Biology subjects

Linnansaari, T.

Publications and source records attributed to Linnansaari, T..

4 recordsLinked to original sources

bioRxiv2021

Hydraulic synchrony of spawning sites amongst Earth's riverine fishes

Earths riverine fishes utilize a suite of reproductive guilds, broadly following four guilds: nest guarders, broadcast pelagic spawners, broadcast benthic spawners and nest non-guarders 1,2, and these guilds utilize different mechanisms to aerate eggs 3,4. Globally, river fishes populations are declining5, and spawning habitat rehabilitation has become a popular tool to counter these declines6. However, there is a lack of understanding as to what classifies suitable spawning habitats for riverine fishes, thereby limiting the efficacy of these efforts and thus the restoration of the target species. Using data from n = 220 peer-reviewed papers and examining n = 128 unique species, we show the existence of a hydraulic pattern (defined by Froude number (Fr), a non-dimensional hydraulic parameter) that characterizes the reproductive guilds of riverine fishes. We found nest guarders, broadcast pelagic spawners, benthic spawners, and nest non-guarders selected sites with mean Fr = 0.05, 0.11, 0.22, and 0.28, respectively. Some of the fishes in this study are living fossils, suggesting that that these hydraulic preference patterns may be consistent across time. Our results suggest this hydraulic pattern can guide spawning habitat rehabilitation for all riverine fish species globally in absence of specific spawning habitat information for a species, where resource managers can establish the reproductive guild of the species of interest, and then apply the specific hydraulic requirements (Fr range) of that reproductive guild, as presented herein, in the rehabilitation of the target species.

ecology↗

bioRxiv2021

The salmon-peloton: hydraulic habitat shifts of adult Atlantic salmon (Salmo salar) due to behaviour thermoregulation

In recent decades there has been an increase in conservation and restoration projects targeting Atlantic salmon (Salmo salar - AS), as populations in eastern Canada decline. Missing however, is an understanding of thermo-hydraulic habitat use by adult AS during summer, and thus the actual benefits of altering in-river physical structures. Here, we illustrated how optical and thermal infrared (TIR) imagery acquired from a UAV can be used in concert with in-situ depth and velocity data to map adult AS and develop models of thermo-hydraulic habitats in the Miramichi River, New Brunswick. We found during optimal thermal conditions (< 19 {degrees}C) proximity to boulders and Froude numbers, a non-dimensional hydraulic metric, were key parameters that characterized adult AS habitat. However, during behavioural thermoregulation events (>19 {degrees}C), proximity to the cool thermal plume and Froude number, a non-dimensional hydraulic parameter, were critical controls on habitat use. We also observed AS formed a distinct geometric formation during behavioural thermoregulation events, and term this formation a thermal-peloton. The primary function of the peloton is undoubtedly to reduce thermally induced stressed; however, we conceptualize the geometry of the peloton attenuates hydraulic-drag, and reduces energetic expenditure of individuals practicing behavioural thermoregulation. These data provide an unrivaled viewpoint of thermo-hydraulic habitat selection by adult AS, and a blue print for restoration work. The use of UAV-based sensors has the potential to instigate a paradigm shift for river sciences. The age of applying hyper-resolution, remote sensing for river science and aquatic ecology is immensely exciting.

ecology↗

bioRxiv2020

Environment-driven reprogramming of gamete DNA methylation occurs during maturation and influences offspring fitness in salmon

An epigenetic basis for transgenerational plasticity is widely theorized, but convincing empirical support is limited by taxa-specific differences in the presence and role of epigenetic mechanisms. In teleost fishes, DNA methylation generally does not undergo extensive reprogramming and has been linked with environmentally-induced intergenerational effects, but solely in the context of early life environmental differences. Using whole genome bisulfite sequencing, we demonstrate that differential methylation of sperm occurs in response to captivity during the maturation of Atlantic Salmon (Salmo salar), a species of major economic and conservation significance. We show that adult captive exposure further induces differential methylation in an F1 generation that is associated with fitness-related phenotypic differences. Genes targeted with differential methylation were consistent with genes differential methylated in other salmonid fishes experiencing early-life hatchery rearing, as well as genes under selection in domesticated species. Our results support a mechanism of transgenerational plasticity mediated by intergenerational inheritance of DNA methylation acquired late in life for salmon. To our knowledge, this is the first-time environmental variation experienced later in life has been directly demonstrated to influence gamete DNA methylation in fish.

evolutionary biology↗

bioRxiv2018

Chromosomal fusion and life history-associated genomic variation contribute to within-river local adaptation of Atlantic salmon

Chromosomal inversions have been implicated in facilitating adaptation in the face of high levels of gene flow, but whether chromosomal fusions also have similar potential remains poorly understood. Atlantic salmon are usually characterized by population structure at multiple spatial scales; however, this is not the case for tributaries of the Miramichi River in North America. To resolve genetic relationships between populations in this system and the potential for known chromosomal fusions to contribute to adaptation we genotyped 728 juvenile salmon using a 50K SNP array. Consistent with previous work, we report extremely weak overall population structuring (Global FST = 0.004) and failed to support hierarchical structure between the rivers two main branches. We provide the first genomic characterization of a previously described polymorphic fusion between chromosomes 8 and 29. Fusion genomic characteristics included high LD, reduced heterozygosity in the fused homokaryotes, and strong divergence between the fused and the unfused rearrangement. Population structure based on fusion karyotype was five times stronger than neutral variation (FST = 0.019) and the frequency of the fusion was associated with summer precipitation supporting a hypothesis that this rearrangement may contribute local adaptation despite weak neutral differentiation. Additionally, both outlier variation among populations and a polygenic framework for characterizing adaptive variation in relation to climate identified a 250 Kb region of chromosome 9, including the gene six6 that has previously been linked to age-at-maturity and run-timing for this species. Overall our results indicate that adaptive processes, independent of major river branching, are more important than neutral processes for structuring these populations.

genomics↗