Can Yilmaz

Geographic Patterns of Genetic Variation in a Broadly Distributed Marine Vertebrate: New Insights into Loggerhead Turtle Stock Structure from Expanded Mitochondrial DNA Sequences

Previous genetic studies have demonstrated that natal homing shapes the stock structure of marine turtle nesting populations. However, widespread sharing of common haplotypes based on short segments of the mitochondrial control region often limits resolution of the demographic connectivity of populations. Recent studies employing longer control region sequences to resolve haplotype sharing have focused on regional assessments of genetic structure and phylogeography. Here we synthesize available control region sequences for loggerhead turtles from the Mediterranean Sea, Atlantic, and western Indian Ocean basins. These data represent six of the nine globally significant regional management units (RMUs) for the species and include novel sequence data from Brazil, Cape Verde, South Africa and Oman. Genetic tests of differentiation among 42 rookeries represented by short sequences (380 bp haplotypes from 3,486 samples) and 40 rookeries represented by long sequences (∼800 bp haplotypes from 3,434 samples) supported the distinction of the six RMUs analyzed as well as recognition of at least 18 demographically independent management units (MUs) with respect to female natal homing. A total of 59 haplotypes were resolved. These haplotypes belonged to two highly divergent global lineages, with haplogroup I represented primarily by CC-A1, CC-A4, and CC-A11 variants and haplogroup II represented by CC-A2 and derived variants. Geographic distribution patterns of haplogroup II haplotypes and the nested position of CC-A11.6 from Oman among the Atlantic haplotypes invoke recent colonization of the Indian Ocean from the Atlantic for both global lineages. The haplotypes we confirmed for western Indian Ocean RMUs allow reinterpretation of previous mixed stock analysis and further suggest that contemporary migratory connectivity between the Indian and Atlantic Oceans occurs on a broader scale than previously hypothesized. This study represents a valuable model for conducting comprehensive international cooperative data management and research in marine ecology.

Nest Site Preference and Hatching Success of Green (Chelonia mydas) and Loggerhead (Caretta caretta) Sea Turtles at Akyatan Beach, Turkey

Abstract We studied nesting site preferences and hatching success of loggerhead (Caretta caretta) and green turtles (Chelonia mydas) on Akyatan Beach, Turkey. The distribution of nests varied annually, with green turtles nesting most often in vegetated areas and loggerhead turtles most commonly in nonvegetated areas. Green turtle hatching success was higher at vegetated vs. nonvegetated nest sites (p < 0.001).

Loggerhead Turtles, Caretta caretta, at Dalyan Beach, Turkey: Nesting Activity (2004–2005) and 19-year Abundance Trend (1987–2005)

Abstract The nesting biology of loggerhead turtles, Caretta caretta, on Dalyan beach, Turkey, was studied during the 2004 and 2005 nesting seasons. In addition, we analyzed nesting trends over 19 consecutive years, from 1987 to 2005. A total of 711 emergences occurred in 2004 and 605 emergences in 2005, of which 223 (31.4%) and 221 (36.5%) nests were deposited, respectively. Mean nesting densities were 47.5 nests km−1 and 47 nests km−1 in 2004 and 2005, respectively. Of the overall nests, 424 (95%) were excavated and 32,339 eggs were counted. Of these eggs, 19,947 (61.7%) hatchlings had come out and 18,607 (93.3% of hatchlings) of them were able to reach the sea. We recorded a total of 3688 nests on Dalyan beach during 19 consecutive years with a mean of 194 nests per year. There were also strong annual fluctuations in the number of nests, which ranged from a minimum of 57 nests (in 1990) to a maximum of 286 (in 2002). No trend in the number of nests over the 19-year period was seen (95% CI −2.7% to 6.7% change per year). The lack of increase was a surprising result when considering the long-term conservation efforts on the beach; although, a similar case was reported in Laganas Bay, Greece. High interannual fluctuations could obscure trends as stated in previous studies.