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T E Dennis - One of the best experts on this subject based on the ideXlab platform.
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distribution abundance and Breeding Cycle of the australian sea lion neophoca cinerea mammalia pinnipedia
Journal of Zoology, 1994Co-Authors: N J Gales, P D Shaughnessy, T E DennisAbstract:Surveys of the Australian sea lion Neophoca cinerea were conducted throughout its range in Western and South Australia between December 1987 and February 1992. Almost every island was visited between Houtman Abrolhos and The Pages (n = 255), many of them more than once. Sea lions breed on at least 50 islands, 27 in Western Australia and 23 in South Australia. Of the 50 Breeding sites, 31 have not been reported previously. A further 19 islands may also support Breeding colonies. A total of 1,941 pups was counted and pup production was estimated at 2,432. Only five colonies produced more than 100 pups each and they accounted for almost half of the pup production. Most of these colonies are near Kangaroo Island, South Australia. A Breeding Cycle of 17–18 months has been reported for N. cinerea at Kangaroo Island and on the west coast of Western Australia; this was also noted at another 11 islands where repeated visits coincided with Breeding. No evidence was found for Breeding seasons shorter or longer than 17–18 months. The Breeding season was not synchronized between islands, as it is in other pinnipeds. A predictive model is developed to estimate the population size from pup production figures. It indicates that pup numbers should be multiplied by between 3.81 and 4.81 to estimate the total population size just before the pupping season begins. This leads to estimates of 9,300–11,700 for the total population, considerably greater than earlier estimates. Causes of the unique reproductive Cycle of N. cinerea are unknown, but we hypothesize that it results from living in a temperate climate in some of the most biologically depauperate waters of the world. It is also clear that day length and water temperature cannot act as exogenous cues for implantation of the blastocyst; the physiological events of gestation must, rather, be cued endogenously.
Eduardo Rocha - One of the best experts on this subject based on the ideXlab platform.
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histochemical evaluation of iron content in the liver of wild female ohrid trout salmo letnica kar along the Breeding Cycle
Contributions Section of Natural Mathematical and Biotechnical Sciences, 2018Co-Authors: Maja Jordanova, Katerina Rebok, Maria Joao Rocha, Eduardo RochaAbstract:Iron is an essential micronutrient for the normal metabolism of all cells. Intracellular iron varies within normality ranges, and depletion or overload of brings serious consequences. As such, iron can also be deleterious when appearing as an environmental toxicant. The aim of this study was to estimate semi-quantitatively the liver iron content in female Ohrid trout, from the Lake Ohrid, during the Breeding Cycle. Seasonal variations in hepatocytic iron were observed. The maximum content occurred at post-spawning, which was significantly higher than loads detected at pre- and early-vitellogenesis. Positive correlations existed between iron amounts and stages of ovary maturation. By the contrary, there were no correlations between iron contents and plasma oestradiol levels. The new uncovered "iron-Breeding associa-tion" strongly endorses that normal seasonal variations in hepatocytic iron content should be taken into consideration in field studies investigating and monitoring the metal burden and toxicological effects of metals on wild fish.
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seasonal changes in hepatocytic lipid droplets glycogen deposits and rough endoplasmic reticulum along the natural Breeding Cycle of female ohrid trout salmo letnica kar a semiquantitative ultrastructural study
Microscopy Research and Technique, 2016Co-Authors: Maja Jordanova, Katerina Rebok, Fernanda Malhao, Maria Joao Rocha, Eduardo RochaAbstract:This study on wild female Ohrid trout was primarily designed to provide a general overview of the Breeding Cycle influence upon selected aspects of hepatocytes. According with a semiquantitatively evaluation, some of these cell's structural compartments change during the Breeding Cycle. Structural modifications were disclosed in the relative occurrence of lipid, glycogen, and RER content during Breeding Cycle. The relative amount of lipid deposits in the hepatocytes was much greater in previtellogenesis, and decreased postspawning. So, while the seasonal changes in RER were positively related with the ovary maturation status, those of the lipid droplets followed an opposite trend. The hepatocytic glycogen occurred rarely, mainly in late-vitellogenesis and spawning, suggesting that in this species such kind of energy storage is comparatively unimportant. Lipid accumulation and later usage is, probably, the relevant biochemical pathway for Ohrid trout in the wild. While glycogen and RER contents were positively correlated with the gonadosomatic index, lipids were negatively correlated. Additionally, glycogen inclusions were positively correlated with the plasma estradiol levels. When comparing seasonal patterns from wild Ohrid trout with those from well-studied rainbow and brown trout (specimens studied were from aquaculture), there are contradicting results as to lipid and glycogen reserves, and also as to RER loads. The differences among the mentioned trout can result from intrinsic interspecies differences or may be associated with natural feeding conditions versus feeding with commercially prepared diets, or other factors. This study offers new data useful as standard to access liver pathology in wild and aquacultured Ohrid trout. Microsc. Res. Tech. 79:700-706, 2016. © 2016 Wiley Periodicals, Inc.
