1
|
Anthwal N, Urban DJ, Sadier A, Takenaka R, Spiro S, Simmons N, Behringer RR, Cretekos CJ, Rasweiler JJ, Sears KE. Insights into the formation and diversification of a novel chiropteran wing membrane from embryonic development. BMC Biol 2023; 21:101. [PMID: 37143038 PMCID: PMC10161559 DOI: 10.1186/s12915-023-01598-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 04/13/2023] [Indexed: 05/06/2023] Open
Abstract
BACKGROUND Through the evolution of novel wing structures, bats (Order Chiroptera) became the only mammalian group to achieve powered flight. This achievement preceded the massive adaptive radiation of bats into diverse ecological niches. We investigate some of the developmental processes that underlie the origin and subsequent diversification of one of the novel membranes of the bat wing: the plagiopatagium, which connects the fore- and hind limb in all bat species. RESULTS Our results suggest that the plagiopatagium initially arises through novel outgrowths from the body flank that subsequently merge with the limbs to generate the wing airfoil. Our findings further suggest that this merging process, which is highly conserved across bats, occurs through modulation of the programs controlling the development of the periderm of the epidermal epithelium. Finally, our results suggest that the shape of the plagiopatagium begins to diversify in bats only after this merging has occurred. CONCLUSIONS This study demonstrates how focusing on the evolution of cellular processes can inform an understanding of the developmental factors shaping the evolution of novel, highly adaptive structures.
Collapse
Affiliation(s)
- Neal Anthwal
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, USA
- Centre for Craniofacial and Regenerative Biology, King's College London, London, UK
| | - Daniel J Urban
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Champaign, USA
- Department of Mammalogy, Division of Vertebrate Biology, American Museum of Natural History, New York, USA
| | - Alexa Sadier
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, USA
- Department of Molecular, Cell, and Developmental Biology, UCLA, Los Angeles, USA
| | - Risa Takenaka
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, USA
| | | | - Nancy Simmons
- Department of Mammalogy, Division of Vertebrate Biology, American Museum of Natural History, New York, USA
| | - Richard R Behringer
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, USA
| | | | - John J Rasweiler
- Department of Obstetrics and Gynecology, State University of New York Downstate Medical Center, New York, USA
| | - Karen E Sears
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, USA.
- Department of Molecular, Cell, and Developmental Biology, UCLA, Los Angeles, USA.
| |
Collapse
|
2
|
Burchardt LS, Briefer EF, Knörnschild M. Novel ideas to further expand the applicability of rhythm analysis. Ecol Evol 2021; 11:18229-18237. [PMID: 35003669 PMCID: PMC8717299 DOI: 10.1002/ece3.8417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 11/10/2021] [Accepted: 11/16/2021] [Indexed: 11/24/2022] Open
Abstract
The temporal structure of animals' acoustic signals can inform about context, urgency, species, individual identity, or geographical origin. We present three independent ideas to further expand the applicability of rhythm analysis for isochronous, that is, metronome-like, rhythms. A description of a rhythm or beat needs to include a description of its goodness of fit, meaning how well the rhythm describes a sequence. Existing goodness-of-fit values are not comparable between methods and datasets. Furthermore, they are strongly correlated with certain parameters of the described sequence, for example, the number of elements in the sequence. We introduce a new universal goodness-of-fit value, ugof, comparable across methods and datasets, which illustrates how well a certain beat frequency in Hz describes the temporal structure of a sequence of elements. We then describe two additional approaches to adapt already existing methods to analyze the rhythm of acoustic sequences of animals. The new additions, a slightly modified way to use the already established Fourier analysis and concrete examples on how to use the visualization with recurrence plots, enable the analysis of more variable data, while giving more details than previously proposed measures. New methods are tested on 6 datasets including the very complex flight songs of male skylarks. The ugof is the first goodness-of-fit value capable of giving the information per element, instead of only per sequence. Advantages and possible interpretations of the new approaches are discussed. The new methods enable the analysis of more variable and complex communication signals. They give indications on which levels and structures to analyze and enable to track changes and differences in individuals or populations, for instance, during ontogeny or across regions. Especially, the ugof is not restricted to the analysis of acoustic signals but could for example also be applied on heartbeat measurements. Taken together, the ugof and proposed method additions greatly broaden the scope of rhythm analysis methods.
