Spur-thighed Tortoise Testudo Graeca Research Articles

Body size variation in a lineage of spur-thighed tortoises (Testudo graeca whitei) contrasts with that expected from the species level

Abstract Ectotherms exhibit varying geographic size patterns shaped by environmental and evolutionary factors. This variability is noticeable within taxonomic groups. For instance, certain testudinids follow Bergmann’s rule (body size increases with latitude) and Rensch’s rule (sexual size dimorphism correlates with body size), while others do not. Here we hypothesize that body size patterns can even vary within a monophyletic lineage. To address this, we evaluated the body size patterns of the spur-thighed tortoise Testudo graeca that globally follows Bergmann’s and Rensch’s rules. We specifically investigated the influence of climate variables, latitude and elevation within the subspecies T. g. whitei throughout its natural distribution in North Africa, and in a recently expanded range in SE Spain (20 kya old). We found that males were smaller than females in both regions. The tortoises from SE Spain were smaller than those from North Africa, which showcased the smallest sizes ever reported for the species. Latitude was the main variable to explain tortoise body size. In particular, body size decreased with latitude in both regions, which contrasts with Bergmann’s rule expectations based on species-level findings. Finally, to further contradict species-level expectations, we did not find any statistical correlation between sexual size dimorphism and body size across the two studied regions. Such contradictory outcomes reveal complex geographic size patterns within T. graeca and raise conservation questions about demographic viability at smaller-sized sites.

The shell measurements that best describe sexual dimorphism in the spur-thighed tortoise <em>Testudo graeca</em> from Algeria

Due to phenotypic plasticity and sex-biased selective pressures, intraspecific variation in tortoise morphology is usually assessed by studying sexual dimorphism. However, inferences may differ based on the choice of shell size measurements for analyses. In this work, we identified linear measurements that best describe sexual dimorphism for the spur-thighed tortoise Testudo graeca whitei. We assessed 34 carapace and plastron measurements in 67 individuals (24 males, 43 females) in a population at the natural Mergueb site located on the central limit of the Algerian steppe. Twenty-two out of 34 measurements significantly showed sexual size dimorphism in ANOVA tests. When analyzing sexual shape dimorphism with ANCOVAs, nine measurements showed no shared allometry with the measurements used as covariates to correct by size. Meanwhile, 17 out of the remaining 23 measurements showed significant differences in shape. PCA analyses similarly described T. graeca’s sexual dimorphism. In general, females tend to be bigger than males, especially in central scutes what is probably linked with clutch sizes commitments. On the other hand, males are larger-sized in anterior and posterior scutes, probably as a result of courtship, male fighting and copulation. Some of the analyzed measurements are revealed as being especially adequate for further studying the geographical variation of sexual dimorphism in Testudo graeca

Cross-sectional study of ticks in the vulnerable free-living spur-thighed tortoise Testudo graeca (Testudines: Testudinidae) from Morocco

ABSTRACT The spur-thighed tortoise (Testudo graeca L., 1758) is classified as a vulnerable species by the IUCN. In this context, it is important to explore the factors affecting its populations to set up an effective conservation plan. The present study was carried out in seven localities of Morocco with the objective to determine the ticks parasitizing this tortoise and their prevalence in relation to host characteristics and environmental factors. We examined 392 free-living tortoises for the presence of ticks during the spring 2018. A total number of 2238 adult ticks (no immature tick detected) were collected and all identified as Hyalomma aegyptium. Infection with at least one tick was detected in 77.6% ± 6.5 of the total tortoises. The infestation prevalence varied according to localities. Infestation intensity varied from 1.5 to 12, while tick abundance ranged from 0.65 to 12 ticks/tortoise. Male tortoises were more infested than females (P < 0.01) and the infestation was age-dependant. Our statistical result provides that the best model drivers tick parasitism was which included locality and age. Further studies are needed to assess the impact of the high intensity of H. aegyptium infestation on the tortoise’s health status and to assess the potential transmission of zoonotic pathogens.

