New video on slavemaking ants

I created a video about a project on slavemaking ants on which I have worked with Tobias Pamminger, Susanne Foitzik and Dirk Metzler.

In this video, we talk about our research on slavemaking ants and their hosts (slaves). The slavemakers are of one species (P. americanus) and the hosts of another species (T. longispinosus). Host ants can be captured by the slavemaker ants, and these captured ants (slaves) normally work for the slavemaker queen. But recently, it was found that they sometimes kill slavemakers (Achenbach and Foitzik 2009 and Pamminger et al. 2013). It is unclear why the slaves do this, because they probably cannot reproduce.

The video is based on the paper: “Oh sister, where art thou? Indirect fitness benefit could maintain a host defense trait” by Tobias Pamminger, Susanne Foitzik, Dirk Metzler and myself, which can be found here: http://arxiv.org/abs/1212.0790. Earlier, I wrote a blog-post about this paper for Haldane’s Sieve.

Selective sweeps in HIV on Arxiv

See here (http://arxiv.org/abs/1303.3666) for a new manuscript on sweeps in HIV. This is work with  Sergey Kryazhimskiy and John Wakeley.

HIV drug resistance review accepted

The review paper on drug resistance in HIV which I wrote in the fall is now officially accepted for publication in Infectious Disease Reports. The preprint is on the Arxiv.

Drug resistance symposium at ESEB 2013 Lisbon

Together with Sarah Cobey (Harvard / U Chicago), Gabriel Perron (U. Ottawa) and Fredrik Inglis (ETH), I organize a symposium, “The Evolution and Genetics of Drug Resistance,” at the European Society for Evolutionary Biology (ESEB) meeting this August. The ESEB meeting is the largest European conference on evolution and takes place every two years. This summer it will be held in Lisbon (https://www.eseb2013.com/). Approximately 1400 people are expected to attend.

There is general consensus that the evolution of drug resistance is an interesting scientific topic and an important public health issue. We are very happy & proud that this year there will be a symposium dedicated to this theme at ESEB. We have invited two great invited speakers, Cally Roper and Craig MacLean. Dr. Roper works on drug resistance in malaria, including its evolution and its global distribution. Dr. MacLean has researched the evolutionary genetics of antibiotic resistance in the opportunistic human pathogen Pseudomonas aeruginosa.

The deadline for abstracts is February 28th. To submit your abstract, please first register at https://www.eseb2013.com/ and then upload your abstract to the site.

The four of us will evaluate the abstracts in a blinded way, so that we will not know whose abstract we are judging. The total amount of time allocated for our symposium depends in part on the number of abstracts received. More submissions will ensure an interesting and lively session. We welcome studies that are based on theory, data analysis, experiment, and/or clinical research.

We hope to see you this summer in Lisbon (which, by the way, is a great city to visit)!

Symposium Description: The Evolution and Genetics of Drug Resistance

The evolution of drug resistance in pathogenic microorganisms is one of the most important challenges facing evolutionary biologists. Evolutionary studies of drug resistance can aid the development of effective clinical strategies. At the same time, such studies help further our general understanding of evolutionary biology. Our symposium provides a venue to discuss experimental and theoretical studies that improve basic understanding and/or inform clinical practice.

Small scale spatial structure in ants – arXiv Preprint

Tobias Pamminger, Susanne Foitzik, Dirk Metzler and I analyzed the small scale spatial structure of ants of the species Temnothorax longispinosus. These ants are the host of a slavemaking ant. The slavemakers go on raids, and steal young from the host species to work as slaves in their nests. We wanted to know whether the slaves still have relatives in the nearby nests. If they do, then their behavior – which influences the slavemakers – could have an effect on their relatives and therefore on their indirect fitness.

To find out if slaves are related to their neighbours, we collected lots of ant nests (they nest in acorns), both in New York and in West Virginia, marked exactly where we found them and genotyped them at six microsatellites.

Photograph by Andreas Gros
Temnothorax longispinosus in acorn

We put little flags at the exact location of an ant nest to measure the distances between the nests.

This is one of the figures from the manuscript. Plot R (from West Virginia) is is shown to demonstrate the distribution of colonies within a plot and to show the distribution of alleles of one of the six microsatellite loci (GT1) among colonies. Each colony is represented by a pie-diagram with the frequencies of different GT1 alleles amongst the genotyped individuals of the colony. R3 is a slavemaker nest (we genotyped the slaves, not the slavemakers) and shares most of its alleles with the free nest R7. R13 and R15 are free living host colonies in close proximity and appear to be related.

Our main conclusion is that the enslaved ants are indeed related to their neighbors. The manuscript can be found on the arXiv here: http://arxiv.org/abs/1212.0790

The manuscript was peer-reviewed at Peerage of Science, a new and very useful community of scientists who agree to review each others papers fairly. See http://www.peerageofscience.org/

The manuscript is part of Tobias Pamminger’s PhD thesis. Tobias defends his thesis this week in Mainz!! Congrats Tobias!

Tobias came up with the awesome title for the paper “Oh sister, where art thou? Indirect fitness benefit could maintain a host defense trait.”

Essay on HIV drug resistance published on the arXiv

A few days ago, I submitted a review paper to Infectious Disease Reports. The review is an invited essay for the special issue they are planning around the World AIDS Day (December 1st).

I was pleasantly surprised to see that the author guidelines of Infectious Disease Reports said: ”Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work.” So, I decided to upload the manuscript to the arXiv.

The essay describes the current situation of drug resistance in HIV. The main conclusion is that, overall, drug resistance is not as big a problem as one may think. Treatments have become very good, which means that the rate of evolution of drug resistance is low. At the same time, many new drugs have become available so that when drug resistance evolves, the patient can be switched to another set of drugs. However, in poor countries, where viral genotyping, viral load monitoring and many new drugs are not available, drug resistance still poses a serious threat to people’s health.

In the essay, I explain that transmitted drug resistance occurs, but at a level that is lower than many would have expected. Roughly 10% of newly infected patients are infected with an HIV strain with at least one major drug-resistance mutation. If the virus is genotyped before treatment is started (as is standard in rich, but not in poor, countries), then treatment success is very high for these patients.

Acquired drug resistance (when resistance evolves during treatment) is more common than transmitted drug resistance, and resistance can evolve even after many years of successful treatment. It can also happen that the virus becomes resistant against multiple drugs. Nowadays, there are many different drugs available, so that even patients with multi-class drug resistance can often be treated successfully, although this is not the case in poor countries, simply because the newer drugs are expensive.

I also describe what is known about resistance due to treatment for the prevention of mother-to-child-transmission (which is a big problem) and resistance due to pre-exposure prophylaxis (which occurs, but is uncommon). I also discuss the issue of low-frequency resistance mutations and their clinical relevance. Throughout the essay, I explain how certain effects are expected or surprising from an evolutionary perspective.

I thank my collaborators Daniel Rosenbloom and Alison Hill (both at Harvard) for useful comments on an earlier version of the manuscript.

Moved to Dmitri Petrov’s lab at Stanford

I am happy to announce that I have joined Dmitri Petrov’s lab at Stanford. Dmitri has a lively group and they do very nice evolutionary work. One of my favorite recent papers from this group is on a soft sweep at an insecticide resistance locus in fruitflies (I admit that I may be somewhat biased – but who can resist the combination of a soft sweep and a resistance locus?).

I spent the last two years in John Wakeley’s group at Harvard, which I enjoyed a lot. I will miss the great people I met there, but not the Boston winter!