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Celiker E, Woodrow C, Mhatre N, Montealegre-Z F. A numerical approach to investigating the mechanisms behind tonotopy in the bush-cricket inner-ear. FRONTIERS IN INSECT SCIENCE 2022; 2:957385. [PMID: 38468802 PMCID: PMC10926389 DOI: 10.3389/finsc.2022.957385] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 07/21/2022] [Indexed: 03/13/2024]
Abstract
Bush-crickets (or katydids) have sophisticated and ultrasonic ears located in the tibia of their forelegs, with a working mechanism analogous to the mammalian auditory system. Their inner-ears are endowed with an easily accessible hearing organ, the crista acustica (CA), possessing a spatial organisation that allows for different frequencies to be processed at specific graded locations within the structure. Similar to the basilar membrane in the mammalian ear, the CA contains mechanosensory receptors which are activated through the frequency dependent displacement of the CA. While this tonotopical arrangement is generally attributed to the gradual stiffness and mass changes along the hearing organ, the mechanisms behind it have not been analysed in detail. In this study, we take a numerical approach to investigate this mechanism in the Copiphora gorgonensis ear. In addition, we propose and test the effect of the different vibration transmission mechanisms on the displacement of the CA. The investigation was carried out by conducting finite-element analysis on a three-dimensional, idealised geometry of the C. gorgonensis inner-ear, which was based on precise measurements. The numerical results suggested that (i) even the mildest assumptions about stiffness and mass gradients allow for tonotopy to emerge, and (ii) the loading area and location for the transmission of the acoustic vibrations play a major role in the formation of tonotopy.
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Affiliation(s)
- Emine Celiker
- University of Lincoln, School of Life and Environmental Sciences, Joseph Banks Laboratories, Lincoln, United Kingdom
| | - Charlie Woodrow
- University of Lincoln, School of Life and Environmental Sciences, Joseph Banks Laboratories, Lincoln, United Kingdom
| | - Natasha Mhatre
- Department of Biology, Western University, London, ON, Canada
- Brain and Mind Institute, Western University, London, ON, Canada
| | - Fernando Montealegre-Z
- University of Lincoln, School of Life and Environmental Sciences, Joseph Banks Laboratories, Lincoln, United Kingdom
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Quantification of bush-cricket acoustic trachea mechanics using Atomic Force Microscopy nanoindentation. Acta Biomater 2022; 153:399-410. [DOI: 10.1016/j.actbio.2022.08.056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 08/22/2022] [Accepted: 08/23/2022] [Indexed: 11/23/2022]
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Warren B, Nowotny M. Bridging the Gap Between Mammal and Insect Ears – A Comparative and Evolutionary View of Sound-Reception. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.667218] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Insects must wonder why mammals have ears only in their head and why they evolved only one common principle of ear design—the cochlea. Ears independently evolved at least 19 times in different insect groups and therefore can be found in completely different body parts. The morphologies and functional characteristics of insect ears are as wildly diverse as the ecological niches they exploit. In both, insects and mammals, hearing organs are constrained by the same biophysical principles and their respective molecular processes for mechanotransduction are thought to share a common evolutionary origin. Due to this, comparative knowledge of hearing across animal phyla provides crucial insight into fundamental processes of auditory transduction, especially at the biomechanical and molecular level. This review will start by comparing hearing between insects and mammals in an evolutionary context. It will then discuss current findings about sound reception will help to bridge the gap between both research fields.
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Celiker E, Jonsson T, Montealegre-Z F. On the tympanic membrane impedance of the katydid Copiphora gorgonensis (Insecta: Orthoptera: Tettigoniidae). THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2020; 148:1952. [PMID: 33138497 DOI: 10.1121/10.0002119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 09/17/2020] [Indexed: 06/11/2023]
Abstract
Katydids (bush-crickets) are endowed with tympanal ears located in their forelegs' tibiae. The tympana are backed by an air-filled tube, the acoustic trachea, which transfers the sound stimulus from a spiracular opening on the thorax to the internal side of the tympanic membranes (TM). In katydids the sound stimulus reaches both the external and internal side of the membranes, and the tympanal vibrations are then transferred to the hearing organ crista acustica (CA) that contains the fluid-immersed mechanoreceptors. Hence the tympana are principally involved in transmitting and converting airborne sound into fluid vibrations that stimulate the auditory sensilla. Consequently, what is the transmission power to the CA? Are the TM tuned to a certain frequency? To investigate this, the surface normal acoustic impedance of the TM is calculated using finite-element analysis in the katydid Copiphora gorgonensis. From this, the reflectance and transmittance are obtained at the TM. Based on the impedance results obtained from the pressure recordings at TM and the velocity field calculations in the AT, in the frequency range 5-40 kHz, it is concluded that the tympana have considerably higher transmission around 23 kHz, corresponding to the dominant frequency of the male pure-tone calling song in this species.
