ORCID Profile
0000-0002-2260-8143
Current Organisations
University of Western Australia
,
University of Bristol
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Proceedings of the National Academy of Sciences
Date: 29-08-2022
Abstract: Efforts to understand human social evolution rely largely on comparisons with nonhuman primates. However, a population of bottlenose dolphins in Shark Bay, Western Australia, combines a chimpanzee-like fission-fusion grouping pattern, mating system, and life history with the only nonhuman ex le of strategic multilevel male alliances. Unrelated male dolphins form three alliance levels, or “orders”, in competition over females: both within-group alliances (i.e., first- and second-order) and between-group alliances (third-order), based on cooperation between two or more second-order alliances against other groups. Both sexes navigate an open society with a continuous mosaic of overlapping home ranges. Here, we use comprehensive association and consortship data to examine fine-scale alliance relationships among 121 adult males. This analysis reveals the largest nonhuman alliance network known, with highly differentiated relationships among in iduals. Each male is connected, directly or indirectly, to every other male, including direct connections with adult males outside of their three-level alliance network. We further show that the duration with which males consort females is dependent upon being well connected with third-order allies, independently of the effect of their second-order alliance connections, i.e., alliances between groups increase access to a contested resource, thereby increasing reproductive success. Models of human social evolution traditionally link intergroup alliances to other ergent human traits, such as pair bonds, but our study reveals that intergroup male alliances can arise directly from a chimpanzee-like, promiscuous mating system without one-male units, pair bonds, or male parental care.
Publisher: The Royal Society
Date: 07-05-2014
Abstract: Socially learned behaviours leading to genetic population structure have rarely been described outside humans. Here, we provide evidence of fine-scale genetic structure that has probably arisen based on socially transmitted behaviours in bottlenose dolphins ( Tursiops sp.) in western Shark Bay, Western Australia. We argue that vertical social transmission in different habitats has led to significant geographical genetic structure of mitochondrial DNA (mtDNA) haplotypes. Dolphins with mtDNA haplotypes E or F are found predominantly in deep (more than 10 m) channel habitat, while dolphins with a third haplotype (H) are found predominantly in shallow habitat (less than 10 m), indicating a strong haplotype–habitat correlation. Some dolphins in the deep habitat engage in a foraging strategy using tools. These ‘sponging’ dolphins are members of one matriline, carrying haplotype E. This pattern is consistent with what had been demonstrated previously at another research site in Shark Bay, where vertical social transmission of sponging had been shown using multiple lines of evidence. Using an in idual-based model, we found support that in western Shark Bay, socially transmitted specializations may have led to the observed genetic structure. The reported genetic structure appears to present an ex le of cultural hitchhiking of mtDNA haplotypes on socially transmitted foraging strategies, suggesting that, as in humans, genetic structure can be shaped through cultural transmission.
Publisher: Wiley
Date: 24-10-2012
Publisher: The Royal Society
Date: 07-2019
Abstract: Behavioural differences among social groups can arise from differing ecological conditions, genetic predispositions and/or social learning. In the past, social learning has typically been inferred as responsible for the spread of behaviour by the exclusion of ecological and genetic factors. This ‘method of exclusion’ was used to infer that ‘sponging’, a foraging behaviour involving tool use in the bottlenose dolphin ( Tursiops aduncus ) population in Shark Bay, Western Australia, was socially transmitted. However, previous studies were limited in that they never fully accounted for alternative factors, and that social learning, ecology and genetics are not mutually exclusive in causing behavioural variation. Here, we quantified the importance of social learning on the diffusion of sponging, for the first time explicitly accounting for ecological and genetic factors, using a multi-network version of ‘network-based diffusion analysis'. Our results provide compelling support for previous findings that sponging is vertically socially transmitted from mother to (primarily female) offspring. This research illustrates the utility of social network analysis in elucidating the explanatory mechanisms behind the transmission of behaviour in wild animal populations.