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changes in the amount of kidney pigmented macrophage aggregates throughout the Breeding Cycle of female ohrid trout salmo letnica kar teleostei salmonidae
Microscopy Research and Technique, 2012Co-Authors: Maja Jordanova, Katerina Rebok, Maria Joao Rocha, Eduardo RochaAbstract:Changes in fish macrophages (Macs) are useful indicators of environmental pressures, but responses due to chemical and nonchemical stresses may be confounded by natural sources of variability. These may include sex and gonadal stage. In this study, we start addressing the following question: is the seasonally dependent ovary stage a factor to consider when using kidney Macs as biomarkers? To tackle this problem, the relative amount of pigmented Macs in kidney (head, trunk, and tail portions) was stereologically estimated in Ohrid trout, and related with the Breeding status. The amount of Macs significantly increased from pre vitellogenesis to late vitellogenesis and showed a decreasing trend then after, with lower values noted after spawning in the head (1.9% versus 7.5% versus 2.0%), trunk (1.8% versus 7.5% versus 2.5%), and tail (2.5% versus 6.7% versus 2.9%) kidney. The decrease seen at spawning was significant in head and trunk kidney, and at post spawning it was significant for all kidney portions. The amounts of Macs were positively correlated with the ovary relative weights and plasma estradiol levels. We proved for the first time that fish kidney pigmented Macs can vary in amount during the Breeding Cycle. Our data, combined with literature, strongly support that the sex-steroid profile and kidney status-seasonal remodeling both influence the Macs pool; likely not only in female trout. So, while increases in Macs may warn of ecosystem problems, we show that using kidney Macs for biomonitoring should also take into account seasonally, particularly that related with ovary maturation. Microsc. Res. Tech. 2011. © 2011 Wiley Periodicals, Inc.
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the hepatocytes of the brown trout salmo trutta fario a stereological study of some cytoplasmic components with the Breeding Cycle
Microscopy Research and Technique, 2010Co-Authors: Eduardo Rocha, Maria Joao Rocha, Maria H. Galante, Alexandre Lobodacunha, Rogério A. F. MonteiroAbstract:Sex differences exist in fish hepatocytes, but studies for characterizing their cytology throughout the Breeding Cycle are still scarce; suggesting changes, but most lacking quantitative data. To address this limitation, to complement baseline data generated from the brown trout model, and to prove that sex-specific seasonal changes exist, we made an unbiased stereological evaluation of the hepatocytic cytoplasm. Unprecedentedly for fish liver, the stereological design was exempt from model (biased) assumptions. Five (3 years old) animals per sex were studied in endogenous vitellogenesis, exogenous vitellogenesis, and spawning season end. Liver pieces for analysis were systematically sampled. Stereology was done in transmission electron microscopy (TEM) micrographs. Primary data generated relative volume estimates of the major cytoplasmic components. Such values were used for deriving absolute volumes (per cell and per liver). Lipid droplets did not show changes. As to other targets, trends at cell and liver levels were not always equal. If the hepatocyte was the reference space, the contents in mitochondria, dense bodies, glycogen, and cytosol changed seasonally, in both sexes. If taking the liver as the reference, changes attained the Golgi apparatus and rough endoplasmic reticulum (RER), besides dense bodies, glycogen (in females), and cytosol. The components volumes (namely per liver) were often positively (negatively for glycogen) correlated with the ovary weight, disclosing new associations and implications in fish. While also offering gold-standard data for backing morphofunctional correlations and pathology, we revealed a new process by which females increase the amount of RER and Golgi throughout vitellogenesis, breaking from the idea on how this event happens in fish. Microsc. Res. Tech. 73:766–778, 2010. © 2010 Wiley-Liss, Inc.
