scholarly journals Individual-based acoustic variation of the alarm calls in the long-tailed ground squirrel

2021 ◽  
Vol 8 (2) ◽  
Author(s):  
Denis Goncharov ◽  
Richard Policht ◽  
Lucie Hambálková ◽  
Viktor Salovarov ◽  
Vlastimil Hart
Keyword(s):  
Individual Variation ◽  
Ground Squirrel ◽  
Function Analysis ◽  
Individual Variability ◽  
Ground Squirrels ◽  
Alarm Calls ◽  
Phylogenetic Position ◽  
Vocal Individuality ◽  
The Individual ◽  
Acoustic Variation

Based on their phylogenetic position, Nearctic ground squirrels are closest relatives to the long-tailed ground squirrel Urocitellus undulates even though it has Palaearctic distribution. We aimed to investigate the variability of alarm calls of the long-tailed ground squirrel to test the individual variation in alarm calls. This species is known to produce two types of alarm calls: whistle alarms and wideband calls. Although ground squirrels are a model group for the study of vocal individuality, this phenomenon has not yet been studied in a species producing two such completely different types of alarms. Most of ground squirrel species produce either whistle or wideband alarms and this species represents a unique model for testing the degree of individual variability depending on completely different acoustic structures. We analysed 269 whistle alarms produced by 13 individuals and 591 wideband alarms from 25 individuals at the western part of Lake Baikal. A discriminant function analysis (DFA) assigned 93.5% (88.9%, cross-validated result) of whistle alarms to the correct individual and 91.4% (84%) of wideband alarms. This is the first evidence of individual variation in wideband alarms compared with whistle alarms and occurrence of vocal individuality in two warning signals of a completely different acoustic structure produced by a ground squirrel.

scholarly journals Geographic variability in the alarm calls of the European ground squirrel

2019 ◽  
Vol 66 (4) ◽  
pp. 407-415 ◽  
Author(s):  
Irena Schneiderová ◽  
Lucie Štefanská ◽  
Lukáš Kratochvíl
Keyword(s):  
Czech Republic ◽  
Ground Squirrel ◽  
Function Analysis ◽  
Mammalian Species ◽  
Ground Squirrels ◽  
Alarm Calls ◽  
Geographic Variability ◽  
The Czech Republic ◽  
Spermophilus Citellus ◽  
Different Origins

Abstract Geographic variability in vocalizations has been documented in many mammalian species. We examined to what extent it applies to the alarm calls of the European ground squirrel Spermophilus citellus. We recorded the calls of 82 adult individuals from 5 natural colonies in the Czech Republic and 24 adult individuals from an artificial seminatural colony located in a Czech zoo. The founders of this colony originated from 4 different natural colonies in the Czech Republic. Our results showed that there are hardly any differences in the acoustic structure of the alarm calls between male and female European ground squirrels. Discriminant function analysis showed the highest degree of discriminability for the most isolated sites (54–74% of individuals classified correctly), whereas the lowest degree of discriminability was found for 2 interconnected colonies (38–40% individuals classified correctly). Individuals from the artificial seminatural colony were often classified correctly to this colony (58% classified correctly); however, the precision of the classification was comparatively relatively low, that is, many individuals from other colonies were incorrectly classified into this seminatural colony. This likely corresponds to the different origins of its founders. These findings indicate that there is a rather substantial geographic variability in the alarm calls of the European ground squirrel, and our study highlights its possible impact on conservation measures such as establishing artificial colonies or reintroductions.

scholarly journals Frequency-modulated second elements of two-element alarm calls do not enhance discrimination of callers in three Eurasian ground squirrels

2012 ◽  
Vol 58 (5) ◽  
pp. 749-757 ◽  
Author(s):  
Irena Schneiderová
Keyword(s):  
Function Analysis ◽  
Basic Structure ◽  
Ground Squirrels ◽  
Alarm Calls ◽  
Acoustic Parameters ◽  
Other Information ◽  
Limited Frequency ◽  
Spermophilus Citellus ◽  
Individual Distinctiveness ◽  
The Individual