Publisher: The Royal Society
Date: 12-06-2019
Abstract: Homophilous behaviour plays a central role in the formation of human friendships. In iduals form social ties with others that show similar phenotypic traits, independently of relatedness. Evidence of such homophily can be found in bottlenose dolphins ( Tursiops aduncus ) in Shark Bay, Western Australia, where females that use marine sponges as foraging tools often associate with other females that use sponges. ‘Sponging’ is a socially learned, time-consuming behaviour, transmitted from mother to calf. Previous research illustrated a strong female bias in adopting this technique. The lower propensity for males to engage in sponging may be due to its incompatibility with adult male-specific behaviours, particularly the formation of multi-level alliances. However, the link between sponging and male behaviour has never been formally tested. Here, we show that male spongers associated significantly more often with other male spongers irrespective of their level of relatedness. Male spongers spent significantly more time foraging, and less time resting and travelling, than did male non-spongers. Interestingly, we found no difference in time spent socializing. Our study provides novel insights into the relationship between tool use and activity budgets of male dolphins, and indicates social homophily in the second-order alliance composition of tool-using bottlenose dolphins.
Publisher: Springer Science and Business Media LLC
Date: 08-2022
DOI: 10.1007/S42991-022-00295-7
Abstract: The photo-identification of uniquely marked in iduals has revealed much about mammalian behaviour and social structure in recent decades. In bottlenose dolphins ( Tursiops spp.), for ex le, the long-term tracking of in iduals has unveiled considerable variation in social structure among populations and various spatio-temporal aspects of group formation. In this study, we investigated associations among in idual males in a small community of Indo-Pacific bottlenose dolphins ( T. aduncus ) residing in an urbanized estuary in southwestern Australia. Given the relative proximity of our study area to other populations in which complex male alliances form for the purpose of mate acquisition, we used long-term photo-identification records and social analyses to assess whether such alliances also occur in smaller and more isolated settings. Our work revealed strong social bonds and long-term, non-random associations among in idual males, suggesting the occurrence of male alliances. Behavioural observations of alliances interacting with potentially receptive adult females from the estuary community and from adjacent communities, and exhibiting sexual display behaviours near females, suggest that these alliances occur in a reproductive context. As the first formal analysis indicating the occurrence of male alliances outside Shark Bay along the vast western coastline of Australia, this study complements previous research and extends our understanding of the evolutionary and ecological processes that drive alliance formation.
Publisher: Cambridge University Press
Date: 27-03-2014
Publisher: Wiley
Date: 10-12-2013
DOI: 10.1111/MMS.12089
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/MF12210
Abstract: Capture–recapture models were used to provide estimates of abundance, apparent survival and temporary emigration of Indo-Pacific bottlenose dolphins (Tursiops sp.) in a 226-km2 study area off Useless Loop in the western gulf of Shark Bay, Western Australia. Photo-identification data were collected during boat-based surveys in Austral autumn to early spring (April–September) from 2007 to 2011. Abundance estimates varied from 115 (s.e. 5.2, 95% CI 105–126) in iduals in 2008 to 208 (s.e. 17.3, 95% CI 177–245) in iduals in 2010. The variability in abundance estimates is likely to be a reflection of how in iduals used the study area, rather than fluctuations in true population size. The best fitting capture–recapture model suggested a random temporary emigration pattern and, when coupled with relatively high temporary emigration rates (0.33 (s.e. 0.07) – 0.66 (s.e. 0.05)) indicated that the study area did not cover the entire ranges of the photo-identified dolphins. Apparent survival rate is a product of true survival and permanent emigration and was estimated annually at 0.95 (s.e. 0.02). Since permanent emigration from the study area is unlikely, true survival was estimated to be close to 0.95. This study provides a robust baseline for future comparisons of dolphin demographics, which may be of importance should climate change or increasing anthropogenic activity affect this population.
Publisher: Frontiers Media SA
Date: 09-02-2016
Publisher: Frontiers Media SA
Date: 22-03-2016
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/MF09240
Abstract: Remote video systems can be expensive, slow to deploy and the data recorded may not be available until the system has been retrieved. To overcome these issues, a rapid, non-destructive and cost-effective remote video and data management system was developed to record benthic habitats in Shark Bay, Western Australia. This system comprises a downward-oriented video camera, linked to a laptop computer, attached to the apex of a stainless steel pyramid to film a 1-m2 area of benthos. The video image of the substratum, spatial coordinates, depth and temperature are recorded in a database at the time of deployment. A web interface was developed to manage the database and examine the video images to determine the percentage cover of seagrass, sponge type (conical/non-conical) and the total number of sponges in the quadrat. Using this system, 1380 video quadrats were collected from a study area of ∼248 km2, ranging in water depth from 2 m to 16 m. An average of 16.4 (±1.3 s.e.) s les was recorded every hour during 15 days. This system could be modified to quantify substratum components at a greater taxonomic resolution or to record details of the mobile fauna.
