scholarly journals From daily movements to population distributions: weather affects competitive ability in a guild of soaring birds

2013 ◽  
Vol 10 (88) ◽  
pp. 20130612 ◽  
Author(s):  
Emily L. C. Shepard ◽  
Sergio A. Lambertucci
Keyword(s):  
Competitive Ability ◽  
Meteorological Factors ◽  
Interspecific Interactions ◽  
Wing Loading ◽  
Spatial And Temporal Scales ◽  
Population Distributions ◽  
Common Resource ◽  
Soaring Flight ◽  
The Cost ◽  
Ephemeral Resources

The ability of many animals to access and exploit food is dependent on the ability to move. In the case of scavenging birds, which use soaring flight to locate and exploit ephemeral resources, the cost and speed of movement vary with meteorological factors. These factors are likely to modify the nature of interspecific interactions, as well as individual movement capacity, although the former are less well understood. We used aeronautical models to examine how soaring performance varies with weather within a guild of scavenging birds and the consequences this has for access to a common resource. Birds could be divided broadly into those with low wing loading that are more competitive in conditions with weak updraughts and low winds (black vultures and caracaras), and those with high wing loading that are well adapted for soaring in strong updraughts and moderate to high winds (Andean condors). Spatial trends in meteorological factors seem to confine scavengers with high wing loading to the mountains where they out-compete other birds; a trend that is borne out in worldwide distributions of the largest species. However, model predictions and carcass observations suggest that the competitive ability of these and other birds varies with meteorological conditions in areas where distributions overlap. This challenges the view that scavenging guilds are structured by fixed patterns of dominance and suggests that competitive ability varies across spatial and temporal scales, which may ultimately be a mechanism promoting diversity among aerial scavengers.

scholarly journals Soaring Flight in the Eleonora's Falcon (Falco eleonorae)

The Auk ◽  
2002 ◽  
Vol 119 (3) ◽  
pp. 835-840 ◽  
Author(s):  
Mikael Rosén ◽  
Anders Hedenström
Keyword(s):  
Flight Behavior ◽  
Small Island ◽  
Cost Of Transport ◽  
Open Sea ◽  
Gliding Flight ◽  
Eleonora’S Falcon ◽  
Soaring Flight ◽  
Falco Eleonorae ◽  
Vertical Winds ◽  
The Cost

Abstract Eleonora's Falcon (Falco eleonorae) breeds in the Mediterranean region and is highly adapted for catching small birds on passage migration between Eurasia and their African winter quarters, which they feed their young. We studied gliding flight behavior of Eleonora's Falcon at a breeding colony located on a small island southwest of Sardinia, Italy. Gliding and soaring flight performance was measured using an optical range finder and evaluated against flight mechanical theory. The male falcon does the majority of hunting and usually sets off from the colony to hunting areas located at high altitude over the open sea to catch prey. To lower the cost of transport and maximize the energy gain from hunting, we show that the birds use vertical winds for soaring when available. The occurrence of rising air changes with wind direction. At north-northwesterly winds (on-shore), slope lift is available outside the nesting cliffs, and at south-southeasterly winds thermals that form over the island drift out over the sea. Our observations demonstrated the flexibility of flight behavior in relation to the wind situation, and birds thereby make full use of available soaring conditions.

Commons and Cognition

2018 ◽  
Vol 19 (2) ◽  
pp. 587-616
Author(s):  
Carol M. Rose
Keyword(s):  
Climate Change ◽  
Collective Action ◽  
Real Life ◽  
Cognitive State ◽  
Common Pool ◽  
Common Resource ◽  
The Commons ◽  
Full Benefit ◽  
The Cost ◽  
Great Knowledge

