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1.
Michael Power Geoffrey Power Francçois Caron Richard R. Doucett Karin R.A. Guiguer 《Environmental Biology of Fishes》2002,64(1-3):75-85
Arctic charr, Salvelinus alpinus, and brook charr, Salvelinus fontinalis, inhabiting three lakes in the de la Trinité River and adjacent watershed, north shore, Gulf of St. Lawrence, were sampled in 1998. Arctic charr growth differed among lakes with the smallest fish coming from the largest lake. Arctic charr weight–length equation exponents were almost identical at all sample sites. Brook charr growth was also similar in all lakes. July stomach samples from Arctic charr consisted almost entirely of cladocerans in the largest lake, less so in the intermediate sized lake and were mostly aquatic insects in the smallest lake. Brook charr stomach contents were more varied and included fish. Carbon, nitrogen and sulphur stable isotope analyses (SIA) were used to provide a spatially and temporally integrated image of charr diets. SIA corroborated observed among-lake differences and similarities in species diets and suggested lake morphometry may influence measured results. The 15N signature in brook charr muscle increased with fork-length, as a result of a shift towards piscivory with size. The 15N signature in Arctic charr muscle tissue showed a significant negative correlation with fork-length in two of the studied lakes that appears related to dietary niche shifts. Results demonstrate the ability of SIA to detect dietary shifts otherwise unobservable from standard gut content analysis. 相似文献
2.
Peter F. Galbreath Nathan D. Adams Lee. W. Sherrill III Thomas H. Martin 《Environmental Biology of Fishes》2006,75(2):183-193
Synopsis An effect of ploidy on thermal tolerance in juvenile trout was assessed in a series of tests comparing time to chronic lethal
maximum (CLMax). Diploid and triploid fish were produced from a common spawn for three different groups each of brook trout
Salvelinus fontinalis and of rainbow trout Oncorhynchus mykiss. One or two CLMax tests were performed per group, on between 15 and 50 individuals per ploidy within groups. The tests involved
exposure of fish to a progressive 2°C day−1 water temperature increase and recording of the time at which each individual fish reached loss of equilibrium (LE). The
time to LE data were rank transformed and analyzed as a randomized complete block design. Although relative performance varied
among trials, the analysis indicated overall differences due to ploidy were small and nonsignificant among both brook trout
and rainbow trout. Size proved to be significantly correlated with time to LE in the brook trout trials, but not in the rainbow
trout trials. Two of the six groups included a large proportion of fish which had received a heat shock following fertilization,
but were not successfully triploidized. In both cases, thermal tolerance of the heat-shocked diploids was similar to that
of the non-heat shocked control diploids, indicating no persistent effect of the heat shock on thermal tolerance. 相似文献
3.
Two brood stocks of brook charr, Sulvelinus fontinalis , are currently maintained by the Ontario Ministry of Natural Resources. The Nipigon brood stock originated from Lake Nipigon, in north-central Ontario, while the Hills Lake stock is believed to have been produced by hybridizing several strains (including charr from a Pennsylvania hatchery as well as charr from Ontario) in the past. The mitochondrial DNA (mtDNA) variability of these brood stocks was characterized using 51 hexanucleotide restriction enzymes. Eleven restriction enzymes, Acc I, Am I, Bun I, Bun II, Hind III, Nco I, Nde I, Nhe I, Nsi I, Pst I and Sph I, were polymorphic between the two brood stocks. Eight hatchery mtDNA haplotypes were detected showing a maximum of 0.41 % sequence divergence. Seven haplotypes are present in the Hills Lake strain, and two in the Nipigon strain. These mtDNA haplotypes are useful markers to determine the degree of reproductive success between planted and native fish. In one comparison in southern Ontario, less than 20% of the wild fish sampled from the head water regions of a small drainage entering Lake Erie could have resulted from random introgression with hatchery fish planted further downstream, because most of these fish possessed a unique Acc 1 cut site. This is one of the few examples in stock analysis studies where such a high degree of genetic discrimination is evident between hatchery and native fish. 相似文献
4.
