Drivers of Population Structure of the Bottlenose Dolphin (Tursiops truncatus) in the Eastern Mediterranean Sea

Gaspari, Stefania; Scheinin, Aviad; Holcer, Draško; Fortuna, Caterina Maria; Natali, Chiara; Genov, Tilen; Frantzis, Alexandros; Chelazzi, Guido; Moura, André E.

doi:10.1007/s11692-015-9309-8

Cited by 57 publications

(65 citation statements)

References 91 publications

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“…The range of this local population is unknown (Genov et al 2016), but evidence from photo-ID (Genov et al 2009) and genetics (Gaspari et al 2015) suggest it is a distinct unit.…”

Section: Discussionmentioning

confidence: 99%

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Behavioural and temporal partitioning of dolphin social groups in the northern Adriatic Sea

Genov

Centrih²,

Kotnjek³

et al. 2018

Mar Biol

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Complex social structure is a prominent feature in several mammal species. Such structure may lead to behavioural diversity not only among populations, but also within a single population, where different subsets of a population may exhibit different types of behaviour. As a consequence, understanding social structure is not only interesting biologically, but may also help conservation and management efforts, because not all segments of a population necessarily respond to or interact with human activities in the same way, or at the same time. In this study, we examined the social structure of common bottlenose dolphins (Tursiops truncatus) in the Gulf of Trieste and adjacent waters (northern Adriatic Sea), based on a 9-year dataset, using social network metrics and association indices. We assessed whether different segments of the population show differences in behaviour and interactions with fisheries. Dolphin social network was structured into distinct social clusters of mixed sexes. We found no evidence of male alliances. The two largest social clusters overlapped spatially, but not temporally, as they used the same area at different times of day. Such diel temporal partitioning does not appear to have been documented in cetaceans previously. The two clusters also differed in ways they interact with fisheries, as one regularly interacted with trawlers, while the other did not. This study demonstrates how different segments of animal populations can interact differently with human activities and in turn respond differently to anthropogenic impacts.

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“…The range of this local population is unknown (Genov et al 2016), but evidence from photo-ID (Genov et al 2009) and genetics (Gaspari et al 2015) suggest it is a distinct unit.…”

Section: Discussionmentioning

confidence: 99%

“…Skin samples were removed and excised with sterilised forceps and surgical scissors, placed in 96% ethanol and stored at − 20 °C until analysis. Samples were analysed as described in Gaspari et al (2015). …”

Section: Methodsmentioning

confidence: 99%

Behavioural and temporal partitioning of dolphin social groups in the northern Adriatic Sea

Genov

Centrih²,

Kotnjek³

et al. 2018

Mar Biol

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“…The mitochondrial CR was amplified using oligonucleotide primers designed for the genes at both the 5′ and 3′ ends of the CR (tRNA Thr and 12S genes; Gaspari et al., ). Predicted amplification size using these primers is 1,265 bp, with final alignment having a length of 919 bp.…”

Section: Methodsmentioning

confidence: 99%

“…To assess the presence of genetic structure between regional locations, samples were divided into the eight main Mediterranean basins, which have been shown to correlate well with genetic differentiation in other cetacean species (e.g., Gaspari et al., ). This included the Levantine, Ionian, Adriatic, Tyrrhenian, Ligurian, Balearic, and Alboran seas, and lastly the Eastern North Atlantic, as represented by samples from Scotland.…”

Section: Methodsmentioning

confidence: 99%

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Spatio-temporal patterns of genetic diversity in the Mediterranean striped dolphin (Stenella coeruleoalba)

Gaspari

Marsili

Natali

et al. 2019

J Zool Syst Evol Res

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Comparing the genetic composition of wild animals between geographic regions with distinct environments is common in evolutionary studies. However, genetic composition can also change through time in response to environmental changes but studies examining this are carried out less often. In this study, we characterize striped dolphin genetic composition in the Mediterranean Sea across both geography and time. We provide genotype data for 15 microsatellite loci and 919 bp of mtDNA control region, collected over 21 years across all main Mediterranean Sea basins. We investigated spatial genetic structure using both classical and Bayesian population structure methods, and compared it with temporal patterns of genetic change using time‐series statistics. We integrated the temporal datasets with known environmental pressures and data on social structure, to infer potential drivers of observed changes. Geographic analyses suggest weak differentiation for striped dolphin in the Mediterranean Sea, with evidence for a recent expansion. Temporal analyses show significant cyclical fluctuations in genetic composition over 21 years, which correspond well with recurrent morbillivirus epizootics. Similarly, social group composition shows changes in the relative number of juveniles and adults per group, and an overall increase in the number of adults per group relative to juveniles over the time period. We suggest that the observed changes in genetic and group composition could relate to specific dynamics of morbillivirus resistance. Overall, our study highlights the importance of tracking long‐term genetic variation and the potential for this species as a model in studying genetic adaptation to environmental stress.

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Decreasing population trend in coastal bottlenose dolphin (Tursiops truncatus) from the Gulf of Guayaquil, Ecuador

Félix

Calderón

Vintimilla³

et al. 2017

Aquatic Conservation

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1. The population status of the coastal bottlenose dolphin (Tursiops truncatus) inhabiting the inner estuary of the Gulf of Guayaquil, Ecuador (3°S, 81°W) was assessed. Evaluated aspects included social organization, abundance and spatial distribution.2. Surveys focused on the western part of the estuary (Posorja and Estero Salado) but other areas in the central and eastern inner estuary were also surveyed.3. Effort included 68 trips, 5001 km of survey and 288.8 h at sea. Between 735 and 793 dolphins in 92 groups were recorded during the study. 4. Dolphins are not evenly distributed but concentrated their activities in the mouths of large channels. 5.A cluster analyses indicated that dolphins organize in partially discrete subunits referred to as communities.6. Abundance estimations were obtained using mark-recapture modelling for two communities:Posorja and Estero Salado (43 dolphins, 95% CI 37-49 and 65 dolphins, 95% CI 52-82 respectively). 7. Four demographic parameters: average size of communities, average group size, average encounter rate and average density were compared with information obtained during the 1990s. In all cases the current values were between 39 and 54% lower; in the last three cases the difference was statistically significant.8. Possible causes of this apparent decline include bycatch, ship strikes, pollution and habitat degradation; however, none of these have been assessed in depth. Most probably, different stressors are affecting dolphin communities to different extents. 9. A comprehensive assessment of the whole population inside the gulf is needed. Identifying major threats is a priority to define concrete actions to prevent further population decline.

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Drivers of Population Structure of the Bottlenose Dolphin (Tursiops truncatus) in the Eastern Mediterranean Sea

Cited by 57 publications

References 91 publications

Behavioural and temporal partitioning of dolphin social groups in the northern Adriatic Sea

Behavioural and temporal partitioning of dolphin social groups in the northern Adriatic Sea

Spatio-temporal patterns of genetic diversity in the Mediterranean striped dolphin (Stenella coeruleoalba)

Decreasing population trend in coastal bottlenose dolphin (Tursiops truncatus) from the Gulf of Guayaquil, Ecuador

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