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831.
Role of Genetic Background in the Success of Reintroduced Peregrine Falcons   总被引:2,自引:0,他引:2  
Abstract: Peregrine Falcons (    Falco peregrinus ) of seven subspecies from four continents were bred in captivity, and approximately 1173 of their progeny were released in the midwestern United States and adjacent regions of Ontario and Manitoba in an attempt to replace the original population that was extirpated by chlorinated hydrocarbon poisoning in the 1950s. We analyzed the success of individuals of the different subspecies introduced to the Midwest. Five of the seven subspecies released have contributed to the current breeding population. Subspecies of breeding Peregrine Falcons were equally represented when breeding birds of high productivity were compared with less prolific breeders. The subspecific makeup of the breeding population did not differ significantly from that of the released population, suggesting that adaptability in this species was sufficient to override genetic differences between subspecies. Peregrines of widely different genetic stocks have thrived after release, making substantial genetic contributions to the new population.  相似文献   
832.
833.
Simultaneous hermaphroditism with outcrossing, a previously unconfirmed sexual system in decapod crustaceans, is documented in the shrimp Lysmata wurdemanni (Gibbes), using time-lapse video observations on mating in pairs of “female-phase” (FP) individuals. Copulations between FPs resulted in successful spawning and development of embryos. However, female-phase hermaphrodites maintained in isolation were unable to self-fertilize spawned eggs. All smaller individuals possessed characters typical of caridean males, including male gonopores, appendices masculinae, ejaculatory ducts, and cincinnuli on the first pleopods. However, the gonad of these male-phase (MP) individuals was an ovotestis with an undeveloped ovarian portion. FPs, which spawn eggs and incubate embryos, also had male gonopores and an ovotestis terminating in ejaculatory ducts containing sperm. In FPs, male pleopod characters were absent or reduced, and a female incubatory character, expanded pleopod flanges, showed a greater relative size. Smaller size classes of the population were composed only of MPs while larger size classes consisted of both MPs and FPs. “Transitionals,” individuals with MP characters but an ovotestis containing vitellogenic oocytes, were rare and overlapped completely in size with FP and larger MP individuals. It is suggested that not all MPs transform into FP hermaphrodites. Social interactions may mediate MP change into FP hermaphrodites in L. wurdemanni. The social system of L. wurdemanni and other Lysmata spp. may determine the exact form of the sexual system in these species. Received: 26 October 1997 / Accepted: 21 April 1998  相似文献   
834.
Chattonella marina, a raphidophycean flagellate, is a highly toxic red tide phytoplankton which causes severe damage to fish farming. Recent studies demonstrated that Chattonella spp. continuously release superoxide anions (O2 ) while they are living. Heterosigma akashiwo, another raphidophycean flagellate, also produces O2 . In the present study, we found that lectins such as concanavalin A (Con A), wheat germ agglutinin (WGA), and castor bean hemagglutinin (CBH) stimulated  C. marina and H. akashiwo to generate enhanced amounts of O2 in a concentration-dependent manner. The lectin-specific sugars potently inhibited the lectin-induced increase of O2 production, suggesting that the effects of lectins are mediated mainly through the interaction of these lectins with carbohydrate moiety present on the flagellate cell surface. In contrast to the potent ability of native Con A (tetravalent), succinylated Con A (divalent) showed only a slight stimulative effect on these flagellates. O2 production was totally inhibited by treatment with proteinase K for 30 min, without affecting the viabilities of flagellates. These results suggest that cell-surface redox enzymes may be involved in O2 production, and such enzymes are responsible for the lectin-stimulation. Received: 21 August 1997 / Accepted: 8 January 1998  相似文献   
835.
Paternity and paternal care in the polygynandrous Smith's longspur   总被引:4,自引:0,他引:4  
In species where females copulate with more than one male during a single breeding attempt, males risk investing in offspring that are not their own. In the polygynandrous Smith's longspur (Calcarius pictus), females copulate sequentially with one to three males for each clutch of eggs and most of these males later assist in feeding the young. Using multilocus DNA profiling, we determined that there was mixed paternity in >75% of broods (n=31) but that few offspring (<1% of 114 nestlings) were sired by males outside the polygynandrous group. Male feeding rate increased significantly with the number of young sired, with males siring four nestlings feeding the brood at double the frequency of males siring only a single nestling. However, male Smith's longspurs appear to show a graded adjustment of paternal care in response to paternity only when other males are available to compensate for reduced care: feeding rate did not vary in relation to paternity when only one male provisioned young at the nest. There was no evidence that males could recognise their own offspring within a brood and feed them preferentially. The number of offspring sired by each male was significantly correlated with the number of days spent copulating with the attending female: on average, a male sired one offspring for every 2 days of copulatory access. If males use their access to females to estimate paternity (and thereby decide on their subsequent level of parental investment), a positive relationship is expected between the amount of female access and the subsequent feeding rate to the nestlings. Nonetheless, male feeding effort was only weakly correlated with female access and more study is needed to determine how males estimate their paternity in a brood. Received: 1 June 1997 / Accepted after revision: 1 April 1998  相似文献   
836.