Abstract Garrett Hardin’s Tragedy of the Commons primarily concerns actions rather than thoughts. But he did famously describe the cognitive state of a hypothetical herder on a grassy field. With respect to the field and its other users, Hardin’s herder is both ignorant and indifferent; he coolly calculates that his best option is to take the full benefit of grazing his stock while suffering only a fraction of the cost — an action that contributes to the decimation of a common resource. While Hardin viewed the herder’s attitude as identical to that of actors in many other collective action situations, the work of other commons theorists suggests several different cognitive stances among such actors, largely depending on the scale of the commons issues they face. Thus participants in the Prisoner’s Dilemma (a very small commons) would appear to be dominated by distrust rather than the hypothetical herder’s ignorance or indifference. Participants in mid-sized commons — such as Hardin’s herders in real life — show some distrust, but also great knowledge and engagement in common pool management. Participants in the largest-scale commons issues are actually those most likely to exhibit the ignorance and indifference that Hardin attributed to the herder. This Article discusses the ways in which these different cognitive stances track the scale of collective action “tragedies” as described by major theorists and concludes with some observations about the cognitive aspects of climate change.

scholarly journals Land-Based Impact of Nutrient Loads and Eutrophication on an Ancient Mediterranean Natural Lake

Hydrology ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 7
Author(s):  
Bachisio Mario Padedda ◽  
Antonella Lugliè ◽  
Giuseppina Grazia Lai ◽  
Filippo Giadrossich ◽  
Cecilia Teodora Satta ◽  
...  
Keyword(s):  
Human Impacts ◽  
Cost Effective ◽  
Nutrient Loads ◽  
Trophic Conditions ◽  
Spatial And Temporal Scales ◽  
Natural Lake ◽  
Management Plans ◽  
Water Management Plans ◽  
The Cost ◽  
The Impact

In water management plans, all human impacts on the aquatic environment are quantified and evaluated. For this purpose, lake-related assessment methods of watersheds are needed. The aim of this study is to present the environmental condition along the watershed–lake continuum of Lake Baratz, located in the northeastern part of Sardinia. We provide a method to evaluate the impact of a small watershed area on the trophic state of this ancient Mediterranean natural lake. This study demonstrates the potentialities of coupling simple land structure-based models with empirical ones, allowing one to hierarchize, interpret, and predict the relationships among the watershed ecological unity and lake trophic conditions at multiple spatial and temporal scales. It also demonstrates how the impact of single and interacting nutrient stressors can have a different impact on the trophic status which, in particular, applies to autotrophs, constituting a key response in the ecosystem. We suggest that the stressor hierarchy should be considered as a way of prioritizing actions in the cost-effective implementation of conservation and management plans.

scholarly journals Estimating the movements of terrestrial animal populations using broad-scale occurrence data

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Sarah R. Supp ◽  
Gil Bohrer ◽  
John Fieberg ◽  
Frank A. La Sorte
Keyword(s):  
Population Level ◽  
Sampling Bias ◽  
Population Movements ◽  
Spatial And Temporal Scales ◽  
Temporal Sampling ◽  
Multiple Observations ◽  
Occurrence Data ◽  
Population Distributions ◽  
Animal Populations ◽  
Broad Scale

AbstractAs human and automated sensor networks collect increasingly massive volumes of animal observations, new opportunities have arisen to use these data to infer or track species movements. Sources of broad scale occurrence datasets include crowdsourced databases, such as eBird and iNaturalist, weather surveillance radars, and passive automated sensors including acoustic monitoring units and camera trap networks. Such data resources represent static observations, typically at the species level, at a given location. Nonetheless, by combining multiple observations across many locations and times it is possible to infer spatially continuous population-level movements. Population-level movement characterizes the aggregated movement of individuals comprising a population, such as range contractions, expansions, climate tracking, or migration, that can result from physical, behavioral, or demographic processes. A desire to model population movements from such forms of occurrence data has led to an evolving field that has created new analytical and statistical approaches that can account for spatial and temporal sampling bias in the observations. The insights generated from the growth of population-level movement research can complement the insights from focal tracking studies, and elucidate mechanisms driving changes in population distributions at potentially larger spatial and temporal scales. This review will summarize current broad-scale occurrence datasets, discuss the latest approaches for utilizing them in population-level movement analyses, and highlight studies where such analyses have provided ecological insights. We outline the conceptual approaches and common methodological steps to infer movements from spatially distributed occurrence data that currently exist for terrestrial animals, though similar approaches may be applicable to plants, freshwater, or marine organisms.

