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McAlpine‐Bellis E, Utsumi KL, Diamond KM, Klein J, Gilbert‐Smith S, Garrison GE, Eifler MA, Eifler DA. Movement patterns and habitat use for the sympatric species: Gambelia wislizenii and Aspidoscelis tigris. Ecol Evol 2023; 13:e10422. [PMID: 37575589 PMCID: PMC10413956 DOI: 10.1002/ece3.10422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/14/2023] [Accepted: 07/24/2023] [Indexed: 08/15/2023] Open
Abstract
Movement is an important characteristic of an animal's ecology, reflecting the perception of and response to environmental conditions. To effectively search for food, movement patterns likely depend on habitat characteristics and the sensory systems used to find prey. We examined movements associated with foraging for two sympatric species of lizards inhabiting the Great Basin Desert of southeastern Oregon. The two species have largely overlapping diets but find prey via different sensory cues, which link to their differing foraging strategies-the long-nosed leopard lizard, Gambelia wislizenii, is a visually-oriented predator, while the western whiptail, Aspidoscelis tigris, relies more heavily on chemosensory cues to find prey. Using detailed focal observations, we characterized the habitat use and movement paths of each species. We placed markers at the location of focal animals every minute for the duration of each 30-min observation. Afterward, we recorded whether each location was in the open or in vegetation, as well as the movement metrics of step length, path length, net displacement, straightness index, and turn angle, and then made statistical comparisons between the two species. The visual forager spent more time in open areas, moved less frequently over shorter distances, and differed in patterns of plant use compared to the chemosensory forager. Path characteristics of step length and turn angle differed between species. The visual predator moved in a way that was consistent with the notion that they require a clear visual path to stalk prey whereas the movement of the chemosensory predator increased their chances of detecting prey by venturing further into vegetation. Sympatric species can partition limited resources through differences in search behavior and habitat use.
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Affiliation(s)
| | - Kaera L. Utsumi
- Erell InstituteLawrenceKansasUSA
- Biodiversity InstituteUniversity of KansasLawrenceKansasUSA
| | | | - Janine Klein
- Department of AnthropologyUniversity of CaliforniaSanta BarbaraCaliforniaUSA
| | | | | | - Maria A. Eifler
- Erell InstituteLawrenceKansasUSA
- Biodiversity InstituteUniversity of KansasLawrenceKansasUSA
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Exotic tree and shrub invasions alter leaf-litter microflora and arthropod communities. Oecologia 2020; 193:177-187. [PMID: 32322986 DOI: 10.1007/s00442-020-04657-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 04/15/2020] [Indexed: 10/24/2022]
Abstract
Approximately 90% of all annual net primary productivity in temperate deciduous forests ends up entering the detritus food web as leaf litter. Due to chemical and physical differences from native litter, inputs from invasive species may impact the litter-dwelling community and ecosystem processes. We compared leaf-litter nutritional quality and decomposition rates from two invasive shrubs, Lonicera maackii and Rhamnus davurica, and the invasive tree Ailanthus altissima to litter from native oak-hickory forest in the Shenandoah Valley of Virginia, USA. We sampled litter from both invaded and uninvaded habitats and conducted litter colonization experiments to test for effects on microflora and the litter-dwelling arthropod communities. Litter from all three invasive species decomposed more rapidly than native litter, with native habitats averaging two to nearly five times as much litter by June. Invasive litter had higher nitrogen concentration and lower C:N ratios than native litter. Invasive litter supported greater growth of bacteria and fungi. Higher numbers of arthropods colonized invasive litter than native litter, but litter arthropod numbers on the forest floor of invaded habitats dropped in the early summer as litter decomposed. Litter had no effect on arthropod richness. Over short time scales, our results indicate that these invasive species represent beneficial, novel resources for the litter-dwelling community. However, the short-lived nature of this resource resulted in a crash in the abundance of the litter-dwelling organisms once the litter decomposed. As a whole, native habitat seems to support a larger, more stable litter-dwelling community over the course of a growing season.
