New grants for Evolution and Ecology researchers

A short description of some of the projects are found below.

Species Range Dynamics Under Climate Change: An Integrative Approach
Robert Muscarella

Forecasting the ecological consequences of climate change requires a stronger synthesis of information about the processes that govern species range dynamics. The aim of this project is to better understand range dynamics of tropical trees by synthesizing data on demographic rates, physiological traits, and current distributions. The project will focus on forests in Puerto Rico, and leverage long-term data from diverse forests across broad climate gradients.

The Genetic Architecture of Sexual Dimorphism
Elina Immonen

Sex differences are commonplace and often the greatest source of phenotypic variation within species. Their evolution is a puzzle, however, because although the sexes commonly experience divergent selection pressures, their independent response to selection is constrained by the largely shared genome. This project will investigate how sex differences in body size evolve by using laboratory evolution, quantitative genetic and genomic techniques, and seed beetles as the model system. By testing several theoretical predictions of what it takes to evolve sexual dimorphism, we hope to get a deeper understanding of how to resolve the conflict over shared genes and where in the genome the resolution lurks.

Climate change and trophic cascade effects on community assembly processes and ecosystem functioning in plankton
Silke Langenheder

The overall aim of the project is to investigate how priority effects, caused by differences in the arrival order of species during initial colonization of a habitat, influence spatial patterns in community composition. More specifically, we will investigate how changes in abiotic conditions resulting from climate change, such as increases in temperature, productivity and environmental fluctuations, interactively affect the strength of priority effects relative to other assembly processes and how that, in turn, influences ecosystem functioning. Further we will investigate if priority effects that occur at higher trophic levels cascade through food webs and cause differences in community composition and ecosystem functioning at lower trophic levels. To address these questions we will use micro- and mesocosms experiments with microbial plankton communities.

Mutation bias in adaptive evolution and the adaptive evolution of mutation bias
David Berger

Evolutionary theory typically considers the phenotypic effects of new mutations as independent of past selection, but this view has recently been challenged. If selection does not only discriminate among the phenotypes that mutation has created, but also influences which phenotypes that mutation initially creates, this would have fundamental implications for the relationship between mutation and its demographic consequences, as well as for the rate and repeatability of evolution. However, we know next to nothing about the conditions under which natural selection can shape mutational effects. This proposal aims to help fill this void by using three different insect models to explore if and how selection shapes the phenotypic penetrance of de novo mutations in life-history, morphology, gene expression and fitness over different evolutionary time frames. Additionally, we will use a comparative dataset on organisms across the tree of life to test the corollary prediction that de novo mutations should have stronger fitness effects in novel environments, where selection has not yet had the opportunity to buffer environmental and genetic stress. The ideas and experiments presented here go well beyond the current state-of-the-art and are aimed at showing how recently proposed challenges to the Modern Synthesis are in fact reconcilable with standard quantitative genetics theory.

Metagenomic time travel to study the evolution of antimicrobial resistance in microbiomes of wild Swedish mammals
Katerina Guschanski

Antimicrobial resistance is a major threat for human health worldwide and poses a significant financial burden in treatment costs. Using dental calculus, the calcified bacterial biofilm that forms on teeth of mammals, we will investigate how the levels of antimicrobial resistance and the diversity of antimicrobial resistance genes have changed through time in several wild mammals, such as bears and reindeer. With the help of museum collections, we will first determine the baseline of antimicrobial resistance in host-associated microbiomes before humans started mass-producing antibiotics in the 1940s. Progressing through time towards the presence, we will study the evolution of antimicrobial resistance in response to increased antibiotic production 1940s-1990s and the effectiveness of the national Strama plan (introduced in 1995) to curb antimicrobial resistance.

Symbiont protection in mutualisms and Symbiont protection - a novel ecological concept and map to drug discovery
Charlotte Jandér

Charlotte Jandér studies the ecology and evolution of mutualisms. Her research looks at how mutualisms avoid enemies from within, such as cheating partners that take the benefits of the interaction without paying the costs. Her recent funding from VR and Formas will extend this work to study enemies that are external to the mutualism: who are they, what are their fitness costs, and how do mutualisms protect themselves against these enemies? Fieldwork will initially focus on the mutualism between fig trees and their pollinating fig wasps, where fitness can easily be quantified.

