Adaptive cellular evolution or cellular system drift in hares

Arnar Pálsson, 20/05/2023

Adaptive cellular evolution or cellular system drift in hares

Arnar Palsson and Sarah Elizabeth Steele.

Perspective, in Molecular Ecology.

Adaptations occur at many levels, from e.g. DNA sequence of regulatory elements and cellular homeostatic systems, to organismal physiology and behaviour (Mayr, 1997). Established adaptations are maintained by purifying and stabilizing selection. Students of animal diversity tend to focus on higher order traits, anatomy, physiology, organismal function and interactions. The core cellular and metabolic systems of metazoans evolved early in their history, and are assumed to be rather similar between groups. The housekeeping functions and core metabolic functions of cells are generally considered relatively static, especially among closely related species. The extent to which evolution shapes core cellular metabolism and physiology in animals is largely unexplored. Ecological opportunities or strong positive selection can alter basal metabolic rate, activity levels and life-history traits (e.g. lifespan, age of maturity, offspring number) and potentially lead to divergence in core cellular and metabolic trait systems (Norin & Metcalfe, 2019; Speakman, 2005). Furthermore, systems under stabilizing selection can also change. Developmental systems of related species may produce the same phenotype or structure, but experience drift that can alter connections and even lead to turnover of cogs in the system (True & Haag, 2001). Are the cellular functions of animals highly constrained, subject to cellular system drift or affected by positive selection? This was tackled by a new study by Kateryna Gaertner and colleagues in a From the Cover manuscript in this issue of Molecular Ecology (Gaertner et al., 2022), using fibroblasts from the closely related but ecologically distinct brown and mountain hares.

90 ára afmæli Guðmundar Eggertssonar erfðafræðings

Arnar Pálsson, 11/05/2023

©Kristinn Ingvarsson

Opnunarávarp dagskrár í tilefni 90 ára afmælis Guðmundar Eggertssonar erfðafræðings.

Litla Torg, HÍ, 26. apríl 2023.

Kæru gestir, vinir og Guðmundur. Í dag fögnum við með Guðmundi Eggertssyni erfðafræðingi. Hann átti 90 ára afmæli á mánudaginn, 24. Apríl. Það er sérstakur heiður að fá að opna þennan fund. Lærlingar Guðmundar munu í dag fjalla um feril hans og störf, rannsóknir og áhrif.

Í gær voru 70 ár síðan þrjár greinar birtust um eiginleika og byggingu DNA, eftir Wilkins, Stokes og Wilson, Franklin og Gosling og Watson og Crick. Spurning hvort þetta sé tilviljun eða nauðsyn?

DNA sameinar allar lífverur á jörðinni, ásamt lögmálum lífefna, fruma, vistkerfa og þróunar. Titill fyrstu bókar Guðmundar var "líf af lífi". Viðfangsefni erfðafræði er hvernig gen kemur af geni. Og í dag sjáum hvernig af Guðmundi koma margir Guðmundar. Ekki bókstaflega litlir Guðmundar, heldur lærlingar innblásnir af fræðunum sem hann kenndi okkur og áhuga á sameindalíffræði sem hann smitaði okkur af.

Guðmundur hefur birt fjölda greina um bakteríuerfðafræði, hvernig erfðatáknmálið er túlkað af frumum og virkni. Einnig erfðafræði hitakærra baktería, sem lagði grunn að rannsóknum í líftækni og örveruvistfræði hverasvæða. Það verður fjallað minna um þessi flóknu og forvitnilegu kerfi í dag, og meira um söguna, störf, persónu og fyrirmyndina.

Áhrif hans á íslensk vísindi og sérstaklega líffræði eru ákaflega jákvæð, víðtæk og margslungin. Ég má til með að deila einni sögu. Grensásvegur 12 var kumbaldi sem lak í rigningu. Guðmundur mætti á slíkum dögum til að tæma og staðsetja fötur sem tóku við lekanum. Einnig fór hann upp á þak til að kítta.

Þrennt vil ég minnast á að síðustu.

Í fyrsta lagi vill ég minnast Sigríðar Helgu Þorbjarnardóttur sem féll frá alltof ung. Hún var sérfræðingur Líffræðistofnunar og vann mjög náið með Guðmundi, var meistaraleiðbeinandi minn og margra annara nemenda. Hún var sérlega klár og vönduð. Ég naut þeirrar forréttinda að hafa bæði Siggu og Guðmund sem leiðbeinendur.

Í öðru lagi vil ég minnast gæsku Guðmundar. Hann er alltaf jákvæður og hvetjandi. Munið þið eftir styggðaryrði eða ofsakasti hans? Nei, því slíkt gerðist ekki. Jafnvel þegar hann og aðrir voru að spyrna við gerræðislegum hugmyndum um gagnagrunn á heilbrigðissviði.

