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Arnaud Pocheville
University of Pittsburgh
Center for Philosophy of Sciences
United States

(Non)-genetic inheritance: a historical overview

poster 

Author(s): Pocheville, A

Summary:

Current debates on the biological relevance and theoretical impacts of non-genetic inheritance in evolution seem to have much in common with archaistic debates between Neo-Lamarckians and Neo-Darwinians on the existence of inheritance of acquired characteristics. In this presentation, we will adopt a historical point of view to put the current debates into perspective. In the first part, we will first recall how the publication of The Origin made the researches about inheritance a central theme of theoretical biology, and how these researches themselves put Darwinism at risk at the turn of the XIXth-XXth centuries. We will recall how Neo-Darwinism and Neo-Lamarckism emerged during the debates on the role of acquired characteristics in heredity. We will show how, as soon as the end of the XIXth century, the inheritance of acquired characteristic has been a heterogeneous concept – heterogeneous enough to seem, in some instances, compatible with Neo-Darwinism. In the second part, we will show how, in the first part of the XXth century, researches on genetic inheritance impacted the debates about the inheritance of acquired characteristics, making them slip towards debates on the "genetic" inheritance of acquired characteristics. We will show how, in parallel, researches on non-genetic inheritance got marginalized, without disappearing totally, before blossoming again at the end of the XXth century. In conclusion, we will draw on our historical account to clarify the conceptual differences between directed mutation, the inheritance of acquired characteristics, and non-genetic inheritance. This will lead us to consider in which respect an Extended Evolutionary Theory could depart from the conceptual matrix of the Modern Synthesis.

Marine Battesti
CNRS
Laboratoire Evolution, Génomes et Spéciation
France

Diffusion of social information within Drosophila group

poster 

Author(s): Battesti, M, Moreno, C, Joly, D, Mery, F

Summary:

Understanding how behavioral diversity arises and is maintained is central to evolutionary biology. Genetically based inheritance has been a predominant research focus of the last century; however, nongenetic inheritance, such as social transmission, has become a topic of increasing interest. How social information impacts behavior depends on the balance between information gathered directly through personal experience versus that gleaned through social interactions and on the diffusion of this information within groups. We investigate how female Drosophila melanogaster use social information under seminatural conditions and whether this information can spread and be maintained within a group, a prerequisite for establishing behavioral transmission. We show that oviposition site choice is heavily influenced by previous social interactions. Naïve observer flies develop a preference for the same egg-laying medium as experienced demonstrator flies conditioned to avoid one of two equally rewarding media. Surprisingly, oviposition site preference was socially transmitted from demonstrators to observers even when they interacted in a cage with only unflavored, pure agar medium, and even when the observer flies had previous personal experience with both rewarding media. Our findings shed light on the diffusion process of social information within groups, on its maintenance, and ultimately, on the roots of behavioral local adaptation.

Philip Leftwich
University of East Anglia
School of Biological Sciences
United Kingdom

Larval diet alters associations with commensal gut bacterial and induces trans-generational effects on host fitness in Ceratitis capitata

poster 

Author(s): Leftwich, PT, Friend, L, Chapman, T

Summary:

The importance of diet and gut bacteria for host health and fitness is well known across vertebrates and invertebrates. In many instances these associations are variable and flexible, but still of fundamental importance to our understanding of animal biology. In the Mediterranean Fruit Fly (medfly) a pest insect of great agricultural importance, it is known that interactions between diet and gut bacteria can have a significant influence on host development, female fecundity, male mating speed and female survival. There can even be vertical transmission of commensal gut bacteria from mother to offspring, via inoculation into the fruit during oviposition and subsequent ingestion by the developing larval offspring. The composition of microbes is affected by larval and adult diet, which explains why laboratory-reared fruit flies, with a relatively invariant diet, generally seem to have restricted microbial communities in comparison to wild fruit flies. However the precise relationship between diet, gut bacteria and host fitness has not been systematically studied in this pest of economic importance. We address this gap by a study in which we systematically altered larval dietary components and found effects on host development, mating success and gut microbiota. In addition we present data to show that these were trans-generational effects, with non-genetic parental influence on the development of offspring.

