TY - JOUR
T1 - Isotopic niche width differentiation between common bottlenose dolphin ecotypes and sperm whales in the Gulf of California
AU - Díaz-Gamboa, Raúl E.
AU - Gendron, Diane
AU - Busquets-Vass, Geraldine
N1 - Publisher Copyright:
© 2017 Society for Marine Mammalogy
PY - 2018/4
Y1 - 2018/4
N2 - World populations or stock distinction of Tursiops truncatus has been difficult to assess, because of large variations in morphology, habitat, feeding habits, and social structure among areas, which may reflect phylogenetic segregation or ecological plasticity. In the Gulf of California, Mexico, two common bottlenose dolphin ecotypes (inshore and offshore) have been reported. The offshore ecotype is frequently observed in association with sperm whales (Physeter macrocephalus) but the reason for this is still unknown. To explore the degree of resource partitioning/overlap between these species and stocks, we used skin stable isotope values (δ13C, δ15N) to estimate quantitative metrics of isotopic niche width (Bayesian standard ellipse areas, SEAB) and estimated their diet composition using Bayesian isotopic mixing models. The inshore ecotype in different regions (north, central, and south) of the Gulf of California exhibited distinct δ15N values and SEAB, suggesting a latitudinal gradient in nitrogen sources of coastal localities. The SEAB of inshore and offshore bottlenose dolphin ecotypes was completely distinct, indicating resource partitioning. Associated offshore ecotype and sperm whales had overlapping SEAB. The isotopic mixing model indicates that a considerable proportion of both species’ diet is large Humbolt squid. Our results suggest that resource partitioning and species association are two strategies that bottlenose dolphin ecotypes use in this zone.
AB - World populations or stock distinction of Tursiops truncatus has been difficult to assess, because of large variations in morphology, habitat, feeding habits, and social structure among areas, which may reflect phylogenetic segregation or ecological plasticity. In the Gulf of California, Mexico, two common bottlenose dolphin ecotypes (inshore and offshore) have been reported. The offshore ecotype is frequently observed in association with sperm whales (Physeter macrocephalus) but the reason for this is still unknown. To explore the degree of resource partitioning/overlap between these species and stocks, we used skin stable isotope values (δ13C, δ15N) to estimate quantitative metrics of isotopic niche width (Bayesian standard ellipse areas, SEAB) and estimated their diet composition using Bayesian isotopic mixing models. The inshore ecotype in different regions (north, central, and south) of the Gulf of California exhibited distinct δ15N values and SEAB, suggesting a latitudinal gradient in nitrogen sources of coastal localities. The SEAB of inshore and offshore bottlenose dolphin ecotypes was completely distinct, indicating resource partitioning. Associated offshore ecotype and sperm whales had overlapping SEAB. The isotopic mixing model indicates that a considerable proportion of both species’ diet is large Humbolt squid. Our results suggest that resource partitioning and species association are two strategies that bottlenose dolphin ecotypes use in this zone.
KW - Dosidicus gigas
KW - Humbolt squid
KW - Physeter macrocephalus
KW - Tursiops truncatus
KW - bottlenose dolphin
KW - isotopic niche width
KW - sperm whale
KW - trophic relationships
UR - http://www.scopus.com/inward/record.url?scp=85036519600&partnerID=8YFLogxK
U2 - 10.1111/mms.12465
DO - 10.1111/mms.12465
M3 - Artículo
SN - 0824-0469
VL - 34
SP - 440
EP - 457
JO - Marine Mammal Science
JF - Marine Mammal Science
IS - 2
ER -