The uneven spatial distribution of biodiversity is a defining feature of nature. In fact, the imp... more The uneven spatial distribution of biodiversity is a defining feature of nature. In fact, the implementation of conservation actions both locally and globally has progressively been guided by the identification of biodiversity ‘hotspots’ (areas with exceptional biodiversity). However, different regions of the world differ drastically in the availability of fine-scale data on the diversity and distribution of species, thus limiting the potential to assess their local environmental priorities. Within South America—a megadiverse continent—Uruguay represents a peculiar area where multiple tropical and non-tropical eco-regions converge, creating highly heterogeneous ecosystems, but where the systematic quantification of biodiversity remains largely anecdotal. To investigate the constraints posed by the limited access to biodiversity data, we employ the most comprehensive database for tetrapod vertebrates in Uruguay (spanning 664 species) assembled to date, to identify hotspots of species...
The continental and marine territories of Uruguay are characterised by a rich convergence of mult... more The continental and marine territories of Uruguay are characterised by a rich convergence of multiple biogeographic ecoregions of the Neotropics, making this country a peculiar biodiversity spot. However, despite the biological significance of Uruguay for the South American subcontinent, the distribution of biodiversity patterns in this country remain poorly understood, given the severe gaps in available records of geographic species distributions. Currently, national biodiversity datasets are not openly available and, thus, a dominant proportion of the primary biodiversity data produced by researchers and institutions across Uruguay remains highly dispersed and difficult to access for the wider scientific and environmental community. In this paper, we aim to fill this gap by developing the first comprehensive, open-access database of biodiversity records for Uruguay (Biodiversidata), which is the result of a large-scale collaboration involving experts working across the entire rang...
Reading scientific articles is fundamental for researchers, not only to keep pace with advances i... more Reading scientific articles is fundamental for researchers, not only to keep pace with advances in their field, but also to know those giants on whose shoulders they are standing. In this sense, Courchamp and Bradshaw (2018) recently proposed a list of 100 seminal papers deemed to be of major importance in ecology, thus providing a general 'must-read' list for any new ecologist. The authors metaphorically speak of ecology as an ever-growing brick wall of published evidence. In order to quantify the degree of interference of the paywall over the wall of science, we took the opportunity given by the 100 seminal papers list and registered how many articles have been made universally and freely available by the publisher. Of the 100 scientific papers proposed as foundations of the wall of ecological knowledge, 66 are behind the paywall, with a total cost of US$1,560. This paywall exacerbates the existing asymmetries in ecological research between researchers from developed countries and the Global South. Diversity in research, as in ecological systems, is a source of robustness. Publishing high-quality articles in regional open peer-reviewed scientific journals is a suitable way to valorize Global South ecology, helping minimize the existing asymmetries.
Evidence is growing on the ability of anurans to make immediate call adjustments in response to t... more Evidence is growing on the ability of anurans to make immediate call adjustments in response to the propagation properties of the environment. However, our understanding of such flexibility is typically based on dichotomous stimuli (i.e. presence/absence), while its condition-dependence has been little explored. We experimentally studied the ability of adjustment and its condition dependence of advertisement calls of Hypsiboas pulchellus in response to different levels of attenuation. Individuals modified most call parameters analyzed, although the direction of adjustments was contingent on individual identity, level of attenuation and trait category (i.e. spectral or temporal). Under low attenuation conditions males lengthened some call elements, partially supporting the hypothesis of plasticity oriented towards maintaining signal transmission, but this trend was not present in the high attenuation treatment. Also, under both attenuation treatments males gave higher frequency notes...
The native species of amphibians and reptiles of Uruguay were categorized according to the IUCN R... more The native species of amphibians and reptiles of Uruguay were categorized according to the IUCN Red List criteria. Out of 47 amphibian species, seven are listed as Critically Endangered (CR), five as Endangered (EN), one as Vulnerable (VU), three as Near Threatened (NT), and two as Data Deficient (DD); the remaining species are considered to be Least Concern (LC). Among the 64 species of reptiles evaluated, one is listed as Critically Endangered (CR), seven as Endangered (EN), two as Vulnerable (VU), one as Near Threatened (NT) and seven as Data Deficient (DD); the rest are considered to be Least Concern (LC). The use of these results as an additional criterion in the definition of protected areas in Uruguay will contribute towards the conservation of the aforementioned threatened species and their associated ecosystems.