Rie Henriksen
IFM Biology, Linköping University
Sweden

Matching or mismatching: effects of maternal heat stress are modified by postnatal heat stress in Japanese quails

poster 

Author(s): Henriksen, R, Rettenbacher, S, Groothuis, T

Summary:

The environment can influence an animal phenotype during various stages of an animal’s life but during embryonic development animals are especially susceptible to changes in their environment due to the speed and complexity of development at this time in life. Changes in the prenatal environment often reflect and are due to changes in the parent’s environment. Phenotypic alterations induced during this early period in life are therefore particularly intriguing because they demonstrate that environmental changes in one generation can influence the development and phenotypic expression in the next generation. Currently researchers are exploring the role of maternal stress during egg formation in oviparous species as an inducer of phenotypic plasticity in offspring. Maternal stress is often reported to reduce the phenotypic quality of the offspring, but it has also been suggested that these maternal effects might prepare offspring for a stressful environment. However, in most studies the environmental conditions in the postnatal environment in which the offspring are raised and tested are ignored. In this study Japanese quail females and their offspring were either heat stressed (35 °C) or housed at control temperature (22 °C) in a split-brood design. Offspring matched to their mother’s hot environment had a significantly faster corticosterone response to 10 min. intense heat stress (40 °C) and a significantly faster recovery than offspring of control mothers. Offspring matched to their mother’s environment had significantly lower but similar corticosterone response to a single ACTH injection and significantly higher but similar respiratory quotient compared to offspring mismatched to their mother’s environment. These results demonstrate that some effects of maternal heat stress are not express if offspring are raised in the same stressful environment and that maternal heat stress might prepare offspring for high temperatures in their postnatal environment.

Elvire Bestion
Station d'Ecologie Expérimentale du CNRS de Moulis
France

Maternal exposure to predators: how to prepare offspring to a risky natal environment?

poster 

Author(s): Bestion, E, Teyssier, A, Cote, J

Summary:

Predation risk is a strong force inducing morphological, physiological and behavioural responses. As predation risk is often higher in early life, antipredator defences should be produced at a juvenile stage. Maternal effects are a good tool to produce antipredator defences early in juvenile life. We investigated if maternal exposure to predator cues during gestation affected juvenile morphology, behaviour at birth and life-history traits in common lizard (Zootoca vivipara). We exposed 22 adult females to cues from a saurophagous snake (Hierophis viridiflavus) for one month of gestation and 22 other females were kept unexposed. At birth, juveniles were measured and tested for thermal preferences and activity levels in presence or in absence of predator cues, and then released in semi-natural enclosures connected to a corridor allowing to monitor dispersal. We also quantified survival and growth rate at the end of the season by capture-recapture sessions. Offspring born from exposed mothers had longer tails at birth and at an older age and preferred lower temperatures than juveniles from unexposed mothers. Tail autotomy and decreased basking behaviour are common antipredator behaviours and thus our results suggest that mothers can prepare juveniles to risky environments. Juveniles from exposed mothers also increased their activity levels in response predator cues showing better abilities to recognize such cues. This increased activity, along with an overall increase in dispersal probability, show that mother also manipulated juvenile flight response. In response to predation risk, mothers can manipulate offspring phenotype to make them more adapted to their natal environment or increase their dispersal ability to find more suitable habitats. Our results show that, in common lizards, these two adaptive mechanisms act conjointly in order to improve offspring survival to predators.

Elin Videvall
Lund University
Department of Biology
Sweden

Pronounced maternal effect on hybrid gene expression in Arabidopsis

poster 

Author(s): Videvall, E, Sletvold, N, Hagenblad, J, Ågren, J, Hansson, B

Summary:

Understanding how hybridization influences phenotype is of major importance for evolutionary biology. Theoretically, phenotypic differences are expected to be controlled mainly by gene regulation, which can be environmentally or genetically determined. However, until recently it has been difficult to accurately measure expression levels and determine whether hybrid gene expression are caused by additive (intermediate expression levels between the parents), dominance (expression levels equal to one of the parents) or parental effects (gene expression similar to that of either the mother or the father). Here we use high throughput RNA-sequencing (Illumina) to test the different expression hypotheses and evaluate gene expression in hybrids between two differentiated populations of Arabidopsis lyrata. Our results showed (i) broad differential expression between populations (9573 significant genes) and (ii) a very strong maternal effect on hybrid gene expression (94.7% of genes followed the expression of the mother rather than the father plant). In plants, where seed dispersal is limited and the developing seedlings will experience similar environmental conditions as their mothers, such maternal effects are expected to be highly beneficial as they can facilitate local adaptation.