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Steinmann T, Casas J. The morphological heterogeneity of cricket flow-sensing hairs conveys the complex flow signature of predator attacks. J R Soc Interface 2018. [PMID: 28637919 DOI: 10.1098/rsif.2017.0324] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Arthropod flow-sensing hair length ranges over more than an order of magnitude, from 0.1 to 5 mm. Previous studies repeatedly identified the longest hairs as the most sensitive, but recent studies identified the shortest hairs as the most responsive. We resolved this apparent conflict by proposing a new model, taking into account both the initial and long-term aspects of the flow pattern produced by a lunging predator. After the estimation of the mechanical parameters of hairs, we measured the flow produced by predator mimics and compared the predicted and observed values of hair displacements in this flow. Short and long hairs respond over different time scales during the course of an attack. By harbouring a canopy of hairs of different lengths, forming a continuum, the insect can fractionize these moments. Short hairs are more agile, but are less able to harvest energy from the air. This may result in longer hairs firing their neurons earlier, despite their slower deflection. The complex interplay between hair agility and sensitivity is also modulated by the predator distance and the attack speed, characteristics defining flow properties. We conclude that the morphological heterogeneity of the hair canopy mirrors the flow complexity of an entire attack, from launch to grasp.
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Affiliation(s)
- Thomas Steinmann
- Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Université François Rabelais, 37200 Tours, France
| | - Jérôme Casas
- Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Université François Rabelais, 37200 Tours, France
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Affiliation(s)
- P. A. Lagos
- Department of Biological Sciences Macquarie University North Ryde Sydney NSW Australia
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Crall JD, Chang JJ, Oppenheimer RL, Combes SA. Foraging in an unsteady world: bumblebee flight performance in field-realistic turbulence. Interface Focus 2017; 7:20160086. [PMID: 28163878 DOI: 10.1098/rsfs.2016.0086] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Natural environments are characterized by variable wind that can pose significant challenges for flying animals and robots. However, our understanding of the flow conditions that animals experience outdoors and how these impact flight performance remains limited. Here, we combine laboratory and field experiments to characterize wind conditions encountered by foraging bumblebees in outdoor environments and test the effects of these conditions on flight. We used radio-frequency tags to track foraging activity of uniquely identified bumblebee (Bombus impatiens) workers, while simultaneously recording local wind flows. Despite being subjected to a wide range of speeds and turbulence intensities, we find that bees do not avoid foraging in windy conditions. We then examined the impacts of turbulence on bumblebee flight in a wind tunnel. Rolling instabilities increased in turbulence, but only at higher wind speeds. Bees displayed higher mean wingbeat frequency and stroke amplitude in these conditions, as well as increased asymmetry in stroke amplitude-suggesting that bees employ an array of active responses to enable flight in turbulence, which may increase the energetic cost of flight. Our results provide the first direct evidence that moderate, environmentally relevant turbulence affects insect flight performance, and suggest that flying insects use diverse mechanisms to cope with these instabilities.
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Affiliation(s)
- J D Crall
- Department of Organismic and Evolutionary Biology , Harvard University , Cambridge, MA , USA
| | - J J Chang
- Department of Neuroscience , Columbia University , New York, NY , USA
| | - R L Oppenheimer
- Department of Biological Sciences , University of New Hampshire , Durham, NH , USA
| | - S A Combes
- Department of Neurobiology, Physiology, and Behavior , University of California, Davis , Davis, CA , USA
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Gal S, Alpern S, Casas J. Prey should hide more randomly when a predator attacks more persistently. J R Soc Interface 2016; 12:20150861. [PMID: 26631332 DOI: 10.1098/rsif.2015.0861] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
When being searched for and then (if found) pursued by a predator, a prey animal has a choice between choosing very randomly among hiding locations so as to be hard to find or alternatively choosing a location from which it is more likely to successfully flee if found. That is, the prey can choose to be hard to find or hard to catch, if found. In our model, capture of prey requires both finding it and successfully pursuing it. We model this dilemma as a zero-sum repeated game between predator and prey, with the eventual capture probability as the pay-off to the predator. We find that the more random hiding strategy is better when the chances of repeated pursuit, which are known to be related to area topography, are high. Our results extend earlier results of Gal and Casas, where there was at most only a single pursuit. In that model, hiding randomly was preferred by the prey when the predator has only a few looks. Thus, our new multistage model shows that the effect of more potential looks is opposite. Our results can be viewed as a generalization of search games to the repeated game context and are in accordance with observed escape behaviour of different animals.
