Ecology and evolution
Ecology and evolution
All organisms are part of ecosystems. Evolution permeates also all aspects of biology, because all organisms are products of evolution and, are continuously changing. Evolution occurs in ecological theaters on geological times but also sometimes amazingly fast.
The research topics of biologists in this field are topics like:
- Which factors shape the microbial communities in geothermal areas? (SB)
- How do owls use different habitats? (GÞH)
- What influences the rate of evolution in spiders? (IA)
- Can parasites provide ecological insights into trophic structure and dynamics? (HSR)
- Which effects do colonizing ants have on Icelandic fauna? (AP)
- Which factors influence the species composition of terrestrial ecosystems? (ISJ)
- Which factors influence colonization of plants (like birch) and progression on glacial flats? (SP, ÞEÞ)
- How repeatable is the evolution of polymorphism in Arctic charr? (ZOJ, AP)
- What evolutionary processes shape parasite evolution? (HSR)
Research projects
Project website
Supervision
About the project
Noise is thought to be one of the main threats to northern bottlenose whales. However, due to their elusive nature, little is known about this species in Iceland and the Northeast Atlantic in general.
This project aims to provide important insights into northern bottlenose whales and evaluate the potential threat of anthropogenic noise disturbance to them by assessing 1) relative abundance and movement directions for the population, 2) individual movement, habitat use, behaviour and responses to noise, and 3) overlap of impulsive anthropogenic noise with whale occurrence and habitat.
To achieve this, the project uses state-of-the-art observation and tracking technologies such as bottom-moored acoustic recorders and satellite tags, combined with photo-identification and surface observations.
Supervision
About the project
Land degradation, often a consequence of human activities, is of global concern. Once an ecosystem has shifted to a degraded state, for example after an extensive period of heavy livestock grazing, excluding grazing may not be sufficient to shift the system back to the original or healthier state. However, the processes that trap ecosystems in a degraded state are not well understood. The aim of this project is to investigate ecosystem processes that slow down or prevent recovery of heavily grazed rangelands following grazing-cessation. More specifically, we will focus on degraded rangeland ecosystems that have not totally collapsed and the role of different plant functional types and soil related processes in retarding or facilitating transitions to a healthier state. Slow responses of such ecosystems following grazing-cessation may be related to the function of the dominating plants that lead to slower decomposition rates and nutrient cycling and lower ecosystem productivity which trap the system in the degraded state. Understanding which processes trap ecosystems in degraded states is a key to sustainable land management plans. We will address the specific research questions through a combination of approaches, from direct observations of relationship between PFTs and ecosystem processes, to experiments (field and laboratory) and modelling approaches.
Supervision
About the project
Concerns over the effects of human-induced environmental changes on marine wildlife, including increasing levels of underwater noise, are rising, particularly in Arctic and subarctic regions. Noise is thought to be one of the main threats for sensitive taxa, such as the most common beaked whale in Icelandic waters, the northern bottlenose whale. However, due to their elusive nature, little is known about this species in Iceland and the Northeast Atlantic in general. This project aims to provide important novel insights into northern bottlenose whales and evaluate the potential threat of anthropogenic noise disturbance to them by assessing
- Relative abundance and movement directions of animals in waters east of Iceland
- Movement, habitat use, behaviour and responses to noise in the North-eastern Atlantic
- Overlap of impulsive anthropogenic noise with whale occurrence and habitat.
To achieve this, the project will use state-of-the-art observation and tracking technologies such as bottom-moored acoustic recorders, satellite tags, and aerial and underwater drones, combined with photo-identification and surface observations. This study will provide unprecedented information on the role of beaked whales in the Icelandic marine ecosystem, and the potential effects of human-generated impulsive noise on sensitive species, with application to confamilial species and other human-induced environmental changes.
