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June 1, 2015

23:52
PhD Evolution of metabolic cross-feeding interactions Dr. Christian Kost, Experimental Ecology and Evolution Research Group, Max Planck Institute for Chemical Ecology A 3-year PhD position is available in my lab at the Max Planck Institute for Chemical Ecology in Jena, Germany. This DFG-funded project will study the evolution of metabolic cross-feeding interactions within bacterial model communities. Using an approach of experimental coevolution between members of the same or different bacterial species, this project aims at (i) identifying the impact of genetic relatedness, and (ii) determining the role of phenotypic heterogeneity during the evolution of cooperative cross-feeding interactions. By combining individual-based modelling with detailed analyses of derived genotypes (whole-genome re-sequencing) and phenotypes (i.e. microscopic analyses on a single-cell level, chemical analyses), unprecedented mechanistic insights into the dynamics that shape the evolution of cooperative cross-feeding interactions can be gained. The project is part of the DFG-funded Priority Programme Phenotypic Heterogeneity and Sociobiology of Bacterial Populations (http://spp1617.de) and will be conducted in close collaboration with other experimental and theoretical working groups. The position requires a master’s degree in biology (or a related field). The successful candidate should be highly motivated, be able to work independently, and have a strong background in microbiology, evolutionary biology and/ or ecology. Previous research experiences in bioinformatics, theoretical biology, analytical chemistry, or molecular biology are advantageous. My group offers an international, dynamic, and interactive scientific environment as well as state-of the art, newly equipped laboratories. Information on our scientific work including recent publications can be found here: http://bit.ly/1K67OYE Please do not hesitate to contact me (christiankost@gmail.com; 0049-(0)3641-571212) for informal enquiries. Your application should consist of: i) Letter of motivation (max. 2 pages: Why you think the project is relevant, why are you interested in it, and what makes you a suitable candidate?) ii) Statement of research experience and interests (max. 1 page) iii) CV (incl. grades of B.Sc and M.Sc) iv) Publication list (if applicable) v) Names and e-mail addresses of three academic referees Please send your application as a single PDF file to Dr. Christian Kost (christiankost@gmail.com). Screening of applications will begin immediately and continue until the position is filled. Dr. Christian Kost Experimental Ecology and Evolution Group Max Planck Institute for Chemical Ecology Beutenberg Campus Hans-Knöll-Straße 8 D-07745 Jena Germany Tel.: ++49 (0)3641 57 1212 Fax.: ++49 (0)3641 57 1202 Email: christiankost@gmail.com http://bit.ly/1FmvfXU http://bit.ly/1K67OYG lty_kost.pdf Christian Kost via Gmail
Source: EVOLDIR
23:52
International Workshop “An Introduction to Geometric Morphometrics using R” October 5-9, 2015 @ CIBIO-InBIO, Vairao, Portugal The analysis of organismal shape is central to many questions in ecology and evolution. This workshop aims at providing an introduction to the theory and methods of geometric morphometrics for analyzing variation in shape and its covariation with other variables. It will provide an overview of the theory underlying the quantification of shape using landmark methods, and a practical guide to data acquisition, standardization for obtaining shape variables, statistical treatment of shape variation, and visualization of the results in the R language for statistical programming. R knowledge is a requirement for the course and it will be assumed that all participants are fluent for data manipulation and basic operations in the R environment. Click here [http://bit.ly/1K67OYA c-morphometrics-using-r] to see the PROGRAMME for this course. COURSE INSTRUCTORS Prof. Dean C. Adams [http://bit.ly/1HHQODd] Dr. Michael Collyer [http://bit.ly/1K67OYC] Dr. Antigoni Kaliontzopoulou [http://bit.ly/1HHQLHx] REGISTRATION DEADLINE Deadline for registration is July 31, 2015. To know more about this course, please visit CIBIO-InBIO’s website [http://bit.ly/1K67OYA c-morphometrics-using-r] or contact us at GM2015@cibio.up.pt. CIBIO Divulgação via Gmail
Source: EVOLDIR
23:36
Dear colleagues, We are extremely happy to announce 11th edition of Poznan Summer School of Bioinformatics. This meeting takes place at Adam Mickiewicz University in Poznan (Poland) from 6th to 10th July 2015. This year’s course will cover modern approaches to RNA analyses, including subjects like: 1. Introduction to RNA biology 2. Applications of next-generation sequencing in RNA studies 3. Transcriptome sequencing, assembly and gene expression estimation 4. Identification and analysis of microRNAs and other small RNAs 5. long non-coding RNAs 6. Secondary and tertiary structures of RNAs The course is suitable both for beginners and for those who already have some basic knowledge in computational biology and find it necessary and interesting to learn more about bioinformatic applications in RNA studies. Our school consists of lectures and hands-on - this combination should fit best your needs as you have a chance to try out the discussed methods yourself. The deadline for REGISTRATION is July 1st. For further information please visit our website: http://bit.ly/1DDxbdc Please forward this announcement to anyone who might be interested. Best regards, PSSB Organizing Committe Contact: genomics@amu.edu.pl Bioinfo School via Gmail
Source: EVOLDIR
13:52