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a qualitative and quantitative study of the hepatic pigmented macrophage aggregates during the Breeding Cycle of ohrid trout salmo letnica kar teloestei salmonidae
Microscopy Research and Technique, 2008Co-Authors: Maja Jordanova, Nada Miteva, Eduardo RochaAbstract:It is well known that factors such as aging and water quality may influence pigmented macrophages (PMacs) in fishes, but it is not established yet if PMacs undergo seasonal and Breeding dependent variations. This study explored this caveat and reports qualitative histological and stereological data on liver PMacs from wild female Ohrid trout, Salmo letnica, during the annual Breeding Cycle. Data showed that a minority of PMacs contained melanin and that the vast majority of them contained only hemosiderin or hemosiderin and lipofuscin/ceroid pigment. It was suggested that this is the normal scenario for the species. One remarkable result was the demonstration of a striking increase, after spawning, of the relative and total volumes of the hepatic macrophages, both parenchyma and stroma located. Because the melano PMacs did not vary, those changes were due to fluctuations in the hemosiderin-laden PMacs. We concluded that Ohrid trout presented a pigment composition in liver macrophages that differed from other fish, including salmonids, where most liver phagocytes essentially display melanin. Our quantitative data support interspecies differences in the amount of liver macrophages and also that after spawning expansion of the macrophage pool is crucial and most likely connected with the needs of liver remodeling (leading to a decrease in hepatic mass). So, we suggested that the hormonal (sex steroidal) constellation influenced the liver macrophage pool. Additionally, we proved that the use of fish liver macrophages for biomonitoring should take into account the considerable natural Breeding/seasonal dependent variations that are expected to occur. Microsc. Res. Tech., 2008. © 2008 Wiley-Liss, Inc.
A P Moller - One of the best experts on this subject based on the ideXlab platform.
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geographical and seasonal variation in the intensity of sexual selection in the barn swallow hirundo rustica a meta analysis
Biological Reviews, 2017Co-Authors: Andrea Romano, Nicola Saino, Alessandra Costanzo, Diego Rubolini, A P MollerAbstract:Sexual selection arises from competition among individuals for access to mates, resulting in the evolution of conspicuous sexually selected traits, especially when inter-sexual competition is mediated by mate choice. Different sexual selection regimes may occur among populations/subspecies within the same species. This is particularly the case when mate choice is based on multiple sexually selected traits. However, empirical evidence supporting this hypothesis at the among-populations level is scarce. We conducted a meta-analysis of the intensity of sexual selection on the largest database to date for a single species, the barn swallow (Hirundo rustica), relying on quantitative estimates of sexual selection. The intensity of sexual selection was expressed as the strength (effect size) of the relationships between six plumage ornaments (tail length, tail asymmetry, size of white spots on tail, ventral plumage colour, throat plumage colour and throat patch size) and several fitness proxies related to reproduction, parental care, offspring quality, arrival date from spring migration, and survival. The data were gathered for four geographically separated subspecies (H. r. rustica, H. r. erythrogaster, H. r. gutturalis, H. r. transitiva). The overall mean effect size (Zr = 0.214; 95% confidence interval = 0.175-0.254; N = 329) was of intermediate magnitude, with intensity of sexual selection being stronger in males than in females. Effect sizes varied during the Breeding Cycle, being larger before egg deposition, when competition for access to mates reaches its maximum (i.e. in the promiscuous part of the Breeding Cycle), and decreasing thereafter. In addition, effect sizes from experiments were not significantly larger than those from correlative studies. Finally, sexual selection on different sexually dimorphic traits varied among subspecies. This last result suggests that morphological divergence among populations has partly arisen from divergent sexual selection, which may eventually lead to speciation.
