Geometric morphometric methods as complementary tools to investigate variability in common dolphins (<i>Delphinus</i> sp.) using museum specimens

Nicolosi, Paola; Loy, Anna

doi:10.1002/aqc.3042

Cited by 10 publications

(6 citation statements)

References 57 publications

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“…Perrin (1984) noted that they were of an intermediate size between those in the NE Atlantic population, with maximum lengths of 250 cm for males and 252 cm for females reported in recent years (Murphy, Pinn, & Jepson, 2013; Read, 2016), and the Black Sea sub‐species D. delphis ponticus , with maximum lengths of 219 cm for males and 200 cm for females (Amaha, 1994; Perrin, 1984). As in other geographic regions, common dolphins in the Mediterranean Sea exhibit sexual size dimorphism, with males reported as larger than females in cranial size (Nicolosi & Loy, 2021).…”

Section: Strandingsmentioning

confidence: 89%

“…Just as genetic diversity may shed light on population structure, phenotypic diversity may also reveal distinguishing features possibly shaped by directional selection or phenotypic plasticity (Ben Cohen & Dor, 2018). Spatial distinction in skull morphology of D. delphis between southern Sicily and the Tyrrhenian Sea was found after cranial morphometric analyses of museum specimens (Nicolosi & Loy, 2021). The ones from the Tyrrhenian Sea were found to be characterized by a slender skull and a narrower occipital region, suggesting adaptations to different foraging resources and potential ecological separation from the dolphins found in southern Sicilian and North African waters.…”

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confidence: 99%

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The conservation of the endangered Mediterranean common dolphin (Delphinus delphis): Current knowledge and research priorities

Vella

Murphy

Giménez

et al. 2021

Aquatic Conservation

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1. Preservation of endangered species is now recognized as a relevant component of regional and global conservation actions achieved through the maintenance of the remaining populations in a favourable conservation status. The Mediterranean common dolphin (Delphinus delphis) is listed as an Endangered subpopulation in the International Union for Conservation of Nature Red List, with declining numbers in some of the areas where it has been studied for numerous years. Prey depletion, fisheries bycatch, pollution, health risks, and climate change are among the recognized threats that the species is facing in the region.2. The existing national, regional, and international legislation pertinent to Mediterranean countries should aid greater science-policy-management integration and support innovative research and monitoring towards effective conservation. The challenges inherent in studying the pelagic D. delphis should not preclude the use of long-term, year-round, multiplatform surveys, side by side with the latest molecular tools, which aid our understanding of its populations' genetic diversity, resistance to diseases, and resilience in a semi-enclosed fast-changing sea.3. Addressing the multiplicity of problems confronting the species requires collaborative effort at all levels to share and merge resources, data, and expertise more efficiently. In this review, we provide an overview of the current knowledge on the Mediterranean common dolphin, the main threats, and knowledge gaps that are priorities for addressing its conservation, while providing clear recommendations for effectively safeguarding the species and its habitat at both local and regional levels.

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Section: Strandingsmentioning

confidence: 89%

mentioning

confidence: 99%

The conservation of the endangered Mediterranean common dolphin (Delphinus delphis): Current knowledge and research priorities

Vella

Murphy

Giménez

et al. 2021

Aquatic Conservation

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“…Today, the only known areas where the Mediterranean common dolphin is relatively abundant are the Alboran Sea (Cañadas & Hammond, 2008) and the waters off Malta (Vella, 1999(Vella, , 2000(Vella, , 2005. Records of the species are also documented in the Pelagos Sanctuary area, in the Sicily Channel near Lampedusa island and in Messina Strait (Pace et al, 2015), off western Sardinia (IUCN, 2012), Israel (Boisseau et al, 2010;Kerem et al, 2012), eastern Ionian Sea (Frantzis, 2009), Aegean Sea (Dede & Öztürk, 2007;Frantzis, 2009;Ryan et al, 2014), and Cap Bon area (northern Tunisia) (Benmessaoud, Chérif, Bradai, & Bejaoui, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…This differentiation is likely to have evolved recently and to have been reinforced by a bottleneck event that recently affected the Ionian common dolphins (Moura, Natoli, Rogan, & Hoelzel, 2013). A recent study on skull morphometrics (Nicolosi & Loy, 2019) found that Mediterranean dolphins are highly divergent from oceanic stocks and showed the highest variability in shape. The authors also found a significant distinction between southern and northern samples.…”

Section: Introductionmentioning

confidence: 99%

The decline of short‐beaked common dolphin (Delphinus delphis) in the waters off the island of Ischia (Gulf of Naples, Italy)