In a laboratory study to examine the responses of slimy sculpin Cottus cognatus to chemical cues of brook charr Salvelinus fontinalis eggs, water that held freshly laid eggs (<20 min old), water-hardened eggs (i.e. eggs >4 h old) or injured eggs was collected and used in a series of two-choice tests. Slimy sculpin were exposed to paired stimuli of (1) hard egg water v . control water, (2) fresh egg water v . control water, (3) hard egg water v . injured egg water or (4) hard egg water v . fresh egg water. Sculpin spent considerably more time on the side of the tank with hard egg water and fresh egg water v . control water and injured egg water v . hard egg water. Sculpin did not show a preference for hard egg water v . fresh egg water. In a field study, brook charr were attracted to chemical cues from brook charr eggs, suggesting that brook charr eggs produce sufficient odour to attract some species under natural conditions. 相似文献
5.
Previous mtDNA and allozyme studies of brook charr Salvelinus fontinalis from northern Ontario lakes that had been extensively stocked with a government hatchery strain, yielded results that were incongruous with a neutral theory of selection in the mtDNA genome. A single haplotype (haplotype 1) predominated in all the fish sampled from these lakes, which is consistent with the observed distribution of this haplotype in northern portions of the species range. However, haplotype 1 does not occur in a high frequency within the hatchery strain. In a direct survivorship experiment, of 1500 fish stocked into an Ontario lake in the spring of 1994 containing a native population of brook charr, no significant differences between stocking and recapture mtDNA distributions were observed in the summer of 1994. However, a survey of young of the year in the following spring did not reveal the presence of any 'private' hatchery haplotypes. Significant differences in the distribution of mtDNA haplotypes were observed in two stocked lakes compared to those in the putative source hatchery strain. Haplotype 1 predominated in both these stocked lakes, suggesting that fish with this haplotype possessed increased survivorship. 相似文献
6.
The feeding rate of a group (DS) of two small, two medium and two large 1+ Arctic charr Salvelinus alpinus was higher than in a group of six fish of the same size (SS), suggesting that size distribution had an effect on feeding behaviour, with a correlation between the size of the fish and the amount of food eaten–the largest fish eating the most. Against predictions, rate of aggression was not higher in the SS groups; rather there was a modest tendency of higher aggression among individuals in the DS groups. 相似文献
7.
Stream-dwelling fish populations have long served as important models of animal movement. Populations of adult stream-dwelling fishes are generally composed of a mix of relatively sedentary and mobile individuals. However, we do not know whether this pattern that we typically observe among adults is indicative of patterns of movement that occur throughout the life cycle. Therefore, we do not know whether we can apply these patterns to understanding or predicting processes such as migration and thus the potential for the evolution of genetic differences among populations. We test the general hypothesis that patterns of movement throughout the life cycle are consistent with patterns of movement inferred by indirect genetic methods and, more specifically, that the characteristics of the mobile fraction of the population are consistent with patterns of genetic differentiation. We used parentage analyses to infer the movements of alevin brook charr (Salvelinus fontinalis) in Freshwater River, Newfoundland, Canada, and a capture-recapture study of one cohort in this population to infer movement throughout the rest of the life cycle. We found that alevins move large distances shortly after emergence, primarily in the downstream direction, and that the population is composed of a mix of relatively sedentary and mobile individuals throughout all other intervals of the life cycle. In contrast, when we considered movements of individuals first captured as juveniles and eventually recovered as reproductively mature adults, we found relatively large and uniform distributions of net movement distance. Thus, heterogeneity in individual movement of adults is not representative of patterns of movement throughout the life cycle and therefore may provide only limited inference of population-level processes such as gene flow. 相似文献
8.