Publisher: Wiley
Date: 28-04-2022
DOI: 10.1111/COBI.13897
Abstract: Human-caused mortality of wildlife is a pervasive threat to bio ersity. Assessing the population-level impact of fisheries bycatch and other human-caused mortality of wildlife has typically relied upon deterministic methods. However, population declines are often accelerated by stochastic factors that are not accounted for in such conventional methods. Building on the widely applied potential biological removal (PBR) equation, we devised a new population modeling approach for estimating sustainable limits to human-caused mortality and applied it in a case study of bottlenose dolphins affected by capture in an Australian demersal otter trawl fishery. Our approach, termed sustainable anthropogenic mortality in stochastic environments (SAMSE), incorporates environmental and demographic stochasticity, including the dependency of offspring on their mothers. The SAMSE limit is the maximum number of in iduals that can be removed without causing negative stochastic population growth. We calculated a PBR of 16.2 dolphins per year based on the best abundance estimate available. In contrast, the SAMSE model indicated that only 2.3-8.0 dolphins could be removed annually without causing a population decline in a stochastic environment. These results suggest that reported bycatch rates are unsustainable in the long term, unless reproductive rates are consistently higher than average. The difference between the deterministic PBR calculation and the SAMSE limits showed that deterministic approaches may underestimate the true impact of human-caused mortality of wildlife. This highlights the importance of integrating stochasticity when evaluating the impact of bycatch or other human-caused mortality on wildlife, such as hunting, lethal control measures, and wind turbine collisions. Although population viability analysis (PVA) has been used to evaluate the impact of human-caused mortality, SAMSE represents a novel PVA framework that incorporates stochasticity for estimating acceptable levels of human-caused mortality. It offers a broadly applicable, stochastic addition to the demographic toolbox to evaluate the impact of human-caused mortality on wildlife.
Publisher: Public Library of Science (PLoS)
Date: 02-04-2014
Publisher: Springer Science and Business Media LLC
Date: 21-08-2010
Publisher: Wiley
Date: 26-08-2011
Publisher: Public Library of Science (PLoS)
Date: 02-07-2014
Publisher: Springer Science and Business Media LLC
Date: 09-2020
DOI: 10.1038/S41598-020-69863-6
Abstract: Increasing human activity along the coast has lified the extinction risk of inshore delphinids. Informed selection and prioritisation of areas for the conservation of inshore delphinids requires a comprehensive understanding of their distribution and habitat use. In this study, we applied an ensemble species distribution modelling approach, combining results of six modelling algorithms to identify areas of high probability of occurrence of the globally Vulnerable Australian humpback dolphin in northern Ningaloo Marine Park (NMP), north-western Australia. Model outputs were based on sighting data collected during systematic, boat-based surveys between 2013 and 2015, and in relation to various ecogeographic variables. Water depth and distance to coast were identified as the most important variables influencing dolphin presence, with dolphins showing a preference for shallow waters (5–15 m) less than 2 km from the coast. Areas of high probability ( 0.6) of dolphin occurrence were primarily (90%) in multiple use areas where extractive human activities are permitted, and were poorly represented in sanctuary (no-take) zones. This spatial mismatch emphasises the need to reassess for future spatial planning and marine park management plan reviews for NMP. Shallow, coastal waters identified here should be considered priority areas for the conservation of this Vulnerable species.
Publisher: Wiley
Date: 18-05-2016
DOI: 10.1111/MEC.13622
Abstract: The identification of species and population boundaries is important in both evolutionary and conservation biology. In recent years, new population genetic and computational methods for estimating population parameters and testing hypotheses in a quantitative manner have emerged. Using a Bayesian framework and a quantitative model-testing approach, we evaluated the species status and genetic connectedness of bottlenose dolphin (Tursiops spp.) populations off remote northwestern Australia, with a focus on pelagic 'offshore' dolphins subject to incidental capture in a trawl fishery. We analysed 71 dolphin s les from three sites beyond the 50 m depth contour (the inshore boundary of the fishery) and up to 170 km offshore, including incidentally caught and free-ranging in iduals associating with trawl vessels, and 273 dolphins s led at 12 coastal sites inshore of the 50 m depth contour and within 10 km of the coast. Results from 19 nuclear microsatellite markers showed significant population structure between dolphins from within the fishery and coastal sites, but also among dolphins from coastal sites, identifying three coastal populations. Moreover, we found no current or historic gene flow into the offshore population in the region of the fishery, indicating a complete lack of recruitment from coastal sites. Mitochondrial DNA corroborated our findings of genetic isolation between dolphins from the offshore population and coastal sites. Most offshore in iduals formed a monophyletic clade with common bottlenose dolphins (T. truncatus), while all 273 in iduals s led coastally formed a well-supported clade of Indo-Pacific bottlenose dolphins (T. aduncus). By including a quantitative modelling approach, our study explicitly took evolutionary processes into account for informing the conservation and management of protected species. As such, it may serve as a template for other, similarly inaccessible study populations.