@db60 wrote:

THIRD INTERNATIONAL ENVIRONMENTAL 'OMICS SYNTHESIS CONFERENCE - IEOS2015

University of St Andrews 6-8 July 2015

http://environmentalomics.org/ieos2015

DEADLINE for registration and abstract submission (talk/poster): 6 June 2015

DEADLINE for application for postgraduate student bursaries: 6 June 2015

KEYNOTE SPEAKERS:

o Professor ELIZABETH THOMPSON, University of Washington

o Professor MARK BLAXTER, University of Edinburgh

o Professor BARBARA METHE, J Craig Venter Institute

INVITED SPEAKERS:

Dr LOGAN KISTLER, University of Warwick

Dr UMER ZEESHAN IJAZ, University of Glasgow

Professor JIANQUAN LIU – Lanzhou University / Sichuan University

Dr NATHAN BAILEY, University of St Andrews

STUDENT BURSARIES:

Postgraduate students who submit abstracts are eligible for a bursary, covering 100% of the registration fee. When submitting an abstract, students should indicate they with to be considered for a bursary. Successful applicants will receive a code for FREE registration.

IEOS2015:

The aim of this conference is to bring together researchers and organisations from a range of disciplines with shared interests in the development of new approaches for data handling, generation and analysis in environmental omics. Science areas of interest include bioinformatics, DNA-barcoding, genomics, metagenomics, metabarcoding, transcriptomics, proteomics, metabolomics, epigenetics, evolutionary and ecological omics, phylogenetics, study of ancient DNA and anthropology, new tools, resources and training, and beyond as applied to the study of the natural environmental and environmentally relevant organisms and systems. It is our hope is that the resulting interaction and exchange of ideas will lead to novel approaches, new collaborations and the consolidation of a wider integrated environmental 'omics community.

EOS and this conference are supported by Natural Environmental Research Council (NERC) through its Mathematics and Informatics for Environmental 'Omics Data Synthesis programme and the UK Science and Technology Facilities Council (STFC) Global Challenges programme.

SUMMER OF V'S

IEOS2015 attendees are also welcome at a separate meeting on Data Science, The Summer of V's, immediately preceding the main registration event for IEOS. Separate registration is required for the Summer of V's: http://www.idir.st-andrews.ac.uk/vs

IEOS2015: http://environmentalomics.org/ieos2015

With best wishes, The IEOS Conference Organising Committee http://environmentalomics.org/ieos2015-committee