The salient features of the river water chemistry and the seasonal variations on the individual chemical parameter were evaluated and characterized. The order of abundance of the ions in the water is determined for both seasons. The contribution of chemical weathering to the water chemistry has been determined using the (Ca2+ + Mg2+)/(Na+ + K+) ratio, ternary, and Gibb’s diagrams. The results show that the chemical composition of river water during premonsoon is controlled mainly by evaporation–crystallization, while in the postmonsoon, the rock–water interaction dominates. The unique characteristic of the river water is the linear relationship among the principal ions. Hydrochemical characteristics of ions in the water were studied using 1:1 equiline diagrams. The nature of the water samples was determined using the piper diagram. The influence of trace metals on the chemical composition and the quality of the river water in the study area has been assessed using Wilcox and US Salinity Laboratory diagrams.  相似文献   
837.
The study area Rameswaram, a holy island, is famous for the sacred Ramanathaswamy temple, which cements people of the country regardless of their place, residence, or their religion or creed. This coastal tract is experiencing a chronic fresh water shortage, despite a few spring sources. The study area is selected for the characterization of physico-chemical parameters viz., pH, EC, TDS, salinity, TA, TH, CH, MH, chloride, and fluoride for 150 groundwater samples and the impact of pre- and post-monsoons on the groundwater quality is studied. The water quality index advocates the transfer of groundwater quality from unacceptable status in the pre-monsoon into an acceptable status in the post-monsoon. The Langelier saturation index reflects the scaling tendency of groundwater in the study area. The Karl Pearson correlation matrix has approved the maximum influence of calcium and chloride on the total dissolved solids. It is interesting to conclude that the groundwater in the study area has very had nature, especially of non-carbonate type.  相似文献   
838.
Contamination of heavy metals, namely, lead, cadmium, zinc, nickel, copper, chromium and mercury was evaluated in the samples of water and tissues of Labeo rohita and Ctenopharyngodon idella of Upper Lake of Bhopal collected during summer, rainy and winter seasons of 2005–2006. Different organs of the fishes accumulated varying quantities of different heavy metals. In L. rohita, accumulation of heavy metals was in the sequence liver > kidney > gills > muscles, and in C. idella, it was gills > liver > kidney > muscles. Zn was the highest accumulating metal in fish, whilst Hg was the lowest and was well corroborated with those of water. The values of heavy metals were so far well within the maximum permissible standard value of heavy metals for drinking water and for fish culture as prescribed by various national and international agencies.  相似文献   
839.
The hydrochemistry of groundwater in the Densu River Basin, Ghana   总被引:1,自引:0,他引:1  
Hydrochemical analyses of groundwater samples were used to establish the hydrochemistry of groundwater in the Densu River Basin. The groundwater was weakly acidic, moderately mineralized, fresh to brackish with conductivity ranging from of 96.6 μS cm???1 in the North to 10,070 μS cm???1 in the South. Densu River basin have special economic significance, representing the countries greatest hydrostructure with freshwater. Chemical constituents are generally low in the North and high in the South. The order of relative abundance of major cations in the groundwater is Na?+??> Ca2?+??> Mg2?+??> K?+? while that of anions is Cl????> HCO $_{3}^{-} >$ SO $_{4}^{2-} >$ NO $_{3}^{-}$ . Four main chemical water types were delineated in the Basin. These include Ca–Mg–HCO3, Mg–Ca–Cl, Na–Cl, and mixed waters in which neither a particular cation nor anion dominates. Silicate weathering and ion exchange are probably the main processes through which major ions enter the groundwater system. Anthropogenic activities were found to have greatly impacted negatively on the quality of the groundwater.  相似文献   
840.
The purpose of this study was to investigate the impact of overland traffic on the spatial distribution of heavy metals in urban soils (Istanbul, Turkey). Road dust, surface, and subsurface soil samples were collected from a total of 41 locations along highways with dense traffic and secondary roads with lower traffic and analyzed for lead (Pb), zinc (Zn), and copper (Cu) concentrations. Statistical evaluation of the heavy metal concentrations observed along highways and along the secondary roads showed that the data were bimodally distributed. The maximum observed Pb, Zn, and Cu concentrations were 1,573, 522 and 136 mg/kg, respectively, in surface soils along highways and 99.3, 156, and 38.1 mg/kg along secondary roads. Correlation analysis of the metal concentrations in road dust, surface and 20-cm depth soils suggests the presence of a common pollution source. However, metal concentrations in the deeper soils were substantially lower than those observed at the surface, indicating low mobility of heavy metals, especially for Pb and Zn. A modified kriging approach that honors the bimodality of the data was used to estimate the spatial distribution of the surface concentrations of metals, and to identify hotspots. Results indicate that despite the presence of some industrial zones within the study area, traffic is the main heavy metal pollution source.  相似文献   
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