Abstract Alarm calls of the European Spermophilus citellus (EGS), Taurus S. taurensis (TGS) and Anatolian S. xanthoprymnus (AGS) ground squirrels share the same basic structure. They are tonal sounds consisting primarily of two different elements. The first element, often produced without the second element, has limited frequency modulation, while the second element is more frequency modulated. The present study examined whether this frequency-modulated element enhances the individual distinc-tiveness of calls, allowing calls to be ascribed with greater confidence to individual callers of the three species. Cross-validated discriminant function analysis (DFA) based on five acoustic parameters of the first element successfully classified calls to correct individuals (EGS: 90%, TGS: 98%, AGS: 96%). Cross-validated DFA based on five acoustic parameters of the second element was also successful in classifications (EGS: 88%, TGS: 86%, AGS: 96%), though discrimination of callers based on parameters of the second versus first element was the same for the AGS, lower for the EGS and significantly lower for the TGS. Cross-validated DFA based on five acoustic parameters of two-element calls also successfully classified calls to correct individuals (EGS: 93%, TGS: 98%, AGS: 97%), though did not improve the extent to which calls could be classified to individuals beyond that based on the first element alone. Thus, the second element does not enhance the individual distinctiveness of calls, but may convey other information such as the location of the caller.

scholarly journals Individual variation of the masticatory system dominates 3D skull shape in the herbivory-adapted marsupial wombats

2019 ◽  
Author(s):  
Vera Weisbecker ◽  
Thomas Guillerme ◽  
Cruise Speck ◽  
Emma Sherratt ◽  
Hyab Mehari Abraha ◽  
...  
Keyword(s):  
Individual Variation ◽  
Principal Component ◽  
Individual Variability ◽  
Shape Variation ◽  
Mandibular Ramus ◽  
Geometric Morphometric ◽  
Skull Shape ◽  
Marsupial Species ◽  
Masticatory System ◽  
The Individual

AbstractBackgroundWithin-species skull shape variation of marsupial mammals is widely considered low and strongly size-dependent (allometric), possibly due to developmental constraints arising from the altricial birth of marsupials. However, species whose skulls are impacted by strong muscular stresses – particularly those produced through mastication of tough food items – may not display such intrinsic patterns very clearly because of the known plastic response of bone to muscle activity of the individual. In such cases, shape variation should not be dominated by allometry; ordination of shape in a geometric morphometric context through principal component analysis (PCA) should reveal main variation in areas under masticatory stress (incisor region/zygomatic arches/mandibular ramus); but this main variation should emerge from high individual variability and thus have low eigenvalues.ResultsWe assessed the evidence for high individual variation through 3D geometric morphometric shape analysis of crania and mandibles of thre species of grazing-specialized wombats, whose diet of tough grasses puts considerable strain on their masticatory system. As expected, we found little allometry and low Principal Component 1 (PC1) eigenvalues within crania and mandibles of all three species. Also as expected, the main variation was in the muzzle, zygomatic arches, and masticatory muscle attachments of the mandibular ramus. We then implemented a new test to ask if the landmark variation reflected on PC1 was reflected in individuals with opposite PC1 scores and with opposite shapes in Procrustes space. This showed that correspondence between individual and ordinated shape variation was limited, indicating high levels of individual variability in the masticatory apparatus.DiscussionOur results are inconsistent with hypotheses that skull shape variation within marsupial species reflects a constraint pattern. Rather, they support suggestions that individual plasticity can be an important determinant of within-species shape variation in marsupials (and possibly other mammals) with high masticatory stresses, making it difficult to understand the degree to which intrinsic constraint act on shape variation at the within-species level. We conclude that studies that link micro- and macroevolutionary patterns of shape variation might benefit from a focus on species with low-impact mastication, such as carnivorous or frugivorous species.

scholarly journals The importance of individual variation in the dynamics of animal collective movements

2018 ◽  
Vol 373 (1746) ◽  
pp. 20170008 ◽  
Author(s):  
Maria del Mar Delgado ◽  
Maria Miranda ◽  
Silvia J. Alvarez ◽  
Eliezer Gurarie ◽  
William F. Fagan ◽  
...  
Keyword(s):  
Individual Variation ◽  
Decision Rules ◽  
Movement Ecology ◽  
Individual Variability ◽  
Collective Movement ◽  
Individual Based Models ◽  
Theoretical Investigations ◽  
Group Heterogeneity ◽  
Collective Movements ◽  
The Individual

