Oğuz Türkozan

Phenotypic plasticity leads to incongruence between morphology-based taxonomy and genetic differentiation in western Palaearctic tortoises (Testudo graeca complex; Testudines, Testudinidae)

Tortoises of the Testudo graeca complex inhabit a patchy range that covers part of three continents (Africa, Europe, Asia). It extends approximately 6500 km in an east-west direction from eastern Iran to the Moroccan Atlantic coast and about 1600 km in a north-south direction from the Danube Delta to the Libyan Cyrenaica Peninsula. Recent years have seen a rapid increase of recognized taxa. Based on morphological investigations, it was suggested that this group consists of as many as 20 distinct species and is paraphyletic with respect to T. kleinmanni sensu lato and T. marginata . Based on samples from representative localities of the entire range, we sequenced the mitochondrial cytochrome b gene and conducted nuclear genomic fingerprinting with ISSR PCR. The T. graeca complex is monophyletic and sister to a taxon consisting of T. kleinmanni sensu lato and T. marginata . The T. graeca complex comprises six well-supported mtDNA clades (A-F). Highest diversity is found in the Caucasian Region, where four clades occur in close neighbourhood. This suggests, in agreement with the fossil record, the Caucasian Region as a radiation centre. Clade A corresponds to haplotypes from the East Caucasus. It is the sister group of another clade (B) from North Africa and western Mediterranean islands. Clade C includes haplotypes from western Asia Minor, the southeastern Balkans and the western and central Caucasus Region. Its sister group is a fourth, widely distributed clade (D) from southern and eastern Asia Minor and the Levantine Region (Near East). Two further clades are distributed in Iran (E, northwestern and central Iran; F, eastern Iran). Distinctness of these six clades and sister group relationships of (A + B) and (C + D) are well-supported; however, the phylogeny of the resulting four clades (A + B), (C + D), E and F is poorly resolved. While in a previous study (Fritz et al., 2005a) all traditionally recognized Testudo species were highly distinct using mtDNA sequences and ISSR fingerprints, we detected within the T. graeca complex no nuclear genomic differentiation paralleling mtDNA clades. We conclude that all studied populations of the T. graeca complex are conspecific under the Biological Species Concept. There is major incongruence between mtDNA clades and morphologically defined taxa. Morphologically well-defined taxa, like T. g. armeniaca or T. g. floweri , nest within clades comprising also geographically neighbouring, but morphologically distinctive populations of other taxa (clade A: T. g. armeniaca , T. g. ibera , T. g. pallasi ; clade D: T. g. anamurensis , T. g. antakyensis , T. g. floweri , T. g. ibera , T. g. terrestris ), while sequences of morphologically similar tortoises of the same subspecies ( T. g. ibera sensu stricto or T. g. ibera sensu lato) scatter over two or three genetically distinct clades (A, C or A, C, D, respectively). This implies that pronounced morphological plasticity, resulting in phenotypes shaped by environmental pressure, masks genetic differentiation. To achieve a more realistic taxonomic arrangement reflecting mtDNA clades, we propose reducing the number of T. graeca subspecies considerably and regard in the eastern part of the range five subspecies as valid ( T. g. armeniaca , T. g. buxtoni , T. g. ibera , T. g. terrestris , T. g. zarudnyi ). As not all North African taxa were included in the present study, we refrain from synonymizing North African taxa with T. g. graeca (mtDNA clade B) that represents a further valid subspecies.

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.

Carapacial scute variation in Loggerhead Turtles, Caretta caretta

Abstract The carapacial scutes of 3511 specimens of hatchling and adult Loggerhead Turtles (Caretta caretta) from five different nesting beaches in Turkey and Cyprus (Dalyan, Fethiye, Belek, Kızılot and Karpaz) were examined. Scutes were examined with regard to variation within carapacial scute series and variation in carapacial scute pattern. The vertebral, costal and marginal series were the most variable and the supracaudal scute was extremely stable for the hatchlings. The adult scute pattern showed stability for all scutes except the marginal series. The most common scute pattern observed was 12 pairs of marginals, 5 pairs of costals, 5 vertebrals, 2 supracaudals and a single nuchal.

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).