Collapse
Affiliation(s)
- Lara S. Burchardt
- Museum für Naturkunde ‐ Leibniz Institute for Evolution and Biodiversity ScienceBerlinGermany
- Institute of Animal BehaviorFreie Universität BerlinBerlinGermany
| | - Elodie F. Briefer
- Behavioural Ecology GroupSection for Ecology & EvolutionDepartment of BiologyUniversity of CopenhagenCopenhagen ØDenmark
- Université Paris‐SaclayUniversité Paris‐SudCNRSUMR 9197Institut des Neurosciences Paris‐SaclayOrsayFrance
| | - Mirjam Knörnschild
- Museum für Naturkunde ‐ Leibniz Institute for Evolution and Biodiversity ScienceBerlinGermany
- Institute of Animal BehaviorFreie Universität BerlinBerlinGermany
- Smithsonian Tropical Research InstituteBalboa AnconPanama
| |
Collapse
|
3
|
Rhinehart TA, Chronister LM, Devlin T, Kitzes J. Acoustic localization of terrestrial wildlife: Current practices and future opportunities. Ecol Evol 2020; 10:6794-6818. [PMID: 32724552 PMCID: PMC7381569 DOI: 10.1002/ece3.6216] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 03/02/2020] [Accepted: 03/04/2020] [Indexed: 01/17/2023] Open
Abstract
Autonomous acoustic recorders are an increasingly popular method for low-disturbance, large-scale monitoring of sound-producing animals, such as birds, anurans, bats, and other mammals. A specialized use of autonomous recording units (ARUs) is acoustic localization, in which a vocalizing animal is located spatially, usually by quantifying the time delay of arrival of its sound at an array of time-synchronized microphones. To describe trends in the literature, identify considerations for field biologists who wish to use these systems, and suggest advancements that will improve the field of acoustic localization, we comprehensively review published applications of wildlife localization in terrestrial environments. We describe the wide variety of methods used to complete the five steps of acoustic localization: (1) define the research question, (2) obtain or build a time-synchronizing microphone array, (3) deploy the array to record sounds in the field, (4) process recordings captured in the field, and (5) determine animal location using position estimation algorithms. We find eight general purposes in ecology and animal behavior for localization systems: assessing individual animals' positions or movements, localizing multiple individuals simultaneously to study their interactions, determining animals' individual identities, quantifying sound amplitude or directionality, selecting subsets of sounds for further acoustic analysis, calculating species abundance, inferring territory boundaries or habitat use, and separating animal sounds from background noise to improve species classification. We find that the labor-intensive steps of processing recordings and estimating animal positions have not yet been automated. In the near future, we expect that increased availability of recording hardware, development of automated and open-source localization software, and improvement of automated sound classification algorithms will broaden the use of acoustic localization. With these three advances, ecologists will be better able to embrace acoustic localization, enabling low-disturbance, large-scale collection of animal position data.
Collapse
Affiliation(s)
- Tessa A. Rhinehart
- Department of Biological SciencesUniversity of PittsburghPittsburghPAUSA
| | | | - Trieste Devlin
- Department of Biological SciencesUniversity of PittsburghPittsburghPAUSA
| | - Justin Kitzes
- Department of Biological SciencesUniversity of PittsburghPittsburghPAUSA
| |
Collapse
|
4
|
Burchardt LS, Knörnschild M. Comparison of methods for rhythm analysis of complex animals' acoustic signals. PLoS Comput Biol 2020; 16:e1007755. [PMID: 32267836 PMCID: PMC7141653 DOI: 10.1371/journal.pcbi.1007755] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 02/28/2020] [Indexed: 12/21/2022] Open
Abstract
Analyzing the rhythm of animals' acoustic signals is of interest to a growing number of researchers: evolutionary biologists want to disentangle how these structures evolved and what patterns can be found, and ecologists and conservation biologists aim to discriminate cryptic species on the basis of parameters of acoustic signals such as temporal structures. Temporal structures are also relevant for research on vocal production learning, a part of which is for the animal to learn a temporal structure. These structures, in other words, these rhythms, are the topic of this paper. How can they be investigated in a meaningful, comparable and universal way? Several approaches exist. Here we used five methods to compare their suitability and interpretability for different questions and datasets and test how they support the reproducibility of results and bypass biases. Three very different datasets with regards to recording situation, length and context were analyzed: two social vocalizations of Neotropical bats (multisyllabic, medium long isolation calls of Saccopteryx bilineata, and monosyllabic, very short isolation calls of Carollia perspicillata) and click trains of sperm whales, Physeter macrocephalus. Techniques to be compared included Fourier analysis with a newly developed goodness-of-fit value, a generate-and-test approach where data was overlaid with varying artificial beats, and the analysis of inter-onset-intervals and calculations of a normalized Pairwise Variability Index (nPVI). We discuss the advantages and disadvantages of the methods and we also show suggestions on how to best visualize rhythm analysis results. Furthermore, we developed a decision tree that will enable researchers to select a suitable and comparable method on the basis of their data.
Collapse
Affiliation(s)
- Lara S. Burchardt
- Museum für Naturkunde, Invalidenstraße, Berlin, Germany
- Animal Behavior Lab, Free University Berlin, Berlin, Germany
| | - Mirjam Knörnschild
- Museum für Naturkunde, Invalidenstraße, Berlin, Germany
- Animal Behavior Lab, Free University Berlin, Berlin, Germany
- Smithsonian Tropical Research Institute, Barro Colorado Island, Balboa, Ancón, Panamá
| |
Collapse
|
5
|
Hintze F, Arias-Aguilar A, Dias-Silva L, Delgado-Jaramillo M, Silva CR, Jucá T, Mischiatti FL, Almeida M, Bezerra B, Aguiar LMS, Ramos Pereira MJ, Bernard E. Molossid unlimited: extraordinary extension of range and unusual vocalization patterns of the bat, Promops centralis. J Mammal 2019. [DOI: 10.1093/jmammal/gyz167] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
The big crested mastiff bat, Promops centralis, occurs in Central and South America, but knowledge of its ecology is limited due to its open space hunting strategy, making captures extremely challenging. Notwithstanding, members of the species produce echolocation calls that are easy to identify. After recording calls of P. centralis 1,500 km away from its known range in Brazil, we hypothesized that the distribution range of this species was probably greatly underestimated. To improve the accuracy of P. centralis’ real distribution, we employed acoustic surveys throughout parts of Brazil, conducted after a bibliographic review to gather additional records, and used MaxEnt to model the species’ potential distribution. We have found that P. centralis has a much wider distribution in South America than previously thought, adding more than 3.8 million km2 to its former known area. We also describe an unusual vocalization pattern of P. centralis, with individuals emitting at least three very distinct but highly variable calls. This study shows that bioacoustic surveys and species distribution models can complement traditional methodologies in studying species that are difficult to capture, such as P. centralis, potentially contributing to more effective conservation and management plans.
