The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
Hansrudolf Guttinger - One of the best experts on this subject based on the ideXlab platform.
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functional aspects of singing in male and female uraeginthus bengalus Estrildidae
Ethology, 2010Co-Authors: Manfred Gahr, Hansrudolf GuttingerAbstract:Both sexes of the African estrildid species Uraeginthus bengalus sing regularly. Song structure and the context of singing were studied in males and females under aviary conditions. It was found that: 1 Males and females have a similar song differing merely in strophe length, medial length being 1.38 ± 0.47 s in females and 2.58 ± 0.63 s in males. 2 Males sing during nesting, laying, incubation and broodcare, but also long before, with a remarkable activity peak at the beginning of incubation, whereas females hardly sing at all during the egg-laying and incubating phases, and their singing peak is long before laying starts. 3 In 52 % of all cases the male responds to his female's song during the pre-incubation period. His reaction includes singing, courtship display and elements introducing copulation.
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prolactin and gonadal steroids during the reproductive cycle of the bengalese finch lonchura striata var domestica Estrildidae a nonseasonal breeder with biparental care
General and Comparative Endocrinology, 1992Co-Authors: H W Seiler, Manfred Gahr, A R Goldsmith, Hansrudolf GuttingerAbstract:Abstract Plasma levels of prolactin (Prl), testosterone (T), and progesterone were determined throughout the breeding cycle in pairwise caged Bengalese finches ( Lonchura striata var. domestica , Estrildidae), a monogamous altricial passerine with nonseasonal breeding, in which parental behavior including incubation is equally shared between males and females. In both sexes, Prl titers increased 4- to 10-fold during incubation period compared to values during nestbuilding. Likewise, Prl levels after fledging of the young were significantly lower compared to titers during incubation. In males, T increased significantly (15-fold) during nestbuilding compared to all other stages of the breeding cycle. In females, T remained basal throughout the entire breeding cycle. Thus, T levels were elevated only during stages with low Prl titers and vice versa. Progesterone titers were elevated during egg-laying in females and fluctuated without any obvious pattern in males. These results suggest that (1) high levels of Prl are involved in the control of parental behavior of male and female Bengalese finches and (2) Prl secretion is controlled by proximate factors of the early reproductive cycle since reproduction is independent of seasonal factors in this species.
H W Seiler - One of the best experts on this subject based on the ideXlab platform.
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prolactin and gonadal steroids during the reproductive cycle of the bengalese finch lonchura striata var domestica Estrildidae a nonseasonal breeder with biparental care
General and Comparative Endocrinology, 1992Co-Authors: H W Seiler, Manfred Gahr, A R Goldsmith, Hansrudolf GuttingerAbstract:Abstract Plasma levels of prolactin (Prl), testosterone (T), and progesterone were determined throughout the breeding cycle in pairwise caged Bengalese finches ( Lonchura striata var. domestica , Estrildidae), a monogamous altricial passerine with nonseasonal breeding, in which parental behavior including incubation is equally shared between males and females. In both sexes, Prl titers increased 4- to 10-fold during incubation period compared to values during nestbuilding. Likewise, Prl levels after fledging of the young were significantly lower compared to titers during incubation. In males, T increased significantly (15-fold) during nestbuilding compared to all other stages of the breeding cycle. In females, T remained basal throughout the entire breeding cycle. Thus, T levels were elevated only during stages with low Prl titers and vice versa. Progesterone titers were elevated during egg-laying in females and fluctuated without any obvious pattern in males. These results suggest that (1) high levels of Prl are involved in the control of parental behavior of male and female Bengalese finches and (2) Prl secretion is controlled by proximate factors of the early reproductive cycle since reproduction is independent of seasonal factors in this species.
Manfred Gahr - One of the best experts on this subject based on the ideXlab platform.