“Reconstructions of the past distribution of Testudo graeca mitochondrial lineages in the Middle East and Transcaucasia support multiple refugia since the Last Glacial Maximum”: A response to Turkozan et al. (2021)

Species distribution models (SDMs) are frequently used to characterise current, past or future realised environmental niches. Two recent studies applied different approaches to infer range dynamics in eastern subspecies of the spur-thighed tortoise Testudo graeca Linnaeus, 1758. We discuss differences in the conclusions of the two papers and use multivariate environmental similarity surface (MESS) analyses to show that the results of the study by Turkozan et al. (2021), recently published in the Herpetological Journal, are compromised by extrapolation and therefore have to be interpreted with caution.

Population density of the spur-thighed tortoise Testudo graeca declines after fire in north-western Africa.

Fire is a key ecological process in several biomes worldwide. Over recent decades, human activities (e.g. rural abandonment, monoculture plantations) and global warming are magnifying the risk of fire, with changes in fire intensity and frequency. Here, we offer the first study that examines the impact of fire on the spur-thighed tortoise Testudo graeca living in a native cork oak forest and pine plantation in north-western Africa. A total of 44 transects (22 burnt and 22 unburnt) were sampled at 8 sites affected by fires of natural cork oak forest and pine plantation with 8 surveys per site in 2015–2017 (264 hours of sampling effort). Tortoise densities were estimated with line-transect distance sampling. The detection probability of tortoises was higher in burnt (0.915) than unburnt (0.474) transects. The density of tortoises was negatively associated with elevation and declined with fire by c. 50% in both forest types. The negative response of T. graeca to fire should be considered in conservation planning of this species in north-western Africa in a future scenario of changes in fire regime.

The importance of protected and unprotected areas for the Mediterranean spur-thighed tortoise demography in northwest Morocco

Abstract Collection for the pet trade has been considered one of the major threats to the Mediterranean spur-thighed tortoise Testudo graeca, since it modulates the size and structure of the species’ populations and, therefore, their demography. Maamora forest is one of the most suitable habitats for this species. The proximity of the forest to Rabat indicated the possibility of these tortoise populations being particularly sensitive to over-collecting. Population demography was studied in four populations, in protected and unprotected areas in Maamora forest. The results showed significant differences as regards population size and structure between protected and unprotected areas. They specifically highlighted: i) higher density (23-17 indiv · ha−1) balanced populations in the protected areas, in which young adults were predominant, ii) a higher body condition in the protected areas, especially the females, and iii) a low density (5.5 ind · ha−1) more unbalance population in the unprotected areas, in which older females and younger males were predominant. In addition, a survey carried out by interviewing local adults () showed that most people owned tortoises (61%, ), mainly juveniles (65%, ). The respondents stated that their tortoises had been captured in the forest (68%, ). Maamora forest is home to one of the highest density populations of Mediterranean spur-thighed tortoises documented to date, and its conservation is essential if this species is to be maintained. Our social survey suggested that one of the challenges is to change the social perception of the Mediterranean spur-thighed tortoise as a pet and highlight its intrinsic ecological value.

The injuries on tortoise shells as a depository of past human impact

The spur-thighed tortoise Testudo graeca has a wide distribution encompassing southern Europe and the Middle East through to northern Africa. The populations at the northern limit of T. graeca’s range in the province of Dobrogea (Romania) are sparsely distributed across the entire area, with higher densities found in the hilly forested areas. Although strictly protected, the spur-thighed tortoise was and continues to be impacted by human activities. This study investigated the presence and characteristics of scars from past injuries on their shells. We studied three populations from protected areas, situated along a north–south gradient of approximately 150 km: Măcin Mountains National Park (northernmost limit of T. graeca’s range), Cetatea Histria, located within the Danube Delta Biosphere Reserve, in the central part of the region, and the Dumbrăveni Forest Natural Reserve in the south. All three populations had individuals with scars from past injuries on their shells. The highest numbers of injured tortoises were in Dumbrăveni Forest (35.78%) and Măcin Mountains (35%) while the population from Cetatea Histria (11.26%) was less affected. Carapace injury frequency was higher in the Măcin Mountains whilst the Dumbrăveni Forest population had a higher frequency of plastron injuries. Human-caused injuries were observed mainly in the anterior and dorsal zones of the carapace and the anterior zone of the plastron. Natural injuries were located on the posterior zone of the carapace, mainly on marginal scutes. Our study showed that the scars of turtle shells proved to be an excellent depository of past and recent human impacts and may offer insights for better conservation and management strategies.