Population decline of loggerhead turtles: two potential scenarios for Fethiye beach, Turkey

Based on nesting data over a 12-year period (1993–2004), this study points to a negative population trend of the loggerhead turtle population at Fethiye beach, Turkey. The number of nests fluctuated from a maximum of 186 in 1995 to a minimum of 58 in 2004. Successively smaller peaks at 3-year intervals were followed by successively smaller troughs. Two analyses—one representing a dampened oscillation, the other retaining the period and the amplitudes of the nesting cycles—predict that nest number will drop to about 40–50 by 2015, i.e. to about 22–27% of its highest value. This drop at Fethiye does not correspond with a visible increase at neighboring beaches, leading to the interpretation that the number of nesting turtles here is declining. Moreover, the carapace size of emerging adult females is apparently decreasing, as are clutch sizes. Such a potential negative trend at a key Turkish nesting beach is cause for concern, an incentive for continued study, and a call for more coordinated and effective conservation programs in this region of the Mediterranean.

Impact of some invertebrates on eggs and hatchlings of the Loggerhead Turtle, Caretta caretta, in Turkey

Abstract The damage caused by some invertebrates to the eggs and hatchlings of Loggerhead Turtles, Caretta caretta, was investigated during 1999 and 2000 on Fethiye beach, Turkey. Nematoda, Acarina, Myrmeleonidae, Elateridae, Scarabeidae, Muscidae and Tenebrionidae were recorded as infesting nests of Loggerhead Turtles. Tenebrionidae (Coleoptera) larvae were found to have the heaviest impact on Loggerhead Turtle eggs and hatchlings. A total of 185 randomly selected nests was examined. Of the nests examined in 2000, almost 50% contained tenebrionid larvae. Tenebrionid larval damage was recorded in 8.1% of the eggs that were counted in the nests containing larvae and in 0.6% of the hatchlings. However, it could not be determined whether the larvae destroy viable eggs and hatchlings. In comparison to previous years, a remarkable increase in tenebrionid larval damage was recorded.

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.

Low conservatism of the climatic niche of sea turtles and implications for predicting future distributions

Understanding how the ecological niches of species are formulated across space is critical for modeling the current and predicting future distributions under climate change. Here, we examine how stable are the realized niches of distinct populations of the endangered green sea turtle (Chelonia mydas) which are defined on the basis of genetic and demographic data and are distributed around the globe. We used 906 georeferenced records of green turtle nesting sites that are embedded within eight Regional Management Units to compare climatic niche for each one of the distinct units. We used an asymmetric overall index and a decision-tree model to assess niche conservatism through a comparison of temperature- and precipitation-based bioclimatic variables that characterize the climatic niche breadth of the spatially distinct population segments. We found a high degree of variance in climatic space, which also lacks any latitudinal pattern. Environmental determinants vary significantly across the studied population units: variables that have been long-recognized as critical for nesting (e.g., maximum temperature of the warmest month) showed only low overlap between some of different regional entities. Our results contribute substantially to the current debate on the predictive power of species distribution models that use only climate variables as predictors when aggregating data from various populations. We argue that studies on climatic-niche evolution and divergent ecological selection mechanisms are required before attempting to identify suitable habitats for a species, describe climatic widths and search for plausible expansions of geographical shifts attributed to climate change.

NEST SITE FACTORS AND INVERTEBRATE INFESTATION OF LOGGERHEAD TURTLE NESTS

This paper reports the physical nest parameters of loggerhead turtle (Caretta caretta) nests at Fethiye Beach, Turkey that predispose individual nests to invertebrate infestation. All data were collected between June and September 2001 and were analyzed using logistic regression. Pimelia sp. (Tene-brionidae), Musca sp. (Muscidae), Myrmeleon sp. (Myrmeleontidae), and Cryptositigmata were established as infesting the loggerhead turtle nests on Fethiye Beach in 2001. When all groups were combined as invertebrates, distance to low vegetation (t-test, b = -0.13) and grain size (t-test, b = -1.30) were found to be the best subsets of the model indicating whether invertebrates infested a nest. Both factors were negatively correlated with the presence of invertebrates. The same analysis was applied for each individual group of invertebrates. The implications of these results are discussed.

First Assessment of Mitochondrial DNA Diversity in the Endangered Nile Softshell Turtle, Trionyx triunguis, in the Mediterranean

Abstract We assessed mitochondrial DNA diversity in Trionyx triunguis from the Mediterranean basin (22 samples) and continental Africa (4 samples). The continental African group comprised 4 different and newly described haplotypes, while the Mediterranean group consisted of only 1 previously known haplotype, with the nucleotide divergence between the 2 groups being 1.5% ± 0.7%.