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the genome of blue capped cordon bleu uncovers hidden diversity of ltr retrotransposons in zebra finch
Genes, 2019Co-Authors: Jesper Boman, Carolina Franklvilches, Michelly Dos S Santos, Edivaldo Herculano Correa De Oliveira, Manfred GahrAbstract:Avian genomes have perplexed researchers by being conservative in both size and rearrangements, while simultaneously holding the blueprints for a massive species radiation during the last 65 million years (My). Transposable elements (TEs) in bird genomes are relatively scarce but have been implicated as important hotspots for chromosomal inversions. In zebra finch (Taeniopygia guttata), long terminal repeat (LTR) retrotransposons have proliferated and are positively associated with chromosomal breakpoint regions. Here, we present the genome, karyotype and transposons of blue-capped cordon-bleu (Uraeginthus cyanocephalus), an African songbird that diverged from zebra finch at the root of estrildid finches 10 million years ago (Mya). This constitutes the third linked-read sequenced genome assembly and fourth in-depth curated TE library of any bird. Exploration of TE diversity on this brief evolutionary timescale constitutes a considerable increase in resolution for avian TE biology and allowed us to uncover 4.5 Mb more LTR retrotransposons in the zebra finch genome. In blue-capped cordon-bleu, we likewise observed a recent LTR accumulation indicating that this is a shared feature of Estrildidae. Curiously, we discovered 25 new endogenous retrovirus-like LTR retrotransposon families of which at least 21 are present in zebra finch but were previously undiscovered. This highlights the importance of studying close relatives of model organisms.
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functional aspects of singing in male and female uraeginthus bengalus Estrildidae
Ethology, 2010Co-Authors: Manfred Gahr, Hansrudolf GuttingerAbstract:Both sexes of the African estrildid species Uraeginthus bengalus sing regularly. Song structure and the context of singing were studied in males and females under aviary conditions. It was found that: 1 Males and females have a similar song differing merely in strophe length, medial length being 1.38 ± 0.47 s in females and 2.58 ± 0.63 s in males. 2 Males sing during nesting, laying, incubation and broodcare, but also long before, with a remarkable activity peak at the beginning of incubation, whereas females hardly sing at all during the egg-laying and incubating phases, and their singing peak is long before laying starts. 3 In 52 % of all cases the male responds to his female's song during the pre-incubation period. His reaction includes singing, courtship display and elements introducing copulation.
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prolactin and gonadal steroids during the reproductive cycle of the bengalese finch lonchura striata var domestica Estrildidae a nonseasonal breeder with biparental care
General and Comparative Endocrinology, 1992Co-Authors: H W Seiler, Manfred Gahr, A R Goldsmith, Hansrudolf GuttingerAbstract:Abstract Plasma levels of prolactin (Prl), testosterone (T), and progesterone were determined throughout the breeding cycle in pairwise caged Bengalese finches ( Lonchura striata var. domestica , Estrildidae), a monogamous altricial passerine with nonseasonal breeding, in which parental behavior including incubation is equally shared between males and females. In both sexes, Prl titers increased 4- to 10-fold during incubation period compared to values during nestbuilding. Likewise, Prl levels after fledging of the young were significantly lower compared to titers during incubation. In males, T increased significantly (15-fold) during nestbuilding compared to all other stages of the breeding cycle. In females, T remained basal throughout the entire breeding cycle. Thus, T levels were elevated only during stages with low Prl titers and vice versa. Progesterone titers were elevated during egg-laying in females and fluctuated without any obvious pattern in males. These results suggest that (1) high levels of Prl are involved in the control of parental behavior of male and female Bengalese finches and (2) Prl secretion is controlled by proximate factors of the early reproductive cycle since reproduction is independent of seasonal factors in this species.
A R Goldsmith - One of the best experts on this subject based on the ideXlab platform.
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prolactin and gonadal steroids during the reproductive cycle of the bengalese finch lonchura striata var domestica Estrildidae a nonseasonal breeder with biparental care
General and Comparative Endocrinology, 1992Co-Authors: H W Seiler, Manfred Gahr, A R Goldsmith, Hansrudolf GuttingerAbstract:Abstract Plasma levels of prolactin (Prl), testosterone (T), and progesterone were determined throughout the breeding cycle in pairwise caged Bengalese finches ( Lonchura striata var. domestica , Estrildidae), a monogamous altricial passerine with nonseasonal breeding, in which parental behavior including incubation is equally shared between males and females. In both sexes, Prl titers increased 4- to 10-fold during incubation period compared to values during nestbuilding. Likewise, Prl levels after fledging of the young were significantly lower compared to titers during incubation. In males, T increased significantly (15-fold) during nestbuilding compared to all other stages of the breeding cycle. In females, T remained basal throughout the entire breeding cycle. Thus, T levels were elevated only during stages with low Prl titers and vice versa. Progesterone titers were elevated during egg-laying in females and fluctuated without any obvious pattern in males. These results suggest that (1) high levels of Prl are involved in the control of parental behavior of male and female Bengalese finches and (2) Prl secretion is controlled by proximate factors of the early reproductive cycle since reproduction is independent of seasonal factors in this species.
