Marine and fish biology

Supervision

 

Arnar Pálsson

Research Portal – Arnar Pálsson

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.

• See further information regarding funding and duration

Supervision

Einar Árnason and Katrín Halldórsdóttir

Research Portal – Einar Árnason

 

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.

• See further information regarding funding and duration

Supervision

Zophonías Oddur Jónsson

Research Portal – Zophonías Oddur Jónsson

 

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.

• See further information regarding funding and duration

Supervision

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.

• See further information regarding funding and duration

Supervision

 

Steven Campana

Research Portal – Steven Campana

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.

• See further information regarding funding and duration