Understanding physiological and environmental determinants of strategies of reproductive allocati... more Understanding physiological and environmental determinants of strategies of reproductive allocation is a pivotal aim in biology. Because of their high metabolic cost, properties of sexual acoustic signals may correlate with body size, temperature, and an individual's energetic state. A quantitative theory of acoustic communication, based on the metabolic scaling with temperature and mass, was recently proposed, adding to the well-reported empirical patterns. It provides quantitative predictions for frequencies, call rate, and durations. Here, we analysed the mass, temperature, and body condition scaling of spectral and temporal attributes of the advertisement call of the treefrog Hypsiboas pulchellus. Mass dependence of call frequency followed metabolic expectations (f~M (-0.25), where f is frequency and M is mass) although non-metabolic allometry could also account for the observed pattern. Temporal variables scaled inversely with mass contradicting metabolic expectations (d~M (0.25), where d is duration), supporting instead empirical patterns reported to date. Temperature was positively associated with call rate and negatively with temporal variables, which is congruent with metabolic predictions. We found no significant association between temperature and frequencies, adding to the bulk of empirical evidence. Finally, a result of particular relevance was that body condition consistently determined call characteristics, in interaction with temperature or mass. Our intraspecific study highlights that even if proximate determinants of call variability are rather well understood, the mechanisms through which they operate are proving to be more complex than previously thought. The determinants of call characteristics emerge as a key topic of research in behavioural and physiological biology, with several clear points under debate which need to be analysed on theoretical and empirical grounds.
Temperature is a major factor affecting population abundance and individual performance. Net repr... more Temperature is a major factor affecting population abundance and individual performance. Net reproductive rate (R 0) and intrinsic rate of increase (r) differ in their response to different temperature regimes, and much of the difference is mediated by generation time (Tg). Here, we evaluate the effects of thermal mean and variability on R 0 , r and Tg, at four population densities in Drosophila melanogaster. The results show that R 0 , r and Tg present differential responses to thermal variation. Although temperature effects on R 0 and Tg are non-linear, r response was negligible. R 0 and Tg comprise a generational time scale, while r is at a chronological time scale. Thus, we argue that individuals growing under different thermal environments perform similarly on a chronological scale, but differently on a generational scale. E nvironmental temperature varies in time and space at different scales and its influence is complex, involving interactions between mechanisms and processes at different levels of ecological organization 1. Physiology, behavior, population dynamics, and interactions with other species depend, to different degrees, on the thermal environment surrounding the organism 2. In this context, the effect of temperature on several demographic parameters of ectotherms is well known 2-6 , as well as how their combined effects impact population dynamics and viability (i.e. 7-9). The relationship between environmental temperature and performance has been commonly described as a unimodal and asymmetric function, with a gradual increase as temperature reaches a maximum (the optimal temperature, T opt), and then an abrupt decay beyond this peak 1,2,4,10,11. Nevertheless, some studies have proposed that the effects of mean temperature and thermal variance may lead to more complex responses in performance curves. In this regard, Estay et al. 11 have suggested that performance could be affected either positively or negatively by temperature, depending on the specific thermal mean. Different measures of performance are available, but demographic parameters deserve special attention. They allow us to establish a direct link between individual performance and population properties, such as viability, equilibrium density 12,13 or the expected pattern of fluctuations 6,11. The most common demographic parameters used as proxies of fitness or performance are R 0 and r. R 0 is the average number of offspring produced by an individual during its lifetime. The intrinsic rate of natural increase, r, is the rate at which the population increases by time step. As can be observed, the main difference between these two measurements is time scale, generational and chronological, respectively. This difference is contained in a third