All posts by Daniel Scantlebury

How Likely Are The Dates From Nicholson et al.?

Recent posts on Anole Annals evaluated the taxonomic implications of Nicholson et al.’s [1] new systematics, yet their manuscript included similarly bold interpretations of anole biogeography and the chronology of their diversification.  Nicholson et al. claim that a single genus genus concept for anoles can stifle “scientific communication regarding evolutionary events” and used their new multi-genera taxonomy “to propose a bold hypothesis of the biogeographic history of the family within the constraints of the phylogeny inferred here, the latest known fossils, and a paleogeographic interpretation of the deep history of the West Indies, North America, Mesoamerica, and South America.”  My goal today is to address if their phylogenetic dating analysis is capable of delivering on such claims.

Anoles are characterized by a sparse and poorly understood fossil record.  Any attempt to elucidate the evolutionary history and biogeography of anoles depends on neontological data in the form of DNA sequences from extant species.  Nicholson et al. utilized molecular clock dating methods to hypothesize about the temporal history of anoles.  They calibrated their tree with two amber fossils containing lizards identifiable as anoles.  They attribute the first, Anolis dominicanus, to the clade containing A. aliniger, A. chlorocyanus, A. coelestinus, and A. singularis and assign an age of 23 million years before present (mypb) to this clade.  They use the second second fossil, A. electrum, to calibrate the split between A. limifrons and A. zeus to 28 mybp.  With this background in hand, let’s turn to evaluating their results.

For the sake of a critical evaluation, I have centered the remainder of the post around a three questions I would have asked had I been selected to review this paper during the peer review process.
Continue reading How Likely Are The Dates From Nicholson et al.?

Macroevolutionary methods in R workshop in Santa Barbara, CA June 11-15, 2012

If you’ve read papers published over the last few years on Anolis diversification, you’ve likely noticed a common pattern: the papers present sophisticated analyses of macroevolutionary patterns that were conducted in R (for instance: 1, 2, and see this teaser for the promise of R with GIS data).  If you’ve contemplated how to introduce yourself to R and get over the initial hurdles of writing code for your own research, opportunity is-a-knock’n.

Co-organizer Luke Harmon invites you to apply to the 2012 Workshop on Comparative Methods in R today!

Over the last few years, Michael Alfaro and Luke Harmon have organized a wonderful workshop on macroevolutionary methods in the R programming language for statistical computing.  They’ve just released the application for this year’s course.  I had the privilege of attending last year and found it to be an enriching experience on several fronts.

Continue reading Macroevolutionary methods in R workshop in Santa Barbara, CA June 11-15, 2012

Anolis hendersoni in the Dominican Republic

Here’s a close up of the Anolis hendersoni I found sleeping one fateful night inside the Dominican Republic.

Anolis hendersoni - male

Anolis hendersoni - male

Prior to finding this species, I had spent the evening looking for Sphaerodactylus armstrongi and S. streptophorus on the northern slopes of the Sierra de Bahoruco NW of Puerto Escondido.  Upon entering a patch of closed-canopy, broad-leafed forest with a dense, bushy understory, I remarked to myself, “I bet there will be Anolis bahorucoensis here.”  Anolis bahorucoensis is a bush anole that is common across the Sierra de Bahoruco, and often found alongside S. armstrongi.  I was not expecting to see A. hendersoni – another dolichocephalic bush dwelling species that is closely related to A. bahorucoensis – because it is generally considered a Haitian endemic whose range doesn’t cross the border into the Dominican Republic. When the sun set and I switched over to night hunting, I was happy to find out my intuition was, for once in my life, a close approximation of reality.

 

Can You Spot the Sleeping Anole?

Somewhere in this photo is a sleeping anole. The species is one that has only been reported from the Dominican Republic a few times.

Somewhere in this photo is a sleeping anole. The species is one that has only been reported from the Dominican Republic a few times.

If you can find the sleeping anole in those photo, you will have contributed to cataloging the anole fauna of the Dominican Republic.  Points if you can identify the species.  Hint – the photo was taken on the northern slopes of the Sierra de Bahorucco approx. 12km east of the Haitian border.

Thanks-giving Far from Home

Giant anoles and new friends

Initially skeptical of my ambitions, a group of security guards celebrate the capture of a massive Anolis baleatus.

Part of any field-based research program are the random, unimagined discoveries that develop into fascinating side projects. (I’m sure that statement made my advisor’s blood pressure swell a tad).  One such “discovery” I’ve been a part of during my adventures in the Dominican Republic are the existence of maggot infestations inside the mouths of crown giant anoles.  Another crucial component to field research are the memories you take home with you – I mean the ones you’re not even sure you believe yourself when you tell your friends and family because they are just too random, bizarre and wonderful to be possible.  And that January night when Miguel Landestoy, Anthony Geneva, and I first glimpsed these writhing maggots in the mouths of giant anoles certainly qualifies…  (Cliff notes: Cipro and solenodon). Continue reading Thanks-giving Far from Home

Honey Holes and Rare Anoles

Saludos desede la República Dominicana!

Male Anolis fowleri

I’m just past the middle of a 6 week trip to the eastern half of Hispaniola to collect specimens and ecological data for geckos of the genus Sphaerodactylus as part of my thesis work.  I’m here for the most part with photographer, naturalist, and fellow adventurer Miguel Landestoy.  We’ve had a number of ups and downs already and I figured it is time to share some photos from one of our first nigths in the field when we stumbled upon a honey hole of rare anoles. Since Anolis fowleri is such a rarely seen and poorly known beast, here are some photos of a pair and their habitat. (sorry to keep this post short, but I’m here for geckos after all and am completely exhausted) Continue reading Honey Holes and Rare Anoles