CharrveinThe arctic charr genome fish, caught in august 2021
Large benthic charr from Lake Thingvallavatn
Pictured are the team, dr Zophonías Jónsson with the individual, on site.
#silentsunday #genome #ArcticCharr #Thingvallavatn #thngvellir
schneckenhausÞingvallavatn, Islands größter natürlicher See, liegt eingebettet in die einzigartige Landschaft des Þingvellir Nationalparks. Mit einer Tiefe von bis zu 114 Metern gehört er zu den tiefsten Seen des Landes. Sein kristallklares, kaltes Wasser flutet die tektonischen Spalten, die den See durchziehen. Als wichtiger Lebensraum beherbergt er seltene Fischarten, darunter die endemische Islandforelle, die sich perfekt an die Bedingungen dieses besonderen Ökosystems angepasst hat.
18.05.2025, #Iceland #Thingvellir #Thingvallavatn #lakes #IcelandNature [8]
18.05.2025, #Iceland #Thingvellir #Thingvallavatn #lakes #IcelandNature [8]
Der Þingvallavatn ist Islands größter natürlicher See und liegt eingebettet in einer weiten, offenen Landschaft. Von den Ufern aus reicht der Blick weit über das stille Wasser bis zu den sanften Hügeln und dunklen Lavafeldern am Horizont. Besonders beeindruckend ist die klare Sicht in die Tiefe, die die besondere Reinheit des Wassers offenbart.
17.05.2025, #Iceland #Thingvallavatn #lake [4]
17.05.2025, #Iceland #Thingvallavatn #lake [4]
charrveinCool results from our bachelor student
Nina Gudrun
She analyzed tooth length variation by morphs in three icelandic lakes.
Allometric relationship - size effect on tooth lengths - varied by morphs
Her BS paper will get integrated with data on bone shape to explore plasticity and divergence in functional traits
#ecology #evolution #biodiversity #iceland #ArcticCharr #adaptation #divergence #plasticity #thingvallavatn #ulfljotsvatn
Good reviews on "Gene flow and habitat heterogeneity shape coexistence dynamics of Arctic charr morphs in connected lakes" at Molecular Ecology
Rejected but encouraged resubmission (which I hate, its plain metric-playing)
The main result being #GeneticStructure of four sympatric morphs in #thingvallavatn #Iceland
#AcademicChatter #rejectResubmit #evolution #genetics #popgen #divergence #ArcticCharr #sympatry #ecology #metapopulation #SourceSink
Tröllafoss spring 2021
Leirvogsá river runs from Leirvogur up to Lake Leirvogsvatn
Leir-vogur translates to clay-cove
Above the waterfall is the lake, and in it the brown trout with lowest level of genetic variation
#ecology #browntrout #popgen #colonization
#waterfall #Tröllafoss #salmonid #iceland #Thingvallavatn #Leirvogsvatn
https://peerj.com/articles/15985/
Genetic structure and relatedness of brown trout (Salmo trutta) populations in the drainage basin of the Ölfusá river, South-Western Iceland
Background Lake Þingvallavatn in Iceland, a part of the river Ölfusá drainage basin, was presumably populated by brown trout soon after it formed at the end of the last Ice Age. The genetic relatedness of the brown trout in Þingvallavatn to other populations in the Ölfusá drainage basin is unknown. After the building of a dam at the outlet of the lake in 1959 brown trout catches declined, though numbers have now increased. The aim of this study was to assess effects of geographic isolation and potential downstream gene flow on the genetic structure and diversity in brown trout sampled in several locations in the western side of the watershed of River Ölfusá. We hypothesized that brown trout in Lake Þingvallavatn constituted several local spawning populations connected by occasional gene flow before the damming of the lake. We also estimated the effective population size (NE) of some of these populations and tested for signs of a recent population bottleneck in Lake Þingvallavatn. Methods We sampled brown trout inhabiting four lakes and 12 rivers within and near the watershed of River Ölfusá by means of electro- and net- fishing. After stringent data filtering, 2,597 polymorphic loci obtained from ddRADseq data from 317 individuals were ascertained as putative neutral markers. Results Overall, the genetic relatedness of brown trout in the Ölfusá watershed reflected the connectivity and topography of the waterways. Ancestry proportion analyses and a phylogenetic tree revealed seven distinct clusters, some of which corresponded