Animal collective movements are a key example of a system that links two clearly defined levels of organization: the individual and the group. Most models investigating collective movements have generated coherent collective behaviours without the inclusion of individual variability. However, new individual-based models, together with emerging empirical information, emphasize that within-group heterogeneity may strongly influence collective movement behaviour. Here we (i) review the empirical evidence for individual variation in animal collective movements, (ii) explore how theoretical investigations have represented individual heterogeneity when modelling collective movements and (iii) present a model to show how within-group heterogeneity influences the collective properties of a group. Our review underscores the need to consider variability at the level of the individual to improve our understanding of how individual decision rules lead to emergent movement patterns, and also to yield better quantitative predictions of collective behaviour. This article is part of the theme issue ‘Collective movement ecology’.

scholarly journals The adaptive utility of Richardson’s ground squirrel (Spermophilus richardsonii) short-range ultrasonic alarm signals

2006 ◽  
Vol 84 (9) ◽  
pp. 1322-1330 ◽  
Author(s):  
David R. Wilson ◽  
James F. Hare
Keyword(s):  
Ground Squirrel ◽  
Ground Squirrels ◽  
Alarm Calls ◽  
Older Individuals ◽  
Alarm Signals ◽  
Active Space ◽  
Spermophilus Richardsonii ◽  
Ultrasonic Calls ◽  
Audible Alarm ◽  
Signal Type

Richardson’s ground squirrels ( Spermophilus richardsonii (Sabine, 1822)) produce audible (ca. 8 kHz) and (or) ultrasonic (ca. 48 kHz) alarm vocalizations that warn conspecifics of impending danger. Audible calls have a larger active space than ultrasonic calls because they travel farther, are louder, and contain frequencies to which conspecific and allospecific recipients are more sensitive. In our first experiment, we presented an alarming stimulus to 103 squirrels to examine the effect of threat proximity on signal type. The ratio of ultrasonic to audible alarm calls increased with increasing distance from the stimulus. We conclude that the size of the active space influences signalling strategy and that squirrels emitting ultrasonic calls can signal conspecifics to the exclusion of distant predators. As recipients of ultrasonic calls must be close to the signaler, one context in which ultrasonic calling may be most adaptive is during natal emergence when juveniles are particularly abundant, highly vulnerable to predation, and clustered in space. In our second experiment, we broadcast ultrasonic alarm signals to emerging juveniles and found that they, like older individuals, responded to calls by increasing vigilance. We discuss the adaptive utility of multiple signalling strategies in light of our findings.

INDIVIDUAL VARIATION IN THE ACOUSTIC BEHAVIOUR OF THE ADULT MALE LEOPARD SEAL, HYDRURGA LEPTONYX

Behaviour ◽  
2002 ◽  
Vol 139 (10) ◽  
pp. 1267-1286 ◽  
Author(s):  
Douglas Cato ◽  
Tracey Rogers
Keyword(s):  
Adult Male ◽  
Individual Variation ◽  
Individual Variability ◽  
Leopard Seal ◽  
Acoustic Characteristics ◽  
Signal Degradation ◽  
Distinct Individual ◽  
Acoustic Variation ◽  
High Degree ◽  
Solitary Species

AbstractVocalisations and vocalising bouts of adult male leopard seals recorded from the Prydz Bay region, East Antarctica, were compared to determine whether they showed individual variability. There were distinct individual patterns in the sequence of vocalisations within vocalising bouts. A sequence could be reliably ascribed to a particular individual with a high degree (83%) of certainty. Such sequences may carry information about the identity of the caller. Acoustic characteristics of the two most commonly used vocalisations, the high and low double trills, showed weak within individual variation. Although differences were observed among individuals in the high double trill few were observed in the low double trill consequently the low double trills of some individuals could not be reliably ascribed to any particular seal. For many species, individual variation occurs in acoustic characteristics of specific vocalisations rather than in the sequence in which the vocalisations are produced. The acoustic displays of solitary species such as the leopard seal, are constrained by the difficulties of detecting and recognising the signal at a distance. Vocalisation sequences may be less adversely affected by signal degradation and so could be effective for communicating information over distance. It has been suggested that individual acoustic variation is found primarily in gregarious species however findings from the current study suggest that solitary animals using long-range underwater acoustic displays may convey individual variability in their vocalising sequence patterns.

scholarly journals Individual variation of the masticatory system dominates 3D skull shape in the herbivory-adapted marsupial wombats

