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Abstracts

Carl André

Staffan Bensch

Grégory Charrier

Sam Dupont and Mike Thorndyke

Lars Gamfeldt

Jon Havenhand

Karin Hårding and Lisa Sundqvist

Kerstin Johannesson

Per Jonsson, theme 2

Per Jonsson, theme 5

Lotta Kvarnemo

Christer Löfstedt

Göran Nylund

Anna Nyqvist

Jeanine Olsen

Stig Omholt

Marina Panova

Karin Rengefors

Hannah Wood

 



Life on the margin II: genetic differentiation and local adaptation in a low-saline marine ecosystem, the Baltic Sea.

Carl André
Department of Marine Ecology - Tjärnö, University of Gothenburg

In CeMEB we use the low saline Baltic Sea as a natural experiment to investigate patterns and processes of species adaptation to environmental change. Baltic populations show a repertoire of physiological, morphological and behavioral adaptations, often related to reproduction.

Finding the genes behind these locally adapted traits and thereby clarify the genetic mechanisms important for adaptation, and estimate the speed by which the new traits have evolved is, however, not trivial.

In this talk I will give an overview of methods to find genes behind local adaptation, summarize existing knowledge as regard to the Baltic, and give more detail for the fish species herring and cod.


Finding genetic differences when differences are small: Patterns of genetic and phenotypic variation across a migratory divide in willow warblers

Staffan Bensch
Animal Ecology, Department of Ecology, Lund University

The migratory program in songbirds has been shown to be genetically controlled and includes genes for direction, distance and timing. Understanding the genetic architecture of the migratory program is a research field in its infancy - no gene or genetic marker has so far been identified as linked to the expression of the migratory program. The sharp migratory divide of willow warblers Phylloscopus trochilus in central Scandinavia is associated with several other trait differences correlated to the two different migration patterns; smaller and greener birds of the subspecies trochilus in southern Scandinavia migrates towards SW for wintering in west Africa whereas larger, grayer birds of the subspecies acredula in northern Scandinavia migrates towards SE for wintering in east and south Africa. Absence of differences at neutral loci between the subspecies (mtDNA, ten polymorphic microsatellite and at >99% of 2000 polymorphic AFLP markers) suggests that the phenotypic trait differences have evolved within the last 10,000 years during the process of postglacial colonization of northern Europe. Population samples of willow warblers around the Baltic demonstrate that the five different traits; coloration, size, migratory direction (inferred from stable isotope analyses) and alleles at two AFLP-derived locus, show drastically different cline patterns along the eastern side of the Baltic, supporting that the willow warbler has colonized Scandinavia via two directions from one common glacial refuge population. We observed that the change in allele frequencies at the locus AFLP-WW2 was coincident with the change in migratory direction both in Scandinavia and east of the Baltic Sea. This result suggests the exciting possibility that the AFLP-WW2 locus is linked to a gene encoding for intraspecific variation of the migratory program.

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Do we really think that phenotypic plasticity is adaptive?

Grégory Charrier
Department of Marine Ecology - Tjärnö, University of Gothenburg
 

Processes shaping the phenotypic variability in wild populations is a central issue for both ecologists and evolutionary biologists. On the one hand, ecologists generally distinguish two main forces governing the phenotypic diversity observed between contrasted habitats: (1) environmentally induced plasticity and (2) genetically controlled adaptation. On the other hand, evolutionary biologists commonly consider phenotypic plasticity as a “noise” and focus essentially on heritable traits in order to to disentangle the effects of (1) neutral evolutionary processes (i.e. genetic drift and gene flow) and (2) selection on the phenotypic variation observed among wild populations.

In general, phenotypic plasticity is opposed to genetic local adaptation. Nevertheless, Genotype x Environment interactions demonstrate that phenotypic plasticity is not under the exclusive influence of environmental factors but can be also a property of the genotype. Therefore, plasticity may be considered itself as an adaptive trait which could evolve under selective pressures.

Understanding the genetic basis and adaptive value of phenotypic plasticity might improve greatly our knowledge about the potential for evolutionary change of natural populations in a changing environment. However this is a very challenging task which requires particularly complex experimental designs.


Evolutionary rules in the brave new ocean.

Sam Dupont (1) and Mike Thorndyke (2)
(1) Department of Marine Ecology - Kristineberg, University of Gothenburg
(2) Swedish Royal Academy, Sven Lovén Centre for Marine Sciences - Kristineberg.