to small populations with reduced genetic diversity. There was no evidence of downstream gene flow from Lake Þingvallavatn, although gene flow was observed from much smaller mountain populations. Most locations showed low NE values (i.e., ~14.6 on average) while the putative anadromous trout from River Sog and the spawning population from River Öxará, that flows into Lake Þingvallavatn, showed notably higher NE values (i.e., 71.2 and 56.5, respectively). No signals of recent population bottlenecks were detected in the brown trout of Lake Þingvallavatn. Discussion This is the first time that the genetic structure and diversity of brown trout in the watershed of River Ölfusá have been assessed. Our results point towards the presence of a metapopulation in the watershed of Lake Þingvallavatn, which has been influenced by restoration efforts and is now dominated by a genetic component originated in River Öxará. Many of the locations studied represent different populations. Those that are isolated in headwater streams and lakes are genetically distinct presenting low genetic diversity, yet they can be important in increasing the genetic variation in downstream populations. These populations should be considered for conservation and direct management.
Rift lake that formed some 10,000
Years ago
Shaped by volcanoic activity and underground rivers feeding it
Study system for 4 sympatric morphs of Arctic charr
Genetics and analysis of shape variation
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0300359
Diversity in the internal functional feeding elements of sympatric morphs of Arctic charr (Salvelinus alpinus)
The diversity of functional feeding anatomy is particularly impressive in fishes and correlates with various interspecific ecological specializations. Intraspecific polymorphism can manifest in divergent feeding morphology and ecology, often along a benthic–pelagic axis. Arctic charr (Salvelinus alpinus) is a freshwater salmonid known for morphological variation and sympatric polymorphism and in Lake Þingvallavatn, Iceland, four morphs of charr coexist that differ in preferred prey, behaviour, habitat use, and external feeding morphology. We studied variation in six upper and lower jaw bones in adults of these four morphs using geometric morphometrics and univariate statistics. We tested for allometric differences in bone size and shape among morphs, morph effects on bone size and shape, and divergence along the benthic-pelagic axis. We also examined the degree of integration between bone pairs. We found differences in bone size between pelagic and benthic morphs for two bones (dentary and premaxilla). There was clear bone shape divergence along a benthic–pelagic axis in four bones (dentary, articular-angular, premaxilla and maxilla), as well as allometric shape differences between morphs in the dentary. Notably for the dentary, morph explained more shape variation than bone size. Comparatively, benthic morphs possess a compact and taller dentary, with shorter dentary palate, consistent with visible (but less prominent) differences in external morphology. As these morphs emerged in the last 10,000 years, these results indicate rapid functional evolution of specific feeding structures in arctic charr. This sets the stage for studies of the genetics and development of rapid and parallel craniofacial evolution.
Fieldwork last fall, capturing arctic charr and brown trout in the interesting lake Úlfljótsvatn.
This lake is down stream of the famous Þingvallavatn, which rests on a rift zone and is home to four morphs of Arctic charr (but only one of Brown trout).
Pictured are Nína Baldursdóttir (BS student), Guðbjörg Jónsdóttir (Phd student), Benóný Jónsson and Magnús Jóhannsson (specilists at Hafro)
#charr #lake #iceland #thingvallavatn #ulfljotsvatn #fishing #66north
#steingrimsstod
Genetic structure and relatedness of brown trout (Salmo trutta) populations in the drainage basin of the Ölfusá river, South-Western Iceland
Marcos Lagunas et al. PeerJ. 2023.
Recently colonized, about 10000 years ago, when #iceage #glacier retreated
Many #anadromous populations but also a few resident ones in lakes and warm mountain streams
Including #Thingvallavatn and #Úlfljótsvatn #evolution #adaptation #geothermal