Collapse
Affiliation(s)
- Frederico Hintze
- Laboratório de Ciência Aplicada à Conservação da Biodiversidade, Departamento de Zoologia, Universidade Federal de Pernambuco, Rua Professor Nelson Chaves s/n, Cidade Universitária, Recife, PE 50670-420, Brasil
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal de Pernambuco, Avenida Professor Moraes Rego s/n, Cidade Universitária, Recife, PE 50670-901, Brasil
| | - Adriana Arias-Aguilar
- Laboratório de Evolução, Sistemática e Ecologia de Aves e Mamíferos, Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Prédio 43435, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Porto Alegre, RS 91540-000, Brasil
| | - Leonardo Dias-Silva
- Laboratório de Ecologia & Conservação, Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Avenida Presidente Antônio Carlos 6.627, Campus UFMG, Pampulha, Belo Horizonte, MG 31270-901, Brasil
| | - Mariana Delgado-Jaramillo
- Laboratório de Ciência Aplicada à Conservação da Biodiversidade, Departamento de Zoologia, Universidade Federal de Pernambuco, Rua Professor Nelson Chaves s/n, Cidade Universitária, Recife, PE 50670-420, Brasil
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal de Pernambuco, Avenida Professor Moraes Rego s/n, Cidade Universitária, Recife, PE 50670-901, Brasil
| | - Carina Rodrigues Silva
- Laboratório de Ciência Aplicada à Conservação da Biodiversidade, Departamento de Zoologia, Universidade Federal de Pernambuco, Rua Professor Nelson Chaves s/n, Cidade Universitária, Recife, PE 50670-420, Brasil
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal de Pernambuco, Avenida Professor Moraes Rego s/n, Cidade Universitária, Recife, PE 50670-901, Brasil
| | - Thays Jucá
- Laboratório de Etologia, Departamento de Zoologia, Universidade Federal de Pernambuco, Avenida Professor Moraes Rego s/n, Cidade Universitária, Recife, PE 50670-901, Brasil
- Instituto de Ciências Biológicas, Universidade de Pernambuco, Rua Arnóbio Marques, 310, Santo Amaro, Recife, PE 50100-130, Brasil
| | - Francyne Lyrio Mischiatti
- Laboratório de Estudos em Quirópteros, Departamento de Ciências Biológicas, Edifício Lydia Behar, Centro de Ciências Humanas e Naturais, Universidade Federal do Espírito Santo, Avenida Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29075-910, Brasil
| | - Márcio Almeida
- Laboratório de Estudos em Quirópteros, Departamento de Ciências Biológicas, Edifício Lydia Behar, Centro de Ciências Humanas e Naturais, Universidade Federal do Espírito Santo, Avenida Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29075-910, Brasil
| | - Bruna Bezerra
- Laboratório de Etologia, Departamento de Zoologia, Universidade Federal de Pernambuco, Avenida Professor Moraes Rego s/n, Cidade Universitária, Recife, PE 50670-901, Brasil
| | - Ludmilla M S Aguiar
- Laboratório de Biologia e Conservação de Morcegos, Departamento de Zoologia, Instituto de Ciências Biológicas, Campus Darcy Ribeiro, Universidade de Brasília, Brasília, DF 70910-900, Brasil
| | - Maria João Ramos Pereira
- Laboratório de Evolução, Sistemática e Ecologia de Aves e Mamíferos, Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Prédio 43435, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Porto Alegre, RS 91540-000, Brasil
- Centro de Estudos do Ambiente e do Mar, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Enrico Bernard
- Laboratório de Ciência Aplicada à Conservação da Biodiversidade, Departamento de Zoologia, Universidade Federal de Pernambuco, Rua Professor Nelson Chaves s/n, Cidade Universitária, Recife, PE 50670-420, Brasil
| |
Collapse
|
6
|
Burchardt LS, Norton P, Behr O, Scharff C, Knörnschild M. General isochronous rhythm in echolocation calls and social vocalizations of the bat Saccopteryx bilineata. ROYAL SOCIETY OPEN SCIENCE 2019; 6:181076. [PMID: 30800360 PMCID: PMC6366212 DOI: 10.1098/rsos.181076] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 11/29/2018] [Indexed: 05/05/2023]
Abstract
Rhythm is an essential component of human speech and music but very little is known about its evolutionary origin and its distribution in animal vocalizations. We found a regular rhythm in three multisyllabic vocalization types (echolocation call sequences, male territorial songs and pup isolation calls) of the neotropical bat Saccopteryx bilineata. The intervals between element onsets were used to fit the rhythm for each individual. For echolocation call sequences, we expected rhythm frequencies around 6-24 Hz, corresponding to the wingbeat in S. bilineata which is strongly coupled to echolocation calls during flight. Surprisingly, we found rhythm frequencies between 6 and 24 Hz not only for echolocation sequences but also for social vocalizations, e.g. male territorial songs and pup isolation calls, which were emitted while bats were stationary. Fourier analysis of element onsets confirmed an isochronous rhythm across individuals and vocalization types. We speculate that attentional tuning to the rhythms of echolocation calls on the receivers' side might make the production of equally steady rhythmic social vocalizations beneficial.