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/MF06218
Abstract: The high potential for dispersal of many marine organisms often results in low population differentiation over large distances. Here, we report that dolphin communities living in very close geographic proximity ( km) but in two different environments – open coast and enclosed embayment – exhibit unexpected genetic differentiation at nine microsatellite loci. Results based on a fixation index and a Bayesian clustering approach suggested that gene flow between communities within an embayment is high, as is gene flow between coastal communities. However, lower gene flow between embayment and open coast communities translated into substantial genetic differentiation between dolphin communities from the two environments, and assignment of in iduals into two populations. Along with patterns observed in 403 bp of the mitochondrial DNA control region, the results suggest that restriction of gene flow likely occurred in the last 6000 years, after coastal dolphins colonised the embayment. We hypothesise that factors such as fidelity to the local area and resource and behavioural specialisations may have played a major role in promoting and maintaining genetic sub ision between dolphins of the two environments. Importantly, our study shows that habitat type can rapidly promote extremely fine-scale genetic structure in a long-lived, highly mobile marine mammal.
Publisher: Springer Science and Business Media LLC
Date: 27-06-2010
DOI: 10.1007/S10519-010-9375-8
Abstract: Some bottlenose dolphins use marine sponges as foraging tools ('sponging'), which appears to be socially transmitted from mothers mainly to their female offspring. Yet, explanations alternative to social transmission have been proposed. Firstly, the propensity to engage in sponging might be due to differences in ing ability caused by variation of mitochondrial genes coding for proteins of the respiratory chain. Secondly, the cultural technique of sponging may have selected for changes in these same genes (or other autosomal ones) among its possessors. We tested whether sponging can be predicted by mitochondrial coding genes and whether these genes are under selection. In 29 spongers and 54 non-spongers from two study sites, the non-coding haplotype at the HVRI locus was a significant predictor of sponging, whereas the coding mitochondrial genes were not. There was no evidence of selection in the investigated genes. Our study shows that mitochondrial gene variation is unlikely to be a viable alternative to cultural transmission as a primary driver of tool use in dolphins.
Publisher: Springer Science and Business Media LLC
Date: 24-03-2009
Publisher: Springer Science and Business Media LLC
Date: 29-09-2010
Publisher: The Royal Society
Date: 04-2020
Abstract: Synchronous displays are hallmarks of many animal societies, ranging from the pulsing flashes of fireflies, to military marching in humans. Such displays are known to facilitate mate attraction or signal relationship quality. Across many taxa, synchronous male displays appear to be driven by competition, while synchronous displays in humans are thought to be unique in that they serve a cooperative function. Indeed, it is well established that human synchrony promotes cooperative endeavours and increases success in joint action tasks. We examine another system in which synchrony is tightly linked to cooperative behaviour. Male bottlenose dolphins form long-lasting, multi-level, cooperative alliances in which they engage in coordinated efforts to coerce single oestrus females. Previous work has revealed the importance of motor synchrony in dolphin alliance behaviour. Here, we demonstrate that allied dolphins also engage in acoustic coordination whereby males will actively match the tempo and, in some cases, synchronize the production of their threat vocalization when coercing females. This finding demonstrates that male dolphins are capable of acoustic coordination in a cooperative context and, moreover, suggests that both motor and acoustic coordination are features of coalitionary behaviour that are not limited to humans.
