Lab-meeting on August 28 2011: Space, time and evolution

It is time for a new semester of intellectually challenging and exciting lab-meetings in order to sharpen our brains. The first one this semester deals with a "new" idéa which turns out to not to be that new at all, although it is the first time it has been explicitly developed. It is a paper by Australian herpetologist Richard Shine and co-workers in the journal PNAS, entitled: "An evolutionary process that assembles phenotypes through space rather than through time". The paper is published through the "Open Access"-option and can be easily be downloaded here.

Time and place as usual: "Argumentet" on Wednesday, August 31 2011 (unless that room is occupied). Fika volunteers are welcome. Below you can find the abstract.

An evolutionary process that assembles phenotypes through space rather than through time

1. Richard Shine^a,¹,
2. Gregory P. Brown^a, and
3. Benjamin L. Phillips^b

+ Author Affiliations

1. ^aSchool of Biological Sciences A08, University of Sydney, Sydney, NSW 2006, Australia; and
2. ^bSchool of Marine and Tropical Biology, James Cook University, Townsville, QLD 4811, Australia

Abstract

In classical evolutionary theory, traits evolve because they facilitate organismal survival and/or reproduction. We discuss a different type of evolutionary mechanism that relies upon differential dispersal. Traits that enhance rates of dispersal inevitably accumulate at expanding range edges, and assortative mating between fast-dispersing individuals at the invasion front results in an evolutionary increase in dispersal rates in successive generations. This cumulative process (which we dub “spatial sorting”) generates novel phenotypes that are adept at rapid dispersal, irrespective of how the underlying genes affect an organism's survival or its reproductive success. Although the concept is not original with us, its revolutionary implications for evolutionary theory have been overlooked. A range of biological phenomena (e.g., acceleration of invasion fronts, insular flightlessness, preadaptation) may have evolved via spatial sorting as well as (or rather than) by natural selection, and this evolutionary mechanism warrants further study.

• colonization
• evolution
• spatial disequilibrium
• nonadaptive evolution

On ancestral temperature tolerances, butterfly colonization, Lolita and Vladimir Nabokov

Picture sources from Wikipedia.

This week's lab-meeting will take place at 13.30 on Wednesday February 9 in "Darwin", in accordance with our new schedule. We will discuss a very interesting article from Naomi Pierce's laboratory, which deals with biogeography and multiple "waves" of colonization of Polyommatus blues (butterflies belonging to the family Lycaenidae), as they crossed the Bering's Strait in North America. This beatiful paper integrates ancestral state reconstructions of an ecological important trait (thermal tolerance), biogeography, phylogeny and is of also of litterary interest, as the authors confirm a hypothesis by amateur lepidopterist and famous russian author Nabokov. 

Vladimir Nabokov worked at the museum in Harvard (where Naomi Pierce is active today), during the middle part of the last century. Nabokov is mainly known as an important figure in litterature for his famous but controversial erotic novel "Lolita", about the sexual attraction a middle-age man felt towards a young 12-year old girl. Then and now quite a forbidden topic. But Nabokov was also an excellent amateur entomologist and systematist, whose expertise in butterflies exceeded many professional systematists.

Nabokovs biogeographical hypothesis about multiple waves of colonization of bluets to the New World was based on considerations of genital morphology, but has now proven to be largely correct and validated by molecular data. An excellent example how natural history, systematics and museum expertise can be predictive sciences and complement molecular systematics, rather than being replaced by it. I think our former postdoc and beloved co-worker Shawn Kuchta will love this paper. There is an interesting popular essay in New York Times as well, which might be of interest and worth reading prior to the lab-meeting. You can find that excellent essay by Carl Zimmer here. A blog post on the interesting phylogenetic blog "Dechronization" also comments on Zimmer's paper.  

Below is the Abstract to the original article in Proc. R. Soc. Lond. B. that we will discuss on Wednesday. It is an "Open Acess"-article, so just follow the link to the abstract and then you should be able to download it.

Phylogeny and palaeoecology of Polyommatus blue butterflies show Beringia was a climate-regulated gateway to the New World

1. Roger Vila1,2,
2. Charles D. Bell3,
3. Richard Macniven1,4,
4. Benjamin Goldman-Huertas1,5,
5. Richard H. Ree6,
6. Charles R. Marshall1,7,
7. Zsolt Bálint8,
8. Kurt Johnson9,
9. Dubi Benyamini10 and
10. Naomi E. Pierce1,*

+ Author Affiliations

1. ¹Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
2. ²ICREA and Institute of Evolutionary Biology (CSIC-UPF), Passeig Marítim de la Barceloneta 37–49, Barcelona 08003, Spain
3. ³Department of Biological Sciences, University of New Orleans, 2000 Lakeshore Drive, New Orleans, LA 70148, USA
4. ⁴Biogen Idec, 14 Cambridge Center, Cambridge, MA 02142, USA
5. ⁵Department of Ecology and Evolution, The University of Arizona, 424 Biosciences West, Tucson, AZ 85721, USA
6. ⁶Department of Botany, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL 60605, USA
7. ⁷University of California Museum of Paleontology, and Department of Integrative Biology, University of California, Berkeley, 1101 Valley Life Sciences Building, Berkeley, CA 02138, USA
8. ⁸Department of Zoology, Hungarian Natural History Museum H-1088, Budapest, Baross utca 13, Hungary
9. ⁹Florida State Collection of Arthropods/McGuire Center, University of Florida Cultural Plaza, Hull Road, Gainesville, FL 32611, USA
10. ¹⁰91 Levona Street, Bet Arye, 71947, Israel

1. * Author for correspondence (npierce@oeb.harvard.edu).

Abstract

Transcontinental dispersals by organisms usually represent improbable events that constitute a major challenge for biogeographers. By integrating molecular phylogeny, historical biogeography and palaeoecology, we test a bold hypothesis proposed by Vladimir Nabokov regarding the origin of Neotropical Polyommatus blue butterflies, and show that Beringia has served as a biological corridor for the dispersal of these insects from Asia into the New World. We present a novel method to estimate ancestral temperature tolerances using distribution range limits of extant organisms, and find that climatic conditions in Beringia acted as a decisive filter in determining which taxa crossed into the New World during five separate invasions over the past 11 Myr. Our results reveal a marked effect of the Miocene–Pleistocene global cooling, and demonstrate that palaeoclimatic conditions left a strong signal on the ecology of present-day taxa in the New World. The phylogenetic conservatism in thermal tolerances that we have identified may permit the reconstruction of the palaeoecology of ancestral organisms, especially mobile taxa that can easily escape from hostile environments rather than adapt to them.