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Luke McNally
University of Edinburgh
Centre for Immunity, Infection and Evolution
United Kingdom

Cooperative niche construction facilitates zoonosis in pathogenic bacteria

poster 

Author(s): McNally, L, Viana, M, Brown, SP

Summary:

The majority of emergent human pathogens are zoonotic in origin. Understanding the factors underlying the evolution of pathogen host range is therefore of critical importance in protecting human health. Classical evolutionary theory predicts that the evolution of generalism in pathogens will be subject to trade-offs, and hence reduced within-host fitness compared to specialists, as pathogens evolve to tolerate multiple host environments. Here we show that rather than passively reacting to host environments, bacteria can use niche construction via cooperative secretions to achieve host generalism. We use an epidemiological framework to show that cooperative niche construction strategies can outcompete both specialists and classical generalists under a wide range of realistic conditions. We then use a phylogenetic comparative analysis of 191 bacterial pathogens to show that larger secretome sizes are associated with a greater probability of zoonosis, in agreement with our theoretical predictions. Our results suggest that cooperative behaviour is a key factor in the evolution of generalism in bacteria, and that monitoring programmes focusing on the horizontal transfer of secreted proteins could help identify future emerging human pathogens.

Deborah Dawson
University of Sheffield
Animal and Plant Sciences
United Kingdom

Engineering microsatellite markers to study and compare a wide range of species

poster 

Author(s): Dawson, DA

Summary:

We have developed a set of conserved avian markers with high cross-species utility in order to save resources and enable new comparisons between species. These markers will not only reduce the necessity and expense of microsatellite isolation for a wide range of genetic studies, including avian parentage and population analyses, but will also now enable comparisons of genetic diversity among different species (and populations) at the same set of loci, with no or reduced bias. No other marker type enables such comparisons. Additionally, these markers (i.e. microsatellites), in contrast to single nucleotide polymorphism (SNP) and genotyping-by-sequencing methods, are readily typed in samples of low DNA quality or concentration (e.g. non-invasive samples or museum specimens), and enable the quick cheap identification of species, hybrids, clones and ploidy. We selected zebra finch (Taeniopygia guttata) sequences that possessed a repeat region and that displayed high sequence similarity to chicken (Gallus gallus). Each primer sequence was a complete match to zebra finch and, after accounting for degenerate bases, at least 86% similar to chicken. These markers are of especially high utility in passerines, but also show utility in non-passerine species. The approach used here can be applied to other taxa in which appropriate genome sequences are available.

Katie Duryea
Dartmouth College
Biology
United States

Females bite back: sexual conflict and the evolution of venom proteins in the reproductive tract of female anole lizards

poster 

Author(s): Duryea, K, Calsbeek, R, Kern, A

Summary:

Reproductive proteins evolve rapidly in many species, yet the ecological significance of these proteins remains largely unknown. In this study, we investigate reproductive proteins in Anolis lizards, a system in which the ecological basis for a fertilization bias has been established. When female A. sagrei mate with multiple males, they preferentially use the sperm from larger sires to produce sons. Field experiments reveal that this bias may be adaptive, based on patterns of offspring survival. Using Next Generation Sequencing, we investigate genes that are expressed in the reproductive tract of female anoles. Comparisons with Drosophila, the system in which female reproductive gene expression has been best studied, reveal broad similarities in the genetic response to mating across these distantly related taxa. Additionally, we investigated the molecular evolution of a group of serine proteases that are differentially expressed after mating in the reproductive tract of female anoles. Of these serine proteases, some appear closely related to snake venom proteins. Due to the deep origin of venom toxin in squamates and the hypothesized origin of Drosophila reproductive serine proteases from digestive proteases, our results suggest that Anolis reproductive serine proteases and venom serine proteases could share a common phylogenetic origin. This would imply that digestive enzymes have been involved in the evolution of cryptic aspects of female choice in multiple mating systems.