scholarly journals Evolution of increased larval competitive ability in Drosophila melanogaster without increased larval feeding rate

2015 ◽  
Author(s):  
Manaswini Sarangi ◽  
Archana Nagarajan ◽  
Snigdhadip Dey ◽  
Joy Bose ◽  
Amitabh Joshi
Keyword(s):  
Competitive Ability ◽  
Unit Volume ◽  
Larval Density ◽  
Larval Feeding ◽  
Food Conversion ◽  
Feeding Rates ◽  
Laboratory Populations ◽  
Larval Crowding ◽  
The Cost

Multiple experimental evolution studies on D. melanogaster in the 1980s and 1990s indicated that enhanced competitive ability evolved primarily through increased larval tolerance to nitrogenous wastes and increased larval feeding and foraging rate, at the cost of efficiency of food conversion to biomass, and this became the widely accepted view of how adaptation to larval crowding evolves in fruitflies. We recently showed that populations of D. ananassae and D. n. nasuta subjected to extreme larval crowding evolved greater competitive ability without evolving higher feeding rates, primarily through a combination of reduced larval duration, faster attainment of minimum critical size for pupation, greater efficiency of food conversion to biomass, increased pupation height and, perhaps, greater urea/ammonia tolerance. This was a very different suite of traits than that seen to evolve under similar selection in D. melanogaster and was closer to the expectations from the theory of K-selection. At that time, we suggested two possible reasons for the differences in the phenotypic correlates of greater competitive ability seen in the studies with D. melanogaster and the other two species. First, that D. ananassae and D. n. nasuta had a very different genetic architecture of traits affecting competitive ability compared to the long-term, laboratory populations of D. melanogaster used in the earlier studies, either because the populations of the former two species were relatively recently wild-caught, or by virtue of being different species. Second, that the different evolutionary trajectories in D. ananassae and D. n. nasuta versus D. melanogaster were a reflection of differences in the manner in which larval crowding was imposed in the two sets of selection experiments. The D. melanogaster studies used a higher absolute density of eggs per unit volume of food, and a substantially larger total volume of food, than the studies on D. ananassae and D. n. nasuta. Here, we show that long-term laboratory populations of D. melanogaster, descended from some of the populations used in the earlier studies, evolve essentially the same set of traits as the D. ananassae and D. n. nasuta crowding-adapted populations when subjected to a similar larval density at low absolute volumes of food. As in the case of D. ananassae and D. n. nasuta, and in stark contrast to earlier studies with D. melanogaster, these crowding-adapted populations of D. melanogaster did not evolve greater larval feeding rates as a correlate of increased competitive ability. The present results clearly suggest that the suite of phenotypes through which the evolution of greater competitive ability is achieved in fruitflies depends critically not just on larval density per unit volume of food, but also on the total amount of food available in the culture vials. We discuss these results in the context of an hypothesis about how larval density and the height of the food column in culture vials might interact to alter the fitness costs and benefits of increased larval feeding rates, thus resulting in different routes to the evolution of greater competitive ability, depending on the details of exactly how the larval crowding was implemented.