Antonia Klein
Faculty of Biology of the University of Regensburg
Department for Evolution, Behaviour and Genetics
Germany

Sex determination in the haplodiploid ant species Cardiocondyla obscurior

poster 

Author(s): Klein, AM, Heinze, J, Oetller, J

Summary:

Sex determination across insects seems to rely on the same pathway: A primary signal induces sex specific alternative splicing of transformer (tra) or its ortholog. This leads to a functional TRA protein in females, whereas an in-frame stop codon in the male transcript leads to no functional protein. TRA induces female specific splicing of doublesex (dsx) and the sex specific DSX protein regulates downstream development of the embryo. While the developmental cascade is conserved across taxa, the primary inducing signals are not, ranging from a single locus (csd) in Apis to maternal imprinting in Nasonia (reviewed in Verhulst et al., 2010). We investigated the sex determination pathway in Cardiocondyla obscurior (Hymenoptera, Formicidae), a model for eusocial traits. Single locus sex determination can be ruled out, because no diploid males were detected despite many generations of inbreeding (Schrempf et al., 2006). We confirmed the exclusive maternal origin of males by genotyping F1-hybrid offspring of a cross of two distinct populations with known genotypes. The sex determination genes tra and dsx were annotated and the cDNA sequences were compared between female and male embryos. Furthermore tra expression in fertilized versus unfertilized eggs was analysed using RT-qPCR to test for maternal provisioning of the zygote as an epigenetic effect and as the primary signal of the sex determinaton pathway in C. obscurior.

Luke Holman
Australian National University
Evolution, Ecology and Genetics
Australia

The benefits, costs and evolutionary consequences of genomic imprinting

poster 

Author(s): Holman, L, Kokko, H

Summary:

Under genomic imprinting, alleles “remember” which parent they are derived from and show differential gene expression. Imprinting is an evolutionary puzzle because it carries all the costs of diploidy but foregoes its principal benefit (protection from recessive mutations). Here, I synthesise and critically evaluate the many evolutionary hypotheses for the origin and maintenance of imprinting, while adding at least one more. I also review imprinting’s many costs, and argue that the origin of imprinting is substantially more difficult than the maintenance because of evolutionary changes wrought by imprinting itself. I finish by using theoretical models to consider the long-term consequences of imprinting for adaptation and population fitness.

Longfei Shu
Eawag/ETH Zürich
Dept. of Aquatic Ecology/Institute of Integrative Biology
Switzerland

The molecular basis of adaptive maternal effects in amphibians

poster 

Author(s): Shu, L, Suter, M, Laurila, A, Räsänen, K

Summary:

Maternal effects, the effect of a mother’s phenotype and environment on offspring phenotype and performance, can influence the speed and direction of trait evolution, responses to divergent selection, as well as population dynamics. However, the mechanisms and the molecular basis of maternal effects are often poorly understood. Here we present data for natural populations of two amphibian species (Rana arvalis and Rana temporaria), which show intra-specific adaptive divergence to acidity via maternally derived egg capsules. Particularly, we use cutting edge molecular approaches (proteomics, glycan analysis) to elucidate the molecular mechanisms behind adaptive maternal effects in these systems, and emphasize the role of egg capsules for adaptation at early life-stages.

Lisa Shama
AWI Wadden Sea Station Sylt
Germany

Transgenerational plasticity in marine sticklebacks: maternal effects mediate impacts of a warming ocean

poster 

Author(s): Shama, LNS, Wegner, M

Summary:

Transgenerational plasticity is a potentially powerful mechanism for species to cope with rapid environmental change. Recent studies show these non-genetic parental effects can facilitate acclimation to environmental stressors (e.g. increased temperature and ocean acidification) across generations. Yet, the relative contribution of maternal vs. paternal effects is not well known. We crossed adult marine sticklebacks acclimated to two experimental temperatures (17°C and 21°C) to produce egg clutches in 4 groups: 17mx17f, 17mx21f, 21mx17f, 21mx21f. Clutches were split and reared at 17°C and 21°C. Egg traits (clutch size, egg size and hatching success) and offspring growth at 30 and 60 days were quantified. We found that 21°C females produced smaller (but not fewer) eggs with a lower hatching success than 17°C females, suggesting that mothers optimise their fitness over that of their offspring in stressful environments. Still, offspring growth at 30 days showed a clear benefit of transgenerational (maternal) plasticity; offspring had higher growth when reared at their maternal temperature. Growth at 60 days was mostly determined by offspring environment, yet maternal effects persisted in the stressful environment. Our results show that transgenerational plasticity can mediate some of the impacts of a warming ocean and may facilitate population persistence under climate change.

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Chairman: Octávio S. Paulo
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Address

XIV Congress of the European Society for Evolutionary Biology

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Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
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Portugal

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