Í þriðja lagi er það frábært skopskyn. Guðmundur hefur mikið gaman að góðu gríni. Hann laumaði litlum bröndurum inn í umfjöllun um tRNA og önnur apparöt frumunar,  og lagði oft glæru með bröndurum úr New Yorker eða sambærilegu á skjávarpan áður en fyrirlestrar hófust, nemendum til ánægju.

Að síðustu, hjartanlega til hamingju með afmælið Guðmundur. Ágæta samkunda, ég lýsi þetta málþing og bjórfund settann.

 

Þakkir fá aðrir í skipulagsnefnd, Sigríður Rut Franzdóttur, Snædís Björnsdóttur, Eiríkur Steingrímsson og Zophonías O. Jónssoni. Einnig þökkum við Verkfræði og náttúruvísindasviði og Líf- og umhverfisvísindadeild fyrir fjárhagslegan stuðning.

Söngfjélagið syngur kl 17:00.

The moral status of stem cell-derived embryo models

Arnar Pálsson, 10/05/2023

"This event will be organised as a mini symposium at the University of Iceland (venue: the university aula). The Nordic Committee on Bioethics has invited some of the most prominent researchers from the Nordics and beyond, with expertise in stem cells- and embryonic research, ethics and law. They will share their research and their reflections in the form of presentations and conversations.

The symposium is in collaboration with the Graduate programme in molecular life sciences, BioMedical Center (BMC) at the University of Iceland and is open to the public (registration is required). No registration fee.

The symposium will also be live-streamed. Please note that the time zone is GMT/Iceland.

Background

Currently, the 14-day rule in science policy and regulation, limits research on human embryos (outside the uterus) to the first 14 days of gestation. This is referred to as the 14-day rule. This means, that week 3-4 of human embryonic development is something of a “black box” because scientists cannot see what is taking place in the uterus during the early stages of gestation beyond the first two weeks. In recent years, progress has been made in early embryo research beyond the first two weeks, via “human embryo models,” developed from stem stells, and the study of mouse embryos. Making further use of these discoveries would, however, require researchers to go beyond the 14-day rule when culturing human embryos and embryo models. This raises various ethical issues, not the least concerning the ethical and legal status of such “embryo models” and it re-actualises the debate on a potential extension of the 14-day rule.

Various ethical dilemmas emerge, which forces us to think about moral principles such as the duty to prevent suffering and the duty to respect the value of human life. Where is the balance concerning the benefits these embryo models provide vs. ethical concerns? What is the legal and ethical status of human-embryo-like structures now and in the future – should it be the same for embryo models as for human embryos? What are the financial interests and how should they be regulated? Why should we want to go beyond the 14-day rule? What are the particular questions that arise from a Nordic point of view with regards to the moral status of a human embryo model and culturing human embryos beyond the 14 days?

Speakers

  • Magdalena Zernicka-Goetz, professor of Development and Stem Cells at the University of Cambridge, UK and California Institute of Technology, USA
  • Fredrik Lanner, Assistant Professor at Department for Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
  • Johanna-Ahola Launonen, Post-Doctoral Researcher at Aalto University, Helsinki, Finland
  • Garðar Árnason, Professor of Philosophy at the University of Akureyri, Iceland"

Variation in personality shaped by evolutionary history, genotype, and developmental plasticity in response to feeding modalities in the Arctic charr

Arnar Pálsson, 04/05/2023

Variation in personality shaped by evolutionary history, genotype, and developmental plasticity in response to feeding modalities in the Arctic charr

AUTHORS

Marion Dellinger, Sarah E. Steele, Evert Sprockel, Joris Philip, Arnar Pálsson, David Benhaïm

Submitted manuscript, sorry not on BioRxiv.

ABSTRACT

Animal personality has been shown to be influenced by both genetic and environmental factors and shaped by natural selection. Currently, little is known about mechanisms influencing personality traits development. This study examines the extent to which personality development is genetically influenced and/or environmentally responsive (plastic). We also investigated the role of evolutionary history, assessing whether personality traits could be canalized along a genetic divergence gradient. We tested the plastic potential of boldness in juveniles of five Icelandic Arctic charr morphs (Salvelinus alpinus) displaying various degrees of genetic divergence from the ancestral charr, split between treatments mimicking benthic vs. pelagic feeding modalities. We show that differences in mean boldness are mostly affected by genetics. While the benthic treatment led to bolder individuals, the environmental effect was rather weak, suggesting that boldness lies under strong genetic influence with reduced plastic potential. Nevertheless, the repeatability of boldness response to treatment varied among morphs, suggesting the early environment may drive personality emergence within populations. Finally, we found hints of differences by morphs in boldness canalization through reduced variance and higher consistency in boldness within morphs. These findings provide new insights on how behavioural development may impact adaptive diversification.