As a consequence of anthropogenic CO2 emissions and climate change, oceans are becoming warmer (global warming) and more acidic (Ocean Acidification, OA). Rates of change are increasingly fast and we can only guess at the kinds of organisms that will suffer (“losers”) or benefit (“winners”) from this mayhem that is radically altering ecosystem structure. OA research is still in its infancy and the increasing amount of data available highlight the complexity of this ecological question. The impact of OA appears to be extremely species- and even population-specific and depends on life-history stages and the processes studied. The current paradigms (e.g. OA will negatively impact calcifiers) are now being revisited making any large scale prediction impossible or over-simplistic. However, sufficient data are now available to move on to the next generation of OA research and start testing hypotheses and predictions. To allow large scale predictions of the impact of climate change on marine ecosystems it is then needed to understand how OA will modify the evolutionary rules shaping marine ecosystems. This presentation will summarize our data on the impact of OA on physiology and energetic balance to identify the new evolutionary rules in this changing ocean using echinoderms as models.

>> personal home page Sam Dupont


The influence of environmental change on species trait diversity and ecosystem processes

Lars Gamfeldt
Department of Marine Ecology, University of Gothenburg

I will present plans for my upcoming project about causes and consequences of changes in biological diversity. Using freshwater rock pools as a model system, my project will explore how the distribution of traits among consumer species is affected by environmental change. Examples of traits are growth rate, dispersal, type of resting stage, and resource requirement. One hypothesis is that multiple environmental stressors will reduce trait diversity to a larger extent than single stressors alone. I will also explore how different distributions of traits affect ecosystem processes, such as production of biomass and consumption of resources. A second hypothesis is thus that reductions in trait diversity will result in decreases in process rates, and that they will also make the system more susceptible to further changes in the environment. By considering, in concert, the influence of ecosystem structuring mechanisms on (i) species trait diversities and (ii) ecosystem processes I hope to increase our understanding of the potentially synergistic and deleterious ecosystem effects of changes in both biodiversity and the environment.


Introduction to Theme 2 "Adaptability": The potential for, and rate of, evolutionary change in natural populations.

Jon Havenhand
Department of Marine Ecology - Tjärnö, University of Gothenburg

The potential for evolutionary change is a fundamental prerequisite for adaptation in a changing environment, and yet almost nothing is known about this - indeed a recent review identified a crucial need for empirical data on the environmental sensitivity of selection. Key issues in this theme are:

  • the extent of potential for evolutionary change in natural populations
  • constrains on evolution under strong directional selection
  • whether recent perturbations influence evolvability
  • how the apparent excess of genetic variation is maintained under stabilizing selection


This presentation will summarize the current status of projects addressing these issues, and highlight some of the key issues that require new focussed effort if we are to achieve the goals of identifying genotype-environment interactions (reaction norms).


Baltic ringed seal and future climate

Karin Hårding and Lisa Sundqvist
Department of Marine Ecology - Gothenburg, University of Gothenburg
 

This study investigates potential effects from increasing temperatures on the dynamics of the Baltic ringed seal (Phoca hispida botnica), by linking predictions of future ice quality to reproductive success. The Baltic ringed seal population encompasses three sub-populations, simulations suggest that all of them will experience severely hampered growth rates during the coming 90 years. The Baltic ringed seal population, currently 11,000 seals, would amount to about 390,000 seals at the end of this century in a theoretical scenario with exponential growth. Adding availability of breeding ice as the only density dependent factor reduces the predicted population size to 20,000-70,000 at the end of the 21st century. These numbers are only 10%-35% of historical population sizes, and thus reduced ice cover alone will restrain the Baltic ringed seals from recovering to pristine conditions. Breeding habitats of other land-locked seal populations are also expected to deteriorate as a consequence of global warming.