The University of St Andrews is a charity registered in Scotland : No SC013532

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Participants: 1

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00:34
Job: RA. Crested Macaques. Indonesia ____What: Position Description___ We are looking for a research assistant to help during 6 months on the data collection for a project on intergroup interactions in crested black macaques (Macaca nigra; http://bit.ly/1ACgUKG and https://www.youtube.com/watch?v=3DbmjCrZNlOps). The aim of this project is to investigate the evolution of parochial altruism. The assistant will need to learn the I.D. of approximately 80 animals and will contribute to: - Behavioural data collection, using a mixture of focal, scan, and ad libitum sampling - Spatial data collection (GPS) - Faecal sample collection for DNA analysis - Performing field experiments (playback) - Data management Although these will be the main responsibilities of the research assistant, some flexibility is expected to adapt to the unpredictable conditions of fieldwork. In general, the weekly schedule will consist of 5 days of field work, 10-12h/day (Dawn to dusk). Training will be provided on site. _______Where______ The study will be conducted at the Tangkoko-Batuangus Nature Reserve in North East Sulawesi (Indonesia) as a part of the Macaca Nigra Project (http://bit.ly/1FicJiG). Accommodation will either be at the field station (http://bit.ly/1ACgRP0), where the conditions are basic, but comfortable (Beds are provided, cellular service is fairly regular, and electricity is available a few hours every day at night), or in the village, about 10 minutes walking from the field site. ____Qualifications/Experience____ Requirements: - Bachelors/undergraduate degree in Biology, Anthropology, Zoology or related subjects. - Fluent in English (Spoken and written) - Previous field work experience with wild animals - Be physically fit and healthy (Able to spend 12h/day in the field 5days/week carrying a backpack, walking and standing most of the time) - Good social skills (being respectful towards others, patient, sympathetic…) - Be able to work independently within a team - Be open-minded and able to work with people from different nationalities, cultures, and backgrounds - Feel comfortable living under basic conditions and being far away from family/friends - Be willing to adapt to a foreign culture - Be able to maintain a positive attitude towards hard and tiring work. - Willing to learn new skills - Ability to follow instructions accurately - Be flexible and responsible - Willingness to learn basic Bahasa Indonesia (i.e. courtesies) Preferred candidates will have experience: - Collecting behavioural data from individually recognized primates - Working in a tropical climate under demanding physical conditions - On international field work - Working in international teams _____Salary/funding_____ This is a volunteer position, no salary provided. Applicants should be able to cover the expenses detailed bellow. At the moment there is no funding available to subsidize the costs, but we have launched a crowdfunding campaign for this end. Any support provided would depend on the success of this campaign http://bit.ly/1ACgRP2 _____Support provided (travel, meals, lodging)___ Currently there is NO funding available to support the field assistant. The costs that the assistant should be ready to cover are: - International travel to Indonesia (if required) - National travel to Manado: 150 approx. (return plane ticket) - Monthly camp fees: 300/month (includes 3 meals per day and bills) - Visa: approx. 100, but country dependent - Permits: 1100 Approx. - Vaccinations (depending on personal requirements) - Travel health insurance (Depending on the company; can be 200 or more) - Personal equipment: field clothes, backpack, appropriate foot gear… (depending on personal requirements) - Personal expenses: trips to town, free-time activities Cost will be subsidized depending on the success of the crowdfunding campaign http://bit.ly/1ACgRP2 ____Term of Appointment______ 6 months (Approx. July 2015- December 2015) ______Application Deadline_______ Applications will be accepted on a rolling basis until 15th June 2015 (included) ____How to apply_____ If interested, please apply by sending an email to Laura Martinez Inigo (lmartinezinigo@lincoln.ac.uk) attaching a cover letter and a CV. The letter should explain why you are interested in the position and why you are a suitable candidate for the post, relating your skills and experience to the requirements in the advertisement. Please include the details of at least 2 referees in your CV. _______Contact Information_______ Laura Martinez Inigo University of Lincoln Brayford Pool Lincoln Lincolnshire LN6 7TS United Kingdom E-mail Address: lmartinezinigo@lincoln.ac.uk “lMartinezInigo@lincoln.ac.uk” via Gmail
Source: EVOLDIR
00:18
If you would like to highlight particularly exploitative volunteer opportunities, internships, and “work experiences” posted to job boards, there is a new site for that! http://bit.ly/1dFV1QD >From the about page: Volunteer $B!H(Bjobs$B!I(B that offer no pay are rampant in wildlife ecology and conservation biology, and it$B!G(Bs time for them to stop. They$B!G(Bre unprofessional, exploitative, limit diversity, immoral, and in some jurisdictions illegal. Gas stations don$B!G(Bt volunteer their products to run field trucks; airlines don$B!G(Bt offer up free flights $B!H(Bfor the experience$B!I(B. Staff should be paid. No money for salaries = no staff. This site isn$B!G(Bt about slogging any individual or organization, but the practice of using volunteers in place of paid staff. This practice has got to stop. And from time to time, we come across $B!H(Bjob$B!I(B adverts that are simply ridiculous. To highlight the problem and widespread nature of the practice, submit unpaid jobs in ecology, wildlife, and conservation and help spread the word. Sean McCann via Gmail
Source: EVOLDIR
00:02