Collapse
Affiliation(s)
- Lara S. Burchardt
- Institute of Animal Behavior, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
- Author for correspondence: Lara S. Burchardt e-mail:
| | - Philipp Norton
- Institute of Animal Behavior, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
| | - Oliver Behr
- University of Erlangen-Nuremberg, Paul-Gordan-Str. 3/5, 91052 Erlangen, Germany
| | - Constance Scharff
- Institute of Animal Behavior, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
| | - Mirjam Knörnschild
- Institute of Animal Behavior, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
- Smithsonian Tropical Research Institute, Barro Colorado Island, Roosevelt Avenue, Tupper Building – 401, Balboa, Ancón, Panamá
- Museum für Naturkunde – Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, 10115 Berlin, Germany
| |
Collapse
|
7
|
Abstract
Some parameters of echolocation signals can be studied using a single receiver. However, studying parameters such as source level, echolocation beam shape, and direction of signal emission require the use of multireceiver arrays. Acoustic localization allows for determination of the position of bats at the time of signal emission. When multiple animals are present, calls can be assigned to individuals based on their location. This combination makes large multireceiver arrays a powerful tool in bioacoustics research. Here, an overview of different array configurations used to record bats in the field is presented. In some studies, the absolute position of bats and not only relative to the array is crucial. Combining acoustic localizations from a source with geo-referenced receivers allows for determining geo-referenced movements of bats. Current applications of arrays aim to improve acoustic monitoring of bats and study anthropogenic impact.
Collapse
Affiliation(s)
- Jens C. Koblitz
- BioAcoustics Network, Neuss, Germany; Department of Collective Behaviour, Max Planck Institute for Ornithology, Radolfzell, Germany; Department of Biology, University of Constance, Konstanz, Germany
- BioAcoustics Network, Neuss, Germany; Department of Collective Behaviour, Max Planck Institute for Ornithology, Radolfzell, Germany; Department of Biology, University of Constance, Konstanz, Germany
| |
Collapse
|
8
|
Abstract
Why do humpback whales sing? This paper considers the hypothesis that humpback whales may use song for long range sonar. Given the vocal and social behavior of humpback whales, in several cases it is not apparent how they monitor the movements of distant whales or prey concentrations. Unless distant animals produce sounds, humpback whales are unlikely to be aware of their presence or actions. Some field observations are strongly suggestive of the use of song as sonar. Humpback whales sometimes stop singing and then rapidly approach distant whales in cases where sound production by those whales is not apparent, and singers sometimes alternately sing and swim while attempting to intercept another whale that is swimming evasively. In the evolutionary development of modern cetaceans, perceptual mechanisms have shifted from reliance on visual scanning to the active generation and monitoring of echoes. It is hypothesized that as the size and distance of relevant events increased, humpback whales developed adaptive specializations for long-distance echolocation. Differences between use of songs by humpback whales and use of sonar by other echolocating species are discussed, as are similarities between bat echolocation and singing by humpback whales. Singing humpback whales are known to emit sounds intense enough to generate echoes at long ranges, and to flexibly control the timing and qualities of produced sounds. The major problem for the hypothesis is the lack of recordings of echoes from other whales arriving at singers immediately before they initiate actions related to those whales. An earlier model of echoic processing by singing humpback whales is here revised to incorporate recent discoveries. According to the revised model, both direct echoes from targets and modulations in song-generated reverberation can provide singers with information that can help them make decisions about future actions related to mating, traveling, and foraging. The model identifies acoustic and structural features produced by singing humpback whales that may facilitate a singer's ability to interpret changes in echoic scenes and suggests that interactive signal coordination by singing whales may help them to avoid mutual interference. Specific, testable predictions of the model are presented.
Collapse
Affiliation(s)
- Eduardo Mercado III
- Department of Psychology, University at Buffalo, The State University of New York, Buffalo, NY, United States
- Evolution, Ecology, and Behavior Program, University at Buffalo, The State University of New York, Buffalo, NY, United States
| |
Collapse
|
9
|
Russo D, Ancillotto L, Jones G. Bats are still not birds in the digital era: echolocation call variation and why it matters for bat species identification. CAN J ZOOL 2018. [DOI: 10.1139/cjz-2017-0089] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The recording and analysis of echolocation calls are fundamental methods used to study bat distribution, ecology, and behavior. However, the goal of identifying bats in flight from their echolocation calls is not always possible. Unlike bird songs, bat calls show large variation that often makes identification challenging. The problem has not been fully overcome by modern digital-based hardware and software for bat call recording and analysis. Besides providing fundamental insights into bat physiology, ecology, and behavior, a better understanding of call variation is therefore crucial to best recognize limits and perspectives of call classification. We provide a comprehensive overview of sources of interspecific and intraspecific echolocation call variations, illustrating its adaptive significance and highlighting gaps in knowledge. We remark that further research is needed to better comprehend call variation and control for it more effectively in sound analysis. Despite the state-of-art technology in this field, combining acoustic surveys with capture and roost search, as well as limiting identification to species with distinctive calls, still represent the safest way of conducting bat surveys.