Repeated evolution of reproductive isolation in a marina snail: unveiling mechanisms of speciation

Kerstin Johannesson
Department of Marine Ecology - Tjärnö, University of Gothenburg

Distinct ecotypes of the snail Littorina saxatilis, each linked to a specific shore microhabitat, form a mosaic-like pattern with narrow hybrid zones, in between, over which gene flow is 10-30% of within-ecotype gene flow. Multi-locus comparisons cluster populations by geographic affinity independent of ecotype, while loci under selection group populations by ecotype. The repeated occurrence of partially reproductively isolated ecotypes and the conflicting patterns in neutral and selected genes can either be explain by separation in allopatry followed by secondary overlap and extensive introgression that homogenizes neutral differences evolved under allopatry, or by repeated evolution in parapatry, or in sympatry, with the same ecotypes appearing in each local site. Data from Spain, UK and Sweden give stronger support for a non-allopatric model of ecotype formation than for an allopatric model. Several different non-allopatric mechanisms can, however, explain the repeated evolution of the ecotypes: (i) parallel evolution by new mutations in different populations, (ii) evolution from standing genetic variation, and (iii) evolution in concert by rapid spread of new positive mutations among populations inhabiting similar environments. These models make different predictions that can be tested using comprehensive phylogenetic information combined with candidate loci sequencing.


Adaptation, Plasticity and Extinction in a changing environment: towards a predictive theory?

Per Jonsson
Department of Marine Ecology - Tjärnö, University of Gothenburg

Recently Chevin et al. (2010) published a paper in PLoS Biology where the authors propose a simple evolutionary model to predict if evolutionary adaptation and phenotypic plasticity are sufficient to allow persistence in a rapidly changing environment. This work is highly relevant to the overall CeMEB objective to predict responses of marine populations to Global Change. I will present the ideas and theoretical framework presented by Chevin et al. with the aim to open a discussion about possible model approaches, and how ongoing and planned research within CeMEB may contribute to predictive modelling.

Chevin et al. (2010)


Connectivity and dispersal barriers in the Baltic-Kattegatt-Skagerrak seas

Per Jonsson
Department of Marine Ecology - Tjärnö, University of Gothenburg

Dispersal and associated gene flow may affect if and how populations can adapt to ongoing global change. Limited dispersal may lead to local adaptations, but may also prevent populations to track changing geographic gradients, Dispersal ability may itself evolve, and climate change can lead to shifts in dispersal patterns, e.g. because of changing ocean circulation. Models predicting the persistence of populations in the face of global change will critically depend on dispersal and connectivity. Here we aim to estimate dispersal potential and connectivity within the Baltic-Kattegatt-Skagerrak region by combining physical models of ocean circulation with biological models of spawning time, pelagic larval duration , propagule behaviour and suitable habitats. With a new theoretical framework we can identify dispersal barriers and the aim is to include connectivity information in simple genetic models to explore the potential for local adaptations. We also plan to explore how connectivity patterns may change under a number of future climate scenarios.


Indirect effects of salinity on natural and sexual selection in sand gobies

Lotta Kvarnemo, Dept of Zoology, Univ. of Gothenburg

There are several known indirect effects of salinity on the reproduction of the sand goby. Almost all appear via changes in the ecosystem. For example, nest site availability in the Baltic is low for sand gobies, since they use empty mussel shells to build nests under, and whilst sand and blue mussels are large, sturdy and abundant at the Swedish west coast, they are small, fragile and scarce in the Baltic. This scarcity of good nest sites affects sexual selection profoundly, shifting it from inter sexual selection through female choice at the Swedish west coast, to intra sexual competition among males for nest sites in the Baltic. Another example of an indirect effect of salinity is risk of egg predation, which differs markedly between the Baltic and the Swedish west coast. In particular two species of egg predators, netted dogwhelks and shore crabs, are very abundant at the Swedish west coast, but do not exist in large parts of the Baltic, due to the lower salinity. Presence of egg predators affects many aspects of reproduction for a sand goby, including the nest-holder’s time budget when it comes to defending against sneaker males or fanning of eggs, but also its nest-building behaviour. Many other indirect effects of salinity are still unexplored. Some of the potentially most important ones are food availability, fungus infections, and the effect of salinity on sperm longevity. The importance of these factors will hopefully be the focus of research projects in the near future.
 