Despite the abundance of studies of genetic diversity in freshwater fishes, few have specifically addressed the role of habitat structure in partitioning genetic variance within and among populations. In this study, we analysed the variability of six microsatellite loci among 24 brook charr population samples in order to correlate hydrographic structure with genetic organization. These populations originated from three Canadian National parks (Kouchibouguac, Fundy and Forillon) that showed distinct hydrographic structure. Considering the general characteristics of these habitats, we formulated specific hypotheses in regard to genetic structure, which were principally based on the potential for gene flow and population size associated with each habitat. The hierarchical analysis of molecular variance and the genetic distances computed among populations revealed that habitat structure analyses constitute an important, but insufficient, predictor of genetic structure. We discuss the importance of habitat complexity on genetic structure in the context of management and conservation. 相似文献
9.
GUY M. L. PERRY TIM L. KING JR
ME ST.‐CYR MANON VALCOURT LOUIS BERNATCHEZ 《Molecular ecology resources》2005,5(2):346-351
The brook charr (Salvelinus fontinalis; Osteichthyes: Salmonidae) is a phenotypically diverse fish species inhabiting much of North America. But relatively few genetic diagnostic resources are available for this fish species. We isolated 41 microsatellites from S. fontinalis polymorphic in one or more species of salmonid fish. Thirty‐seven were polymorphic in brook charr, 15 in the congener Arctic charr (Salvelinus alpinus) and 14 in the lake charr (Salvelinus namaycush). Polymorphism was also relatively high in Oncorhynchus, where 21 loci were polymorphic in rainbow trout (Oncorhynchus mykiss) and 16 in cutthroat trout (Oncorhynchus clarkii) but only seven and four microsatellite loci were polymorphic in the more distantly related lake whitefish (Coregonus clupeaformis) and Atlantic salmon (Salmo salar), respectively. One duplicated locus (Sfo228Lav) was polymorphic at both duplicates in S. fontinalis. 相似文献
10.
Supportive breeding and stocking performed with non‐native or domesticated fish to support sport fishery industry is a common practice throughout the world. Such practices are likely to modify the genetic integrity of natural populations depending on the extent of genetic differences between domesticated and wild fish and on the intensity of stocking. The purpose of this study is to assess the effects of variable stocking intensities on patterns of genetic diversity and population differentiation among nearly 2000 brook charr (Salvelinus fontinalis) from 24 lakes located in two wildlife reserves in Québec, Canada. Our results indicated that the level of genetic diversity was increased in more intensively stocked lakes, mainly due to the introduction of new alleles of domestic origin. As a consequence, the population genetic structure was strongly homogenized by intense stocking. Heavily stocked lakes presented higher admixture levels and lower levels of among lakes genetic differentiation than moderately and un‐stocked lakes. Moreover, the number of stocking events explained the observed pattern of population genetic structure as much as hydrographical connections among lakes in each reserve. We discuss the implications for the conservation of exploited fish populations and the management of stocking practices. 相似文献
11.
Translocation of plants and animal populations between environments is one of the major forms of anthropogenic perturbation experienced by pristine populations, and consequently, human‐mediated hybridization by stocking practices between wild and exogenous conspecifics is of increasing concern. In this study, we compared the expression of seven candidate genes involved in multifactorial traits and regulatory pathways for growth as a function of level of introgressive hybridization between wild and domestic brook charr to test the null hypothesis of no effect of introgression on wild fish. Our analyses revealed that the expression of two of the genes tested, cytochrome c oxidase VIIa and the growth hormone receptor isoform I, was positively correlated with the level of introgression. We also observed a positive relationship between the extent of introgression and physiological status quantified by the Fulton's condition index. The expression of other genes was influenced by other variables, including year of sampling (reflecting different thermal conditions), sampling method and lake of origin. This is the first demonstration in nature that introgression from stocked populations has an impact on the expression of genes playing a role in important biological functions that may be related with fitness in wild introgressed populations. 相似文献
12.