Collapse
Affiliation(s)
- Danilo Russo
- Wildlife Research Unit, Dipartimento di Agraria, Università degli Studi di Napoli Federico II, 80055 Portici, Italy
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, United Kingdom
| | - Leonardo Ancillotto
- Wildlife Research Unit, Dipartimento di Agraria, Università degli Studi di Napoli Federico II, 80055 Portici, Italy
| | - Gareth Jones
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, United Kingdom
| |
Collapse
|
10
|
Thiagavel J, Cechetto C, Santana SE, Jakobsen L, Warrant EJ, Ratcliffe JM. Auditory opportunity and visual constraint enabled the evolution of echolocation in bats. Nat Commun 2018; 9:98. [PMID: 29311648 PMCID: PMC5758785 DOI: 10.1038/s41467-017-02532-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 12/07/2017] [Indexed: 11/09/2022] Open
Abstract
Substantial evidence now supports the hypothesis that the common ancestor of bats was nocturnal and capable of both powered flight and laryngeal echolocation. This scenario entails a parallel sensory and biomechanical transition from a nonvolant, vision-reliant mammal to one capable of sonar and flight. Here we consider anatomical constraints and opportunities that led to a sonar rather than vision-based solution. We show that bats' common ancestor had eyes too small to allow for successful aerial hawking of flying insects at night, but an auditory brain design sufficient to afford echolocation. Further, we find that among extant predatory bats (all of which use laryngeal echolocation), those with putatively less sophisticated biosonar have relatively larger eyes than do more sophisticated echolocators. We contend that signs of ancient trade-offs between vision and echolocation persist today, and that non-echolocating, phytophagous pteropodid bats may retain some of the necessary foundations for biosonar.
Collapse
Affiliation(s)
- Jeneni Thiagavel
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Clément Cechetto
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230, Odense C, Denmark
| | - Sharlene E Santana
- Department of Biology and Burke Museum of Natural History and Culture, University of Washington, Seattle, WA, 98195, USA
| | - Lasse Jakobsen
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230, Odense C, Denmark
| | - Eric J Warrant
- Department of Biology, Lund University, Sölvegatan 35, 22362, Lund, Sweden
| | - John M Ratcliffe
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada. .,Department of Biology, University of Southern Denmark, Campusvej 55, 5230, Odense C, Denmark. .,Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, ON, L5L 1C6, Canada. .,Department of Natural History, Royal Ontario Museum, 100 Queens Park, Toronto, ON, M5S 2C6, Canada.
| |
Collapse
|
11
|
Corcoran AJ, Moss CF. Sensing in a noisy world: lessons from auditory specialists, echolocating bats. J Exp Biol 2017; 220:4554-4566. [DOI: 10.1242/jeb.163063] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ABSTRACT
All animals face the essential task of extracting biologically meaningful sensory information from the ‘noisy’ backdrop of their environments. Here, we examine mechanisms used by echolocating bats to localize objects, track small prey and communicate in complex and noisy acoustic environments. Bats actively control and coordinate both the emission and reception of sound stimuli through integrated sensory and motor mechanisms that have evolved together over tens of millions of years. We discuss how bats behave in different ecological scenarios, including detecting and discriminating target echoes from background objects, minimizing acoustic interference from competing conspecifics and overcoming insect noise. Bats tackle these problems by deploying a remarkable array of auditory behaviors, sometimes in combination with the use of other senses. Behavioral strategies such as ceasing sonar call production and active jamming of the signals of competitors provide further insight into the capabilities and limitations of echolocation. We relate these findings to the broader topic of how animals extract relevant sensory information in noisy environments. While bats have highly refined abilities for operating under noisy conditions, they face the same challenges encountered by many other species. We propose that the specialized sensory mechanisms identified in bats are likely to occur in analogous systems across the animal kingdom.
Collapse
Affiliation(s)
- Aaron J. Corcoran
- Department of Biology, Wake Forest University, Box 7325 Reynolda Station, Winston-Salem, NC 27109, USA
| | - Cynthia F. Moss
- Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| |
Collapse
|
12
|
Ter Hofstede HM, Ratcliffe JM. Evolutionary escalation: the bat-moth arms race. ACTA ACUST UNITED AC 2017; 219:1589-602. [PMID: 27252453 DOI: 10.1242/jeb.086686] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Echolocation in bats and high-frequency hearing in their insect prey make bats and insects an ideal system for studying the sensory ecology and neuroethology of predator-prey interactions. Here, we review the evolutionary history of bats and eared insects, focusing on the insect order Lepidoptera, and consider the evidence for antipredator adaptations and predator counter-adaptations. Ears evolved in a remarkable number of body locations across insects, with the original selection pressure for ears differing between groups. Although cause and effect are difficult to determine, correlations between hearing and life history strategies in moths provide evidence for how these two variables influence each other. We consider life history variables such as size, sex, circadian and seasonal activity patterns, geographic range and the composition of sympatric bat communities. We also review hypotheses on the neural basis for anti-predator behaviours (such as evasive flight and sound production) in moths. It is assumed that these prey adaptations would select for counter-adaptations in predatory bats. We suggest two levels of support for classifying bat traits as counter-adaptations: traits that allow bats to eat more eared prey than expected based on their availability in the environment provide a low level of support for counter-adaptations, whereas traits that have no other plausible explanation for their origination and maintenance than capturing defended prey constitute a high level of support. Specific predator counter-adaptations include calling at frequencies outside the sensitivity range of most eared prey, changing the pattern and frequency of echolocation calls during prey pursuit, and quiet, or 'stealth', echolocation.