Publisher: Wiley
Date: 24-11-2022
DOI: 10.1002/RSE2.313
Abstract: Aerial surveys are frequently used to estimate the abundance of marine mammals, but their accuracy is dependent upon obtaining a measure of the availability of animals to visual detection. Existing methods for characterizing availability have limitations and do not necessarily reflect true availability. Here, we present a method of using small, vessel‐launched, multi‐rotor Unoccupied Aerial Vehicles (UAVs, or drones) to collect video of dolphins to characterize availability and investigate error surrounding group size estimates. We collected over 20 h of aerial video of e‐surfacing behaviour across 32 encounters with Australian humpback dolphins Sousa sahulensis off north‐western Australia. Mean surfacing and e periods were 7.85 sec ( se = 0.26) and 39.27 sec ( se = 1.31) respectively. Dolphin encounters were split into 56 focal follows of consistent group composition to which ex le approaches to estimating availability were applied. Non‐instantaneous availability estimates, assuming a 7 sec observation window, ranged between 0.22 and 0.88, with a mean availability of 0.46 (CV = 0.34). Availability tended to increase with increasing group size. We found a downward bias in group size estimation, with true group size typically one in idual more than would have been estimated by a human observer during a standard aerial survey. The variability of availability estimates between focal follows highlights the importance of s ling across a variety of group sizes, compositions and environmental conditions. Through data re‐s ling exercises, we explored the influence of s le size on availability estimates and their precision, with results providing an indication of target s le sizes to minimize bias in future research. We show that UAVs can provide an effective and relatively inexpensive method of characterizing dolphin availability with several advantages over existing approaches. The ex le estimates obtained for humpback dolphins are within the range of values obtained for other shallow‐water, small cetaceans, and will directly inform a government‐run program of aerial surveys in the region.
Publisher: Springer Science and Business Media LLC
Date: 13-04-2017
DOI: 10.1038/SREP46354
Abstract: Within-species variation in social structure has attracted interest recently because of the potential to explore phenotypic plasticity and, specifically, how demographic and ecological variation influence social structure. Populations of bottlenose dolphins ( Tursiops spp.) vary in male alliance formation, from no alliances to simple pairs to, in Shark Bay, Western Australia, the most complex nested alliances known outside of humans. Examination of ecological contributions to this variation is complicated by differences among populations in other potentially explanatory traits, such as phylogenetic distance, as well as female reproductive schedules, sexual size dimorphism, and body size. Here, we report our discovery of systematic spatial variation in alliance structure, seasonal movements and access to mates within a single continuous social network in the Shark Bay population. Participation in male trios (versus pairs), the sizes of seasonal range shifts and consortship rates all decrease from north to south along the 50 km length of the study area. The southern habitat, characterised by shallow banks and channels, may be marginal relative to the open northern habitat. The discovery of variation in alliance behaviour along a spatial axis within a single population is unprecedented and demonstrates that alliance complexity has an ecological component.
Publisher: Wiley
Date: 21-08-2018
DOI: 10.1111/MMS.12435
Publisher: Springer Science and Business Media LLC
Date: 20-10-2017
DOI: 10.1038/S41598-017-13898-9
Abstract: Sexual displays enriched by object carrying serve to increase in idual male fitness, yet are uncommon phenomena in the animal kingdom. While they have been documented in a variety of taxa, primarily birds, they are rare outside non-human mammals. Here, we document marine sponge presenting associated with visual and acoustic posturing found in several, geographically widespread populations of Australian humpback dolphins ( Sousa sahulensis ) over ten years of observation. Only adult males presented marine sponges, typically doing so in the presence of sexually mature females, although social groups predominantly consisted of mixed age and sex classes. Male humpback dolphins appear to be using sponges for signalling purposes in multi-modal sexual displays. Further, based on limited behavioural and genetic data, we hypothesise that pairs of adult male Sousa form at least temporary coalitions or alliances. The use of objects in sexual displays by non-human mammals is rare and, moreover, cooperation between males in the pursuit of an in isible resource is an evolutionary hurdle relatively few species have overcome. These findings suggest a hitherto unrecognised level of social complexity in humpback dolphins.