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Affiliation(s)
- Emine Celiker
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln, LN6 7DL, United Kingdom
| | - Thorin Jonsson
- Institute of Biology, Universitätsplatz 2, Karl-Franzens-University Graz, 8010 Graz, Austria
| | - Fernando Montealegre-Z
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln, LN6 7DL, United Kingdom
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Abstract
Insect auditory receivers provide an excellent comparative resource to understand general principles of auditory transduction, but analysis of the electrophysiological properties of the auditory neurons has been hampered by their tiny size and inaccessibility. Here we pioneer patch-clamp recordings from the auditory neurons of Müller's organ of the desert locust Schistocerca gregaria to characterize dendritic spikes, axonal spikes, and the transduction current. We demonstrate that dendritic spikes, elicited by sound stimuli, trigger axonal spikes, and that both types are sodium and voltage dependent and blocked by TTX. Spontaneous discrete depolarizations summate upon acoustic stimulation to produce a graded transduction potential that in turn elicits the dendritic spikes. The transduction current of Group III neurons of Müller's organ, which are broadly tuned to 3 kHz, is blocked by three ion channel blockers (FM1-43, streptomycin, and 2-APB) that are known to block mechanotransduction channels. We investigated the contribution of the candidate mechanotransduction ion channel Nanchung-Inactive-which is expressed in Müller's organ-to the transduction current. A specific agonist of Nanchung-Inactive, pymetrozine, eliminates the sound-evoked transduction current while inducing a tonic depolarizing current of comparable amplitude. The Nanchung-Inactive ion channels, therefore, have the required conductance to carry the entire transduction current, and sound stimulation appears not to open any additional channels. The application of three mechanotransduction ion channel blockers prevented the pymetrozine-induced depolarizing current. This implies that either Nanchung-Inactive is, or forms part of, the mechanotransduction ion channel or it amplifies a relatively small current (<30 pA) produced by another mechanotransduction ion channel such as NompC.SIGNIFICANCE STATEMENT The mechanically activated ion channel underpinning hearing is not known. We have pioneered intracellular patch-clamp recordings from locust auditory neurons to unravel the role of the candidate mechanotransduction ion channel Nanchung-Inactive in auditory transduction in insects.
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Lakes-Harlan R, Scherberich J. Position-dependent hearing in three species of bushcrickets (Tettigoniidae, Orthoptera). ROYAL SOCIETY OPEN SCIENCE 2015; 2:140473. [PMID: 26543574 PMCID: PMC4632538 DOI: 10.1098/rsos.140473] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 05/14/2015] [Indexed: 06/05/2023]
Abstract
A primary task of auditory systems is the localization of sound sources in space. Sound source localization in azimuth is usually based on temporal or intensity differences of sounds between the bilaterally arranged ears. In mammals, localization in elevation is possible by transfer functions at the ear, especially the pinnae. Although insects are able to locate sound sources, little attention is given to the mechanisms of acoustic orientation to elevated positions. Here we comparatively analyse the peripheral hearing thresholds of three species of bushcrickets in respect to sound source positions in space. The hearing thresholds across frequencies depend on the location of a sound source in the three-dimensional hearing space in front of the animal. Thresholds differ for different azimuthal positions and for different positions in elevation. This position-dependent frequency tuning is species specific. Largest differences in thresholds between positions are found in Ancylecha fenestrata. Correspondingly, A. fenestrata has a rather complex ear morphology including cuticular folds covering the anterior tympanal membrane. The position-dependent tuning might contribute to sound source localization in the habitats. Acoustic orientation might be a selective factor for the evolution of morphological structures at the bushcricket ear and, speculatively, even for frequency fractioning in the ear.