measurement, the generation time (Tg), which is estimated as the average time between the birth of a female and the birth of her first female offspring. Despite their applicability as measurements of fitness, Pásztor, et al. 14 and Koz owski 15 pointed out that the use of demographic parameters in life history studies needs to be taken with caution, because each parameter must be interpreted in its own context and is constrained by its own assumptions. Thus, these parameters must be used under limited conditions. For instance, R 0 must be used when the state of the trait under study, o, is fixed along an individual's lifetime. Contrarily, r is an accurate measure of fitness when the state of an individual changes from year to year 14. These restrictions have profound consequences in the design of experiments, the interpretation of results obtained in the laboratory, and their extrapolation to field conditions. In a comprehensive study, Huey and Berrigan 3 showed that net reproductive rate (R 0) and intrinsic rate of increase (r) differed in their response to different constant temperature regimes, and that much of this difference was mediated by generation time (Tg). For instance, among ectotherms, the optimal temperature for r is generally
The Journal of the Acoustical Society of America, 2010
The structure of the environment determines patterns of signal degradation and attenuation, poten... more The structure of the environment determines patterns of signal degradation and attenuation, potentially affecting communication. The expected adjustment in call structure improving signal transmission in an environment was formalized in the acoustic adaptation ...
The structure of the environment surrounding signal emission produces different patterns of degra... more The structure of the environment surrounding signal emission produces different patterns of degradation and attenuation. The expected adjustment of calls to ensure signal transmission in an environment was formalized in the acoustic adaptation hypothesis. Within this framework, most studies considered anuran calls as fixed attributes determined by local adaptations. However, variability in vocalizations as a product of phenotypic expression has also been reported. Empirical evidence supporting the association between environment and call structure has been inconsistent, particularly in anurans. Here, we identify a plausible causal structure connecting environment, individual attributes, and temporal and spectral adjustments as direct or indirect determinants of the observed variation in call attributes of the frog Hypsiboas pulchellus. For that purpose, we recorded the calls of 40 males in the field, together with vegetation density and other environmental descriptors of the calling site. Path analysis revealed a strong effect of habitat structure on the temporal parameters of the call, and an effect of site temperature conditioning the size of organisms calling at each site and thus indirectly affecting the dominant frequency of the call. Experimental habitat modification with a styrofoam enclosure yielded results consistent with field observations, highlighting the potential role of call flexibility on detected call patterns. Both, experimental and correlative results indicate the need to incorporate the so far poorly considered role of phenotypic plasticity in the complex connection between environmental structure and individual call attributes.
Size-density relationships (SDRs) frequently follow a power-law relationship, with exponents that... more Size-density relationships (SDRs) frequently follow a power-law relationship, with exponents that compensate for the increase in populationlevel metabolic demand-the energetic equivalence rule. However, these exponents present a range of values, and elucidating its methodological and biological determinants has become a main issue. So far, a restricted set of potential relationships, mechanisms, and taxa have been considered. Here, we analyzed SDR in a population of tadpoles inhabiting a network of 16 temporal ponds. Alternative scaling regimes were detected using pacewise regressions and estimating exponents with maximum likelihood (ML). If discontinuities in the SDR are ignored, a scaling close to values reported elsewhere is observed. However, estimated slopes between discontinuities are steeper (threefold to fivefold) than those often reported, but congruent with the performance predicted for ML and the biases reported for other methods. Our estimations largely deviate from an energetic equivalence, suggesting that large individuals use less energy per unit area. The detection of different SDRs in the same database, with a strong decay in abundance with body size, points to a pattern poorly considered in previous studies, widening the range of patterns, mechanisms, and ecological, or evolutionary consequences of the SDRs.