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Affiliation(s)
- Shmuel Gal
- Department of Statistics, University of Haifa, Haifa, Israel
| | - Steve Alpern
- ORMS Group, Warwick Business School, University of Warwick, Coventry CV4 7AL, UK
| | - Jérôme Casas
- Insitut Universitaire de France & Insitut de Recherches en Biologie de l'Insecte, UMR CNRS 7261, Université of Tours, Tours 37200, France
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Crall JD, Ravi S, Mountcastle AM, Combes SA. Bumblebee flight performance in cluttered environments: effects of obstacle orientation, body size and acceleration. ACTA ACUST UNITED AC 2016; 218:2728-37. [PMID: 26333927 DOI: 10.1242/jeb.121293] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Locomotion through structurally complex environments is fundamental to the life history of most flying animals, and the costs associated with movement through clutter have important consequences for the ecology and evolution of volant taxa. However, few studies have directly investigated how flying animals navigate through cluttered environments, or examined which aspects of flight performance are most critical for this challenging task. Here, we examined how body size, acceleration and obstacle orientation affect the flight of bumblebees in an artificial, cluttered environment. Non-steady flight performance is often predicted to decrease with body size, as a result of a presumed reduction in acceleration capacity, but few empirical tests of this hypothesis have been performed in flying animals. We found that increased body size is associated with impaired flight performance (specifically transit time) in cluttered environments, but not with decreased peak accelerations. In addition, previous studies have shown that flying insects can produce higher accelerations along the lateral body axis, suggesting that if maneuvering is constrained by acceleration capacity, insects should perform better when maneuvering around objects laterally rather than vertically. Our data show that bumblebees do generate higher accelerations in the lateral direction, but we found no difference in their ability to pass through obstacle courses requiring lateral versus vertical maneuvering. In sum, our results suggest that acceleration capacity is not a primary determinant of flight performance in clutter, as is often assumed. Rather than being driven by the scaling of acceleration, we show that the reduced flight performance of larger bees in cluttered environments is driven by the allometry of both path sinuosity and mean flight speed. Specifically, differences in collision-avoidance behavior underlie much of the variation in flight performance across body size, with larger bees negotiating obstacles more cautiously. Thus, our results show that cluttered environments challenge the flight capacity of insects, but in surprising ways that emphasize the importance of behavioral and ecological context for understanding flight performance in complex environments.
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Affiliation(s)
- James D Crall
- Concord Field Station, Department of Organismic and Evolutionary Biology, Harvard University, 100 Old Causeway Rd, Bedford, MA 01730, USA
| | - Sridhar Ravi
- School of Aerospace Mechanical and Manufacturing Engineering, RMIT University, Melbourne, VIC 3001, Australia
| | - Andrew M Mountcastle
- Concord Field Station, Department of Organismic and Evolutionary Biology, Harvard University, 100 Old Causeway Rd, Bedford, MA 01730, USA
| | - Stacey A Combes
- Concord Field Station, Department of Organismic and Evolutionary Biology, Harvard University, 100 Old Causeway Rd, Bedford, MA 01730, USA
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Casas J, Steinmann T. Predator-induced flow disturbances alert prey, from the onset of an attack. Proc Biol Sci 2015; 281:rspb.2014.1083. [PMID: 25030986 DOI: 10.1098/rspb.2014.1083] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Many prey species, from soil arthropods to fish, perceive the approach of predators, allowing them to escape just in time. Thus, prey capture is as important to predators as prey finding. We extend an existing framework for understanding the conjoint trajectories of predator and prey after encounters, by estimating the ratio of predator attack and prey danger perception distances, and apply it to wolf spiders attacking wood crickets. Disturbances to air flow upstream from running spiders, which are sensed by crickets, were assessed by computational fluid dynamics with the finite-elements method for a much simplified spider model: body size, speed and ground effect were all required to obtain a faithful representation of the aerodynamic signature of the spider, with the legs making only a minor contribution. The relationship between attack speed and the maximal distance at which the cricket can perceive the danger is parabolic; it splits the space defined by these two variables into regions differing in their values for this ratio. For this biological interaction, the ratio is no greater than one, implying immediate perception of the danger, from the onset of attack. Particular attention should be paid to the ecomechanical aspects of interactions with such small ratio, because of the high degree of bidirectional coupling of the behaviour of the two protagonists. This conclusion applies to several other predator-prey systems with sensory ecologies based on flow sensing, in air and water.