The monthly review of the EvolDir is available from the EvolDir website - http://bit.ly/17VdShI. For more information or for help send mail to Golding@McMaster.CA. Please see the above website for instructions for the EvolDir. This includes ways to limit/reduce the messages you receive from the EvolDir. A reminder: The userid for the web site user list is `evoldir’ and the password is `2EvolBulletins’. [ This was done to limit the access of spammers (e.g. SpeakOut.Com and others). ] Brian Golding via Gmail

Source: EVOLDIR

May 31, 2015

22:00
With consequences for disease severity, resistance or clearance of a pathogen infection by an individual can be enhanced by a previous exposure to that pathogen, occurring either within an individual or even in its parents. This form of immune memory, traditionally thought the province of the vertebrate adaptive immune response, can also arise from innate immune pathways of vertebrates and invertebrates, and through distinct pathways in plants and bacteria. Researchers studying this phenomenon rarely interact across taxonomic boundaries, however, and use a preponderance of disparate terms to describe this innate immune mediated memory, including immune memory, immune priming, trained immunity, and systemic acquired resistance. This catalysis meeting will facilitate a synthesis of disparate researchers to better understand commonalities among these different forms of innate immune memory and key consequences for disease. We will use this opportunity to produce a broad interest synthesis manuscript elaborating upon specific avenues by which an improved understanding of innate immune memory will inspire future research, with direct and indirect benefits for human health. First, better understanding of how vertebrate immune memory works in retaining specific memory stands to improve vaccine design and delivery. Second, the specificity of immune memory could be manipulated to leave harmful pests, vectors, and human parasites susceptible to pathogen mediated biocontrol, while improving the health of beneficial organisms such as agricultural plants, animals, and pollinators that ensure human food security. Our approach aims to identify model systems functionally analogous to human innate immune memory that maximize our flexibility to interrogate the genetics, constraints, and functional manipulations of innate immune memory. Finally, this synthesis will elucidate fundamental concepts underlying host-pathogen evolution and the limits of immunological plasticity.
Source: NESCent
16:30

On this blog we occasionally draw your attention to the overlap between the scientific world and the artistic world. The language tree shown below is from the Stand Still Stay Silent site, which describes itself as "a post apocalyptic webcomic with elements from Nordic mythology". The tree data apparently come from the Ethnologue language database.

The detail about the Nordic languages derives from the fact that the author, Minna Sundberg, is Finnish-Swedish, and the Scandinavian languages have next to nothing in common with the Finno-Ugric languages.

Posters and prints of the tree are available for purchase.