Predicting the interactions between “ecologically equivalent” indigenous and nonindigenous brachyurans

2012 ◽  
Vol 69 (5) ◽  
pp. 983-995 ◽  
Author(s):  
Erin Breen ◽  
Anna Metaxas
Keyword(s):  
Predictive Models ◽  
Species Interactions ◽  
Interspecific Interactions ◽  
Specific Information ◽  
Functional Responses ◽  
Spatial And Temporal Scales ◽  
Qualitative And Quantitative ◽  
Abiotic And Biotic Factors ◽  
Species Specific ◽  
Per Capita Consumption

Predictive models used to determine the impacts of nonindigenous brachyurans on their “ecological equivalents” in marine ecosystems are sorely lacking. Determining the spatial and temporal extent and magnitude of such impacts by nonindigenous species is difficult because of the broad range of qualitative and quantitative criteria currently used to describe their effects. Forecasting potential impacts requires the development of predictive models that incorporate the effects of interspecific interactions and the mechanisms that give rise to these interactions. Successful validation of such models requires improved techniques for measuring and estimating the functional responses on bioenergetic processes across species compositions, abundances, and environmental conditions. Species-specific information used to support predictive modeling of nonindigenous brachyurans is currently heavily biased towards (i) estimating per capita consumption and growth rates in laboratory conditions and (ii) incorporating the effects of abiotic and biotic factors on these measures. Robust predictive models require repetitive experimentation that advances the understanding of species’ interactions (beyond consumption alone) across variable densities and considers their effects across different spatial and temporal scales.

scholarly journals Conspecific sperm precedence is reinforced but sexual selection weakened in sympatric populations ofDrosophila

2016 ◽  
Author(s):  
Dean M. Castillo ◽  
Leonie C. Moyle
Keyword(s):  
Sexual Selection ◽  
Reproductive Isolation ◽  
Sperm Competition ◽  
Competitive Ability ◽  
Genetic Basis ◽  
Direct Selection ◽  
Sperm Precedence ◽  
Sympatric Populations ◽  
Selection For ◽  
The Cost

SUMMARYSexual selection is well recognized as a driver of reproductive isolation between lineages. However, selection for increased reproductive isolation could reciprocally change the outcomes of sexual selection, when these processes share a genetic basis. Direct selection for reproductive isolation occurs in the context of ‘reinforcement’, where selection acts to increase prezygotic barriers to reduce the cost of heterospecific matings. Many studies of reinforcement focus on premating reproductive barriers, however postmating traits-such as conspecific sperm precedence (CSP)-can also respond to reinforcing selection. We tested whether i) CSP responded to reinforcing selection, and ii) this response in sympatric populations altered intraspecific sperm competition (ISC) and the strength of sexual selection, with the sister speciesDrosophila pseudoobscuraandD. persimilis. We used sperm competition experiments to evaluate differences in CSP and ISC between two sympatric and two allopatric populations ofD. pseudoobscura. Using multiple genotypes for each population allowed us to estimate not only patterns of phenotype divergence, but also the opportunity for sexual selection within each population. Consistent with a pattern of reinforcement, the sympatric populations had higher mean CSP. Moreover, ISC was altered in sympatric populations, where we observed decreased average offensive sperm competitive ability against conspecific males, allowing less opportunity for sexual selection to operate within these populations. These data demonstrate that strong reinforcing selection for reproductive isolation can have consequences for sexual selection and sexual interactions within species, in these important postmating sperm competition traits.

scholarly journals Exploitation by cheaters facilitates the preservation of essential public goods in microbial communities

2016 ◽  
Author(s):  
Clara Moreno-Fenoll ◽  
Matteo Cavaliere ◽  
Esteban Martinez-Garcia ◽  
Juan F Poyatos
Keyword(s):  
Public Goods ◽  
Microbial Communities ◽  
Experimental System ◽  
Lag Phase ◽  
The Public ◽  
Common Resource ◽  
The Cost ◽  
The Impact ◽  
Spontaneous Mutants

How are public goods maintained in bacterial cooperative populations? The presence of these compounds is usually threatened by the rise of cheaters that do not contribute but just exploit the common resource. Minimizing cheater invasions appears then as a necessary maintenance mechanism. However, that invasions can instead add to the persistence of cooperation is a prospect that has yet remained largely unexplored. Here, we show that the detrimental consequences of cheaters can actually preserve public goods, at the cost of recurrent collapses and revivals of the population. The result is made possible by the interplay between spatial constraints and the essentiality of the shared resource. We validate this counter-intuitive effect by carefully combining theory and experiment, with the engineering of an explicit synthetic community in which the public compound allows survival to a bactericidal stress. Notably, the characterization of the experimental system identifies additional factors that can matter, like the impact of the lag phase on the tolerance to stress, or the appearance of spontaneous mutants. Our work emphasizes the unanticipated consequences of the eco-evolutionary feedbacks that emerge in microbial communities relying on essential public goods to function, feedbacks that reveal fundamental for the adaptive change of ecosystems at all scales.

