Molecular evidence of male-biased dispersal in loggerhead turtle juveniles

Casale, Paolo; Laurent, Luc; Gerosa, Gino; Argano, Roberto

doi:10.1016/s0022-0981(01)00365-3

Cited by 40 publications

(34 citation statements)

References 15 publications

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“…Since the sex ratio of Atlantic specimens entering the Mediterranean is probably male-biased (Casale et al 2002), the sex ratio of ~1:1 reported here would imply that the sex ratio of Mediterranean juveniles, or at least of those from some nesting sites, is female-biased. This scenario would explain why a higher proportion of males was observed among small specimens in the north-west Mediterranean but not among those from other study areas.…”

Section: Discussionmentioning

confidence: 69%

Sex ratios of juvenile loggerhead sea turtles Caretta caretta in the Mediterranean Sea

Casale¹,

Lazar²,

Pont³

et al. 2006

Mar. Ecol. Prog. Ser.

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Species with environmental sex determination may show sex ratios that differ from 1:1; therefore, sex ratio is an important variable when studying the population dynamics of these species. For instance, when estimating population size and productivity, sex ratio would be a required parameter. For endangered species, such as sea turtles, this is particularly important in order to understand the possible effects of human impacts and conservation measures. Unfortunately, only adult sea turtles show evident external sexual dimorphism; sex ratios are more difficult to obtain for the juvenile class, which represents the largest part of a population. Here we present the first extensive assessment of the sex ratio of juvenile loggerhead turtles Caretta caretta in the Mediterranean Sea. A total of 310 dead turtles from 4 different areas were sexed by direct examination of gonads, the most reliable sexing method. Females comprised 54.2% of the whole sample, and no significant differences were observed among study areas. However, this value cannot be ascribed to a single population, because specimens from different nesting sites - both within and outside the Mediterranean - share the same foraging areas, and each population may potentially contribute a different sex ratio. Although we recorded an unbiased sex ratio, our results were compatible with a hypothetical scenario in which Mediterranean nesting beaches produce a majority of females when other information from the region (distribution, mixed stocks and sex ratios) was considered. © Inter-Research 2006

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Section: Discussionmentioning

confidence: 69%

Sex ratios of juvenile loggerhead sea turtles Caretta caretta in the Mediterranean Sea

Casale¹,

Lazar²,

Pont³

et al. 2006

Mar. Ecol. Prog. Ser.

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“…However, the recovery in this study of the CC-A10.1 haplotype is very interesting because this is common only along the coasts of the Gulf of Mexico and Florida (Shamblin et al 2012) and represents the first observation of Atlantic loggerhead turtles in the Adriatic feeding ground, whereas the previous observations of Atlantic individuals into the Mediterranean Sea were made in the Tyrrhenian Sea and Lampedusa Island (Casale et al 2002;Garofalo et al 2013). This finding highlights the importance of the Adriatic Basin as a foraging area, for C. caretta not only from the mid-eastern Mediterranean rookeries, but also from Atlantic rookeries.…”

Section: Discussionmentioning

confidence: 76%

Mitochondrial DNA reveals the natal origin of Caretta caretta (Testudines: Cheloniidae) stranded or bycaught along the Southwestern Adriatic coasts

Splendiani

Fioravanti

Giovannotti

et al. 2017

The European Zoological Journal

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“…Studies using length-frequency (Carr, 1986;Bolten et al, 1993), tag returns (Bolten, 2003) and genetic markers Casale et al, 2002;Carreras et al, 2006) have confirmed the relationships between juveniles of the eastern Atlantic, mainly with the rookeries of the western Atlantic. Nevertheless, the variation in the distribution of different rookeries in these areas has been poorly studied with only a single survey in the Mediterranean Sea showing structure among feeding grounds explained by the pattern of sea surface currents and water masses (Carreras et al, 2006).…”

Section: Introductionmentioning

confidence: 96%

Variation in spatial distribution of juvenile loggerhead turtles in the eastern Atlantic and western Mediterranean Sea

Monzón‐Argüello

Rico

Carreras

et al. 2009

Journal of Experimental Marine Biology and Ecology

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a b s t r a c t Loggerhead sea turtles (Caretta caretta) originating from the Western Atlantic carry out one of the largest marine migrations, reaching the eastern Atlantic and Mediterranean Sea. It has been proposed that this transatlantic journey is simply a consequence of drifting, with the lack of a target destination and a passive dispersal with oceanic currents. This predicts that the size of the source populations and geographic distance to the feeding grounds should play important roles in defining stock composition in the eastern Atlantic and Mediterranean Sea. Under this scenario, near pelagic stocks would have no genetic structure, and would be composed of similar cohorts from regional rookeries. To address this question, we sampled individuals from one important eastern Atlantic feeding ground, the Canary Islands, and sequenced a fragment of the mitochondrial DNA control region. We compared the composition of this feeding stock with published data of other proximal areas: Madeira, Azores and Andalusia. "Rookery-centric" mixed stock analysis showed that the distribution of loggerhead sea turtles along the eastern Atlantic feeding grounds was in latitudinal accordance to their natal origin: loggerhead turtles from Florida were significantly more abundant in Azores (30%) than in Canary Islands (13%), while those from Mexico had a poor representation in Azores (13%) but were more prevalent in Canary Islands (34%). Also, genetic stability in temporal and size analyses of the Canary Island aggregation was found, showing a long period of residency. These results indicate a nonrandom distribution of loggerhead juveniles in oceanic foraging grounds. We discuss possible explanations to this latitudinal variation..

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Molecular evidence of male-biased dispersal in loggerhead turtle juveniles

Cited by 40 publications

References 15 publications

Sex ratios of juvenile loggerhead sea turtles Caretta caretta in the Mediterranean Sea

Sex ratios of juvenile loggerhead sea turtles Caretta caretta in the Mediterranean Sea

Mitochondrial DNA reveals the natal origin of Caretta caretta (Testudines: Cheloniidae) stranded or bycaught along the Southwestern Adriatic coasts

Variation in spatial distribution of juvenile loggerhead turtles in the eastern Atlantic and western Mediterranean Sea

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