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Outi Savolainen 《Euphytica》1996,92(1-2):139-145
Summary Plant populations in extreme conditions differ from those in more favorable conditions in many respects. They have developed special physiological adaptations for withstanding e.g. extreme temperatures or drought. On the other hand, low survival and fertility may cause smaller effective population sizes, which in turn influences patterns of genetic variation. Scots pine has the widest range of all pine species, extending in the north far beyond the arctic circle. Close to the tree limit, the growing season is short and survival is low. Very northern populations also have lower and more irregular male and female flowering and seed production than southern ones. The consequences of these conditions on genetic variation have been examined. All Finnish populations have similar patterns of variation at allozyme loci and nuclear DNA markers: high variation but no differentiation between populations. Northern populations seem to have slightly fewer recessive deleterious alleles than southern ones. There is, however, strong differentiation between populations with respect to adaptation to the very short growing season. In common garden experiments, northern populations cease growth and set buds much earlier and develop frost tolerance earlier than southern populations. The genetic basis for this high differentiation in bud set can be explored by using dense maps of molecular markers. The implications of these patterns of variations on conservation of genetic resources and tree breeding will be discussed. 相似文献
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Tero Ahvenharju Riitta Savolainen Jouni Tulonen & Kari Ruohonen 《Aquaculture Research》2005,36(9):857-867
Effects of size grading and stocking density on growth and survival of 3.5‐month‐old signal crayfish (Pacifastacus leniusculus Dana) juveniles were investigated in a 3 × 2 factorial design with size group (small, large and mixed) and stocking density (25 and 200 individuals m?2) as factors for 90 days. Carapace length and wet weight growth of the juveniles were affected by the presence or absence of other size groups, stocking density and animal size. All factors had statistically significant interactions, which make the interpretation of the results more complicated. The smaller crayfish grew faster in the absence of large animals and larger animals benefited from the presence of smaller cospecies. Increasing density decreased the growth in length and weight. Survival (82–100%) was good in all groups. Subsequently, the within population dynamics was studied by selectively removing the largest individuals (selectively removing (SR) group). Effects on growth and survival of the remaining juveniles were evaluated on 6‐month‐old P. leniusculus juveniles reared in plastic tanks (100 juveniles m?2) for 122 days. Size distribution manipulation was performed at days 34 and 70. Juveniles in SR group grew significantly faster in comparison with a control group (RR), from which juveniles were removed randomly. Also, the survival rate was significantly higher in the SR group than in the RR group. In conclusion, size grading of juvenile P. leniusculus either at the start of the experiment or repeatedly during the experiment increased growth performance of smaller animals in length and weight. 相似文献
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Savolainen P Zhang YP Luo J Lundeberg J Leitner T 《Science (New York, N.Y.)》2002,298(5598):1610-1613
The origin of the domestic dog from wolves has been established, but the number of founding events, as well as where and when these occurred, is not known. To address these questions, we examined the mitochondrial DNA (mtDNA) sequence variation among 654 domestic dogs representing all major dog populations worldwide. Although our data indicate several maternal origins from wolf, >95% of all sequences belonged to three phylogenetic groups universally represented at similar frequencies, suggesting a common origin from a single gene pool for all dog populations. A larger genetic variation in East Asia than in other regions and the pattern of phylogeographic variation suggest an East Asian origin for the domestic dog, approximately 15,000 years ago. 相似文献
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The effects of tank bottom substrates and presence of shelter on growth, survival and condition of cheliped in the juvenile (stage 2) signal crayfish, Pacifastacus leniusculus (Dana), with an initial stocking density of 200 individuals m?2 were investigated. In the first trial, three different tank bottom substrates with or without shelter were used. The three bottom types were loose gravel, glued gravel and bare bottom. The fastest growth both in terms of wet weight and carapace length was observed on loose gravel bottom. Also survival (range 30.1% to 49.8%) was affected by bottom type being higher on gravel bottoms than on bare bottom. Shelter improved survival only on loose gravel bottom. Bottom type influenced also the number of animals with cheliped injuries. The highest proportion of animals with no injuries (59.5%) was found on bare bottom and the proportion was about 12% and 13% units less on loose gravel and on glued gravel bottom. The presence of shelter had a marginal probability in increasing the number of animals without injuries. In the second trial, the substitution of ordinary gravel as tank bottom substrate with crushed limestone was studied. The mean final wet weights were 0.517 g on ordinary gravel bottom and 0.481 g on limestone bottom. The survivals were about 74% and 80% respectively. Limestone bottom decreased marginally final wet weight, and increased survival but did not affect the final carapace length that had a mean value of 13.6 mm. We conclude from the present experiments that the type of tanks and the rearing system used supported good growth of juvenile signal crayfish. The best growth results could be obtained by using loose gravel (or loose limestone) on the bottom of the tanks with a sufficient quantity of hiding places. However, there appears to be an increased risk for cheliped injuries on bottoms with loose materials. 相似文献
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Michelle A. Savolainen J. Matthew Fannin Rex H. Caffey 《Human Dimensions of Wildlife》2014,19(1):72-87
IMPLAN Version 3.0 was used with a 2008 IMPLAN data package to estimate the economic impacts of the recreational for-hire (RFH) fishing industry in the U.S. Gulf of Mexico (GOM). Initial, direct, indirect, and induced impacts were estimated. Impacts were estimated for head, charter, and guide boat operations for Texas, Louisiana, Mississippi, and Alabama (combined), and West Florida as individual state models, while introducing multiregional spillover effects that account for regional linkages between states. These updated data are necessary to meet national standards set forth by the Magnuson-Stevens Act, such that social and economic ramifications of proposed federal fishing regulations in the GOM can be made part of the overall decision- and policymaking process. 相似文献
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Whitefish, Coregonus lavaretus, of initial mean weight 260–265 g were fed either a high-fat or a low-fat diet (dietary fat: 27.5% vs. 12.6%) to examine the influence of dietary fat level on feed intake, growth and patterns of fat deposition. The fish were held at 14.5 °C under a 24L:0D photoperiod, and were fed for 4 h each day. The experiment was run for 11 weeks during which feed intake (three times by X-radiography) and growth were monitored. Samples of fish were taken for body composition analysis at the start and end of the experiment. There were only small differences between dietary treatment groups in feed intake and final body weights, but the body composition of the fish was significantly influenced by the fat content of the diet. The whitefish fed the high-fat diet tended to have higher relative fat contents in the viscera [% fat as mean (SD): 29.6 (9.4)% vs. 22.1 (10.0)%] and carcass [% fat: 12.7 (1.9)% vs. 10.5 (1.3)%] than their counterparts fed the low-fat diet. This resulted in a higher whole-body fat concentration [% fat: 14.0 (1.9)% vs. 11.5 (1.5)%] amongst the fish fed the high-fat diet, and these fish had a higher energy gain than the whitefish fed the low-fat diet. The results confirm that it is possible to manipulate the chemical composition of whitefish by changing dietary composition. © Rapid Science Ltd. 1998 相似文献