The density mass–relationship (DMR) between abundance and body size is a key attribute of biodive... more The density mass–relationship (DMR) between abundance and body size is a key attribute of biodiversity organisation. The identification of the determinants of the DMR has consolidated as a major research area, focused on both statistical and ecological issues. Here, we advance the connection between food webs and DMR, by showing how gape limitation could determine the amount of resources available
The uneven spatial distribution of biodiversity is a defining feature of nature. In fact, the imp... more The uneven spatial distribution of biodiversity is a defining feature of nature. In fact, the implementation of conservation actions both locally and globally has progressively been guided by the identification of biodiversity ‘hotspots’ (areas with exceptional biodiversity). However, different regions of the world differ drastically in the availability of fine-scale data on the diversity and distribution of species, thus limiting the potential to assess their local environmental priorities. Within South America—a megadiverse continent—Uruguay represents a peculiar area where multiple tropical and non-tropical eco-regions converge, creating highly heterogeneous ecosystems, but where the systematic quantification of biodiversity remains largely anecdotal. To investigate the constraints posed by the limited access to biodiversity data, we employ the most comprehensive database for tetrapod vertebrates in Uruguay (spanning 664 species) assembled to date, to identify hotspots of species...
The continental and marine territories of Uruguay are characterised by a rich convergence of mult... more The continental and marine territories of Uruguay are characterised by a rich convergence of multiple biogeographic ecoregions of the Neotropics, making this country a peculiar biodiversity spot. However, despite the biological significance of Uruguay for the South American subcontinent, the distribution of biodiversity patterns in this country remain poorly understood, given the severe gaps in available records of geographic species distributions. Currently, national biodiversity datasets are not openly available and, thus, a dominant proportion of the primary biodiversity data produced by researchers and institutions across Uruguay remains highly dispersed and difficult to access for the wider scientific and environmental community. In this paper, we aim to fill this gap by developing the first comprehensive, open-access database of biodiversity records for Uruguay (Biodiversidata), which is the result of a large-scale collaboration involving experts working across the entire rang...
Reading scientific articles is fundamental for researchers, not only to keep pace with advances i... more Reading scientific articles is fundamental for researchers, not only to keep pace with advances in their field, but also to know those giants on whose shoulders they are standing. In this sense, Courchamp and Bradshaw (2018) recently proposed a list of 100 seminal papers deemed to be of major importance in ecology, thus providing a general 'must-read' list for any new ecologist. The authors metaphorically speak of ecology as an ever-growing brick wall of published evidence. In order to quantify the degree of interference of the paywall over the wall of science, we took the opportunity given by the 100 seminal papers list and registered how many articles have been made universally and freely available by the publisher. Of the 100 scientific papers proposed as foundations of the wall of ecological knowledge, 66 are behind the paywall, with a total cost of US$1,560. This paywall exacerbates the existing asymmetries in ecological research between researchers from developed countries and the Global South. Diversity in research, as in ecological systems, is a source of robustness. Publishing high-quality articles in regional open peer-reviewed scientific journals is a suitable way to valorize Global South ecology, helping minimize the existing asymmetries.
Evidence is growing on the ability of anurans to make immediate call adjustments in response to t... more Evidence is growing on the ability of anurans to make immediate call adjustments in response to the propagation properties of the environment. However, our understanding of such flexibility is typically based on dichotomous stimuli (i.e. presence/absence), while its condition-dependence has been little explored. We experimentally studied the ability of adjustment and its condition dependence of advertisement calls of Hypsiboas pulchellus in response to different levels of attenuation. Individuals modified most call parameters analyzed, although the direction of adjustments was contingent on individual identity, level of attenuation and trait category (i.e. spectral or temporal). Under low attenuation conditions males lengthened some call elements, partially supporting the hypothesis of plasticity oriented towards maintaining signal transmission, but this trend was not present in the high attenuation treatment. Also, under both attenuation treatments males gave higher frequency notes...
The native species of amphibians and reptiles of Uruguay were categorized according to the IUCN R... more The native species of amphibians and reptiles of Uruguay were categorized according to the IUCN Red List criteria. Out of 47 amphibian species, seven are listed as Critically Endangered (CR), five as Endangered (EN), one as Vulnerable (VU), three as Near Threatened (NT), and two as Data Deficient (DD); the remaining species are considered to be Least Concern (LC). Among the 64 species of reptiles evaluated, one is listed as Critically Endangered (CR), seven as Endangered (EN), two as Vulnerable (VU), one as Near Threatened (NT) and seven as Data Deficient (DD); the rest are considered to be Least Concern (LC). The use of these results as an additional criterion in the definition of protected areas in Uruguay will contribute towards the conservation of the aforementioned threatened species and their associated ecosystems.