Dennis Rodder - One of the best experts on this subject based on the ideXlab platform.
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continental shelf as potential retreat areas for austral asian estrildid finches passeriformes Estrildidae during the pleistocene
Journal of Avian Biology, 2013Co-Authors: Kathrin Schidelko, Darius Stiels, Renate Van Den Elzen, Nicole Wustenhagen, Dennis RodderAbstract:Studies dealing with changes of biodiversity in time and space constitute an important part of biogeography, ecology and conservation biology. Areas of long-term climate stability are particularly interesting as they might have facilitated the survival of species over historical times and thus are crucial for understanding contemporary diversity patterns. In this study, we assessed the potential distribution of 23 estrildid finch species in order to analyse stability in recent and past diversity patterns and diversity centres in the Austral-Asiatic region. We used Maxent to predict recent distributions of each species and to project them onto the climatic conditions of the Last Glacial Maximum (LGM, 21 000 yr BP) using two different scenarios (CCSM, MIROC). The resulting diversity patterns were tested on presence and possible shifts of distribution centres. Diversity patterns of forest- and savannah-living species were considered combined and separately. During the LGM, potential diversity patterns of forest-living species corroborated well with postulated rainforest refuges situated on the eastern coast of Cape York Peninsula. Our results indicate a remarkably high stability of existing diversity centres. Although projections into the past show some differences in detail in the extent and exact position of the diversity centres, they reveal largely congruent large scale patterns in both time slices. However, the models suggest a northward shift towards exposed continental shelf areas that where dry during the LGM. Clearly, centres of diversity were situated on this land bridge between Australia and New Guinea, highlighting their importance as areas of retreat for estrildid finches and maybe other savannah species in times of changing climatic conditions and associated sea-level fluctuations.
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predicting the potential distribution of the invasive common waxbill passeriformes Estrildidae
2011Co-Authors: Darius Stiels, Kathrin Schidelko, Jan O Engler, Renate Van Den Elzen, Dennis RodderAbstract:Human transport and commerce have led to an increased spread of non-indigenous species. Alien invasive species can have major impacts on many aspects of ecological systems. Therefore, the ability to predict regions potentially suitable for alien species, which are hence at high risk, has become a core task for successful management. The Common Waxbill is a widespread African species, which has been successfully introduced to many parts of the world. Herein, we used MAXENT software, a machine-learning algorithm, to assess its current potential distribution based on species records compiled from various sources. Models were trained separately with records from the species' native range and from both invaded and native ranges. Subsequently, the models were projected onto different future climate change scenarios. They successfully identified the species known range as well as some regions that seem climatically well suited, where the Common Waxbill is not yet recorded. Assuming future conditions, the models suggest poleward range shifts. However, its potential distribution pattern within its tropical native and invasive ranges appears to be more complex. Although the results of both separate analyses showed general similarities, many differences have become obvious. Niche overlap analysis shows that the invasive range includes only a small fraction of the ecological space that can be found in the native range. Thus, we tentatively prefer the model based on native locations only, but in particular, we highlight the importance of the selection process of species records for modelling invasive species.