scholarly journals The Tropical Subseasonal Variability Simulated in the NASA GISS General Circulation Model

2012 ◽  
Vol 25 (13) ◽  
pp. 4641-4659 ◽  
Author(s):  
Daehyun Kim ◽  
Adam H. Sobel ◽  
Anthony D. Del Genio ◽  
Yonghua Chen ◽  
Suzana J. Camargo ◽  
...  
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Circulation Model ◽  
Tropical Convection ◽  
Entrainment Rate ◽  
Spatial And Temporal Scales ◽  
Subseasonal Variability ◽  
The Mean ◽  
Goddard Institute ◽  
The Cost

Abstract The tropical subseasonal variability simulated by the Goddard Institute for Space Studies general circulation model, Model E2, is examined. Several versions of Model E2 were developed with changes to the convective parameterization in order to improve the simulation of the Madden–Julian oscillation (MJO). When the convective scheme is modified to have a greater fractional entrainment rate, Model E2 is able to simulate MJO-like disturbances with proper spatial and temporal scales. Increasing the rate of rain reevaporation has additional positive impacts on the simulated MJO. The improvement in MJO simulation comes at the cost of increased biases in the mean state, consistent in structure and amplitude with those found in other GCMs when tuned to have a stronger MJO. By reinitializing a relatively poor-MJO version with restart files from a relatively better-MJO version, a series of 30-day integrations is constructed to examine the impacts of the parameterization changes on the organization of tropical convection. The poor-MJO version with smaller entrainment rate has a tendency to allow convection to be activated over a broader area and to reduce the contrast between dry and wet regimes so that tropical convection becomes less organized. Besides the MJO, the number of tropical-cyclone-like vortices simulated by the model is also affected by changes in the convection scheme. The model simulates a smaller number of such storms globally with a larger entrainment rate, while the number increases significantly with a greater rain reevaporation rate.

scholarly journals Topographic drivers of flight altitude over large spatial and temporal scales

The Auk ◽  
2019 ◽  
Vol 136 (2) ◽  
Author(s):  
Adam E Duerr ◽  
Tricia A Miller ◽  
Leah Dunn ◽  
Douglas A Bell ◽  
Peter H Bloom ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Ground Level ◽  
Spatial And Temporal Variation ◽  
Flight Altitude ◽  
Spatial And Temporal Scales ◽  
The North ◽  
Topographic Roughness ◽  
Topographic Characteristics ◽  
Soaring Flight ◽  
East West

Abstract Bird movements vary spatially and temporally, but the primary drivers that explain such variation can be difficult to identify. For example, it is well known that the availability of updraft influences soaring flight and that topography interacts with weather to produce these updrafts. However, the influences of topography on flight are not well understood. We determined how topographic characteristics influenced flight altitude above ground level (AGL) of a large soaring bird, the Golden Eagle (Aquila chrysaetos), over several regions within the State of California, USA. Primary drivers of flight AGL, those to which eagles showed the same response at all spatial scales, were topographic roughness, ground elevation and the east-west component of aspect (eastness). Each of these is related to formation of thermal updrafts. Secondary drivers, those to which eagles showed region-specific patterns, included topographic position, percent slope, and the north-south component of aspect (northness). In contrast to primary drivers, these secondary drivers were related to formation of both thermal and orographic updrafts. Overall, drivers of flight altitudes that were related to thermal updrafts showed different levels of complexity due to spatial and temporal variation of those drivers than did flight altitudes related to orographic updrafts.

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