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Vera Weisbecker ◽  
Thomas Guillerme ◽  
Cruise Speck ◽  
Emma Sherratt ◽  
Hyab Mehari Abraha ◽  
...  
Keyword(s):  
Individual Variation ◽  
Principal Component ◽  
Individual Variability ◽  
Shape Variation ◽  
Mandibular Ramus ◽  
Geometric Morphometric ◽  
Skull Shape ◽  
Marsupial Species ◽  
Masticatory System ◽  
The Individual

Abstract Background Within-species skull shape variation of marsupial mammals is widely considered low and strongly size-dependent (allometric), possibly due to developmental constraints arising from the altricial birth of marsupials. However, species whose skulls are impacted by strong muscular stresses – particularly those produced through mastication of tough food items – may not display such intrinsic patterns very clearly because of the known plastic response of bone to muscle activity of the individual. In such cases, allometry may not dominate within-species shape variation, even if it is a driver of evolutionary shape divergence; ordination of shape in a geometric morphometric context through principal component analysis (PCA) should reveal main variation in areas under masticatory stress (incisor region/zygomatic arches/mandibular ramus); but this main variation should emerge from high individual variability and thus have low eigenvalues. Results We assessed the evidence for high individual variation through 3D geometric morphometric shape analysis of crania and mandibles of three species of grazing-specialized wombats, whose diet of tough grasses puts considerable strain on their masticatory system. As expected, we found little allometry and low Principal Component 1 (PC1) eigenvalues within crania and mandibles of all three species. Also as expected, the main variation was in the muzzle, zygomatic arches, and masticatory muscle attachments of the mandibular ramus. We then implemented a new test to ask if the landmark variation reflected on PC1 was reflected in individuals with opposite PC1 scores and with opposite shapes in Procrustes space. This showed that correspondence between individual and ordinated shape variation was limited, indicating high levels of individual variability in the masticatory apparatus. Discussion Our results are inconsistent with hypotheses that skull shape variation within marsupial species reflects a constraint pattern. Rather, they support suggestions that individual plasticity can be an important determinant of within-species shape variation in marsupials (and possibly other mammals) with high masticatory stresses, making it difficult to understand the degree to which intrinsic constraints act on shape variation at the within-species level. We conclude that studies that link micro- and macroevolutionary patterns of shape variation might benefit from a focus on species with low-impact mastication, such as carnivorous or frugivorous species.

scholarly journals A neurodevelopmental origin of behavioral individuality

2019 ◽  
Author(s):  
Gerit Arne Linneweber ◽  
Maheva Andriatsilavo ◽  
Suchetana Dutta ◽  
Liz Hellbruegge ◽  
Guangda Liu ◽  
...  
Keyword(s):  
Individual Variation ◽  
Neural Circuit ◽  
Control Object ◽  
Causal Link ◽  
Object Orientation ◽  
Individual Variability ◽  
Monocular Deprivation ◽  
The Individual ◽  
Developmental Noise ◽  
And Control

AbstractThe genome versus experience, or “Nature versus Nurture”, debate has dominated our understanding of individual behavioral variation. A third factor, namely variation in complex behavior potentially due to non-heritable “developmental noise” in brain development, has been largely ignored. Using the Drosophila vinegar fly we demonstrate a causal link between variation in brain wiring due to developmental noise, and behavioral individuality. A population of visual system neurons called DCNs shows non-heritable, inter-individual variation in right/left wiring asymmetry, and control object orientation in freely walking flies. We show that DCN wiring asymmetry predicts an individual’s object responses: the greater the asymmetry, the better the individual orients. Silencing DCNs abolishes correlations between anatomy and behavior, while inducing visual asymmetry via monocular deprivation “rescues” object orientation in DCN-symmetric individuals.One Sentence SummaryNon-heritable individual variation in neural circuit development underlies individual variability in behavior.

Inter-individual variation shapes the human microbiome

2019 ◽  
Vol 42 ◽  
Author(s):  
Emily F. Wissel ◽  
Leigh K. Smith
Keyword(s):  
Individual Differences ◽  
Individual Variation ◽  
Human Microbiome ◽  
Individual Variability ◽  
Microbiota Composition ◽  
Target Article ◽  
Microbiome Research

Abstract The target article suggests inter-individual variability is a weakness of microbiota-gut-brain (MGB) research, but we discuss why it is actually a strength. We comment on how accounting for individual differences can help researchers systematically understand the observed variance in microbiota composition, interpret null findings, and potentially improve the efficacy of therapeutic treatments in future clinical microbiome research.

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