We determined the amount and temporal stability of genetic differentiation among brook cham sampled from five rivers on Cape Race, Newfoundland, with an electrophoretic analysis of 42 protein coding loci. Fish from four of these rivers were analysed for restriction fragment length polymorphisms in mitochondrial DNA (mtDNA). A single mtDNA clone was observed in all rivers sampled, except one, where 47% offish were from a different and relatively divergent clone (0.31 % sequence divergence). In contrast, Cape Race brook charr show large amounts of genetic differentiation at six enzyme coding loci; Nei's genetic distance ranged between 0,020 and 0.048. This differentiation is relatively stable as no significant differences in allele frequencies were detected between fish sampled from two rivers over two consecutive years. The most divergent population based on protein polymorphism is not that with two mtDNA clonal lineages. In contrast to the commonly held view, mtDNA analyses do not necessarily provide greater resolution of population structure than allozyme analyses. 相似文献
13.
Polymorphism at five microsatellite genetic markers (genotyped n = 496) and mark-recapture tagging data (tagged n = 9813) were used to define the population structure of brook charr, Salvelinus fontinalis from the Indian Bay watershed, Newfoundland, Canada. Despite the absence of physical barriers to migration among lakes, both genetic and tagging data suggest that brook charr in each lake represent reproductively isolated populations. Exact tests comparing allele frequencies, θ (global value = 0·063), R st (global value = 0·052), individual assignment tests, and Nei's genetic distance provided congruent estimates of population subdivision in agreement with the tagging data (only 2·2% of recaptures were lake-to-lake). The genetic structure of the brook charr populations corresponded with the geographic structure of the drainage basin on a qualitative level, although linear distance over water was not significantly correlated with the tagging data or the genetic distance measures. The agreement between the tagging and the genetic data suggest that microsatellite markers can be useful tools for defining real biological units. The results also suggest that brook charr exhibit microgeographic population structure at the watershed scale, and that this is the scale at which conservation and management of this salmonid might best be implemented. 相似文献
14.
Fabien C. Lamaze Scott A. Pavey Eric Normandeau Gabriel Roy Dany Garant Louis Bernatchez 《Molecular ecology》2014,23(7):1730-1748
The capacity of an individual to battle infection is an important fitness determinant in wild vertebrate populations. The major histocompatibility complex (MHC) genes are crucial for a host's adaptive immune system to detect pathogens. However, anthropogenic activities may disrupt natural cycles of co‐evolution between hosts and pathogens. In this study, we investigated the dynamic sequence and expression variation of host parasite interactions in brook charr (Salvelinus fontinalis) in a context of past human disturbance via population supplementation from domestic individuals. To do so, we developed a new method to examine selection shaping MHC diversity within and between populations and found a complex interplay between neutral and selective processes that varied between lakes that were investigated. We provided evidence for a lower introgression rate of domestic alleles and found that parasite infection increased with domestic genomic background of individuals. We also documented an association between individual MHC alleles and parasite taxa. Finally, longer cis‐regulatory minisatellites were positively correlated with MHC II down‐regulation and domestic admixture, suggesting that inadvertent selection during domestication resulted in a lower immune response capacity, through a trade‐off between growth and immunity, which explained the negative selection of domestic alleles at least under certain circumstances. 相似文献
15.
The aggression index is a more reliable method for assessing the social status of Arctic charr Salvelinus alpinus held in small groups, than is food intake or position relative to a defensible food resource. However, care must be taken when assigning rank, as all three of these commonly used methods can result in different social ranks for an individual fish. 相似文献
16.
The behaviour of juvenile Arctic charr Salvelinus alpinus was studied in groups of four siblings composed of familiar and unfamiliar individuals or in mixed groups of four where both siblings and unrelated individuals were present. The frequency of aggressive acts was significantly higher in the mixed groups compared to the pure sibling groups and the difference was present at all levels of the hierarchy rank order, based on a dominance index, except the lowest ranked individuals. The difference was significant after but not before feeding, implying that competition with non-kin for a food resource increased the aggression. No significant difference in weight gain was observed between sibling and mixed groups during the 6 days of the experiment, but the RNA contents of lateral musculature in dominant individuals from sibling groups were significantly higher than the corresponding fish in the mixed group, suggesting a difference in growth rate when the experiments ended. No significant difference in RNA content was observed between subordinate fish of the two treatments, i.e. siblings v . mixed. 相似文献
17.