Understanding physiological and environmental determinants of strategies of reproductive allocati... more Understanding physiological and environmental determinants of strategies of reproductive allocation is a pivotal aim in biology. Because of their high metabolic cost, properties of sexual acoustic signals may correlate with body size, temperature, and an individual's energetic state. A quantitative theory of acoustic communication, based on the metabolic scaling with temperature and mass, was recently proposed, adding to the well-reported empirical patterns. It provides quantitative predictions for frequencies, call rate, and durations. Here, we analysed the mass, temperature, and body condition scaling of spectral and temporal attributes of the advertisement call of the treefrog Hypsiboas pulchellus. Mass dependence of call frequency followed metabolic expectations (f~M (-0.25), where f is frequency and M is mass) although non-metabolic allometry could also account for the observed pattern. Temporal variables scaled inversely with mass contradicting metabolic expectations (d~M (0.25), where d is duration), supporting instead empirical patterns reported to date. Temperature was positively associated with call rate and negatively with temporal variables, which is congruent with metabolic predictions. We found no significant association between temperature and frequencies, adding to the bulk of empirical evidence. Finally, a result of particular relevance was that body condition consistently determined call characteristics, in interaction with temperature or mass. Our intraspecific study highlights that even if proximate determinants of call variability are rather well understood, the mechanisms through which they operate are proving to be more complex than previously thought. The determinants of call characteristics emerge as a key topic of research in behavioural and physiological biology, with several clear points under debate which need to be analysed on theoretical and empirical grounds.
Temperature is a major factor affecting population abundance and individual performance. Net repr... more Temperature is a major factor affecting population abundance and individual performance. Net reproductive rate (R 0) and intrinsic rate of increase (r) differ in their response to different temperature regimes, and much of the difference is mediated by generation time (Tg). Here, we evaluate the effects of thermal mean and variability on R 0 , r and Tg, at four population densities in Drosophila melanogaster. The results show that R 0 , r and Tg present differential responses to thermal variation. Although temperature effects on R 0 and Tg are non-linear, r response was negligible. R 0 and Tg comprise a generational time scale, while r is at a chronological time scale. Thus, we argue that individuals growing under different thermal environments perform similarly on a chronological scale, but differently on a generational scale. E nvironmental temperature varies in time and space at different scales and its influence is complex, involving interactions between mechanisms and processes at different levels of ecological organization 1. Physiology, behavior, population dynamics, and interactions with other species depend, to different degrees, on the thermal environment surrounding the organism 2. In this context, the effect of temperature on several demographic parameters of ectotherms is well known 2-6 , as well as how their combined effects impact population dynamics and viability (i.e. 7-9). The relationship between environmental temperature and performance has been commonly described as a unimodal and asymmetric function, with a gradual increase as temperature reaches a maximum (the optimal temperature, T opt), and then an abrupt decay beyond this peak 1,2,4,10,11. Nevertheless, some studies have proposed that the effects of mean temperature and thermal variance may lead to more complex responses in performance curves. In this regard, Estay et al. 11 have suggested that performance could be affected either positively or negatively by temperature, depending on the specific thermal mean. Different measures of performance are available, but demographic parameters deserve special attention. They allow us to establish a direct link between individual performance and population properties, such as viability, equilibrium density 12,13 or the expected pattern of fluctuations 6,11. The most common demographic parameters used as proxies of fitness or performance are R 0 and r. R 0 is the average number of offspring produced by an individual during its lifetime. The intrinsic rate of natural increase, r, is the rate at which the population increases by time step. As can be observed, the main difference between these two measurements is time scale, generational and chronological, respectively. This difference is contained in a third measurement, the generation time (Tg), which is estimated as the average time between the birth of a female and the birth of her first female offspring. Despite their applicability as measurements of fitness, Pásztor, et al. 14 and Koz owski 15 pointed out that the use of demographic parameters in life history studies needs to be taken with caution, because each parameter must be interpreted in its own context and is constrained by its own assumptions. Thus, these parameters must be used under limited conditions. For instance, R 0 must be used when the state of the trait under study, o, is fixed along an individual's lifetime. Contrarily, r is an accurate measure of fitness when the state of an individual changes from year to year 14. These restrictions have profound consequences in the design of experiments, the interpretation of results obtained in the laboratory, and their extrapolation to field conditions. In a comprehensive study, Huey and Berrigan 3 showed that net reproductive rate (R 0) and intrinsic rate of increase (r) differed in their response to different constant temperature regimes, and that much of this difference was mediated by generation time (Tg). For instance, among ectotherms, the optimal temperature for r is generally
The Journal of the Acoustical Society of America, 2010
The structure of the environment determines patterns of signal degradation and attenuation, poten... more The structure of the environment determines patterns of signal degradation and attenuation, potentially affecting communication. The expected adjustment in call structure improving signal transmission in an environment was formalized in the acoustic adaptation ...