Publisher: Inter-Research Science Center
Date: 07-02-0880
DOI: 10.3354/ESR00784
Publisher: Wiley
Date: 12-05-2023
DOI: 10.1111/MEC.16984
Abstract: Bottlenose dolphins ( Tursiops spp.) are found in waters around Australia, with T. truncatus typically occupying deeper, more oceanic habitat, while T. aduncus occur in shallower, coastal waters. Little is known about the colonization history of T. aduncus along the Western Australian coastline however, it has been hypothesized that extant populations are the result of an expansion along the coastline originating from a source in the north of Australia. To investigate the history of coastal T. aduncus populations in the area, we generated a genomic SNP dataset using a double‐digest restriction‐site‐associated DNA (ddRAD) sequencing approach. The resulting dataset consisted of 103,201 biallelic SNPs for 112 in iduals which were s led from eleven coastal and two offshore sites between Shark Bay and Cygnet Bay, Western Australia. Our population genomic analyses showed a pattern consistent with the proposed source in the north with significant isolation by distance along the coastline, as well as a reduction in genomic ersity measures along the coastline with Shark Bay showing the most pronounced reduction. Our demographic analysis indicated that the expansion of T. aduncus along the coastline began around the last glacial maximum and progressed southwards with the Shark Bay population being founded only 13 kya. Our results are in line with coastal colonization histories inferred for Tursiops globally, highlighting the ability of delphinids to rapidly colonize novel coastal niches as habitat is released during glacial cycle‐related global sea level and temperature changes.
Publisher: Inter-Research Science Center
Date: 10-01-2012
DOI: 10.3354/MEPS09410
Publisher: Frontiers Media SA
Date: 16-02-2016
Publisher: Elsevier
Date: 2016
DOI: 10.1016/BS.AMB.2015.08.002
Abstract: Determining the sex of free-ranging cetaceans can be challenging. Sexual dimorphism among external features may allow inferences on sex, but such patterns may be difficult to detect and are often confounded by age and geographic variation. Dorsal fin images of 107 female and 54 male Australian humpback dolphins, Sousa sahulensis, from Western Australia (WA) and Queensland (QLD) were used to investigate sex, age and geographic differences in colouration, height/length quotient and number of notches. Adult males exhibited more dorsal fin notches (p<0.001) and a significantly greater loss of pigmentation on the upper half of their dorsal fins (p<0.001) than did adult females. These differences likely reflect that males experience a higher frequency and/or intensity of intraspecific aggression than females. In QLD, heavily spotted dorsal fins were more frequent among females than males (p<0.001). Logistic regression analyses revealed that dorsal fin spotting and loss of pigmentation on the upper half of the dorsal fin provided the best model parameters for predicting the sex of s led adults, with 97% accuracy. This technique offers a rapid, non-invasive method for predicting sex in Australian humpback dolphins, which could potentially be applied to populations throughout their range. In contrast to adults, presumed immature animals showed little or no loss of pigmentation or spotting however, the rate of development of these features remains unknown. There were pronounced differences between QLD and WA in the intensity of spotting on dorsal fins and the extent of pigmentation loss around the posterior insertion and trailing edge of the dorsal fin. While based on a limited s le size, these geographic differences may have conservation implications in terms of population sub ision and should be investigated further.
Publisher: Elsevier BV
Date: 06-2009
Publisher: Wiley
Date: 15-12-2022
DOI: 10.1111/EVA.13516
Abstract: Knowledge of an animal's chronological age is crucial for understanding and predicting population demographics, survival and reproduction, but accurate age determination for many wild animals remains challenging. Previous methods to estimate age require invasive procedures, such as tooth extraction to analyse growth layers, which are difficult to carry out with large, mobile animals such as cetaceans. However, recent advances in epigenetic methods have opened new avenues for precise age determination. These ‘epigenetic clocks’ present a less invasive alternative and can provide age estimates with unprecedented accuracy. Here, we present a species‐specific epigenetic clock based on skin tissue s les for a population of Indo‐Pacific bottlenose dolphins ( Tursiops aduncus ) in Shark Bay, Western Australia. We measured methylation levels at 37,492 cytosine‐guanine sites (CpG sites) in 165 s les using the mammalian methylation array. Chronological age estimates with an accuracy of ±1 year were available for 68 animals as part of a long‐term behavioral study of this population. Using these s les with known age, we built an elastic net model with Leave‐One‐Out‐Cross‐Validation, which retained 43 CpG sites, providing an r = 0.86 and median absolute age error (MAE) = 2.1 years (5% of maximum age). This model was more accurate for our data than the previously published methylation clock based on skin s les of common bottlenose dolphins ( T. truncatus : r = 0.83, MAE = 2.2) and the multi‐species odontocete methylation clock ( r = 0.68, MAE = 6.8), highlighting that species‐specific clocks can have superior performance over those of multi‐species assemblages. We further developed an epigenetic sex estimator, predicting sex with 100% accuracy. As age and sex are critical parameters for the study of animal populations, this clock and sex estimator will provide a useful tool for extracting life history information from skin s les rather than long‐term observational data for free‐ranging Indo‐Pacific bottlenose dolphins worldwide.