Diversity in the internal functional feeding elements of sympatric morphs of Arctic charr (Salvelinus alpinus)

Arnar Pálsson, 24/02/2023

 

Two special courses this spring

Arnar Pálsson, 17/02/2023
The biology programme offers two short courses this spring.
2 ECTS 7-DAY SUMMER COURSE

This 7-day workshop will be based on the recently published Conservation and the Genomics of Populations (3rd edition, Allendorf et al. 2022). This established book provides a comprehensive overview of the essential background, concepts, and tools required to understand how genetics and genomics can be used to conserve species, reduce the threat of extinction, and manage species of ecological or commercial importance. Allendorf will present the subject of the book over three days and then students will prepare and present a short lecture of their project or article. New genomic techniques and statistical analyses are crucial tools for the conservation geneticist. This workshop will provide an essential toolkit grounded in population genetics theory, coupled with basic and applied research examples from plants, animals, and microbes. The workshop will examine genetic and phenotypic variation in natural populations, the principles and mechanisms of evolutionary change, evolutionary response to anthropogenic change, and applications in conservation and management. Topics 1. Introduction 2. Genomic variation in populations 3. Hardy-Weinberg principle 4. Genetic drift & effective population size 5. Natural selection 6. Mutation 7. Gene flow & population structure 8. Multiple loci 9. Hybridization 10. Inbreeding depression 11. Units of conservation 12. Demography and extinction 13. Exploited populations 14. Climate change 15. Genetic monitoring

Learning Outcomes:

At the end of the course, a students should be able to:

  • to describe the background and the concepts of population genetics with relation to conservation
  • to describe the main genetic and genomic methods which can be applied in species conservation
  • to describe applications of genetics and genomics in management of ecological and commercial importance.
For more info contact

Snæbjörn Pálsson
2 ECT 5-DAY SUMMER SCHOOL
The mesopelagic zone (between 200-1000m depth) is the habitat of the largest fish biomass in the ocean.
Mesopelagic fish likely hold a key role in global climate change by participating in the largest migration in the animal kingdom, transporting and storing carbon into the deep sea.

Credit: Leif Grimsmo, SINTEF Ocean

About the course
The SUMMER (Sustainable Management of Mesopelagic Resources, 2019-2024) EU project aims to evaluate if and how mesopelagic resources can be sustainably exploited.
To share the knowledge of the mesopelagic zone, experts from the SUMMER project have arranged a 5-day summer school course for 2 ECT credits, with the Marine and Freshwater Research Institute and the University of Iceland, in Iceland May 22nd – May 26th 2023.
The course will feature lectures from world-leading experts on mesopelagic research, engaging discussions, as well as hands-on laboratory work on mesopelagic fishes – in addition to the dissection of a marine mammal, apex predator of mesopelagic fish.
After completing the course
Students will be familiar with:
• Biology and Ecology of the Mesopelagic Zone
• Taxonomy and Diversity of Mesopelagic Fish
• Mesopelagic Fisheries (Economy, Governance,
Technology)
• Dissection of Mesopelagic Fish and Mammals
Students will develop valuable knowledge of one of the most understudied ecosystems in the world’s oceans, meet worldwide leaders in mesopelagic research, and study in an international group.
Students will also get to experience Reykjavik, the capital of Iceland in May – during a wonderfully bright spring.
The course itself is free for participatnts, but travel expenses (food, lodgings, and transport) must be covered individually.
International students are encouraged to apply, and housing is available on the university campus.
For more information
Website: www.summerh2020.eu
Email: hrandhawa@hi.is

The mesopelagic zone - 5 day course in May.

Arnar Pálsson, 20/01/2023
2 ECT 5-DAY SUMMER SCHOOL COURSE
The mesopelagic zone (between 200-1000m depth) is the habitat of the largest fish biomass in the ocean.
Mesopelagic fish likely hold a key role in global climate change by participating in the largest migration in the animal kingdom, transporting and storing carbon into the deep sea.