Collapse
Affiliation(s)
- Hannah M Ter Hofstede
- Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA
| | - John M Ratcliffe
- Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, ON, Canada L5L 1C6
| |
Collapse
|
13
|
Brinkløv S, Elemans CPH, Ratcliffe JM. Oilbirds produce echolocation signals beyond their best hearing range and adjust signal design to natural light conditions. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170255. [PMID: 28573036 PMCID: PMC5451837 DOI: 10.1098/rsos.170255] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 04/25/2017] [Indexed: 06/07/2023]
Abstract
Oilbirds are active at night, foraging for fruits using keen olfaction and extremely light-sensitive eyes, and echolocate as they leave and return to their cavernous roosts. We recorded the echolocation behaviour of wild oilbirds using a multi-microphone array as they entered and exited their roosts under different natural light conditions. During echolocation, the birds produced click bursts (CBs) lasting less than 10 ms and consisting of a variable number (2-8) of clicks at 2-3 ms intervals. The CBs have a bandwidth of 7-23 kHz at -6 dB from signal peak frequency. We report on two unique characteristics of this avian echolocation system. First, oilbirds reduce both the energy and number of clicks in their CBs under conditions of clear, moonlit skies, compared with dark, moonless nights. Second, we document a frequency mismatch between the reported best frequency of oilbird hearing (approx. 2 kHz) and the bandwidth of their echolocation CBs. This unusual signal-to-sensory system mismatch probably reflects avian constraints on high-frequency hearing but may still allow oilbirds fine-scale, close-range detail resolution at the upper extreme (approx. 10 kHz) of their presumed hearing range. Alternatively, oilbirds, by an as-yet unknown mechanism, are able to hear frequencies higher than currently appreciated.
Collapse
Affiliation(s)
- Signe Brinkløv
- Sound Communication and Behaviour Group, Department of Biology, University of Southern Denmark, 5230 Odense M, Denmark
| | - Coen P. H. Elemans
- Sound Communication and Behaviour Group, Department of Biology, University of Southern Denmark, 5230 Odense M, Denmark
| | - John M. Ratcliffe
- Sound Communication and Behaviour Group, Department of Biology, University of Southern Denmark, 5230 Odense M, Denmark
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, CanadaL5C 1C6
| |
Collapse
|
14
|
Ing RK, Colombo R, Gembu GC, Bas Y, Julien JF, Gager Y, Hassanin A. Echolocation Calls and Flight Behaviour of the Elusive Pied Butterfly Bat (Glauconycteris superba), and New Data on Its Morphology and Ecology. ACTA CHIROPTEROLOGICA 2016. [DOI: 10.3161/15081109acc2016.18.2.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Ros Kiri Ing
- Institut Langevin, UMR 7587 CNRS, Université Paris Diderot (Paris 7), 1 rue Jussieu, 75238 PARIS Cedex 05, France
| | - Raphaël Colombo
- Asellia Ecologie, 60 chemin de la Nuirie, 04200 Sisteron, France
| | - Guy-Crispin Gembu
- Faculté des Sciences, Université de Kisangani, République Démocratique du Congo
| | - Yves Bas
- Centre d'Ecologie et de Sciences de la Conservation, UMR 7204 CNRS MNHN, Museum national d'Histoire naturelle, 43, rue Buffon, 75005 Paris, France
| | - Jean-François Julien
- Centre d'Ecologie et de Sciences de la Conservation, UMR 7204 CNRS MNHN, Museum national d'Histoire naturelle, 43, rue Buffon, 75005 Paris, France
| | - Yann Gager
- Department of Migration and Immuno-Ecology, Max Planck Institute for Ornithology, 78315 Radolfzell, Germany
| | - Alexandre Hassanin
- Institut de Systématique, Evolution, Biodiversité, UMR 7205 CNRS MNHN UPMC, Muséum national d'Histoire naturelle, 55, rue Buffon, 75005 Paris, France
| |
Collapse
|
15
|
Clutter and conspecifics: a comparison of their influence on echolocation and flight behaviour in Daubenton's bat, Myotis daubentonii. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2015; 201:295-304. [PMID: 25552318 DOI: 10.1007/s00359-014-0977-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 11/12/2014] [Accepted: 12/22/2014] [Indexed: 10/24/2022]
Abstract
We compared the influence of conspecifics and clutter on echolocation and flight speed in the bat Myotis daubentonii. In a large room, actual pairs of bats exhibited greater disparity in peak frequency (PF), minimum frequency (F MIN) and call period compared to virtual pairs of bats, each flying alone. Greater inter-individual disparity in PF and F MIN may reduce acoustic interference and/or increase signal self-recognition in the presence of conspecifics. Bats flying alone in a smaller flight room, to simulate a more cluttered habitat as compared to the large flight room, produced calls of shorter duration and call period, lower intensity, and flew at lower speeds. In cluttered space, shorter call duration should reduce masking, while shorter call period equals more updates to the bat's auditory scene. Lower intensity likely reflects reduced range detection requirements, reduced speed the demands of flying in clutter. Our results show that some changes (e.g. PF separation) are associated with conspecifics, others with closed habitat (e.g. reduced call intensity). However, we demonstrate that call duration, period, and flight speed appear similarly influenced by conspecifics and clutter. We suggest that some changes reduce conspecific interference and/or improve self-recognition, while others demonstrate that bats experience each other like clutter.