A reductionist approach reveals reductase speciation genes

Christer Löfstedt
Chemical Ecology and Ecotoxicology, Department of Ecology, Lund University

Pheromone-based behaviours are crucial in animals from insects to mammals, and reproductive isolation is often based on pheromone differences. However, the genetic mechanisms by which pheromone signals change during the evolution of new species are largely unknown. Female moths emit a species-specific pheromone blend that attracts males over long distances. The European corn borer, Ostrinia nubilalis, consists of two sex pheromone races, Z and E, that use different ratios of the cis and trans isomers of acetate pheromone components. This subtle difference leads to strong reproductive isolation in the field. Female sex pheromone production and male behavioural response are under the control of different major genes, but the identity of these genes is unknown. Here we show that allelic variation in a fatty-acyl reductase gene essential for pheromone biosynthesis accounts for the phenotypic variation in female pheromone production, leading to race-specific signals. Both the cis and trans pheromone precursors are produced by both races, but the precursors are differentially reduced to yield opposite ratios in the final pheromone blend as a result of the substrate specificity of the enzymes encoded by the Z and E alleles. This is the first functional characterization of a gene contributing to intraspecific behavioural reproductive isolation in moths, highlighting the importance of evolutionary diversification in a lepidopteran-specific family of reductases. Accumulation of substitutions in the coding region of a single biosynthetic enzyme can produce pheromone differences resulting in reproductive isolation, with speciation as a potential end result.


Phenotypic plasticity and local adaptation in Fucus vesiculosus in relation to interactions with herbivores

Göran Nylund
Department of Marine Ecology - Tjärnö

The belt-forming perennial brown alga Fucus vesiculosus is a common intertidal alga in rocky shores along the Atlantic coast, including the Swedish west coast. It is the dominant macroalga in the Baltic, where it is considered a keystone species. Herbivory in marine littoral environments is typically intense and generates strong selection for algal chemical defences. Accordingly, F. vesiculosus contains high levels of defensive secondary metabolites, phlorotannins, which function as a chemical defence against herbivory. The overall aim of this project is to study phenotypic plasticity and local adaptation in F. vesiculosus in relation to interaction with herbivores, by using the Skagerrak-Baltic salinity gradient as a model system. As a start, we are planning a manipulative experiment to study if the different grazer regime between the Baltic Sea and Skagerrak have selected for different defensive properties in F. vesiculosus. This will be assessed by using a transcriptomic and metabolomic approach, and today’s presentation will focus on the design of this experiment.
 


Spread of the clones and how that depend on environmental variability

Anna Nyqvist
Department of Marine Ecology - Gothenburg, University of Gothenburg

Many species have lineages with different modes of reproduction from sexual to asexual by cloning and parthenogenesis. The geographical distribution of individuals with different reproductive strategies often differ, while sexual morphs are more abundant in the core habitat (where the species might have existed for a long time), asexual forms are often found in marginal habitats along the edge of the species distribution. This pattern can be found for example along the north-south gradient in the Northern hemisphere. The mechanisms behind this spatial segregation are hotly debated. Here, a simple two-patch metapopulation model including two morphs with different reproductive modes is used to test the influence of different kinds of environmental variation on this pattern. Both morphs are similar to each other, except, when few, there is an Allée-effect on the reproduction of the sexual morph, and the asexual morph has a lower capacity to cope with bad years and to utilize good years. The carrying capacity is larger in patch one compared to patch two, to reflect the environmental gradient in the system. The size of the environmental variation and the size of the autocorrelation of the variation over time is tested in combination with different sizes of dispersal in the system.


Response to global warming in the shallow subtidal: the phylogeography of transcriptomics in a key foundational species, the seagrass Zostera marina

Jeanine L. Olsen
Dept. Marine Benthic Ecology & Evolution, Centre for Ecological and Evolutionary Studies, University of Groningen, The Netherlands

Climate change is a human-mediated and planet-wide experiment in rapid selection. While adaptation to environmental change is a widespread phenomenon, the underlying genetic basis and variation is still largely unresolved. Short-term evolutionary adaptation of tolerance within a species, is mainly mediated by changes in gene expression rather than by structural changes of the genes. However, 5-15% of the expressed genes may also be under selection and these are of particular relevance to understanding local adaptation. Our goal is to examine both of these aspects in order to produce a dynamic snapshot of how Zostera marina copes with changing temperatures through the lens of the relative contributions of phenotypic plasticity (differential gene expression) and evolutionary change (selection). Because Zostera marina can reproduce clonally, it is possible to separate genotype x environment effects at the level of coastlines, populations within coastlines and genotypes within populations. This makes it feasible to address scale-dependence, broad sense heritability and consistency of transcriptomic evolution. This project will be utilize “common-stress-garden” experimental approach in an aquatron in which variation in gene expression will be analyzed—under normal and stressed conditions—using massive, parallel 454 sequencing of non-normalized libraries; thereby assessing gene expression as transcript frequency and frequency differences. This talk will focus on preliminary results from experiments conducted last year and the set-up the 2010 experiment. I will also discuss some of the other transcriptomic projects being conducted in my laboratory.