Supervision
Kalina Hristova Kapralova og Michael Blair Morrissey
About the project
The Arctic charr (Salvelinus alpinus) of Lake Thingvallavatn are ideally suited for studies of the ecology and genetics of adaptive diversification: i) it is an extraordinarily well-characterised system, ii) it has young evolutionary history, iii) it has diverged into four morphs with distinct variation in life history characteristics, behavior and trophic morphology, suggesting rapid adaptive diversification. This system thus represents an extremely compelling case of rapid adaptive differentiation. However, to date, the system has been under-used to answer fundamental questions about the genetic basis of this diversification, due in large part to a lag in the development of genomic resources, and the long generation time. These issues have recently been overcome, and it is now possible to get at some long-outstanding questions. The overall aim of this project is answer fundamental questions about the genetic basis of this extraordinary case of rapid adaptive differentiation, by determining the number, genomic distribution, range of effect sizes and evidence of selection of loci contributing to adaptive diversification. We will answer these questions by deploying a series of studies, using both classical genetic study designs (QTL mapping) of carefully constructed laboratory crosses, and modern population genomic analyses of field-collected specimens.
Supervision
About the project
Humpback whales were near depletion during the mid-20th century, but for the last 2 decades they have been recovering rapidly, particularly in Polar Regions the last few years. The humpback is a migrating baleen whale whose behavior is believed to be largely discrete between their breeding and feeding grounds. Recent evidences on the migration behavior of humpbacks in the North Atlantic have shown a much more delayed winter migration and even overwintering of this species in the subarctic. Recent findings by the applicant showed how males engage in active singing (a male breeding display) during their reported breeding season in the subarctic, indicating a trade-off between growth and reproduction on a polar feeding ground; a strategy which possibly assisted the recovery of humpback whales. Consequently, the humpbacks might play a much larger ecological role in subarctic waters than previously stated. The nature of this role is poorly understood and the scale of the impact in the ecosystem has not been measured. The aim of this study is, therefore, to provide new information about the life history strategy of humpback whales wintering in a polar region by investigating their body condition, reproduction and foraging strategy on a year-round basis with a set of both robust and state of the art methods. The findings will provide a new global perspective of the life history dynamics of this species and their possible response to the rapidly changing climate of the Polar Regions.
Supervision
About the project
Do species with extensive phenotypic plasticity diversify more rapidly than other species or does plasticity hinder evolution? How does plasticity evolve after colonization of new habitats? Does phenotypic plasticity correlate with plasticity in gene expression in underlying tissues? Here we propose to investigate the patterns of plasticity and divergence, and the developmental basis of plasticity and polymorphism, using a phenotypically diverse salmonid. Arctic charr (Salvelinus alpinus) has, in about 10,000 years, invaded and adapted to diverse habitats, often resulting in sympatric morphs in landlocked lakes. In experiments Arctic charr show various levels of phenotypic plasticity, for instance depending on food types offered. We propose to study wild charr populations, anadromous and several lake charr morphs varying in ecological specialization, induce plastic responses in the feeding apparatus (by giving juveniles benthic or limnetic food) and survey the phenotypic responses with geometric morphometrics of body, head and jaws. Furthermore we plan to study the molecular correlates of the observed plastic changes and evolved differences using RNA sequencing of samples form juveniles. Finally we plan to study the inheritance of plasticity by assessing phenotypes and gene expression in hybrids of wild morphs. The proposed work can reveal the patterns and mechanistic basis of genotype by environmental interactions.
Supervision
About the project
High fecundity translates into a potential to withstand strong and substantial natural selection and allows for rapid adaptation to various environments. A diverse group of organisms ranging from fungi to codfish are highly fecund. Codfish are among the most fecund vertebrates. Their rapid adaptations are the basis of their ecological success that enables codfish to support major fisheries of great economic importance. We aim to understand the biology of high fecundity and how codfish can support major fisheries. To this end we propose to (A) explore if codfish can be characterized by sweepstake mode of reproduction; (B) investigate if hybridization and introgression can be a source of adaptive genetic variation in codfish and thus facilitating rapid adaptation to very different habitats; (C) examine whether the putative sweepstake mode of reproduction of codfish in combination with selection leads to rapid adaptation, and if genes under strong selection, possibly due to fisheries, can be identified in highly fecund codfish. To achieve our aims we will obtain massive amounts of whole genome DNA sequence data of codfish and study chromosomal structural variation using latest technology, and apply rigorous mathematical modeling involving genomic population models of high fecundity and genomic multiple-merger coalescent models. The results will have huge impact on population and evolutionary genomics and on conservation and management of an important natural resource.