May 30, 2015

23:35

Job: RA. Crested Macaques. Indonesia ____What: Position Description___ We are looking for a research assistant to help during 6 months on the data collection for a project on intergroup interactions in crested black macaques (Macaca nigra; http://bit.ly/1ACgUKG and https://www.youtube.com/watch?v=3DbmjCrZNlOps). The aim of this project is to investigate the evolution of parochial altruism. The assistant will need to learn the I.D. of approximately 80 animals and will contribute to: - Behavioural data collection, using a mixture of focal, scan, and ad libitum sampling - Spatial data collection (GPS) - Faecal sample collection for DNA analysis - Performing field experiments (playback) - Data management Although these will be the main responsibilities of the research assistant, some flexibility is expected to adapt to the unpredictable conditions of fieldwork. In general, the weekly schedule will consist of 5 days of field work, 10-12h/day (Dawn to dusk). Training will be provided on site. _______Where______ The study will be conducted at the Tangkoko-Batuangus Nature Reserve in North East Sulawesi (Indonesia) as a part of the Macaca Nigra Project (http://bit.ly/1FicJiG). Accommodation will either be at the field station (http://bit.ly/1ACgRP0), where the conditions are basic, but comfortable (Beds are provided, cellular service is fairly regular, and electricity is available a few hours every day at night), or in the village, about 10 minutes walking from the field site. ____Qualifications/Experience____ Requirements: - Bachelors/undergraduate degree in Biology, Anthropology, Zoology or related subjects. - Fluent in English (Spoken and written) - Previous field work experience with wild animals - Be physically fit and healthy (Able to spend 12h/day in the field 5days/week carrying a backpack, walking and standing most of the time) - Good social skills (being respectful towards others, patient, sympathetic…) - Be able to work independently within a team - Be open-minded and able to work with people from different nationalities, cultures, and backgrounds - Feel comfortable living under basic conditions and being far away from family/friends - Be willing to adapt to a foreign culture - Be able to maintain a positive attitude towards hard and tiring work. - Willing to learn new skills - Ability to follow instructions accurately - Be flexible and responsible - Willingness to learn basic Bahasa Indonesia (i.e. courtesies) Preferred candidates will have experience: - Collecting behavioural data from individually recognized primates - Working in a tropical climate under demanding physical conditions - On international field work - Working in international teams _____Salary/funding_____ This is a volunteer position, no salary provided. Applicants should be able to cover the expenses detailed bellow. At the moment there is no funding available to subsidize the costs, but we have launched a crowdfunding campaign for this end. Any support provided would depend on the success of this campaign http://bit.ly/1ACgRP2 _____Support provided (travel, meals, lodging)___ Currently there is NO funding available to support the field assistant. The costs that the assistant should be ready to cover are: - International travel to Indonesia (if required) - National travel to Manado: 150 approx. (return plane ticket) - Monthly camp fees: 300/month (includes 3 meals per day and bills) - Visa: approx. 100, but country dependent - Permits: 1100 Approx. - Vaccinations (depending on personal requirements) - Travel health insurance (Depending on the company; can be 200 or more) - Personal equipment: field clothes, backpack, appropriate foot gear… (depending on personal requirements) - Personal expenses: trips to town, free-time activities Cost will be subsidized depending on the success of the crowdfunding campaign http://bit.ly/1ACgRP2 ____Term of Appointment______ 6 months (Approx. July 2015- December 2015) ______Application Deadline_______ Applications will be accepted on a rolling basis until 15th June 2015 (included) ____How to apply_____ If interested, please apply by sending an email to Laura Martinez Inigo (lmartinezinigo@lincoln.ac.uk) attaching a cover letter and a CV. The letter should explain why you are interested in the position and why you are a suitable candidate for the post, relating your skills and experience to the requirements in the advertisement. Please include the details of at least 2 referees in your CV. _______Contact Information_______ Laura Martinez Inigo University of Lincoln Brayford Pool Lincoln Lincolnshire LN6 7TS United Kingdom E-mail Address: lmartinezinigo@lincoln.ac.uk The University of Lincoln, located in the heart of the city of Lincoln, has established an international reputation based on high student satisfaction, excellent graduate employment and world-class research. The information in this e-mail and any attachments may be confidential. If you have received this email in error please notify the sender immediately and remove it from your system. Do not disclose the contents to another person or take copies. Email is not secure and may contain viruses. The University of Lincoln makes every effort to ensure email is sent without viruses, but cannot guarantee this and recommends recipients take appropriate precautions. The University may monitor email traffic data and content in accordance with its policies and English law. Further information can be found at: http://bit.ly/QxjI68. via Gmail