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On the the genotype-phenotype map and its role in understanding evolutionary change.

Stig Omholt
Norwegian University of Life Sciences (UMB) and
Director of the national core facility “Centre for Integrative Genetics” (CIGENE)

In order to be able to predict how populations and species evolve under new environmental conditions one actually needs to understand the capacities for variation in a population and how the capacities for variation of interacting populations together with the ambient environment influence the evolutionary outcome. This is far beyond reach today, but it is something that should be strived for. The genotype-phenotype map is a key concept in this connection. The talk will focus on how the genotype-phenotype map relates to evolutionary change and how multiscale modeling of complex physiological systems can be tied to this concept in order to get a better understanding of the variational potential of a complex trait.

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Microarrays to identify molecular basis of adaptations in Littorina.

Marina Panova
Department of Marine Ecology - Tjärnö, University of Gothenburg

Identification of molecular mechanisms of adaptation is an important question in evolutionary biology. Genetic variation underlying phenotypic variation can be roughly divided into regulatory changes and structural variation in proteins. There are different point of views on which of the two types of genetic mechanisms is more important for ecological divergence.

In a recently started project, we use microarray to identify genes, involved in ecotype divergence in the snail Littorina saxatilis through both regulatory and structural changes as 1) Genes that are differentially regulated in the two ecotypes in the field and/or in controlled laboratory conditions; 2) Genes that are expressed in one or both ecotypes in response to specific stress-factors, typical for their environments. We are mostly interested in inherited differences in gene expression between ecotypes, resulting from divergent selection, and not plastic responses. However, the pilot experiment comparing gene expression patterns of the two Littorina ecotypes in the field revealed high variation among biological replicates (i.e. individuals and localities). This indicates that there may be large environmental variance (plasticity) in gene expression, caused by other factors, than ecotype/habitat.


Local adaptation and genetic divergence in Antarctic protists

Karin Rengefors
Director of the Graduate School in Genomic Ecology (GENECO), Limnology, Biology Department, Lund University

A fundamental question in ecology is whether microorganisms exhibit biogeographic patterns. It has been argued that microorganisms have unrestricted dispersal and no biogeographies, due to their small size and high abundance. Consequently species diversity should be low and gene flow unrestricted. Recent studies show both evidence of genetic isolation by distance and restricted gene flow among populations. Here, we investigated possible genetic divergence due to either local adaptation and/or geographic isolation, i. e. mechanisms which may lead to speciation. As a model system, we used dinoflagellates in recently formed Antarctic saline lakes. Clonal strains of two different species were isolated from lakes of different salinities. To study local adaptation, we tested salinity tolerance in marine and limnic strains. The genetic difference among the strains was determined using the DNA fingerprinting technique (AFLP). The AFLP analyses indicated that the lake strains were more closely related to each other than to the marine strains. The salinity tolerance experiments showed that the limnic strains had a wider salinity tolerance than the marine strains, and that the limnic strains were adapted to the salinity ranges of their lake of origin. We tentatively suggest that the limnic populations have undergone local adaptation and may be genetically isolated from the marine populations.

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Idotea baltica - Local Adaptation & Co evolution, or just a tough little beast?

Hannah Wood
Department of Marine Ecology - Kristineberg, University of Gothenburg

The isopod Idotea baltica is found in the littoral zone of many temperate regions, often in association with the alga Fucus vesiculosis. This species is notable for its presence in the Baltic sea, down to salinities as low as 4psu. As a brooding species I. Baltica generally has a low dispersal range, and as such the persistence of this species into the Baltic is highly directional along the Swedish coast. In addition, the associated F. vesiculosis has also invaded the Baltic, despite the presence of the grazer I. baltica. The species history and Baltic invasion of I. baltica provide an ideal framework to investigate potential adaptation and co evolution (with F. vesiculosis). To investigate this three populations of I. baltica from progressively lower salinities in the Kattegat and Baltic, were kept for 12 weeks in a laboratory experiment with salinity, food quality and population as factors. As a fully crossed experimental design, individuals from each isopod population were exposed to each combination of salinity and food quality. Basic physiological measurements were taken to investigate differences between the populations: food consumption, weight/length increase, and metabolism. The results from this experiment will be presented here.
 

Page Manager: Eva Marie Rödström|Last update: 5/27/2010
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