Collapse
|
16
|
|
17
|
Mora EC, Fernández Y, Hechavarría J, Pérez M. Tone-deaf ears in moths may limit the acoustic detection of two-tone bats. BRAIN, BEHAVIOR AND EVOLUTION 2014; 83:275-85. [PMID: 24942265 DOI: 10.1159/000361035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 08/21/2013] [Indexed: 11/19/2022]
Abstract
Frequency alternation in the echolocation of insectivorous bats has been interpreted in relation to ranging and duty cycle, i.e. advantages for echolocation. The shifts in frequency of the calls of these so-called two-tone bats, however, may also play its role in the success of their hunting behavior for a preferred prey, the tympanate moth. How the auditory receptors (e.g. the A1 and A2 cells) in the moth's ear detect such frequency shifts is currently unknown. Here, we measured the auditory responses of the A1 cell in the noctuid Spodoptera frugiperda to the echolocation hunting sequence of Molossus molossus, a two-tone bat. We also manipulated the bat calls to control for the frequency shifts by lowering the frequency band of the search and approach calls. The firing response of the A1 receptor cell significantly decreases with the shift to higher frequencies during the search and approach phases of the hunting sequence of M. molossus; this could be explained by the receptor's threshold curve. The frequency dependence of the decrease in the receptor's response is supported by the results attained with the manipulated sequence: search and approach calls with the same minimum frequency are detected by the moth at the same threshold intensity. The two-tone bat M. molossus shows a call frequency alternation behavior that may enable it to overcome moth audition even in the mid-frequency range (i.e. 20-50 kHz) where moths hear best.
Collapse
Affiliation(s)
- Emanuel C Mora
- Research Group in Bioacoustics and Neuroethology, Department of Animal and Human Biology, Faculty of Biology, Havana University, Havana, Cuba
| | | | | | | |
Collapse
|
18
|
Fenton B, Jensen FH, Kalko EKV, Tyack PL. Sonar Signals of Bats and Toothed Whales. BIOSONAR 2014. [DOI: 10.1007/978-1-4614-9146-0_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
|
19
|
Denzinger A, Schnitzler HU. Bat guilds, a concept to classify the highly diverse foraging and echolocation behaviors of microchiropteran bats. Front Physiol 2013; 4:164. [PMID: 23840190 PMCID: PMC3699716 DOI: 10.3389/fphys.2013.00164] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 06/13/2013] [Indexed: 11/23/2022] Open
Abstract
Throughout evolution the foraging and echolocation behaviors as well as the motor systems of bats have been adapted to the tasks they have to perform while searching and acquiring food. When bats exploit the same class of environmental resources in a similar way, they perform comparable tasks and thus share similar adaptations independent of their phylogeny. Species with similar adaptations are assigned to guilds or functional groups. Habitat type and foraging mode mainly determine the foraging tasks and thus the adaptations of bats. Therefore, we use habitat type and foraging mode to define seven guilds. The habitat types open, edge and narrow space are defined according to the bats' echolocation behavior in relation to the distance between bat and background or food item and background. Bats foraging in the aerial, trawling, flutter detecting, or active gleaning mode use only echolocation to acquire their food. When foraging in the passive gleaning mode bats do not use echolocation but rely on sensory cues from the food item to find it. Bat communities often comprise large numbers of species with a high diversity in foraging areas, foraging modes, and diets. The assignment of species living under similar constraints into guilds identifies patterns of community structure and helps to understand the factors that underlie the organization of highly diverse bat communities. Bat species from different guilds do not compete for food as they differ in their foraging behavior and in the environmental resources they use. However, sympatric living species belonging to the same guild often exploit the same class of resources. To avoid competition they should differ in their niche dimensions. The fine grain structure of bat communities below the rather coarse classification into guilds is determined by mechanisms that result in niche partitioning.
Collapse
Affiliation(s)
- Annette Denzinger
- Animal Physiology, Institute for Neurobiology, University of Tübingen Tübingen, Germany
| | | |
Collapse
|
20
|
|
21
|
Knörnschild M, Jung K, Nagy M, Metz M, Kalko E. Bat echolocation calls facilitate social communication. Proc Biol Sci 2012; 279:4827-35. [PMID: 23034703 DOI: 10.1098/rspb.2012.1995] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Bat echolocation is primarily used for orientation and foraging but also holds great potential for social communication. The communicative function of echolocation calls is still largely unstudied, especially in the wild. Eavesdropping on vocal signatures encoding social information in echolocation calls has not, to our knowledge, been studied in free-living bats so far. We analysed echolocation calls of the polygynous bat Saccopteryx bilineata and found pronounced vocal signatures encoding sex and individual identity. We showed experimentally that free-living males discriminate approaching male and female conspecifics solely based on their echolocation calls. Males always produced aggressive vocalizations when hearing male echolocation calls and courtship vocalizations when hearing female echolocation calls; hence, they responded with complex social vocalizations in the appropriate social context. Our study demonstrates that social information encoded in bat echolocation calls plays a crucial and hitherto underestimated role for eavesdropping conspecifics and thus facilitates social communication in a highly mobile nocturnal mammal.