The genomic repeatability of life history adaptation
Göran Arnqvist

Insight into the repeatability of adaptation represents a current challenge in evolutionary biology, because it requires a detailed understanding both of the presumed complex genetic architecture of adaptation and of the interplay between deterministic and contingent forces in evolution. Such an understanding is generally not in place. I will employ a unique set of replicated bi-directional experimental evolution lines of an insect, maintained for more than 300 generations. I will perform life history phenotyping, a major comprehensive next-generation sequencing effort and a quantitative genetic breeding design in order to assess the extent to which similar adaptive phenotypic evolutionary trajectories involve similar genetic trajectories. I will be able to determine the number of genes and gene networks that are involved in life history adaptation and will estimate repeatability at several different levels (i.e., phenotypes, networks, haplotypes, genes, transcripts and SNPs). Dedicated efforts will be made to determine the relative roles of coding and non-coding regions of the genome and to identify epistatic interactions that mediate life history adaptation. This project greatly extends previous studies of microbes and those of simper traits, and is beyond state-of-the-art by (1) aiming to understand the genomic repeatability of complex life history adaptations in a metazoan and (2) using a deep and exceptionally integrative methodological and inferential strategy.

Evolution of sex determination
Sophie Karrenberg

The evolution of separate sexes is of fundamental importance in biology. Sex determining mechanisms are highly variable and labile and sex chromosomes often degenerate; however, the underlying evolutionary mechanisms are unclear. Theoretical studies predict that sex chromosome evolution is driven by sex ratio selection and/or by different forms of genetic conflict, for example, between males and females or between cytoplasm and nucleus. Empirical evidence for these predictions is scarce, in part because the best-studied systems are animals with ancient sex chromosomes. This project investigates a plant family with separate sexes (Salicaeae, willows and poplars) where a high turnover of recently emerged sex chromosomes has been suggested and sex ratio bias is common. The project has three main objectives: (1) identify the mechanisms for sex determination and sex ratio bias, (2) analyze signs of degeneration in sex-associated region(s), and (3) investigate the evolutionary history and dynamics of genomic region(s) associated with sex-determination and sex-ratio bias. This comprehensive approach will allow us to gain novel insights into sex chromosome evolution and evolutionary processes at large.

Molecular mechanisms and evolutionary forces underlying recombination frequency in butterflies and Characterization of the genetic basis of migratory behavior in butterflies                          
Niclas Backström

Despite the central role of recombination in chromosome segregation accuracy, speciation processes, adaptive potential of populations and generation and maintenance of diversity, knowledge about recombination rate variation is limited to a handful of model organisms with little relevance to natural conditions. The aim of this project is therefore to quantify the mechanistic and evolutionary underpinnings and consequences of recombination rate variation. Butterflies are tractable organisms for this quest; they demonstrate high diversity in adaptations, behavior and speciation and have specific characteristics suitable for investigating causes and consequences of variation in recombination. High-density recombination maps will be developed for three closely related species of butterflies using a combination of cutting-edge techniques. The data will be used to characterize the main determinants and consequences of recombination rate variation. This is a timely topic since living organisms are currently facing one of the greatest environmental emergencies in history, exemplified by recent reports on massive declines and rapidly changing behavior in many butterflies. Characterization of mechanisms underlying recombination will lead to novel understanding about forces affecting genetic diversity and adaptive potential in natural populations.

Genomic, phenotypic and ecological divergence in a diverse clade of passerine birds
Per Alström

Understanding how new species are formed is one of the most fundamental questions in evolutionary biology. Speciation involves divergence in genetic and phenotypic traits, but the interplay between and relative roles of different factors for the evolution of reproductive isolation are poorly known. The purpose of this study is to address several outstanding issues in speciation research, relating to (1) genomic, phenotypic and ecological correlates of speciation and divergence; (2) identification of genomic regions under selection; and (3) evolution of reproductive isolation. We will study the ~80 species in the avian family Phylloscopidae (leaf warblers), for which a wealth of data on morphology, vocalisations, ecology and geographical distributions are available. Using whole genomes, we will ask: (i) whether divergent genomic regions have arisen in homologous or different parts of the genome across species; (ii) whether repeated phenotypic changes have a similar genetic basis; (iii) whether clades or species with novel phenotypic traits show distinct genetic signatures compared to their nearest relatives; (iv) whether genomic and phenotypic evolution is faster on islands than on continents; and (v) how divergence in genetic, phenotypic and ecological traits are linked to reproductive isolation and establishment of sympatry. By studying genomic, phenotypic and ecological diversity at all stages of divergence this project will provide unique insights into the process of speciation.