountains are, the factors contributing to this outsized contribution to biodiversity are not very well-understood, especially at broad spatial scales. In this work, we attempted to provide some new insights, using ferns as a model.
We think ferns make a pretty good group for studying these types of questions -- they form a diverse clade (10k++ spp), are well-represented in mountains, have a long and well-documented evolutionary history, and their distributions aren't obscured by pesky things like flowers.
We ended up using ~800k occurrence records (thanks, collectors, curators, and taxonomists!) covering about 75% of extant fern diversity, a big time-calibrated phylogeny, and ecological/climate layers to address some central questions about global fern diversity.
Where are hotspots of fern diversity? We find eight hotspots, mostly in mountainous areas of the tropics and subtropics. The tropical Andes, Mesoamerica, Greater Antilles, Guiana Shield, southeastern Brazil, Malesia, Madagascar, and East Asia all stand out as being very ferny.
How important are mountains to fern diversity? Very. ~60% of fern species occur in these hotspots; on a per-unit-area basis, mountains are especially important . % endemism tends to be higher in mountains too -- by our estimates, 3/4 of the ferns in Malesia are endemic (!)
How did these hotspots come to be? It's complicated, and depends on the place -- there's more than one way to build a hotspot. Young mountain systems tend to see really high rates of speciation, but persistence of old lineages plays an important role in places like Malesia.
Looking globally, fern diversity is closely linked to environmental heterogeneity -- places with variable climate, topography, and soil have lots of ferns! The Andean fern hotspot covers < 2% of Earth's land area, but encompasses more than 1/2 of its temp-precip variation.
Speciation rates are positively correlated with environmental heterogeneity, too. This hold across most of our hotspots, and non-hotspot areas, but the pattern really comes through in places like East Asia, the Andes, and Mesoamerica. These are all great places to find ferns 
There's a lot more going on in the paper, but those are some of the main takeaways. If you want to learn more, you can find it at @JBiogeography! Again, big 
to @frondley_fern for leading this -- now I really want to get to some tropical mountains and do some fieldwork 
to @frondley_fern for leading this -- now I really want to get to some tropical mountains and do some fieldwork
