Ethan Linck

Postdoc @ U. Tennessee

New preprint : Geographic sampling and species limits in "Western" Empidonax

Back in December, my coauthors and I posted a preprint of our study of species limits in the tricky (some might say “infamous”) Empidonax difficilis / Empidonax occidentalis group of western North American flycatchers. Like all Empidonax, the Pacific-slope and Cordilleran Flycatchers look extremely similar. In fact, they used to be treated as a single species, the “Western Flycatcher,” before a series of papers by Ned Johnson led to their split based on phenotypic and genetic data. However, evidence of ample hybridization in contact and the general overwhelming similarity of these species has meant there have always been a few skeptics who’d rather have left them lumped. Using genome-wide DNA sequence data and 300-plus (!) samples, we asked how including populations of E. occidentalis south of the US / Mexico border changed the story. Were Mexican birds simply a southern partition of the Rocky Mountain deme? Or were we overlooking hidden diversity?

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New preprint : MAF cutoffs and inferring population structure

Inferring population structure – the subdivision of a species into groups of individuals interbreeding with each other at a higher frequency than expected by chance – is a fundamental goal of population genetics. Beyond its obvious relevance to systematics, taxonomy, and conservation, understanding patterns of population structure is crucial for a range of applications, from detecting selection and migration to identifying genetic variants associated with specific traits in genome-wide association studies (the red-hot “GWAS” trend). While on the one hand, the wealth of data resulting from the advent of next generation sequencing technology has proved a boon for describing subdivision in nonmodel organisms, it has also provided challenges. For example, many computational methods for detecting structure were developed prior to the genomics era and may not be suited to the unique characteristics of large SNP datasets. Of these, Pritchard et al.’s structure is the most widely cited, and the basis for a raft of other methods that feature an underlying generative model and explicitly estimate a suite of population genetic parameters.

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Blog resurrection

Brendan skiing Ulrich’s Couloir off the summit of Mt. Stuart this May.

It’s been over a year since I last posted at Beyond the Ranges. I’m a little sad about this. My old blog was a labor of love, a reminder that I love taking photographs, and the archive of a half decade of adventure between the end of college and the present day. There are a number of reasons why I couldn’t keep it up, though. Writing for The Stranger and my subsequent increase in freelancing activity certainly cut in to my desire to pen 3000-plus carefully considered words about sliding on snow. My own interest in reading about running and skiing has decreased lately, and blogs in general appear to be a thing of the past. Most importantly, I needed to start a real professional website (this one), which became my primary home on the internet, but BTR proved a bit too big and clunky to import from WordPress.

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