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secondary sexual characters parasites and testosterone in the barn swallow hirundo rustica
Animal Behaviour, 1994Co-Authors: Nicola Saino, A P MollerAbstract:Abstract Abstract. The immuno-competence hypothesis predicts that the expression of secondary sex traits should be positively related to testosterone levels, but that androgens should simultaneously have negative effects on the immune defence system. Relatively high levels of circulating androgens should therefore result in elevated levels of parasite infections. Parasite load and testosterone levels will be uncorrelated, or even negatively correlated, however, if males with high testosterone levels and large secondary sexual characters are reliable advertisers of genetic resistance to parasites. In male barn swallows, testosterone concentrations peaked during the pre-laying period. Males that had high levels of testosterone (adjusted for the stage of the Breeding Cycle) at one stage of the Breeding Cycle also had relatively high levels at other stages. The length of the outermost tail feathers, which are secondary sexual characters currently involved in sexual selection, was positively related to adjusted circulating levels of testosterone, even when potentially confounding variables were controlled statistically. The prevalence (proportion of hosts infected) and intensity (number of parasites per host individual) of ecto-parasites (two species of Mallophaga, one species of Acari) infecting barn swallows were unrelated to adjusted testosterone concentrations. Intensities of ecto-parasite infections were negatively related to tail length of male barn swallows, and unmated males had higher intensities of infections than mated males. These results are consistent with the immuno-competence version of the handicap principle.
Nicola Saino - One of the best experts on this subject based on the ideXlab platform.
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geographical and seasonal variation in the intensity of sexual selection in the barn swallow hirundo rustica a meta analysis
Biological Reviews, 2017Co-Authors: Andrea Romano, Nicola Saino, Alessandra Costanzo, Diego Rubolini, A P MollerAbstract:Sexual selection arises from competition among individuals for access to mates, resulting in the evolution of conspicuous sexually selected traits, especially when inter-sexual competition is mediated by mate choice. Different sexual selection regimes may occur among populations/subspecies within the same species. This is particularly the case when mate choice is based on multiple sexually selected traits. However, empirical evidence supporting this hypothesis at the among-populations level is scarce. We conducted a meta-analysis of the intensity of sexual selection on the largest database to date for a single species, the barn swallow (Hirundo rustica), relying on quantitative estimates of sexual selection. The intensity of sexual selection was expressed as the strength (effect size) of the relationships between six plumage ornaments (tail length, tail asymmetry, size of white spots on tail, ventral plumage colour, throat plumage colour and throat patch size) and several fitness proxies related to reproduction, parental care, offspring quality, arrival date from spring migration, and survival. The data were gathered for four geographically separated subspecies (H. r. rustica, H. r. erythrogaster, H. r. gutturalis, H. r. transitiva). The overall mean effect size (Zr = 0.214; 95% confidence interval = 0.175-0.254; N = 329) was of intermediate magnitude, with intensity of sexual selection being stronger in males than in females. Effect sizes varied during the Breeding Cycle, being larger before egg deposition, when competition for access to mates reaches its maximum (i.e. in the promiscuous part of the Breeding Cycle), and decreasing thereafter. In addition, effect sizes from experiments were not significantly larger than those from correlative studies. Finally, sexual selection on different sexually dimorphic traits varied among subspecies. This last result suggests that morphological divergence among populations has partly arisen from divergent sexual selection, which may eventually lead to speciation.
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seasonal meteorological and microhabitat effects on Breeding success and offspring phenotype in the barn swallow hirundo rustica
Ecoscience, 2006Co-Authors: Roberto Ambrosini, Raffaella Paola Ferrari, Roberta Martinelli, Maria Romanò, Nicola SainoAbstract:ABSTRACT Breeding performance and offspring quality can be affected by temporal and spatial variation in ecological conditions. We analyzed the concomitant effects of timing of Breeding, ambient temperature at different stages of the Breeding Cycle, and microhabitat conditions (presence or absence of livestock farming) on Breeding success, morphology, and immunity of the offspring in an aerially insectivorous passerine bird, the barn swallow (Hirundo rustica). A seasonal decline in Breeding success was observed, while maximum offspring phenotypic values of different characters were attained at different times in the Breeding season, depending on presence or absence of livestock farming. In addition, environmental temperature at different stages of the Breeding Cycle (pre-incubation, incubation, and nestling stage) of individual pairs affected all the components of nestling phenotypic quality. The results of this correlational study suggest that parents are faced with complex decisions about optimal timing...