Supervision
About the project
The White-tailed eagle (Haliaeetus albicilla) in Iceland lowered in numbers after the mid-1800s from 150 breeding pairs down to 20 pairs in 1914 when it was protected by law. Despite protection the population did not grow until 1970, mainly due to fox poisoning. The growth rate is slow and its fecundity is mucl lower than among White-tailed eagles in Scandinavia. The aim of the project is to analyse the effect of small population size and inbreeding on genomic variation and fitness, by analysing a unique sample and dataset gathered over years 2001-2016. Firstly, genomic variation of the population in Iceland today will be compared to genomic variation from before and during the bottleneck. Secondly, the genomic variation of the contemporary population in Iceland will be compared to the larger population in mainland Europe. Thirdly, inbreeding depression will be studied by comparing variation in fitness with kinship and genetic variation and telomere length, and in relation to extrinsic factors such as parasitic load and environmental information. The genomic variation gives possibility to evaluate hypotheses regarding the effects of natural selection and population bottleneck on molecular variation. The result of this study has implications for both evolutionary and conservational biology and the coservation of the White-tailed eagle in Iceland.
Supervision
About the project
Availability of fixed nitrogen is essential for primary production. We will gather information on biological nitrogen fixation (BNF) in eight defined subarctic habitats (EUNIS classification) representing nearly 90% of cryptogam (lichen, moss and biocrust) cover in uncultivated areas of Iceland; by measuring of BNF, by identification of the bacteria and nitrogen fixation systems involved, including the alternative Vnf system, and by testing hypotheses regarding the major players in laboratory experiments, making use of chemical and isotope analysis, gene sequencing technology and bioinfomatics.
The objectives are:
- Obtain reliable estimates of BNF in major cryptogam habitats using ARA (acetylene reduction assay) standardized with 15N uptake.
- Characterize nitrogen fixing bacteria and main components in the selected habitats using methods of microbiology and gene sequencing.
- Carry out field observations, plus field and laboratory experiments to quantify cyanobacteria and environmental factors controlling BNF.
- Establish the contribution of the alternative Vnf system to nitrogen fixation in the cryptogam communities, both in the field and in the laboratory.
For this we will a) determine 15N isotope discrimination by mass spectrometry (greater with Vnf than Nif), and b) determine levels of vnf and nif gene expression by reverse transcript quantitative PCR. 5) Extend findings to habitats with same EUNIS classification elsewhere, model BNF and assess global relevance.
Supervision
About the project
The interaction of evolution and development lies at the core of morphological adaptation. To understand this interaction it is helpful to study natural populations that show signs of strong selection for and even repeated evolution of particular traits. An interesting example of this is found in Iceland, where small benthic morphs of Arctic charr have evolved in multiple lakes and four distinct morphs have evolved within the Lake Þingvallavatn in the last ~10,000 years. We have studied mRNA and miRNA expression in Þingvallavatn charr and found interesting clues as to what lies behind their different head-shapes. Those clues include gene networks that are differentially expressed between morphs during development. We now want to take the logical next step and identify regulators of the pathways and polymorphisms of functional significance that give rise to those differences. We will use next generation sequencing in three different ways to generate three important datasets for synthesis. We will start by obtaining genomic sequence data for Arctic charr. We will use reduced representation bisulfite sequencing to take a snapshot of methylation states during development and analyze their association with expression differences. We will use targeted resequencing to compare genomic regions of interest in the Þingvallavatn morphs to other populations of charr. Finally, we will perform studies in cell culture and in zebrafish to address the functional relevance of our findings.