Publisher: Springer Science and Business Media LLC
Date: 30-06-2023
DOI: 10.1007/S10071-023-01804-Y
Abstract: The social intelligence hypothesis holds that complex social relationships are the major selective force underlying the evolution of large brain size and intelligence. Complex social relationships are exemplified by coalitions and alliances that are mediated by affiliative behavior, resulting in differentiated but shifting relationships. Male Indo-Pacific bottlenose dolphins in Shark Bay, Australia, form three alliance levels or ‘orders’, primarily among non-relatives. Strategic alliance formation has been documented within both first- and second-order alliances and between second-order alliances (‘third-order alliances’), revealing that the formation of strategic inter-group alliances is not limited to humans. Here we conducted a fine-scale study on 22 adult males over a 6-year period to determine if third-order alliance relationships are differentiated, and mediated by affiliative interactions. We found third-order alliance relationships were strongly differentiated, with key in iduals playing a disproportionate role in maintaining alliances. Nonetheless, affiliative interactions occurred broadly between third-order allies, indicating males maintain bonds with third-order allies of varying strength. We also documented a shift in relationships and formation of a new third-order alliance. These findings further our understanding of dolphin alliance dynamics and provide evidence that strategic alliance formation is found in all three alliance levels, a phenomenon with no peer among non-human animals.
Publisher: Oxford University Press (OUP)
Date: 28-11-2019
Abstract: Male alliances are an intriguing phenomenon in the context of reproduction since, in most taxa, males compete over an in isible resource, female fertilization. Adult male bottlenose dolphins (Tursiops aduncus) in Shark Bay, Western Australia, form long-term, multilevel alliances to sequester estrus females. These alliances are therefore critical to male reproductive success. Yet, the long-term processes leading to the formation of such complex social bonds are still poorly understood. To identify the criteria by which male dolphins form social bonds with other males, we adopted a long-term approach by investigating the ontogeny of alliance formation. We followed the in idual careers of 59 males for 14 years while they transitioned from adolescence (8–14 years of age) to adulthood (15–21 years old). Analyzing their genetic relationships and social associations in both age groups, we found that the vast majority of social bonds present in adolescence persisted through time. Male associations in early life predict alliance partners as adults. Kinship patterns explained associations during adolescence but not during adulthood. Instead, adult males associated with males of similar age. Our findings suggest that social bonds among peers, rather than kinship, play a central role in the development of adult male polyadic cooperation in dolphins.
Publisher: Springer Science and Business Media LLC
Date: 31-08-2016
DOI: 10.1007/S10071-016-1026-X
Abstract: Two recent papers by Kuczaj et al. (Anim Cognit 18:543-550, 2015) and Eskelinen et al. (Anim Cognit 19:789-797, 2016) claim to have demonstrated that (i) bottlenose dolphins (Tursiops truncatus) cooperated to solve a novel task and (ii) vocal signals were important for coordinating these cooperative efforts. Although it is likely that bottlenose dolphins may share communicative signals in order to achieve a common goal, we suggest that this has not been demonstrated in the aforementioned studies. Here, we discuss the two main problems that preclude any definitive conclusions being drawn on cooperative task success and vocal communication from these studies. The first lies in the experimental design. The 'cooperative task', involving an apparatus that requires two dolphins to pull in opposite directions in order to achieve a food reward, is not conducive to cooperation, but could instead reflect a competitive 'tug-of-war'. It is therefore of questionable use in distinguishing competitive from cooperative interactions. Second, the suggestion that the occurrence of burst-pulsed signals in this task was indicative of cooperation is disputable, as (i) this study could not determine which dolphins were actually producing the signals and (ii) this sound type is more commonly associated with aggressive signalling in dolphins. We commend the authors for investigating this exciting and topical area in animal communication and cognition, but the question of whether dolphins cooperate and communicate to solve a cooperative task remains as yet unanswered.