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secondary sexual characters parasites and testosterone in the barn swallow hirundo rustica
Animal Behaviour, 1994Co-Authors: Nicola Saino, A P MollerAbstract:Abstract Abstract. The immuno-competence hypothesis predicts that the expression of secondary sex traits should be positively related to testosterone levels, but that androgens should simultaneously have negative effects on the immune defence system. Relatively high levels of circulating androgens should therefore result in elevated levels of parasite infections. Parasite load and testosterone levels will be uncorrelated, or even negatively correlated, however, if males with high testosterone levels and large secondary sexual characters are reliable advertisers of genetic resistance to parasites. In male barn swallows, testosterone concentrations peaked during the pre-laying period. Males that had high levels of testosterone (adjusted for the stage of the Breeding Cycle) at one stage of the Breeding Cycle also had relatively high levels at other stages. The length of the outermost tail feathers, which are secondary sexual characters currently involved in sexual selection, was positively related to adjusted circulating levels of testosterone, even when potentially confounding variables were controlled statistically. The prevalence (proportion of hosts infected) and intensity (number of parasites per host individual) of ecto-parasites (two species of Mallophaga, one species of Acari) infecting barn swallows were unrelated to adjusted testosterone concentrations. Intensities of ecto-parasite infections were negatively related to tail length of male barn swallows, and unmated males had higher intensities of infections than mated males. These results are consistent with the immuno-competence version of the handicap principle.
Maja Jordanova - One of the best experts on this subject based on the ideXlab platform.
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histochemical evaluation of iron content in the liver of wild female ohrid trout salmo letnica kar along the Breeding Cycle
Contributions Section of Natural Mathematical and Biotechnical Sciences, 2018Co-Authors: Maja Jordanova, Katerina Rebok, Maria Joao Rocha, Eduardo RochaAbstract:Iron is an essential micronutrient for the normal metabolism of all cells. Intracellular iron varies within normality ranges, and depletion or overload of brings serious consequences. As such, iron can also be deleterious when appearing as an environmental toxicant. The aim of this study was to estimate semi-quantitatively the liver iron content in female Ohrid trout, from the Lake Ohrid, during the Breeding Cycle. Seasonal variations in hepatocytic iron were observed. The maximum content occurred at post-spawning, which was significantly higher than loads detected at pre- and early-vitellogenesis. Positive correlations existed between iron amounts and stages of ovary maturation. By the contrary, there were no correlations between iron contents and plasma oestradiol levels. The new uncovered "iron-Breeding associa-tion" strongly endorses that normal seasonal variations in hepatocytic iron content should be taken into consideration in field studies investigating and monitoring the metal burden and toxicological effects of metals on wild fish.
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seasonal changes in hepatocytic lipid droplets glycogen deposits and rough endoplasmic reticulum along the natural Breeding Cycle of female ohrid trout salmo letnica kar a semiquantitative ultrastructural study
Microscopy Research and Technique, 2016Co-Authors: Maja Jordanova, Katerina Rebok, Fernanda Malhao, Maria Joao Rocha, Eduardo RochaAbstract:This study on wild female Ohrid trout was primarily designed to provide a general overview of the Breeding Cycle influence upon selected aspects of hepatocytes. According with a semiquantitatively evaluation, some of these cell's structural compartments change during the Breeding Cycle. Structural modifications were disclosed in the relative occurrence of lipid, glycogen, and RER content during Breeding Cycle. The relative amount of lipid deposits in the hepatocytes was much greater in previtellogenesis, and decreased postspawning. So, while the seasonal changes in RER were positively related with the ovary maturation status, those of the lipid droplets followed an opposite trend. The hepatocytic glycogen occurred rarely, mainly in late-vitellogenesis and spawning, suggesting that in this species such kind of energy storage is comparatively unimportant. Lipid accumulation and later usage is, probably, the relevant biochemical pathway for Ohrid trout in the wild. While glycogen and RER contents were positively correlated with the gonadosomatic index, lipids were negatively correlated. Additionally, glycogen inclusions were positively correlated with the plasma estradiol levels. When comparing seasonal patterns from wild Ohrid trout with those from well-studied rainbow and brown trout (specimens studied were from aquaculture), there are contradicting results as to lipid and glycogen reserves, and also as to RER loads. The differences among the mentioned trout can result from intrinsic interspecies differences or may be associated with natural feeding conditions versus feeding with commercially prepared diets, or other factors. This study offers new data useful as standard to access liver pathology in wild and aquacultured Ohrid trout. Microsc. Res. Tech. 79:700-706, 2016. © 2016 Wiley Periodicals, Inc.