Hannah Dugdale
University of Sheffield
Animal and Plant Sciences
United Kingdom

Fewer invited talks by women in evolutionary biology: men accept invitations to speak more often than women

poster 

Author(s): Dugdale, HL, Schroeder, J, Radersma, R, Hinsch, M, Buehler, DM, Saul, J, Porter, L, Liker, A, De Cauwer, I, Johnson, PJ, Santure, AW, Griffin, AS, Bolund, E, Ross, L, Webb, TJ, Feulner, PGD, Winney, I, Szulkin, M, Komdeur, J, Versteegh, MA, Hemelrijk, CK, Svensson, EI, Edwards, H, Karlsson, M, West, SA, Barrett, ELB, Richardson, DS, Van den Brink, V, Wimpenny, JH, Ellwood, SA, Rees, M, Matson, KD, Charmantier, A, Dos Remedios, N, Schneider, NA, Teplitsky, C, Laurance, WF, Butlin, RK, Horrocks, NP

Summary:

Lower ‘visibility’ of female scientists, compared to male scientists, is a potential reason for the under-representation of women among senior academic ranks. Visibility in the scientific community stems partly from presenting research as an invited speaker at organised meetings. We analysed the sex ratio of presenters at the European Society for Evolutionary Biology Congress 2011, where all abstract submissions were accepted for presentation. Women were under-represented among invited speakers at symposia (15% women) compared to all presenters (46%), regular oral presenters (41%) and plenary speakers (25%). At the ESEB congresses in 2001–2011, 8–23% of invited speakers were women. This under-representation of women is partly attributable to a larger proportion of women, than men, declining invitations: in 2011, 50% of women declined an invitation to speak compared to 26% of men. We expect invited speakers to be senior scientists or authors of recent papers in high-impact journals. Considering all invited speakers (including declined invitations), 23% were women. This was lower than the baseline sex ratios of early–mid career stage scientists, but was similar to senior scientists and authors published in high-impact journals. High-quality science by women therefore has low exposure at international meetings, which will constrain Evolutionary Biology from reaching its full potential. We wish to highlight the wider implications of turning down invitations to speak. In particular, under-representation of women among invited speakers reduces the number of female role models for evolutionary biology students and contributes to the leaky pipeline. We encourage conference organisers to implement steps to increase acceptance rates of invited talks.

Cristian Cañestro
Universitat de Barcelona
Genètica
Spain

Functional impact of gene loss in genome evolution and animal diversity: the chordate Oikopleura dioica as a case study

poster 

Author(s): Cañestro, C, Martí-Solans, J, Badia-Ramentol, J, Godoy-Marin, H, Albalat, R

Summary:

What is the impact of gene losses in the generation of biodiversity is a crucial question in Evolutionary Biology that still remains largely unknown. Until now, gene losses have been often neglected because the proof for gene loss is negative and difficult to detect, especially in complex genomes outside bacteria and yeast. The state-of-the-art sequencing technology offers us for the first time the exciting opportunity to perform exhaustive genome-wide analyses to detect unambiguous cases of gene losses in animals with complex genomes. Our group has started an ambitious project with two main aims. First, we will sequence full genomes of a several individuals from many populations and species of the larvacean class to gain novel insights into the dynamics of gene losses, to understand the correlation of gene loss with phenotypic traits, and to test for evolutionary gene dispensability (EGD), a new concept that we have developed in this project. Second, we will perform systematic knockdown experiments and RNA–seq analyses to provide functional evidence for the impact of gene loss, and test for adaptive and neutral events of gene loss in the context of genetic robustness and gene network connectivity. In this project, we use the urochordate Oikopleura dioica (and other related larvacean species) as case study, because the recent genome-sequencing project, in which we participated, revealed that this organism exhibits the smallest genome and the largest genomic plasticity of all metazoans known to date, including an extraordinary amount of gene losses. Preliminary results show the feasibility to identify actual genes that are in the process of being lost in different populations, which appear as potential candidates of losses that can be adaptive.