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Montealegre-Z F, Robert D. Biomechanics of hearing in katydids. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2014; 201:5-18. [DOI: 10.1007/s00359-014-0976-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 11/20/2014] [Accepted: 11/26/2014] [Indexed: 12/19/2022]
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Hummel J, Wolf K, Kössl M, Nowotny M. Processing of simple and complex acoustic signals in a tonotopically organized ear. Proc Biol Sci 2014; 281:20141872. [PMID: 25339727 DOI: 10.1098/rspb.2014.1872] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Processing of complex signals in the hearing organ remains poorly understood. This paper aims to contribute to this topic by presenting investigations on the mechanical and neuronal response of the hearing organ of the tropical bushcricket species Mecopoda elongata to simple pure tone signals as well as to the conspecific song as a complex acoustic signal. The high-frequency hearing organ of bushcrickets, the crista acustica (CA), is tonotopically tuned to frequencies between about 4 and 70 kHz. Laser Doppler vibrometer measurements revealed a strong and dominant low-frequency-induced motion of the CA when stimulated with either pure tone or complex stimuli. Consequently, the high-frequency distal area of the CA is more strongly deflected by low-frequency-induced waves than by high-frequency-induced waves. This low-frequency dominance will have strong effects on the processing of complex signals. Therefore, we additionally studied the neuronal response of the CA to native and frequency-manipulated chirps. Again, we found a dominant influence of low-frequency components within the conspecific song, indicating that the mechanical vibration pattern highly determines the neuronal response of the sensory cells. Thus, we conclude that the encoding of communication signals is modulated by ear mechanics.
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Affiliation(s)
- Jennifer Hummel
- Institute of Cell Biology and Neuroscience, Goethe University, Max-von-Laue-Straße 13, 60438 Frankfurt am Main, Germany
| | - Konstantin Wolf
- Institute of Cell Biology and Neuroscience, Goethe University, Max-von-Laue-Straße 13, 60438 Frankfurt am Main, Germany
| | - Manfred Kössl
- Institute of Cell Biology and Neuroscience, Goethe University, Max-von-Laue-Straße 13, 60438 Frankfurt am Main, Germany
| | - Manuela Nowotny
- Institute of Cell Biology and Neuroscience, Goethe University, Max-von-Laue-Straße 13, 60438 Frankfurt am Main, Germany
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Montealegre-Z F, Jonsson T, Robson-Brown KA, Postles M, Robert D. Convergent evolution between insect and mammalian audition. Science 2012; 338:968-71. [PMID: 23162003 DOI: 10.1126/science.1225271] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In mammals, hearing is dependent on three canonical processing stages: (i) an eardrum collecting sound, (ii) a middle ear impedance converter, and (iii) a cochlear frequency analyzer. Here, we show that some insects, such as rainforest katydids, possess equivalent biophysical mechanisms for auditory processing. Although katydid ears are among the smallest in all organisms, these ears perform the crucial stage of air-to-liquid impedance conversion and signal amplification, with the use of a distinct tympanal lever system. Further along the chain of hearing, spectral sound analysis is achieved through dispersive wave propagation across a fluid substrate, as in the mammalian cochlea. Thus, two phylogenetically remote organisms, katydids and mammals, have evolved a series of convergent solutions to common biophysical problems, despite their reliance on very different morphological substrates.
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Affiliation(s)
- Fernando Montealegre-Z
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol, BS8 1UG, UK.
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Rajaraman K, Mhatre N, Jain M, Postles M, Balakrishnan R, Robert D. Low-pass filters and differential tympanal tuning in a paleotropical bushcricket with an unusually low frequency call. ACTA ACUST UNITED AC 2012; 216:777-87. [PMID: 23125342 DOI: 10.1242/jeb.078352] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Low-frequency sounds are advantageous for long-range acoustic signal transmission, but for small animals they constitute a challenge for signal detection and localization. The efficient detection of sound in insects is enhanced by mechanical resonance either in the tracheal or tympanal system before subsequent neuronal amplification. Making small structures resonant at low sound frequencies poses challenges for insects and has not been adequately studied. Similarly, detecting the direction of long-wavelength sound using interaural signal amplitude and/or phase differences is difficult for small animals. Pseudophylline bushcrickets predominantly call at high, often ultrasonic frequencies, but a few paleotropical species use lower frequencies. We investigated the mechanical frequency tuning of the tympana of one such species, Onomarchus uninotatus, a large bushcricket that produces a narrow bandwidth call at an unusually low carrier frequency of 3.2 kHz. Onomarchus uninotatus, like most bushcrickets, has two large tympanal membranes on each fore-tibia. We found that both these membranes vibrate like hinged flaps anchored at the dorsal wall and do not show higher modes of vibration in the frequency range investigated (1.5-20 kHz). The anterior tympanal membrane acts as a low-pass filter, attenuating sounds at frequencies above 3.5 kHz, in contrast to the high-pass filter characteristic of other bushcricket tympana. Responses to higher frequencies are partitioned to the posterior tympanal membrane, which shows maximal sensitivity at several broad frequency ranges, peaking at 3.1, 7.4 and 14.4 kHz. This partitioning between the two tympanal membranes constitutes an unusual feature of peripheral auditory processing in insects. The complex tracheal shape of O. uninotatus also deviates from the known tube or horn shapes associated with simple band-pass or high-pass amplification of tracheal input to the tympana. Interestingly, while the anterior tympanal membrane shows directional sensitivity at conspecific call frequencies, the posterior tympanal membrane is not directional at conspecific frequencies and instead shows directionality at higher frequencies.