Source: EVOLDIR
18:00
Background: Intraspecific variability is seen as a central component of biodiversity. We investigated genetic differentiation, contemporary patterns of demographic connectivity and intraspecific variation of adaptive behavioural traits in two lineages of an intertidal mussel (Perna perna) across a tropical/subtropical biogeographic transition. Results: Microsatellite analyses revealed clear genetic differentiation between western (temperate) and eastern (subtropical/tropical) populations, confirming divergence previously detected with mitochondrial (COI) and nuclear (ITS) markers.Gene flow between regions was predominantly east-to-west and was only moderate, with higher heterozygote deficiency where the two lineages co-occur. This can be explained by differential selection and/or oceanographic dynamics acting as a barrier to larval dispersal.Common garden experiments showed that gaping (periodic closure and opening of the shell) and attachment to the substratum differed significantly between the two lineages. Western individuals gaped more and attached less strongly to the substratum than eastern ones. Conclusions: These behavioural differences are consistent with the geographic and intertidal distributions of each lineage along sharp environmental clines, indicating their strong adaptive significance. We highlight the functional role of diversity below the species level in evolutionary trends and the need to understand this when predicting biodiversity responses to environmental change.
18:00
Background: The presence of intraspecific color polymorphism can have multiple impacts on the ecology of a species; as a consequence, particular color morphs may be strongly selected for in a given habitat type. For example, the asp viper (Vipera aspis) shows a high level of color polymorphism. A blotched morph (cryptic) is common throughout its range (central and western Europe), while a melanistic morph is frequently found in montane populations, presumably for thermoregulatory reasons. Besides, rare atypical uniformly colored individuals are known here and there. Nevertheless, we found in a restricted treeless area of the French Alps, a population containing a high proportion (>50%) of such specimens.The aim of the study is to bring insight into the presence and function of this color morph by (i) studying the genetic structure of these populations using nine microsatellite markers, and testing for (ii) a potential local diversifying selection and (iii) differences in dispersal capacity between blotched and non-blotched vipers. Results: Our genetic analyses support the occurrence of local diversifying selection for the non-blotched phenotype. In addition, we found significant color-biased dispersal, blotched individuals dispersing more than atypical individuals. Conclusion: We hypothesize that, in this population, the non-blotched phenotype possess an advantage over the typical one, a phenomenon possibly due to a better background matching ability in a more open habitat. In addition, color-biased dispersal might be partly associated with the observed local diversifying selection, as it can affect the genetic structure of populations, and hence the distribution of color morphs.

May 29, 2015

00:06

Convergence is a central concept in evolutionary studies because it provides strong evidence for adaptation. It also provides information about the nature of the fitness landscape and the repeatability of evolution, and can mislead phylogenetic inference. To understand the role of adaptive convergence, we need to understand the patterns of nonadaptive convergence. Here, we consider the relationship between nonadaptive convergence and divergence in mitochondrial and model proteins. Surprisingly, nonadaptive convergence is much more common than expected in closely related organisms, falling off as organisms diverge. The extent of the convergent drop-off in mitochondrial proteins is well predicted by epistatic or coevolutionary effects in our "evolutionary Stokes shift" models and poorly predicted by conventional evolutionary models. Convergence probabilities decrease dramatically if the ancestral amino acids of branches being compared have diverged, but also drop slowly over evolutionary time even if the ancestral amino acids have not substituted. Convergence probabilities drop-off rapidly for quickly evolving sites, but much more slowly for slowly evolving sites. Furthermore, once sites have diverged their convergence probabilities are extremely low and indistinguishable from convergence levels at randomized sites. These results indicate that we cannot assume that excessive convergence early on is necessarily adaptive. This new understanding should help us to better discriminate adaptive from nonadaptive convergence and develop more relevant evolutionary models with improved validity for phylogenetic inference.

