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ESR 44:237-251 (2021)  -  DOI: https://doi.org/10.3354/esr01095

Reproductive output, foraging destinations, and isotopic niche of olive ridley and loggerhead sea turtles, and their hybrids, in Brazil

Luciano S. Soares1,2,*, Karen A. Bjorndal1,2, Alan B. Bolten1,2, Marta L. Wayne2,3, Jaqueline C. Castilhos4, Marilda I. Weber4, Milagros López-Mendilaharsu5, Maria A. Marcovaldi5, Sibelle T. Vilaça6, Eugenia Naro-Maciel7

1Archie Carr Center for Sea Turtle Research, University of Florida, Gainesville, FL 32611, USA
2Department of Biology, University of Florida, Gainesville, FL 32611, USA
3University of Florida Genetics Institute, University of Florida, Gainesville, FL 32611, USA
4Projeto TAMAR/Fundação Pró-TAMAR, Aracaju, SE 49035-730, Brazil
5Projeto TAMAR/Fundação Pró-TAMAR, Salvador, BA 41510-045, Brazil
6Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara 44121, Italy
7Liberal Studies, New York University, New York, NY 10003, USA
*Corresponding author:

ABSTRACT: Hybridization is a fundamental evolutionary and ecological process with significant conservation ramifications. Sea turtle hybridization occurs at unusually high frequencies along the northeastern coast of Brazil. To better understand the process, we studied the reproductive output, migration patterns (through satellite telemetry), and isotopic niches of loggerhead turtles Caretta caretta and olive ridley turtles Lepidochelys olivacea and their hybrids. We classified 154 nesting females as loggerhead (n = 91), olive ridley (n = 38), or hybrid (n = 25) based on mitochondrial and nuclear DNA. Further, we compared nesting female morphological data and reproductive parameters (clutch size, emergence success, hatchling production, incubation period) of 405 nests among hybrids and parental species. We found no significant differences among the 3 groups when hatchling production was corrected for female body size, indicating that hybrids and parental species produce similar numbers of hatchlings per clutch. Satellite tracking of 8 post-nesting hybrid females revealed shared foraging grounds with both parental species, as well as neritic migrations between foraging and nesting areas similar to those previously reported for loggerheads and olive ridleys. Analyses of 13C and 15N isotope values (n = 69) further confirmed this pattern, as hybrid isotopic niches overlapped extensively with both parental species. Thus, given the similarities presented between hybrids and their parental species in reproductive, ecological, and behavioral characteristics, we conclude that these hybrids may persist along with other sea turtle nesting populations in the area, with research and conservation implications.


KEY WORDS: Hybridization · Marine turtle · Satellite tracking · Reproductive output · Foraging · Migration · Isotopic niche · Mitochondrial and nuclear DNA


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Cite this article as: Soares LS, Bjorndal KA, Bolten AB, Wayne ML and others (2021) Reproductive output, foraging destinations, and isotopic niche of olive ridley and loggerhead sea turtles, and their hybrids, in Brazil. Endang Species Res 44:237-251. https://doi.org/10.3354/esr01095

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