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Affiliation(s)
- Jérôme Casas
- Institut Universitaire de France IUF and Institut de Recherche sur la Biologie de l'Insecte, University of Tours, IRBI UMR CNRS 7261, Av. Monge, 37200 Tours, France
| | - Thomas Steinmann
- Institut Universitaire de France IUF and Institut de Recherche sur la Biologie de l'Insecte, University of Tours, IRBI UMR CNRS 7261, Av. Monge, 37200 Tours, France
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Droogendijk H, Casas J, Steinmann T, Krijnen GJM. Performance assessment of bio-inspired systems: flow sensing MEMS hairs. BIOINSPIRATION & BIOMIMETICS 2014; 10:016001. [PMID: 25524894 DOI: 10.1088/1748-3190/10/1/016001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Despite vigorous growth in biomimetic design, the performance of man-made devices relative to their natural templates is still seldom quantified, a procedure which would however significantly increase the rigour of the biomimetic approach. We applied the ubiquitous engineering concept of a figure of merit (FoM) to MEMS flow sensors inspired by cricket filiform hairs. A well known mechanical model of a hair is refined and tailored to this task. Five criteria of varying importance in the biological and engineering fields are computed: responsivity, power transfer, power efficiency, response time and detection threshold. We selected the metrics response time and detection threshold for building the FoM to capture the performance in a single number. Crickets outperform actual MEMS on all criteria for a large range of flow frequencies. Our approach enables us to propose several improvements for MEMS hair-sensor design.
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Affiliation(s)
- H Droogendijk
- MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands
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10
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Sharks modulate their escape behavior in response to predator size, speed and approach orientation. ZOOLOGY 2014; 117:377-82. [DOI: 10.1016/j.zool.2014.06.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 05/30/2014] [Accepted: 06/12/2014] [Indexed: 11/23/2022]
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Verdeny-Vilalta O, Aluja M, Casas J. Relative roles of resource stimulus and vegetation architecture on the paths of flies foraging for fruit. OIKOS 2014. [DOI: 10.1111/oik.01557] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Oriol Verdeny-Vilalta
- Dept of Functional and Evolutionary Ecology; Estación Experimental de Zonas Áridas (EEZA-CSIC). Carretera de Sacramento, s/n; ES-04120 La Cañada de San Urbano, Almería Spain
| | - Martín Aluja
- Inst. de Ecología, A.C.; Apartado Postal 63 MX-91000 Xalapa, Veracruz Mexico
| | - Jérôme Casas
- Inst. de Recherches sur la Biologie de l'Insecte, Univ. de Tours; IRBI UMR CNRS 7261, Av. Monge FR-37200 Tours France
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Gal S, Casas J. Succession of hide-seek and pursuit-evasion at heterogeneous locations. J R Soc Interface 2014; 11:20140062. [PMID: 24621817 DOI: 10.1098/rsif.2014.0062] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Many interactions between searching agents and their elusive targets are composed of a succession of steps, whether in the context of immune systems, predation or counterterrorism. In the simplest case, a two-step process starts with a search-and-hide phase, also called a hide-and-seek phase, followed by a round of pursuit-escape. Our aim is to link these two processes, usually analysed separately and with different models, in a single game theory context. We define a matrix game in which a searcher looks at a fixed number of discrete locations only once each searching for a hider, which can escape with varying probabilities according to its location. The value of the game is the overall probability of capture after k looks. The optimal search and hide strategies are described. If a searcher looks only once into any of the locations, an optimal hider chooses it's hiding place so as to make all locations equally attractive. This optimal strategy remains true as long as the number of looks is below an easily calculated threshold; however, above this threshold, the optimal position for the hider is where it has the highest probability of escaping once spotted.
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Affiliation(s)
- Shmuel Gal
- Department of Statistics, University of Haifa, , Haifa, Israel
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