Showing posts with label Molecular ecology. Show all posts
Showing posts with label Molecular ecology. Show all posts

Friday, November 2, 2012

Congratulations to Maren Wellenreuther for obtaining "Junior Project Grant"



The Swedish Research Council (VR) recently announced its grants decision for 2012, and I am happy to congratulate one of our lab-members and current postdoc Maren Wellenreuther, to have obtained a "Junior Project Grant" for the next four years. These highly attractive but competitive grants is one way of entering the job market and path towards a research or faculty position in Sweden. Competition was severe this year, as previous years, with only about 16 % of all applications being granted. Well done Maren! It will be exciting to follow Marens research the coming  years, which will focus on chromosomal inversions and evolutionary divergence in seaweed flies around the coasts of Scandinavia.

Last year Jessica Abbott got a similar grant, and it continues to go very well for young researchers both within our lab and in the rest of the Biology Department in Lund. I also encourage those of you who applied this year and did not get a grant (no one mentioned, but nobody forgotten), to not give up but try again next year. Competition is severe, and margins are often tight, but it is necessary to be persistent and believe in one's idéas. I, for myself, is also very happy and grateful that I got a grant this year, and I am looking forward to not have to apply for a while, but concentrate on research.

Lastly, I would like to congratulate former PhD-student Anna Runemark, who recently got one of her thesis-papers accepted in Molecular Ecology: a study on the relationship between inbreeding depression and secondary sexual character divergence in islant populations of Podarcis-lizards. I wish Anna all luck as she awaits the postdoctoral grant decisions from VR and EU/Marie Curie later this year. 

Monday, June 11, 2012

Scientific misconceptions, publication stress and criticism of molecular ecology as a research field





Posted by Erik Svensson

At Juha Merilä's research group blog, EGRU-blog, one often finds very interesting and provocative posts, that stimulates self-reflection and critical thinking. Here is one such post, which raises some critical questions about the field of molecular ecology and the lack of rigour among some of the scientists defining themselves as belonging to this novel field.

This short post actually refers to a recent Invited Review, which is likely to upset some molecular ecologists, as it is very provocative and questions much of the research practices in this very young and technologically-oriented discipline. I do not necessarily endorse everything in this article, and some points that are discussed are beyond my expertise and research interests. As for myself, I do not get very upset or feel very threatened by the message, because I am not a molecular ecologist (and will never become one), even though we have used molecular techniques in our research lab for several years now, and published several papers in the journal Molecular Ecology as well (e. g. this, this and this).

But using molecular techniques, like we have done in these studies, and even endorsing them, is not the same thing as being a molecular ecologist, in my opinion. It is not even enough to publish in the journal Molecular Ecology, I think. I, for myself,  would never define myself as molecular ecologist. Rather, I define myself as an old-fashioned evolutionary biologist interested in the ecological aspects of evolutionary change. Or sometimes I simply define myself an evolutionary ecologist, who is prepared to use observations, field and lab experiments, quantitative genetics and molecular techniques, depending on what is needed and what question that is being adressed.

In contrast, molecular ecology as a field, as I perceive it, is a primarily a discipline defined by techniques and the use of molecular markers, rather than being defined by research questions. And that is why I have never been very interested in this field, as I tend to be more interested in conceptual problems in ecology and evolution, while not being hostile towards new techniques, when they help to solve these classical problems (which is not always the case, however). Molecular Ecology partly grew out from behavioural ecology during the eighties and nineties, as new molecular methods for determining paternity in birds and other animals were developed (first DNA-fingerprinting and later microsattelites). Later, the field came to include many other research questions being adressed by the use of molecular markers, such as phylogeography and molecular population genetic structure etc.

The current review is - interestingly - published in Molecular Ecology - which I think is to the benefit of this outlet as it shows some self-criticism of the same field that the journal is built upon. Hopefully, this article will help to promote self-reflection and critical thinking, both among molecular ecologists (the main target), but also other biologists using molecular techniques. The paper is Open Acess and can be downloaded here. 

