Gangvirki æxlunareinangrunar milli samsvæða bleikjuafbrigða - verkefni lokið

Fréttatilkynning verkefnisstjóra

22.4.2024

Við beittum aðferðum vistfræði, atferlisfræði, þroskunarfræði og erfðafræði til að varpa ljósi á það hvernig tvö bleikjuafbrigðanna hafa náð að aðskiljast æxlunarlega. Við beittum skipulegum veiðum og beinum athugunum kafara á mökunaratferli á hrygningarslóð, svo og eldistilraunum þar sem afkvæmi þessara afbrigða og blendingsafkvæmi þeirra voru rannsökuð til að athuga þroskun sköpulags og atferlis. Niðurstöður okkar gefa til kynna (i) mismunandi makaval og ólíka nýtingu riðastöðva svo og (ii) arfbundinn mun í þroskun líkamsbyggingar, hegðunar og lífsferlis afbrigðanna sem virðist geta raskast í blendingafkvæmum. Við lýsum einnig sameindafræðilegum ferlum (í tjáningu gena) sem reyndust ólíkir í fóstrum afbrigðanna tveggja og í blendingsafkvæmum þeirra og sem gætu skýrt hraða þróun mismunandi sköpulags þeirra og mögulega varpað ljósi á auknar líkur á dauðsföllum meðal blendingsafkvæma.

English:

Speciation (how new species form) is a fundamental concept in evolution and conservation biology, but our understanding of its underlying processes remains limited. Arctic charr in Thingvallavatn have rapidly evolved physical and behavioural differences as adaptations to different habitats within this lake. Therefore, these fishes offer a unique opportunity to study how populations evolves into separate species under the effects of natural selections and in despite the absence of geographic barriers. We combined ecological, behavioural, developmental and genetic approaches to understand how two of these different charr (i.e., morphs) became reproductively isolated. We completed field studies (fishing surveys and diving expeditions) and mate-choice experiments to this aim. We also reared the offspring of the two charr as well as artificially produced hybrids to described the developmental of their morphology and behaviour. Our results suggest (i) differences in mate choice and in the use of the spawning sites and (ii) genetically based differences in the combined development of morphology, behaviour, and life-history in the two morphs that appear to be disrupted in hybrids. We also described molecular mechanisms (gene expression patterns) that differed in embryos of the two morphs and their hybrids, and which may explain the rapid evolution of physical differences between the two charr as well as a possible lack of viability in the hybrids.

Information on how the results will be applied:
1. Fundamental research in evolutionary biology: First, our project featured a remarkable biological system in which two young populations are strongly diverging in sympatry. This allowed us to conduct a thorough study about how natural and sexual selection can drive divergence and speciation without physical barriers to gene flow. Second, our study brought new insights about the role of hybridisation in speciation. Through extensive common-garden experiments, we explored how interactions among a large diversity of traits (related to behaviour, morphology and life-history) can influence the development of adaptive and maladaptive hybrid phenotypes. Third, this project enabled the descriptions of molecular mechanisms related to the development of ecologically relevant trait, their role in phenotypic divergence and in determining hybrid fitness.

2. Conservation: The Arctic charr morphs of Thingvallavatn contributes significantly to the Icelandic
cultural and natural heritage, and also represent an illustrative example of populations at an advanced stage of adaptive divergence. However, such divergence may be reversible and collapse as a result of human activities. Using a characteristic and pristine system to investigate to what extent reproductive isolation maintains polymorphisms (i.e. intraspecific diversity) in sympatry will constitute a strong basis of knowledge for predicting and mitigating such threats, not only to the Icelandic Arctic charr, but also to freshwater fishes in the habiting the Arctic and other alpine habitats.

A list of the project’s outputs:
- PhD thesis of the project leader.
- Four published scientific articles with the project leader as a first author.
- One published scientific article with the project leader as a co-author.
- RNA-sequencing dataset of Arctic charr embryos, publicly available for the research
community on NCBI: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE193797
- 6 conference presentations as first author and presenter + coauthorship contributions to 4
conference presentations.
- 3 conference posters as first author.

Heiti verkefnis: Gangvirki æxlunareinangrunar milli samsvæða bleikjuafbrigða/Mechanisms of reproductive isolation between sympatric morphs of Arctic Charr
Verkefnisstjóri: Quentin Jean Baptiste Horta-Lacueva, Háskóla Íslands
Tegund styrks: Doktorsnemastyrkur
Styrktímabil: 2021
Fjárhæð styrks kr. 6.615.000
Tilvísunarnúmer Rannís: 217350