Kay Lucek
University of Bern
Institute of Ecology and Evolution
Switzerland

Historical contingency and parallel parapatric divergence between lake and stream stickleback pairs of variable age

poster 

Author(s): Lucek, K, Sivasundar, A, Kristjánsson, BK, Skúlason, S, Seehausen, O

Summary:

When genetic constraints restrict phenotypic evolution, diversification is predicted to evolve along the so-called line of least resistance, the leading axis of the underlying G matrix. To address the importance of such constraints and their resolutions, empirical studies on parallel cases of phenotypic divergence of different age are valuable. However such studies are very rare. Here we study the parapatric evolution of six independently evolved lake and stream stickleback systems from Iceland and Switzerland, ranging in age from a few decades to several millennia. Using phenotypic data, we test to which degree parallel evolution occurs among independent lake-stream freshwater systems as well as during the marine-freshwater transition. We furthermore investigate in both cases how the underlying evolutionary trajectories diverge through time. We find that strong and consistent phenotypic divergence occurred independent of time for both the parapatric lake-stream systems and for the marine-freshwater transition. The extent of phenotypic divergence differs however between the two countries studied here. This indicates that historical contingency partially shapes the phenotypic outcome of divergent selection in lake-stream environments. Moreover, our results suggest that parapatric phenotypic divergence can evolve along a common evolutionary trajectory for some trait combinations, independently of their evolutionary age. The directionality of change in these traits may however differ due to historical contingency or environmental constraints. Other trait combinations differ rather between the two investigated countries but less within, suggesting that the underlying G matrix of each country could be differentially constrained. Thus phenotypic plasticity may play an important role during the colonization of novel habitats, where adaptive peak shifts may be readily achieved.

Sascha Krenek
Faculty of Environmental Sciences of Technische Universität Dresden
Institute of Hydrobiology
Germany

Hsp70 gene family evolution and differential expression in microbial eukaryotes

poster 

Author(s): Krenek, S, Schlegel, M, Berendonk, TU

Summary:

In eukaryotes, members of the 70 kDa heat-shock protein family (Hsp70) are separated into four subfamilies according to their sub-cellular localisation and function. While in metazoans multiple cytosolic Hsp70s can be found, which are either constitutively expressed and/or stress-inducible, information about the copy number and diversity as well as differential expression of hsp70 genes in microbial eukaryotes is scarce. In this study, we have characterised the hsp70 gene family of the ciliate Paramecium caudatum to gain insight into the evolution and differential response to temperature stress of the distinct Hsp70 family members in protists. We further focused on the evolution of heat-inducibility in cytosolic hsp70s and investigated intraspecific differences in hsp70 gene expression to evaluate its potential use as biomarkers for temperature adaptation studies in Paramecium. Phylogenetic analyses disclosed five homologous groups, each with a closer relationship to orthologous hsp70s of Paramecium tetraurelia than to another P. caudatum Hsp70-group, indicating duplication events preceding Paramecium speciation. Furthermore, heat-shock expression studies and comparative EST analyses revealed one cytosolic group as the major heat inducible hsp70s in both P. caudatum and P. tetraurelia, suggesting a functionally conserved evolution of this gene family in Paramecium. In addition, the herein developed RT-qPCR assay unveiled different expression patterns between diverse thermal tolerant P. caudatum clones, demonstrating the potential use of Hsp70 as a biomarker for environmental stress studies in Paramecium. Interestingly, our analyses also suggest that heat-inducibility of cytosolic hsp70s evolved several times independently during the course of eukaryotic evolution, thereby indicating convergent evolution during Hsp70 subfunctionalization.