 Here are some excerpts, and quite critical and provocative quotations from the paper (Abstract and full reference given below this post):

"Many misconceptions in the various subdisciplines of molecular ecology arise as a consequence of the huge amount of data that can be relatively easily and rapidly generated and analysed. There are many more automated DNA sequencers than classes in population genetic theory, and as self-educated molecular ecologists contribute in professional service, we sometimes see misconceptions perpetuated by journal authors, reviewers and editors."

And:

"At the end of this review, many readers will still believe that if they can properly format data for mega (Tamura et al. 2011) or arlequin(Excoffier et al. 2005), they do not need population genetic theory, they can pick it up along the way, or all the information they need is in the manual. Considering the high error rate (49.9%) in publications of a simple calculation of a population genetic parameter revealed bySchenekar & Weiss (2011), our answer is this: about half of you are right."


Finally, here is some very harsh criticism against the data publication culture in the field of molecular ecology,  and the tendency to crank out too many papers, with too many authors and ignoring much of the classic work that has already been published and which would be relevant to cite:





Abstract: The field of molecular ecology has burgeoned into a large discipline spurred on by technical innovations that facilitate the rapid acquisition of large amounts of genotypic data, by the continuing development of theory to interpret results, and by the availability of computer programs to analyse data sets. As the discipline grows, however, misconceptions have become enshrined in the literature and are perpetuated by routine citations to other articles in molecular ecology. These misconceptions hamper a better understanding of the processes that influence genetic variation in natural populations and sometimes lead to erroneous conclusions. Here, we consider eight misconceptions commonly appearing in the literature: (i) some molecular markers are inherently better than other markers; (ii) mtDNA produces higher FST values than nDNA; (iii) estimated population coalescences are real; (iv) more data are always better; (v) one needs to do a Bayesian analysis; (vi) selective sweeps influence mtDNA data; (vii) equilibrium conditions are critical for estimating population parameters; and (viii) having better technology makes us smarter than our predecessors. This is clearly not an exhaustive list and many others can be added. It is, however, sufficient to illustrate why we all need to be more critical of our own understanding of molecular ecology and to be suspicious of self-evident truths.

Wednesday, January 11, 2012

New journal cover in Molecular Ecology: Vicariance divergence and gene flow among islet populations of an endemic lizard


















I study genetic, morphological and behavioural divergence in islet populations of the Skyros wall lizard, Podarcis gaigeae. This species shows strong morphological divergence, including island gigantism (see the cover image, with adult male lizards from mainland populations to the left and islet populations to the right ). In this paper (found here) we have used isolation with migration models to investigate divergence times and levels of gene flow between islet populations and their closest mainland populations. Such background information is valuable for example for inferring rates of morphological and genetical divergence. Our results support that the studied islet populations have been sequentially separated by rising sea levels in the Aegean.

Abstract:

Allopatry and allopatric speciation can arise through two different mechanisms: vicariance or colonization through dispersal. Distinguishing between these different allopatric mechanisms is difficult and one of the major challenges in biogeographical research. Here, we address whether allopatric isolation in an endemic island lizard is the result of vicariance or dispersal. We estimated the amount and direction of gene flow during the divergence of isolated islet populations and subspecies of the endemic Skyros wall lizard Podarcis gaigeae, a phenotypically variable species that inhabits a major island and small islets in the Greek archipelago. We applied isolation-with-migration models to estimate population divergence times, population sizes and gene flow between islet–mainland population pairs. Divergence times were significantly correlated with independently estimated geological divergence times. This correlation strongly supports a vicariance scenario where islet populations have sequentially become isolated from the major island. We did not find evidence for significant gene flow within P. g. gaigeae. However, gene-flow estimates from the islet to the mainland populations were positively affected by islet area and negatively by distance between the islet and mainland. We also found evidence for gene flow from one subspecies (P. g. weigandi) into another (P. g. gaigeae), but not in the other direction. Ongoing gene flow between the subspecies suggests that even in this geographically allopatric scenario with the sea posing a strong barrier to dispersal, divergence with some gene flow is still feasible.