We tested for differences in the predicted optimal ages at first maturity in brook charr ( Salvelinus fontinalis ) in Freshwater River, Newfoundland, when life-history data were collated based on the marker-assisted estimation of the relationship between body size and reproductive success rather than using fecundity as a surrogate for reproductive success. Jointly with capture–recapture data to estimate the growth and survival costs of reproduction, we found that weak relationships between body size and reproductive success generate selection against delayed maturation. This finding would not have held for females if the relationship between body size and fecundity had been used as a surrogate for the relationship between body size and reproductive success. This shows that predictions of optimal life histories can be qualitatively changed when using molecular markers to directly evaluate age- and/or size-specific effects of body size on reproductive success. 相似文献
18.
Landscape genetics holds promise for the forecasting of spatial patterns of genetic diversity based on key environmental features. Yet, the degree to which inferences based on single species can be extended to whole communities is not fully understood. We used a pristine and spatially structured community of three landlocked salmonids (Salvelinus fontinalis, Salmo salar, and Salvelinus alpinus) from Gros Morne National Park (Newfoundland, Canada) to test several predictions on the interacting effects of landscape and life history variation on genetic diversity, neutral divergence, and gene flow (m, migration rate). Landscape factors consistently influenced multispecies genetic patterns: (i) waterfalls created strong dichotomies in genetic diversity and divergence between populations above and below them in all three salmonids; (ii) contemporary m decreased with waterway distance in all three species, while neutral genetic divergence (θ) increased with waterway distance, albeit in only two taxa; (iii) river flow generally produced downstream‐biased m between populations when waterfalls separated these, but not otherwise. In contrast, we expected differential life history to result in a hierarchy of neutral divergence (S. salar > S. fontinalis > S. alpinus) based on disparities in dispersal abilities and population size from previous mark‐recapture studies. Such hierarchy additionally matched varying degrees of spatial genetic structure among species revealed through individual‐based analyses. We conclude that, whereas key landscape attributes hold power to predict multispecies genetic patterns in equivalent communities, they are likely to interact with species‐specific life history attributes such as dispersal, demography, and ecology, which will in turn affect holistic conservation strategies. 相似文献
19.
20.
Dana R. Warren Jason M. Robinson Daniel C. Josephson Daniel R. Sheldon Clifford E. Kraft 《Global Change Biology》2012,18(6):1804-1811
Redd (nest) surveys for resident brook trout (Salvelinus fontinalis) were conducted annually in a mountain lake in northern New York for 11 years with multiple surveys conducted during the spawning season in eight of those years. Repeated surveys throughout the spawning season allowed us to fit an individually based parametric model and estimate the day of year on which spawning was initiated, reached its midpoint, and ended during each year. Spawning phenology was then assessed relative to (1) mean of maximum daily air temperature and (2) mean of maximum daily water temperature at the lake bottom during summer in each year using a linear model. Elevated temperatures in summer were correlated with a delay in spawning and a reduction in the total number of redds constructed. Increasing the summer mean of maximum daily air temperatures by 1 °C delayed spawning by approximately 1 week and decreased the total number of redds constructed by nearly 65. Lake spawning brook trout select redd sites based on the presence of discharging groundwater that is relatively constant in temperature within and across years, leading to relatively consistent egg incubation times. Therefore, delayed spawning is likely to delay fry emergence, which could influence emergence synchrony with prey items. This work highlights non‐lethal and sub‐lethal effects of elevated summer temperatures on native resident salmonids in aquatic environments with limited thermal refugia. 相似文献