Richard Allen
School of Biological Sciences, University of Edinburgh
Institute of Evolutionary Biology
United Kingdom

Maintenance of co-operation by positive feedback in quorum sensing networks

poster 

Author(s): Allen, RC, Brown, SP

Summary:

Signal blind mutants are naturally occurring bacterial strains that are defective for cell to cell signalling. These mutants can produce signal but do not respond to it, so they have reduced expression of quorum sensing regulated genes. Public goods are often regulated by quorum sensing and so signal blind mutants act as defectors, exploiting signal competent co-operators. Critically, signal blind strains are unable to increase their signal output in line with co-operators, because signal production is increased in response to signal, via a positive feedback loop. Therefore signal concentration in the environment is expected to be reduced when signal blind defectors are common. When public goods are regulated by quorum sensing, lower signal concentrations may reduce the production of public goods, minimising exploitation. Using knock-out strains of Pseudomonas aeruginosa we demonstrate that signal in the environment decreases as signal competent co-operators become rare. We show that this translates to a reduced co-operator output of secreted protease. Using competition experiments we then demonstrate that this can lead to negative frequency dependence of co-operator fitness, because co-operators behave as phenotypic defectors when rare. Frequency dependence has important implications as socio-microbiology is applied to new fields, notably the emergence of drug resistance.

Tobias Warnecke
Centre for Genomic Regulation (CRG)
Bioinformatics & Genomics
Spain

Nucleosome positions in eukaryotes and archaea primarily reflect rather than affect sequence evolution

poster 

Author(s): Warnecke, T, Becker, E, Facciotti, M, Supek, F, Nislow, C, Lehner, B

Summary:

Histone proteins can affect the evolution of the sequences they bind. Their presence can promote or impede the formation of DNA lesions or interfere with efficient DNA repair, so that some mutations may occur more, others less frequently in a nucleosomal context. In addition, selection can eliminate mutations that disrupt beneficial nucleosome architecture, for example around promoters.

Conversely, evolution at the sequence level can affect chromatin organization. Notably, as nucleosomes form preferentially on more bendable DNA, mutations that render the DNA template less bendable can prompt the nucleosome to shift to a position that is more conducive to nucleosome formation.

In short, nucleosomes (and other DNA-binding proteins) can both affect and reflect sequence evolution.

Several studies, screening a variety of eukaryotic genomes, have observed non-random associations between patterns of sequence evolution and nucleosome footprints. But do these associations reflect mutational biases or selection or are they evidence for sequence-directed nucleosome repositioning through evolution? And can we use comparative genomic data to discriminate between these competing hypotheses?

Combining large-scale phylogenetic reconstruction of substitution histories with high-resolution nucleosome maps from eukaryotes and archaea, we show that – at the level of between-species divergence – substitution dynamics around nucleosome dyads are not consistent with mutational biases or purifying selection. Instead, they are consistent with frequent local nucleosome repositioning through evolution. Our results highlight the importance of considering the direction of causality between genetic and epigenetic change when interpreting variation at the genetic or epigenetic level and especially when trying to infer selection from patterns of genetic conservation.

Marek Kwiatkowski
University of Neuchatel
Switzerland

Ontogenetic growth models and life history theory

poster 

Author(s): Kwiatkowski, M, Koella, J

Summary:

Ontogenetic growth depends on a number of factors, among them food availability and temperature. For example, compared to ideal conditions, cold-blooded animals mature later and at smaller size when food is scarce, but later and at a larger size when growth is retarded by low temperatures (this is known as the Berrigan-Charnov puzzle). In this talk we introduce a food- and themperature-explicit mathematical model of ontogenetic growth which allows us to interpret this and similar phenomena simply as life-history decisions of the organism seeking to maximise its expected reproductive output. We conclude by discussing future applications of our model to resource ecology of host-parasite interactions.

Contacts

Chairman: Octávio S. Paulo
Tel: 00 351 217500614 direct
Tel: 00 351 217500000 ext22359
Fax: 00 351 217500028
email: mail@eseb2013.com

Address

XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon
Portugal

Website

Computational Biology & Population Genomics Group 
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