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Papers by Anna Kasparson

Research paper thumbnail of Temporal resolution of birth rate analysis in zooplankton and its implications for identifying strong interactions in ecology

Ecology and Evolution

Expanding on Haeckel's classical definition, ecology can be defined as the study of strong an... more Expanding on Haeckel's classical definition, ecology can be defined as the study of strong and weak interactions between the organism and the environment, hence the need for identifying strong interactions as major drivers of population and community dynamics. The solution to this problem is facilitated by the fact that the frequency distribution of interaction strengths is highly skewed, resulting in few or, according to Liebig's law of the minimum, just one strong interaction. However, a single strong interaction often remains elusive. One of the reasons may be that, due to the ever‐present dynamics of ecological systems, a single strong interaction is likely to exist only on relatively short time intervals, so methods with sufficient temporal resolution are required. In this paper, we study the temporal resolution of contribution analysis of birth rate in zooplankton, a method to assess the relative strength of bottom‐up (food) versus top‐down (predation) effects. Birth r...

Research paper thumbnail of Color properties of the motion detectors projecting to the gold ̄sh tectum: III. Color-opponent interactions in the receptive ̄eld

Interactions between color channels (long-wave (L), middle-wave (M) and short-wave (S)) in the re... more Interactions between color channels (long-wave (L), middle-wave (M) and short-wave (S)) in the receptive ̄eld of direction-selective (DS) and orientation-selective (OS) ganglion cells (GCs) were investigated with combined selective stimulation of pairs of cone types (L andM, L and S, M and S). In the experiments with DS GCs of both ON and OFF types, it was shown that: (1) M and S channels were synergistic relative to each other and opponent to L channel. (2) Three-parameter signal (from L, M and S cones) is transformed to one-parameter signal at the output of DS GC, thus illustrating the principle of univariance. (3) In the experiments with OS GCs, it was shown that L and M channels were synergistic in the OFF-pathway, while the S channel was opponent to them. Our results suggested that photoreceptor synaptic connectivity of the bipolar cells hypothetically involved in the gold ̄sh OS circuitry substantially di®ers from connectivity of bipolar cells presumably targeting DS GC. (4) T...

Research paper thumbnail of Updated functional segregation of retinal ganglion cell projections in the tectum of a cyprinid fish—further elaboration based on microelectrode recordings

Fish Physiology and Biochemistry

Research paper thumbnail of Assessing the relative strength of the effects of food resources and predators on a population: A review of methods

Research paper thumbnail of Color properties of the motion detectors projecting to the goldfish tectum: I. A color matching study

Journal of Integrative Neuroscience, 2014

Research paper thumbnail of Colour cues proved to be more informative for dogs than brightness

Proceedings of the Royal Society B: Biological Sciences, 2013

Research paper thumbnail of Allee effects and the spatial dynamics of a locally endangered butterfly, the high brown fritillary ( Argynnis adippe )

Ecological Applications, 2014

Conservation of endangered species necessitates a full appreciation of the ecological processes a... more Conservation of endangered species necessitates a full appreciation of the ecological processes affecting the regulation, limitation, and persistence of populations. These processes are influenced by birth, death, and dispersal events, and characterizing them requires careful accounting of both the deterministic and stochastic processes operating at both local and regional population levels. We combined ecological theory and observations on Allee effects by linking mathematical analysis and the spatial and temporal population dynamics patterns of a highly endangered butterfly, the high brown fritillary, Argynnis adippe. Our theoretical analysis showed that the role of density-dependent feedbacks in the presence of local immigration can influence the strength of Allee effects. Linking this theory to the analysis of the population data revealed strong evidence for both negative density dependence and Allee effects at the landscape or regional scale. These regional dynamics are predicted to be highly influenced by immigration. Using a Bayesian state-space approach, we characterized the local-scale births, deaths, and dispersal effects together with measurement and process uncertainty in the metapopulation. Some form of an Allee effect influenced almost three-quarters of these local populations. Our joint analysis of the deterministic and stochastic dynamics suggests that a conservation priority for this species would be to increase resource availability in currently occupied and, more importantly, in unoccupied sites.