Mussi

Vivaldi

Antonio

et al. 2019

Aquatic Conservation

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1. This study presents data on a local population of short-beaked common dolphin monitored in the waters off Ischia Island (Gulf of Naples, Italy) over a 16-year period (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015). We examine dolphin occurrence and distribution and perform photoidentification analysis.2. The data presented support the hypothesis that the waters around Ischia Island represent a feeding area, as well as a calving and an important nursery area for this local population, providing favourable conditions in which to give birth and raise calves.3. The levelling-off of the photoidentification curves together with the continuous decline of the encounter rate lead us to believe that the area has been a hotspot for a local population (mainly resident) for years and that now this population is dying (has died) or is moving (has moved) to other locations. 4. Several expanding human activities at sea have the potential to impact on the common dolphin in the study area, the most significant possibly being habitat disturbance and degradation (including traffic and noise pollution) and overexploitation of food resources by the fishery.5. The data presented in this study offer a strong argument for explicit and urgent population-specific conservation and management strategies to be developed and applied locally for common dolphins, considering that they rely on the region for important biological processes.

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“…In particular-in analogy to the interpretation of genetic distancesmorphological differences between populations may indicate local adaptation (Colangelo et al, 2012;Meloro, 2011;Meloro, Guidarelli, Colangelo, Ciucci, & Loy, 2017). Current conservation studies of endangered taxa rarely use morphological data to determine phenotypic differentiation below the species level (Dierickx, Shultz, Sato, Hiraoka, & Edwards, 2015;Wilting et al, 2015); and most quantitatively rigorous assessment of phenotypic differentiation remains the domain of taxonomic studies (Celik et al, 2019;Meloro et al, 2017;Nicolosi & Loy, 2019;Senczuk et al, 2018;Sveegaard et al, 2015). Therefore, quantifying morphological variation within a species represents a largely untapped potential for understanding the phenotypic variation between taxonomic units and testing of hypotheses of adaptation and relatedness within a species.…”

Section: Introductionmentioning

confidence: 99%

Skull shape of a widely distributed, endangered marsupial reveals little evidence of local adaptation between fragmented populations

Viacava

Blomberg

Sansalone

et al. 2020

Ecology and Evolution

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The biogeographic distribution of diversity among populations of threatened mammalian species is generally investigated using population genetics. However, intraspecific phenotypic diversity is rarely assessed beyond taxonomy‐focused linear measurements or qualitative descriptions. Here, we use a technique widely used in the evolutionary sciences—geometric morphometrics—to characterize shape diversity in the skull of an endangered marsupial, the northern quoll, across its 5,000 km distribution range along Northern Australia. Skull shape is a proxy for feeding, behavior, and phenotypic differentiation, allowing us to ask whether populations can be distinguished and whether patterns of variation indicate adaptability to changing environmental conditions. We analyzed skull shape in 101 individuals across four mainland populations and several islands. We assessed the contribution of population, size, sex, rainfall, temperature, and geography to skull shape variation using principal component analysis, Procrustes ANOVA, and variation partitioning analyses. The populations harbor similar amounts of broadly overlapping skull shape variation, with relatively low geographic effects. Size predicted skull shape best, coinciding with braincase size variation and differences in zygomatic arches. Size‐adjusted differences in populations explained less variation with far smaller effect sizes, relating to changes in the insertion areas of masticatory muscles, as well as the upper muzzle and incisor region. Climatic and geographic variables contributed little. Strikingly, the vast majority of shape variation—76%—remained unexplained. Our results suggest a uniform intraspecific scope for shape variation, possibly due to allometric constraints or phenotypic plasticity beyond the relatively strong allometric effect. The lack of local adaptation indicates that cross‐breeding between populations will not reduce local morphological skull (and probably general musculoskeletal) adaptation because none exists. However, the potential for heritable morphological variation (e.g., specialization to local diets) seems exceedingly limited. We conclude that 3D geometric morphometrics can provide a comprehensive, statistically rigorous phenomic contribution to genetic‐based conservation studies.

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Geometric morphometric methods as complementary tools to investigate variability in common dolphins (Delphinus sp.) using museum specimens

Cited by 10 publications

References 57 publications

The conservation of the endangered Mediterranean common dolphin (Delphinus delphis): Current knowledge and research priorities

The conservation of the endangered Mediterranean common dolphin (Delphinus delphis): Current knowledge and research priorities

The decline of short‐beaked common dolphin (Delphinus delphis) in the waters off the island of Ischia (Gulf of Naples, Italy)

Skull shape of a widely distributed, endangered marsupial reveals little evidence of local adaptation between fragmented populations

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