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Affiliation(s)
- Kaveri Rajaraman
- Center for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India
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Palghat Udayashankar A, Kössl M, Nowotny M. Tonotopically arranged traveling waves in the miniature hearing organ of bushcrickets. PLoS One 2012; 7:e31008. [PMID: 22348035 PMCID: PMC3278424 DOI: 10.1371/journal.pone.0031008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 12/30/2011] [Indexed: 11/19/2022] Open
Abstract
Place based frequency discrimination (tonotopy) is a fundamental property of the coiled mammalian cochlea. Sound vibrations mechanically conducted to the hearing organ manifest themselves into slow moving waves that travel along the length of the organ, also referred to as traveling waves. These traveling waves form the basis of the tonotopic frequency representation in the inner ear of mammals. However, so far, due to the secure housing of the inner ear, these waves only could be measured partially over small accessible regions of the inner ear in a living animal. Here, we demonstrate the existence of tonotopically ordered traveling waves covering most of the length of a miniature hearing organ in the leg of bushcrickets in vivo using laser Doppler vibrometery. The organ is only 1 mm long and its geometry allowed us to investigate almost the entire length with a wide range of stimuli (6 to 60 kHz). The tonotopic location of the traveling wave peak was exponentially related to stimulus frequency. The traveling wave propagated along the hearing organ from the distal (high frequency) to the proximal (low frequency) part of the leg, which is opposite to the propagation direction of incoming sound waves. In addition, we observed a non-linear compression of the velocity response to varying sound pressure levels. The waves are based on the delicate micromechanics of cellular structures different to those of mammals. Hence place based frequency discrimination by traveling waves is a physical phenomenon that presumably evolved in mammals and bushcrickets independently.
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Affiliation(s)
- Arun Palghat Udayashankar
- AK Neurobiologie and Biosensorik, Institute of Cell Biology and Neuroscience, J.W. Goethe University, Frankfurt, Germany
| | - Manfred Kössl
- AK Neurobiologie and Biosensorik, Institute of Cell Biology and Neuroscience, J.W. Goethe University, Frankfurt, Germany
| | - Manuela Nowotny
- AK Neurobiologie and Biosensorik, Institute of Cell Biology and Neuroscience, J.W. Goethe University, Frankfurt, Germany
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Hummel J, Kössl M, Nowotny M. Sound-induced tympanal membrane motion in bushcrickets and its relationship to sensory output. ACTA ACUST UNITED AC 2012; 214:3596-604. [PMID: 21993788 DOI: 10.1242/jeb.054445] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the auditory system of bushcrickets, sound can reach the receptors via two different paths: (i) by acting on the outside of the tympana situated on both sides of each foreleg or (ii) through the acoustic trachea that opens at a spiracle on the thorax. While the spiracle is considered to be the main point of sound entry for higher audio and ultrasonic frequencies, the role of the tympana is still unclear. The tympana border the air-filled acoustic trachea as well as the fluid-filled haemolymph channel containing the receptor organs. To understand their role during sound transduction, the sound-induced neuronal response of the hearing organ was recorded in combination with measurement of tympanal membrane motion using laser-Doppler vibrometry. For far-field stimulation, the frequency of the most sensitive hearing (∼16 kHz) matched the frequency of a pronounced maximum of tympanal membrane vibration. A second maximum of tympanum motion at lower frequencies (∼7 kHz) was correlated with an increased nerve activity at higher intensities (>70 dB sound pressure level, SPL). These correlations support the hypothesis of functional coupling between tympanum motion and nerve activity. When sound stimuli were applied locally, through either the tympanum or the spiracle, significant differences between tympanum motion and nerve activity were found. These discrepancies show that tympanum motion and neuronal response are not coupled directly and that there is no linear relationship with the applied SPL. Taken together, these data verify a functional, albeit indirect, coupling of tympanum motion and sensory cell activity for one of the pronounced vibration maxima, which appears to represent a resonance frequency of the tympanum.