The structure of the environment surrounding signal emission produces different patterns of degra... more The structure of the environment surrounding signal emission produces different patterns of degradation and attenuation. The expected adjustment of calls to ensure signal transmission in an environment was formalized in the acoustic adaptation hypothesis. Within this framework, most studies considered anuran calls as fixed attributes determined by local adaptations. However, variability in vocalizations as a product of phenotypic expression has also been reported. Empirical evidence supporting the association between environment and call structure has been inconsistent, particularly in anurans. Here, we identify a plausible causal structure connecting environment, individual attributes, and temporal and spectral adjustments as direct or indirect determinants of the observed variation in call attributes of the frog Hypsiboas pulchellus. For that purpose, we recorded the calls of 40 males in the field, together with vegetation density and other environmental descriptors of the calling site. Path analysis revealed a strong effect of habitat structure on the temporal parameters of the call, and an effect of site temperature conditioning the size of organisms calling at each site and thus indirectly affecting the dominant frequency of the call. Experimental habitat modification with a styrofoam enclosure yielded results consistent with field observations, highlighting the potential role of call flexibility on detected call patterns. Both, experimental and correlative results indicate the need to incorporate the so far poorly considered role of phenotypic plasticity in the complex connection between environmental structure and individual call attributes.
Size-density relationships (SDRs) frequently follow a power-law relationship, with exponents that... more Size-density relationships (SDRs) frequently follow a power-law relationship, with exponents that compensate for the increase in populationlevel metabolic demand-the energetic equivalence rule. However, these exponents present a range of values, and elucidating its methodological and biological determinants has become a main issue. So far, a restricted set of potential relationships, mechanisms, and taxa have been considered. Here, we analyzed SDR in a population of tadpoles inhabiting a network of 16 temporal ponds. Alternative scaling regimes were detected using pacewise regressions and estimating exponents with maximum likelihood (ML). If discontinuities in the SDR are ignored, a scaling close to values reported elsewhere is observed. However, estimated slopes between discontinuities are steeper (threefold to fivefold) than those often reported, but congruent with the performance predicted for ML and the biases reported for other methods. Our estimations largely deviate from an energetic equivalence, suggesting that large individuals use less energy per unit area. The detection of different SDRs in the same database, with a strong decay in abundance with body size, points to a pattern poorly considered in previous studies, widening the range of patterns, mechanisms, and ecological, or evolutionary consequences of the SDRs.
The density mass–relationship (DMR) between abundance and body size is a key attribute of biodive... more The density mass–relationship (DMR) between abundance and body size is a key attribute of biodiversity organisation. The identification of the determinants of the DMR has consolidated as a major research area, focused on both statistical and ecological issues. Here, we advance the connection between food webs and DMR, by showing how gape limitation could determine the amount of resources available
Uploads
Papers by Lucia Ziegler