Publisher: Springer Science and Business Media LLC
Date: 10-07-2017
DOI: 10.1038/S41598-017-05189-0
Abstract: The incidental capture of wildlife in fishing gear presents a global conservation challenge. As a baseline to inform assessments of the impact of bycatch on bottlenose dolphins ( Tursiops truncatus ) interacting with an Australian trawl fishery, we conducted an aerial survey to estimate dolphin abundance across the fishery. Concurrently, we carried out boat-based dolphin photo-identification to assess short-term fidelity to foraging around trawlers, and used photographic and genetic data to infer longer-term fidelity to the fishery. We estimated abundance at ≈ 2,300 dolphins (95% CI = 1,247–4,214) over the ≈ 25,880-km 2 fishery. Mark-recapture estimates yielded 226 (SE = 38.5) dolphins associating with one trawler and some in iduals photographed up to seven times over 12 capture periods. Moreover, photographic and genetic re-s ling over three years confirmed that some in iduals show long-term fidelity to trawler-associated foraging. Our study presents the first abundance estimate for any Australian pelagic dolphin community and documents in iduals associating with trawlers over days, months and years. Without trend data or correction factors for dolphin availability, the impact of bycatch on this dolphin population’s conservation status remains unknown. These results should be taken into account by management agencies assessing the impact of fisheries-related mortality on this protected species.
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/MF13130
Abstract: Assessments of incidental wildlife mortality resulting from fishing rarely account for unobserved by-catch. We assessed by-catch of protected and vulnerable wildlife species in an Australian trawl fishery by comparing in-trawl video footage with data collected by an on-board observer. Data were obtained from 44 commercial trawls with two different by-catch reduction devices (BRDs). Eighty-six in iduals from six major taxa (dolphins, sharks, rays, sea snakes, turtles and sygnathids) were documented from video analysis, including the endangered scalloped hammerhead shark (Sphyrna lewini) and the critically endangered green sawfish (Pristis zijsron). On the basis of the 2008–2009 fishing effort of 4149 trawls and scaling from these results, we estimated the annual catch of protected and vulnerable species (± 1 s.e.) at 8109 ± 910 in iduals. Only 34% of by-catch was expelled through the BRDs. Independent observer data for the 44 trawls showed that 77% of the landed by-catch from these taxa were dead when discarded. The results indicate that unaccounted by-catch in trawl fisheries can be substantial, and that current methods of recording by-catch on-board vessels are likely to underestimate total fishing mortality. We recommend gear modifications and their validation through dedicated observer coverage, combined with in-trawl video camera deployments to improve current approaches to by-catch mitigation.
Publisher: Inter-Research Science Center
Date: 03-12-2009
DOI: 10.3354/MEPS07979
Publisher: The Royal Society
Date: 07-06-2014
Abstract: Culturally transmitted tool use has important ecological and evolutionary consequences and has been proposed as a significant driver of human evolution. Such evidence is still scarce in other animals. In cetaceans, tool use has been inferred using indirect evidence in one population of Indo-Pacific bottlenose dolphins ( Tursiops sp.), where particular dolphins (‘spongers’) use marine sponges during foraging. To date, evidence of whether this foraging tactic actually provides access to novel food items is lacking. We used fatty acid (FA) signature analysis to identify dietary differences between spongers and non-spongers, analysing data from 11 spongers and 27 non-spongers from two different study sites. Both univariate and multivariate analyses revealed significant differences in FA profiles between spongers and non-spongers between and within study sites. Moreover, FA profiles differed significantly between spongers and non-spongers foraging within the same deep channel habitat, whereas the profiles of non-spongers from deep channel and shallow habitats at this site could not be distinguished. Our results indicate that sponge use by bottlenose dolphins is linked to significant differences in diet. It appears that cultural transmission of tool use in dolphins, as in humans, allows the exploitation of an otherwise unused niche.
Publisher: Wiley
Date: 21-12-2006
Publisher: Springer Science and Business Media LLC
Date: 08-08-2006
Publisher: Springer Science and Business Media LLC
Date: 17-07-2019
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2008
End Date: 2010
Funder: Fisheries Research and Development Corporation
View Funded ActivityStart Date: 2012
End Date: 2014
Funder: Australian Marine Mammal Centre, Australian Antarctic Division
View Funded ActivityStart Date: 2017
End Date: 2018
Funder: Sea World Research and Rescue Foundation
View Funded ActivityStart Date: 2013
End Date: 2015
Funder: International Fund for Animal Welfare
View Funded Activity