Supervision
Sigurður Sveinn Snorrason og Kalina Hristova Kapralova
About the project
The Arctic charr (Salvelinus alpinus) of Lake Thingvallavatn is ideally suited for studies of divergence and evolution of reproductive barriers: i) it has a short evolutionary history in the lake, ii) yet it has diverged into four morphs with distinct variation in life history characteristics, behavior and trophic morphology, suggesting rapid adaptive diversification, possibly followed by or causing build-up of reproductive barriers. We will focus on the two smallest morphs, a planktivorous (PL) and small benthic charr (SB), which have diverged along the limnetic-benthic ecological axis. The central hypothesis underlying our investigation is that reproductive isolation between SB and PL charr is partly due to strong negative selection against hybrid offspring and/or differences in the exact timing of spawning (i.e. time of the day), precise spawning location and mating behavior. The project consists of 4 Work packages (WP). In WPI we will establish hybrid and pure crosses and compare fitness related traits such as survival, hatching time, body size and craniofacial morphology between hybrid and pure progeny. In WPII we will investigate putative incompatibilities detected in WPI by comparing the expression of essential developmental genes between hybrids and pure morphs. In WPIII and WPVI we will study the exact timing and spawning location and their mating behavior by conducting observations in the wild and laboratory experiments.
Supervision
About the project
This study proposes to take advantage of unique, century-long collections of otoliths (earstones) from two of the largest Atlantic cod (Gadus morhua) populations in the world in order to develop the longest and most detailed growth and temperature biochronologies available for any marine fish species. The growth and temperature records from these biochronologies, developed from growth increment measurements and oxygen isotope assays, will then be related to the long-term population dynamics of the Icelandic and Northeast Arctic cod stocks, to century-scale temperature and climate indices developed from bivalves living on the Icelandic and Norwegian continental shelves, to instrumental records, and to ocean circulation model predictions of flow fields, to identify the conditions driving variability in cod stock production over a time scale that has seldom been attempted for any global fish population. The results of the project will provide a perspective on overall groundfish population dynamics in the Northeast Atlantic which is simply not possible using shorter time series. We anticipate that the results of the project will not only inform the future assessment and management of two of the world’s largest and most valuable ground fisheries, it will serve as the basis for comprehensive climate change predictions on the groundfish community and marine ecosystem in the entire northeast Atlantic.
Supervision
About the project
Symbiosis is a major theme in the evolution of life. Worldwide, biotas are challenged by environmental stress due to climate change, with especially severe effects on fine-tuned, intimately interacting symbioses such as the lichen symbiosis. Survival can be achieved by tolerating stressful conditions, through specific adaptations which often rely on modulating gene expression. How organisms tolerate stress can dictate their capacity to respond to climate changes, yet the mechanisms of stress alleviation are understudied in fungal symbioses. We propose to study ecological genomics and phenotypic traits of two lichen symbioses representing abundant species in northern ecosystems. These lichens co-occur in many sites, but associate with primary photobionts belonging to different kingdoms. First, we will expand a RAD sequencing study of population structure in Peltigera membranacea to P. leucophlebia. Second, we plan to study gene expression (RNAseq, qPCR) and trait response to thermal stress in a controlled laboratory setting. The data and analyses enable us to partition the effect of genetic background from environmental acclimatization, and point to putative adaptive systems that influence acclimation and trait differences of symbiotic systems, thus being of broad relevance to the community of researchers studying symbiotic systems.
Supervision
Denis Warshan
About the project
Cyanobacteria in symbioses with fungi (cyanolichens) and mosses contribute nearly 30% of the dinitrogen-fixation on land, establishing these symbioses as major players of biogeochemical cycles. Despite its ecological importance, molecular understanding of the establishment of cyanolichen symbioses lags far behind many other symbiotic systems, and little is known about the cyanobacterial gene repertoire needed to form the association. The proposed work will provide additional characterization of these associations at unique levels:
- Evolutionary history of cyanobacteria forming cyanolichens.
- Metabolomics of cyanolichen partners during the early step of symbiosis formation.
- Genetic analysis of candidate genes involved in establishing and maintaining the interaction.
The objectives of the project are to:
- Determine what gene acquisitions are associated with the evolution of cyanobacteria forming lichens by comparative genomic and by symbiosis reconstruction experiments with lichen hosts.
- Deciphering signaling exchange between lichen partners during symbiosis formation
- Characterize the function of cyanobacterial symbiotic candidate genes by using targeted knockouts of genes retained in the symbiotic cyanobacteria.
The proposed work will create the first model system of molecular interaction between partners for the cyanolichen symbiosis and it will design new methods and molecular tools to monitor adaptation and health of these symbioses and their ecosystems.