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predicting the potential distribution of the invasive common waxbill estrilda astrild passeriformes Estrildidae
Journal of Ornithology, 2011Co-Authors: Darius Stiels, Kathrin Schidelko, Jan O Engler, Renate Van Den Elzen, Dennis RodderAbstract:Human transport and commerce have led to an increased spread of non-indigenous species. Alien invasive species can have major impacts on many aspects of ecological systems. Therefore, the ability to predict regions potentially suitable for alien species, which are hence at high risk, has become a core task for successful management. The Common Waxbill Estrilda astrild is a widespread African species, which has been successfully introduced to many parts of the world. Herein, we used MAXENT software, a machine-learning algorithm, to assess its current potential distribution based on species records compiled from various sources. Models were trained separately with records from the species’ native range and from both invaded and native ranges. Subsequently, the models were projected onto different future climate change scenarios. They successfully identified the species known range as well as some regions that seem climatically well suited, where the Common Waxbill is not yet recorded. Assuming future conditions, the models suggest poleward range shifts. However, its potential distribution pattern within its tropical native and invasive ranges appears to be more complex. Although the results of both separate analyses showed general similarities, many differences have become obvious. Niche overlap analysis shows that the invasive range includes only a small fraction of the ecological space that can be found in the native range. Thus, we tentatively prefer the model based on native locations only, but in particular, we highlight the importance of the selection process of species records for modelling invasive species.
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historical stability of diversity patterns in african estrildid finches aves Estrildidae
Biological Journal of The Linnean Society, 2011Co-Authors: Kathrin Schidelko, Darius Stiels, Dennis RodderAbstract:Studying shifts in species diversity through time and space is an essential component of many aspects of biogeography and ecology. In this study, we predict the potential distribution of 61 species of African estrildid finches in order to assess current and past diversity patterns. Models were projected onto two climatic scenarios (Community Climate System Model, CCSM, and Model for Interdisciplinary Research on Climate, MIROC) representing past climate conditions, as might be expected during the Last Glacial Maximum 21 000 years BP. Subsequent overlays of the resulting potential distributions were conducted under different dispersal assumptions and compared with expert maps. Our results suggest highly similar current distribution patterns obtained by both methods. Projections onto Pleistocene scenarios showed similar patterns, with only small differences under limited and unlimited dispersal assumptions. Looking separately at diversity patterns predicted for forest and savannah species, diversity hot spots of forest species under MIROC conditions were consistent with suggested forest refugia, but were inconsistent under CCSM conditions. According to our models, savannah species were more widely distributed during the cooler and drier conditions of the Pleistocene. By using ecological niche models we show that current diversity patterns of a whole species group may have changed only slightly since the Pleistocene, suggesting a pattern of general spatial stability. However, we emphasize the importance of using different climatic scenarios as well as including the supposed dispersal of organisms in the modelling, as these factors influence results on a broad scale. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 455–470. ADDITIONAL KEYWORDS: diversity hot spots – ecological niche modelling – Last Glacial Maximum – MAXENT – Pleistocene – refugia.
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Historical stability of diversity patterns in African estrildid finches (Aves: Estrildidae)?
Biological Journal of The Linnean Society, 2011Co-Authors: Kathrin Schidelko, Darius Stiels, Dennis RodderAbstract:Studying shifts in species diversity through time and space is an essential component of many aspects of biogeography and ecology. In this study, we predict the potential distribution of 61 species of African estrildid finches in order to assess current and past diversity patterns. Models were projected onto two climatic scenarios (Community Climate System Model, CCSM, and Model for Interdisciplinary Research on Climate, MIROC) representing past climate conditions, as might be expected during the Last Glacial Maximum 21 000 years BP. Subsequent overlays of the resulting potential distributions were conducted under different dispersal assumptions and compared with expert maps. Our results suggest highly similar current distribution patterns obtained by both methods. Projections onto Pleistocene scenarios showed similar patterns, with only small differences under limited and unlimited dispersal assumptions. Looking separately at diversity patterns predicted for forest and savannah species, diversity hot spots of forest species under MIROC conditions were consistent with suggested forest refugia, but were inconsistent under CCSM conditions. According to our models, savannah species were more widely distributed during the cooler and drier conditions of the Pleistocene. By using ecological niche models we show that current diversity patterns of a whole species group may have changed only slightly since the Pleistocene, suggesting a pattern of general spatial stability. However, we emphasize the importance of using different climatic scenarios as well as including the supposed dispersal of organisms in the modelling, as these factors influence results on a broad scale. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 455–470. ADDITIONAL KEYWORDS: diversity hot spots – ecological niche modelling – Last Glacial Maximum – MAXENT – Pleistocene – refugia.