Collapse
Affiliation(s)
- Mirjam Knörnschild
- Institute of Experimental Ecology, University of Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany.
| | | | | | | | | |
Collapse
|
22
|
Jakobsen L, Kalko EKV, Surlykke A. Echolocation beam shape in emballonurid bats, Saccopteryx bilineata and Cormura brevirostris. Behav Ecol Sociobiol 2012. [DOI: 10.1007/s00265-012-1404-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
23
|
Stilz WP, Schnitzler HU. Estimation of the acoustic range of bat echolocation for extended targets. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2012; 132:1765-1775. [PMID: 22978903 DOI: 10.1121/1.4733537] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Extended natural structures of the bat environment such as trees, meadows, and water surfaces were ensonified in distances from 1 to 20 m and the echoes recorded using a mobile ultrasonic sonar system. By compensating the atmospheric attenuation, the attenuation of the reflected echo caused by diffraction, energy absorption of the target, and two-way-geometric spreading was calculated for each distance. For each target type the attenuation of the compensated echo sound pressure level was fitted over distance using a linear function which yields simple laws of reflection loss and geometric spreading. By adding to this function again variable atmospheric attenuation, the overall attenuation of a signal reflected from these targets can be estimated for various conditions. Given the dynamic range of a sonar system, the acoustic maximum detection distance can thus be estimated. The results show that the maximum range is dominantly limited by atmospheric attenuation. Energy loss in the reflecting surface is more variable than geometric spreading loss and accounts for most of the differences between the ensonified targets. Depending on atmospheric conditions, echolocation frequency, and the dynamic range of the sonar system, the maximum range for extended backgrounds such as a forest edge can be as short as 2.4 m.
Collapse
Affiliation(s)
- Wolfram-Peter Stilz
- Animal Physiology, Institute for Neurobiology, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany.
| | | |
Collapse
|
24
|
Voigt CC, Lewanzik D. 'No cost of echolocation for flying bats' revisited. J Comp Physiol B 2012; 182:831-40. [PMID: 22526262 DOI: 10.1007/s00360-012-0663-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2012] [Revised: 03/21/2012] [Accepted: 04/03/2012] [Indexed: 11/29/2022]
Abstract
Echolocation is energetically costly for resting bats, but previous experiments suggested echolocation to come at no costs for flying bats. Yet, previous studies did not investigate the relationship between echolocation, flight speed, aerial manoeuvres and metabolism. We re-evaluated the 'no-cost' hypothesis, by quantifying the echolocation pulse rate, the number of aerial manoeuvres (landings and U-turns), and the costs of transport in the 5-g insectivorous bat Rhogeessa io (Vespertilionidae). On average, bats (n = 15) travelled at 1.76 ± 0.36 m s⁻¹ and performed 11.2 ± 6.1 U-turns and 2.8 ± 2.9 ground landings when flying in an octagonal flight cage. Bats made more U-turns with decreasing wing loading (body weight divided by wing area). At flight, bats emitted 19.7 ± 2.7 echolocation pulses s⁻¹ (range 15.3-25.8 pulses s⁻¹), and metabolic rate averaged 2.84 ± 0.95 ml CO₂ min⁻¹, which was more than 16 times higher than at rest. Bats did not echolocate while not engaged in flight. Costs of transport were not related to the rate of echolocation pulse emission or the number of U-turns, but increased with increasing number of landings; probably as a consequence of slower travel speed when staying briefly on ground. Metabolic power of flight was lower than predicted for R. io under the assumption that energetic costs of echolocation call production is additive to the aerodynamic costs of flight. Results of our experiment are consistent with the notion that echolocation does not add large energetic costs to the aerodynamic power requirements of flight in bats.
Collapse
Affiliation(s)
- Christian C Voigt
- Evolutionary Ecology Research Group, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany.
| | | |
Collapse
|
25
|
Moss CF, Chiu C, Surlykke A. Adaptive vocal behavior drives perception by echolocation in bats. Curr Opin Neurobiol 2011; 21:645-52. [PMID: 21705213 DOI: 10.1016/j.conb.2011.05.028] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 05/19/2011] [Accepted: 05/27/2011] [Indexed: 11/29/2022]
Abstract
Echolocation operates through adaptive sensorimotor systems that collectively enable the bat to localize and track sonar objects as it flies. The features of sonar signals used by a bat to probe its surroundings determine the information available to its acoustic imaging system. In turn, the bat's perception of a complex scene guides its active adjustments in the features of subsequent sonar vocalizations. Here, we propose that the bat's active vocal-motor behaviors play directly into its representation of a dynamic auditory scene.
Collapse
Affiliation(s)
- Cynthia F Moss
- University of Maryland, Department of Psychology, Biology-Psychology Building, College Park, MD 20742, United States.
| | | | | |
Collapse
|
26
|
Ecology and neuroethology of bat echolocation: a tribute to Gerhard Neuweiler. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2011; 197:399-402. [DOI: 10.1007/s00359-011-0633-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 02/10/2011] [Accepted: 02/12/2011] [Indexed: 10/18/2022]
|