Research paper thumbnail of Color properties of movement detectors in the Carassius gibelio (Bloch, 1782) tectum opticum studied by selective stimulation of different cone types

Archives of Biological Sciences, 2009

Research paper thumbnail of Temporal resolution of birth rate analysis in zooplankton and its implications for identifying strong interactions in ecology

Ecology and Evolution

Expanding on Haeckel's classical definition, ecology can be defined as the study of strong an... more Expanding on Haeckel's classical definition, ecology can be defined as the study of strong and weak interactions between the organism and the environment, hence the need for identifying strong interactions as major drivers of population and community dynamics. The solution to this problem is facilitated by the fact that the frequency distribution of interaction strengths is highly skewed, resulting in few or, according to Liebig's law of the minimum, just one strong interaction. However, a single strong interaction often remains elusive. One of the reasons may be that, due to the ever‐present dynamics of ecological systems, a single strong interaction is likely to exist only on relatively short time intervals, so methods with sufficient temporal resolution are required. In this paper, we study the temporal resolution of contribution analysis of birth rate in zooplankton, a method to assess the relative strength of bottom‐up (food) versus top‐down (predation) effects. Birth r...

Research paper thumbnail of Color properties of the motion detectors projecting to the gold ̄sh tectum: III. Color-opponent interactions in the receptive ̄eld

Interactions between color channels (long-wave (L), middle-wave (M) and short-wave (S)) in the re... more Interactions between color channels (long-wave (L), middle-wave (M) and short-wave (S)) in the receptive ̄eld of direction-selective (DS) and orientation-selective (OS) ganglion cells (GCs) were investigated with combined selective stimulation of pairs of cone types (L andM, L and S, M and S). In the experiments with DS GCs of both ON and OFF types, it was shown that: (1) M and S channels were synergistic relative to each other and opponent to L channel. (2) Three-parameter signal (from L, M and S cones) is transformed to one-parameter signal at the output of DS GC, thus illustrating the principle of univariance. (3) In the experiments with OS GCs, it was shown that L and M channels were synergistic in the OFF-pathway, while the S channel was opponent to them. Our results suggested that photoreceptor synaptic connectivity of the bipolar cells hypothetically involved in the gold ̄sh OS circuitry substantially di®ers from connectivity of bipolar cells presumably targeting DS GC. (4) T...

Research paper thumbnail of Updated functional segregation of retinal ganglion cell projections in the tectum of a cyprinid fish—further elaboration based on microelectrode recordings

Fish Physiology and Biochemistry

Research paper thumbnail of Assessing the relative strength of the effects of food resources and predators on a population: A review of methods

Research paper thumbnail of Color properties of the motion detectors projecting to the goldfish tectum: I. A color matching study

Journal of Integrative Neuroscience, 2014

Research paper thumbnail of Colour cues proved to be more informative for dogs than brightness

Proceedings of the Royal Society B: Biological Sciences, 2013

Research paper thumbnail of Allee effects and the spatial dynamics of a locally endangered butterfly, the high brown fritillary ( Argynnis adippe )

Ecological Applications, 2014

Conservation of endangered species necessitates a full appreciation of the ecological processes a... more Conservation of endangered species necessitates a full appreciation of the ecological processes affecting the regulation, limitation, and persistence of populations. These processes are influenced by birth, death, and dispersal events, and characterizing them requires careful accounting of both the deterministic and stochastic processes operating at both local and regional population levels. We combined ecological theory and observations on Allee effects by linking mathematical analysis and the spatial and temporal population dynamics patterns of a highly endangered butterfly, the high brown fritillary, Argynnis adippe. Our theoretical analysis showed that the role of density-dependent feedbacks in the presence of local immigration can influence the strength of Allee effects. Linking this theory to the analysis of the population data revealed strong evidence for both negative density dependence and Allee effects at the landscape or regional scale. These regional dynamics are predicted to be highly influenced by immigration. Using a Bayesian state-space approach, we characterized the local-scale births, deaths, and dispersal effects together with measurement and process uncertainty in the metapopulation. Some form of an Allee effect influenced almost three-quarters of these local populations. Our joint analysis of the deterministic and stochastic dynamics suggests that a conservation priority for this species would be to increase resource availability in currently occupied and, more importantly, in unoccupied sites.

Research paper thumbnail of Color properties of movement detectors in the Carassius gibelio (Bloch, 1782) tectum opticum studied by selective stimulation of different cone types

Archives of Biological Sciences, 2009

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