Credit: Leif Grimsmo, SINTEF Ocean

About the course
The SUMMER (Sustainable Management of Mesopelagic Resources, 2019-2024) EU project aims to evaluate if and how mesopelagic resources can be sustainably exploited.
To share the knowledge of the mesopelagic zone, experts from the SUMMER project have arranged a 5-day summer school course for 2 ECT credits, with the Marine and Freshwater Research Institute and the University of Iceland, in Iceland May 22nd – May 26th 2023.
The course will feature lectures from world-leading experts on mesopelagic research, engaging discussions, as well as hands-on laboratory work on mesopelagic fishes – in addition to the dissection of a marine mammal, apex predator of mesopelagic fish.
After completing the course
Students will be familiar with:
• Biology and Ecology of the Mesopelagic Zone
• Taxonomy and Diversity of Mesopelagic Fish
• Mesopelagic Fisheries (Economy, Governance,
Technology)
• Dissection of Mesopelagic Fish and Mammals
Students will develop valuable knowledge of one of the most understudied ecosystems in the world’s oceans, meet worldwide leaders in mesopelagic research, and study in an international group.
Students will also get to experience Reykjavik, the capital of Iceland in May – during a wonderfully bright spring.
The course itself is free for participatnts, but travel expenses (food, lodgings, and transport) must be covered individually.
International students are encouraged to apply, and housing is available on the university campus.
For more information
Website: www.summerh2020.eu
Email: hrandhawa@hi.is

Manuscript on craniofacial variation in sympatric ecomorphs of Arctic charr

Arnar Pálsson, 09/11/2022

This darling is nearly ready for submission. Very cool results from a study led by Guðbjörg Ósk Jónsdóttir and Sarah Steele, based on pioneering work by Finnur Ingimarsson and Sigurður S. Snorrason.

Diversity in the internal functional feeding elements of sympatric morphs of Arctic charr (Salvelinus alpinus) 

Jónsdóttir, G.Ó., von Elm, L-M, Ingimarsson, F., Tersigni, S., Snorrason, S.S, Pálsson, A. and Steele, S.E. 

One cool figure from the manuscript, showing shape variation in bones in the four sympatric morphs of Arctic charr in Lake Þingvallavatn.

Shape variation in the articular angular, part of the lower jaw, PCA of individuals and the first two axes of shape variation (after size correction).

Colour coding follows previous publications, large benthic (Green), small benthic (blue), planktivorous (red) and piscivorous charr (purple).

The morphs are genetically separable, with a twist...

Jóhannes Guðbrandsson, Kalina H. Kapralova, Sigríður R. Franzdóttir, Þóra Margrét Bergsveinsdóttir, Völundur Hafstað, Zophonías O. Jónsson, Sigurður S. Snorrason, Arnar Pálsson. 2019. Extensive genetic differentiation between recently evolved sympatric Arctic charr morphs Ecology and Evolution.  9:10964–10983. doi: 10.1002/ece3.5516.

A novel region within a conserved domain in ATG7 emerged in vertebrates.

Arnar Pálsson, 24/08/2022

A nice paper by Valgerður Hjaltalín and colleagues was accepted to Autophagy Reports. She worked on this during covid, with some help from us and others. Then added a nice experimental data to the manuscript during revisions. More on this as it emerges on the journal website.

A novel region within a conserved domain in ATG7 emerged in vertebrates.

Valgerdur J. Hjaltalin, Vivian Pogenberg, Kévin J. A. Ostacolo, Arnar Pálsson, Margrét Helga Ogmundsdottir

DNA methylation differences during development distinguish sympatric morphs of Arctic charr (Salvelinus alpinus)

Arnar Pálsson, 25/07/2022
DNA methylation differences during development distinguish sympatric morphs of Arctic charr (Salvelinus alpinus)
Accepted in Molecular Ecology, first published: 18 July 2022

Changes in DNA methylation in specific coding or non-coding regions can influence development and potentially divergence in traits within species and groups. While the impact of epigenetic variation on developmental pathways associated with evolutionary divergence is the focus of intense investigation, few studies have looked at recently diverged systems. Phenotypic diversity between closely related populations of Arctic charr (Salvelinus alpinus), which diverged within the last 10 000 years, offers an interesting ecological model to address such effects. Using bisulfite sequencing, we studied general DNA methylation patterns during development in the four sympatric morphs of Arctic charr from Lake Thingvallavatn. The data revealed strong differences between developmental timepoints and between morphs (mainly along the benthic – limnetic axis), both at single CpG sites and in 1,000bp-regions. Genes located close to differentially methylated CpG sites were involved in nucleosome assembly, regulation of osteoclast differentiation, and cell-matrix adhesion. Differentially methylated regions were enriched in tRNA and rRNA sequences, and half of them were located close to transcription start sites. The expression of 14 genes showing methylation differences over time or between morphs was further investigated by qPCR and nine of these were found to be differentially expressed between morphs. Four genes (ARHGEF37-like, H3-like, MPP3 and MEGF9) showed a correlation between methylation and expression. Lastly, histone gene clusters displayed interesting methylation differences between timepoints and morphs, as well as intragenic methylation variation. The results presented here provide a motivation for further studies on the contribution of epigenetic traits, such as DNA methylation, to phenotypic diversity and developmental mechanisms.