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changes in the amount of kidney pigmented macrophage aggregates throughout the Breeding Cycle of female ohrid trout salmo letnica kar teleostei salmonidae
Microscopy Research and Technique, 2012Co-Authors: Maja Jordanova, Katerina Rebok, Maria Joao Rocha, Eduardo RochaAbstract:Changes in fish macrophages (Macs) are useful indicators of environmental pressures, but responses due to chemical and nonchemical stresses may be confounded by natural sources of variability. These may include sex and gonadal stage. In this study, we start addressing the following question: is the seasonally dependent ovary stage a factor to consider when using kidney Macs as biomarkers? To tackle this problem, the relative amount of pigmented Macs in kidney (head, trunk, and tail portions) was stereologically estimated in Ohrid trout, and related with the Breeding status. The amount of Macs significantly increased from pre vitellogenesis to late vitellogenesis and showed a decreasing trend then after, with lower values noted after spawning in the head (1.9% versus 7.5% versus 2.0%), trunk (1.8% versus 7.5% versus 2.5%), and tail (2.5% versus 6.7% versus 2.9%) kidney. The decrease seen at spawning was significant in head and trunk kidney, and at post spawning it was significant for all kidney portions. The amounts of Macs were positively correlated with the ovary relative weights and plasma estradiol levels. We proved for the first time that fish kidney pigmented Macs can vary in amount during the Breeding Cycle. Our data, combined with literature, strongly support that the sex-steroid profile and kidney status-seasonal remodeling both influence the Macs pool; likely not only in female trout. So, while increases in Macs may warn of ecosystem problems, we show that using kidney Macs for biomonitoring should also take into account seasonally, particularly that related with ovary maturation. Microsc. Res. Tech. 2011. © 2011 Wiley Periodicals, Inc.
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a qualitative and quantitative study of the hepatic pigmented macrophage aggregates during the Breeding Cycle of ohrid trout salmo letnica kar teloestei salmonidae
Microscopy Research and Technique, 2008Co-Authors: Maja Jordanova, Nada Miteva, Eduardo RochaAbstract:It is well known that factors such as aging and water quality may influence pigmented macrophages (PMacs) in fishes, but it is not established yet if PMacs undergo seasonal and Breeding dependent variations. This study explored this caveat and reports qualitative histological and stereological data on liver PMacs from wild female Ohrid trout, Salmo letnica, during the annual Breeding Cycle. Data showed that a minority of PMacs contained melanin and that the vast majority of them contained only hemosiderin or hemosiderin and lipofuscin/ceroid pigment. It was suggested that this is the normal scenario for the species. One remarkable result was the demonstration of a striking increase, after spawning, of the relative and total volumes of the hepatic macrophages, both parenchyma and stroma located. Because the melano PMacs did not vary, those changes were due to fluctuations in the hemosiderin-laden PMacs. We concluded that Ohrid trout presented a pigment composition in liver macrophages that differed from other fish, including salmonids, where most liver phagocytes essentially display melanin. Our quantitative data support interspecies differences in the amount of liver macrophages and also that after spawning expansion of the macrophage pool is crucial and most likely connected with the needs of liver remodeling (leading to a decrease in hepatic mass). So, we suggested that the hormonal (sex steroidal) constellation influenced the liver macrophage pool. Additionally, we proved that the use of fish liver macrophages for biomonitoring should take into account the considerable natural Breeding/seasonal dependent variations that are expected to occur. Microsc. Res. Tech., 2008. © 2008 Wiley-Liss, Inc.