00:06

Whole-genome duplication, which leads to polyploidy, has been implicated in speciation and biological novelty. In plants, many species exhibit ploidy variation, which is likely representative of an early stage in the evolution of polyploid lineages. To understand the evolution of such multiploidy systems, we must address questions such as whether polyploid lineage(s) had a single or multiple origins, whether admixture occurs between ploidies, and the timescale over which ploidy variation affects the evolution of populations. Here we analyze three genomic data sets using nonparametric and parametric analyses, including coalescent-based methods, to study the evolutionary history of a geographically widespread autotetraploid variant of Arabidopsis arenosa, a new model system for understanding the molecular basis of autopolyploid evolution. Autotetraploid A. arenosa populations are widely distributed across much of Northern and Central Europe, whereas diploids occur in Eastern Europe and along the southern Baltic coast; the two ploidies overlap in the Carpathian Mountains. We find that the widespread autotetraploid populations we sampled likely arose from a single ancestral population approximately 11,000–30,000 generations ago in the Northern Carpathians, where its closest extant diploid relatives are found today. Afterward, the tetraploid population split into at least four major lineages that colonized much of Europe. Reconstructions of population history suggest that substantial interploidy admixture occurred in both directions, but only among geographically proximal populations. We find two cases in which selection likely acted on an introgressed locus, suggesting that persistent interploidy gene flow has a local influence on patterns of genetic variation in A. arenosa.

00:06

We investigated global patterns of variation in 157 whole-genome sequences of Vibrio parahaemolyticus, a free-living and seafood associated marine bacterium. Pandemic clones, responsible for recent outbreaks of gastroenteritis in humans, have spread globally. However, there are oceanic gene pools, one located in the oceans surrounding Asia and another in the Mexican Gulf. Frequent recombination means that most isolates have acquired the genetic profile of their current location. We investigated the genetic structure in the Asian gene pool by calculating the effective population size in two different ways. Under standard neutral models, the two estimates should give similar answers but we found a 27-fold difference. We propose that this discrepancy is caused by the subdivision of the species into a hundred or more ecotypes which are maintained stably in the population. To investigate the genetic factors involved, we used 51 unrelated isolates to conduct a genome-wide scan for epistatically interacting loci. We found a single example of strong epistasis between distant genome regions. A majority of strains had a type VI secretion system associated with bacterial killing. The remaining strains had genes associated with biofilm formation and regulated by cyclic dimeric GMP signaling. All strains had one or other of the two systems and none of isolate had complete complements of both systems, although several strains had remnants. Further "top down" analysis of patterns of linkage disequilibrium within frequently recombining species will allow a detailed understanding of how selection acts to structure the pattern of variation within natural bacterial populations.

00:06

The demographic history of modern humans constitutes a combination of expansions, colonizations, contractions, and remigrations. The advent of large scale genetic data combined with statistically refined methods facilitates inference of this complex history. Here we study the demographic history of two genetically admixed ethnic groups in Central Asia, an area characterized by high levels of genetic diversity and a history of recurrent immigration. Using Approximate Bayesian Computation, we infer that the timing of admixture markedly differs between the two groups. Admixture in the traditionally agricultural Tajiks could be dated back to the onset of the Neolithic transition in the region, whereas admixture in Kyrgyz is more recent, and may have involved the westward movement of Turkic peoples. These results are confirmed by a coalescent method that fits an isolation-with-migration model to the genetic data, with both Central Asian groups having received gene flow from the extremities of Eurasia. Interestingly, our analyses also uncover signatures of gene flow from Eastern to Western Eurasia during Paleolithic times. In conclusion, the high genetic diversity currently observed in these two Central Asian peoples most likely reflects the effects of recurrent immigration that likely started before historical times. Conversely, conquests during historical times may have had a relatively limited genetic impact. These results emphasize the need for a better understanding of the genetic consequences of transmission of culture and technological innovations, as well as those of invasions and conquests.