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Affiliation(s)
- Jennifer Hummel
- Department of Cell Biology and Neuroscience, AK Neurobiology and Biosensors, Max-von-Laue-Strasse 13, Goethe University Frankfurt am Main, 60438, 60323 Frankfurt am Main, Germany.
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Mhatre N, Bhattacharya M, Robert D, Balakrishnan R. Matching sender and receiver: poikilothermy and frequency tuning in a tree cricket. J Exp Biol 2011; 214:2569-78. [DOI: 10.1242/jeb.057612] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Animals communicate in non-ideal and noisy conditions. The primary method they use to improve communication efficiency is sender-receiver matching: the receiver's sensory mechanism filters the impinging signal based on the expected signal. In the context of acoustic communication in crickets, such a match is made in the frequency domain. The males broadcast a mate attraction signal, the calling song, in a narrow frequency band centred on the carrier frequency (CF), and the females are most sensitive to sound close to this frequency. In tree crickets, however, the CF changes with temperature. The mechanisms used by female tree crickets to accommodate this change in CF were investigated at the behavioural and biomechanical level. At the behavioural level, female tree crickets were broadly tuned and responded equally to CFs produced within the naturally occurring range of temperatures (18 to 27°C). To allow such a broad response, however, the transduction mechanisms that convert sound into mechanical and then neural signals must also have a broad response. The tympana of the female tree crickets exhibited a frequency response that was even broader than suggested by the behaviour. Their tympana vibrate with equal amplitude to frequencies spanning nearly an order of magnitude. Such a flat frequency response is unusual in biological systems and cannot be modelled as a simple mechanical system. This feature of the tree cricket auditory system not only has interesting implications for mate choice and species isolation but may also prove exciting for bio-mimetic applications such as the design of miniature low frequency microphones.
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Affiliation(s)
- Natasha Mhatre
- School of Biological Sciences, Woodland Road, University of Bristol, Bristol BS8 1UG, UK
| | - Monisha Bhattacharya
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India
| | - Daniel Robert
- School of Biological Sciences, Woodland Road, University of Bristol, Bristol BS8 1UG, UK
| | - Rohini Balakrishnan
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India
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Lomas K, Montealegre-Z F, Parsons S, Field LH, Robert D. Mechanical filtering for narrow-band hearing in the weta. J Exp Biol 2011; 214:778-85. [DOI: 10.1242/jeb.050187] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
This paper constitutes a major attempt to associate tympanic deflections with the mechanoreceptor organ location in an acoustic insect. The New Zealand tree weta (Hemideina thoracica) has tympanal ears located on each of the prothoracic tibiae. The tympana exhibit a sclerotized oval plate, membranous processes bulging out from the tibial cuticle and many loosely suspended ripples. We used microscanning laser Doppler vibrometry to determine how such a tympanal membrane vibrates in response to sound and whether the sclerotized region plays a role in hearing. The tympanum displays a single resonance at the calling frequency of the male, an unusual example of an insect tympana acting as a narrow bandpass filter. Both tympana resonate in phase with the stimulus and with each other. Histological sections show that the tympanal area is divided into two distinct regions, as in other ensiferans. An oval plate lies in the middle of a thickened region and is surrounded by a transparent and uniformly thin region. It is hinged dorsally to the tympanal rim and thus resembles the model of a ‘hinged flap’. The thickened region appears to act as a damping mass on the oscillation of the thin region, and vibration displacement is reduced in this area. The thinner area vibrates with higher amplitude, inducing mechanical pressure on the dorsal area adjacent to the crista acustica. We present a new model showing how the thickened region might confer a mechanical gain onto the activation of the crista acustica sensory neurons during the sound-induced oscillations.
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Affiliation(s)
- Kathryn Lomas
- University of Auckland, School of Biological Sciences, Private Bag 92019, Auckland 1142, New Zealand
| | - Fernando Montealegre-Z
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK
| | - Stuart Parsons
- University of Auckland, School of Biological Sciences, Private Bag 92019, Auckland 1142, New Zealand
| | - Larry H. Field
- School of Biological Sciences, University of Canterbury, Edward Percival Field Station, The Esplanade, Kaikoura 7300, New Zealand
| | - Daniel Robert
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK
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