Dataset Information

Population connectivity: dam migration mitigations and contemporary site fidelity in arctic char.

ABSTRACT: BACKGROUND: Animal feeding and spawning migrations may be limited by physical barriers and behavioral interactions. Dam constructions (e.g. hydropower) commonly include gateways for fish migrations to sustain ecological connectivity. Relative genetic impacts of fish passage devices versus natural processes (e.g. hybrid inferiority) are, however, rarely studied. We examined genetic (i.e. microsatellite) population connectivity of highly migrating lake-dwelling Arctic char (Salvelinus alpinus), introduced 20 generations ago, across and within two subalpine lakes separated by a dam with a subterranean tunnel and spill gates after 7 generations. Due to water flow regime, the time window for fish migration is highly restricted. RESULTS: Char populations, with similar genetic structuring and diversity observed across and within lakes, were admixed across the dam with fishways during feeding. For spawning, however, statistically significant, but very low population differentiation (?; 0.002 - 0.013) was found in nine out of ten reproductive site comparisons, reflecting interactions between extensive migration (mean first generation (F0) = 10.8%) and initial site fidelity. Simulations indicated that genetic drift among relatively small effective populations (mean N(e) = 62) may have caused the observed contemporary differentiation. Novel Bayesian analyses indicated mean contributions of 71% F0 population hybrids in spawning populations, of which 76% had maternal or paternal native origin. CONCLUSIONS: Ecological connectivity between lakes separated by a dam has been retained through construction of fishways for feeding migration. Considerable survival and homing to ancestral spawning sites in hybrid progeny was documented. Population differentiation despite preceding admixture is likely caused by contemporary reduced reproductive fitness of population hybrids. The study documents the beginning stages of population divergence among spatial aggregations with recent common ancestry.

SUBMITTER: Wollebæk J

PROVIDER: S-EPMC3161007 | biostudies-other | 2011

REPOSITORIES: biostudies-other

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Population connectivity: dam migration mitigations and contemporary site fidelity in arctic char.

Wollebæk Jens J Heggenes Jan J Røed Knut H KH

BMC evolutionary biology 20110714

<h4>Background</h4>Animal feeding and spawning migrations may be limited by physical barriers and behavioral interactions. Dam constructions (e.g. hydropower) commonly include gateways for fish migrations to sustain ecological connectivity. Relative genetic impacts of fish passage devices versus natural processes (e.g. hybrid inferiority) are, however, rarely studied. We examined genetic (i.e. microsatellite) population connectivity of highly migrating lake-dwelling Arctic char (Salvelinus alpin ...[more]

PMID: 21756324

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Project description:Background:Site fidelity is considered as an animal's tendency to return to a previously occupied place; this is a component of animal behaviour that allows us to understand movement patterns and aspects related to the animal's life history. Although there are many site fidelity metrics, the lack of standardisation presents a considerable challenge in terms of comparability among studies. Methods:This investigation focused on the theoretical development of a standardised composite site fidelity index and its statistical distribution in order to obtain reliable population-level site fidelity comparisons. The arithmetic and harmonic means were used as mathematical structures in order to create different indexes by combining the most commonly used indicators for site fidelity such as Occurrence, Permanence and Periodicity. The index performance was then evaluated in simulated populations and one real population of Commerson's dolphins (Cephalorhynchus commersonii (Lacépède 1804)). In the first case, the indexes were evaluated based on how they were affected by different probability values such as the occurrence of the individual within the study area (?) and capture probability (p). As a precision measure for the comparison of the indexes, the Wald confidence interval (CI) and the mean square error were applied. Given that there was no previous data concerning the distribution parameters of this population, bootstrap CIs were applied for the study case. Results:Eight alternative indexes were developed. The indexes with an arithmetic mean structure, in general, had a consistently inferior performance than those with a harmonic mean structure. The index IH4, in particular, achieved the best results in all of the scenarios and in the study case. Additionally, this index presented a normal distribution. As such, it was proposed as a standardised measure for site fidelity (Standardised Site Fidelity Index-SSFI). Discussion:The SSFI is the first standardised metric that quantifies site fidelity at a populational level. It is an estimator that varies between zero and one and works in situations where detection is not perfect and effort can be constant or not. Moreover, it has an associated CI that allows users to make comparisons.

Project description:Gene expression analyses have been performed on brain, liver and muscle of eels (Anguilla anguilla) sampled in three different segment of the Canal des Etangs ( artificial canal linking Arcachon Basin and Lacanau Lake). The present study relies on intraspecific differences of glass eels encountered below and above the water dams. Eels were collected using electric fishing under similar climatic and hydrological conditions. Individuals were sampled below the obstacle, close to the fishway entry in segment 1 (Pas du Bouc; +44° 50' 27.95, -1° 9' 8.09) and 2 (Langouarde, +44° 51' 32.92, -1° 9' 5.03). Fish from the segment 3 (Joncru; +44° 52' 57.13, -1° 8' 11.70) were sampled on the fishway, as water depth before the obstacle, approximately 2 meters, precluded the use of electro-fishing technique. Ten individuals were selected from each site according to their body size (between 83 and 155 mm) and health status (no externally visible pathogens) criteria. Internal parasites such as Anguilicola crassus were taken into account. Sampled and selected fish were immediately sacrified by decapitation and the whole brain, liver and muscle tissue (posterior bottom body part) were dissected and stored at -80°C in separate tubes with RNAlater buffer (Quiagen) for gene expression analysis. Microarray analysis was conducted using an European eel-specific array consisting of a total of 14,913 probes based on a large collection of high-throughput transcriptomic sequences (Pujolar et al. 2012). Probe sequences and further details on the microarray platform can be found on the GEO database under accession number GPL15124. A comparative analysis of gene expression was conducted between eels sampled in differents segments of Canal des Etangs. Total RNAs were extracted from the whole liver,muscle and brain using the Absolutely RNA RT-PCR Miniprep kit (Agilent) according to the manufacturer’s instructions. Three independent RNA pools, each consisting of three individuals RNA samples, were prepared for each sampling site and tissues. Due to technical problems, it was no possible to perform microarray analyses in muscle of eels sampled in forebay 3. Accordingly, DNA microarray analysis has been performed in a total of 24 pools. RNAs’ quality was evaluated by electrophoresis on a 1% agarose gel and their concentrations were determined by spectrophotometry. Total RNA was stored in RNAse free water at -80° C. Sample labelling and hybridization were conducted following the details in Pujolar et al. (2012). Hybridized slides were scanned at 5 µm resolution using an Agilent DNA microarray scanner. Slides were scanned at two different sensitivity levels (XDR Hi 100% and XDR Lo 10%) and the two linked images generated were analysed together. Data were extracted and background subtracted using the standard procedure in Agilent Feature Extraction (FE) software v. 9.5.1. Data were normalized separately for each tissue using a quantile normalization procedure using R (http://www.r-project.org).

Dataset Information

Population connectivity: dam migration mitigations and contemporary site fidelity in arctic char.

Publications

Population connectivity: dam migration mitigations and contemporary site fidelity in arctic char.

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