Comparative Morphology of Three Populations of Testudo graeca Linnaeus, 1758 from the Western Taurus Mountains, Turkey

We examined a total of 65 specimens of the Mediterranean spur-thighed tortoise Testudo graeca Linnaeus, 1758 from three distinct localities in the western Taurus Mountains of the Mediterranean region of Turkey: Kalkan (12 ♀, 14 ), Ciglikara (6 ♀, 7 ♂), and Akseki (7 ♀, 19 ♂). For morphological comparisons 15 morphometric characters and 17 ratios developed by combination of characters were investigated. Post-ANOVA pairwise analysis (Tukey’s) across all groups verified sexual dimorphism in the Kalkan and Ciglikara populations in terms of the following ratios: plastron length/plastron width 2 ( p = 0.02) and straight carapace length/femoral suture length ( p = 0.04), respectively. Females in all three populations are larger than males, and in the Ciglikara population individuals are larger than those from other populations (ANOVA F (2.22) = 16.28, p < 0.0001). The maximum straight carapace length measured was of a female in the Ciglikara population (295 mm). This is a new record size for Turkish tortoises. Discriminant analysis based on 13 ratios confirms that the Kalkan population tends to differ from the other two populations. This difference was more clear between Akseki and Kalkan.

URBANIZATION AND SAND DUNES IN ISRAEL: DIRECT AND INDIRECT EFFECTS

ABSTRACT Considerable attention has been given lately to the effects of habitat fragmentation and destruction on wildlife. Here, we summarize their effects on animal abundance and plant cover during a three-year study period (1987–90) of the sand dunes of the coastal plain of Israel. Populations of the gray monitor Varanus griseus, the spur-thighed tortoise Testudo graeca, and the mountain gazelle Gazella gazella in the study area declined markedly and plant cover increased significantly. Habitat destruction and fragmentation, introduced animals (especially dogs and carrion crows), a continuing change in the native herbivore fauna, and blockage of wind-borne sand are all believed to be responsible for the observed changes. We recommend that small areas, unsuitable for full protection, be declared “city reserves,” to be used for educational and recreational purposes. Nature reserves need to be managed in order to maintain the existing fauna and flora.

Using digital images in the study of fluctuating asymmetry in the spur-thighed tortoise Testudo graeca

Fluctuating asymmetry has been proposed as a useful noninvasive tool for detecting the influence of the environment on body development. In the present study, we used digital images to estimate the fluctuating asymmetry of the plastron in an isolated Testudo graeca population in Dobrogea, Romania. We extracted data from the photos regarding the area, height, and width of 3 plastron scutes. A total of 155 adult tortoises analysed showed reduced variation in plastron asymmetry and no significant relationship was detected between fluctuating asymmetry and sex or body size. We suggest that fluctuating asymmetry may be an individual trait, with no predictive value at the population level.

Predicting the distribution of cryptic species: the case of the spur-thighed tortoise in Andalusia (southern Iberian Peninsula)

Some species are very difficult to observe in the wild, and some of these present an apparently incongruent distribution, as is the case of the spur-thighed tortoise Testudo graeca in the southern Iberian Peninsula. This species has a discontinuous distribution with two main reproductive areas: one in the contiguous provinces of Almeria and Murcia, and the other in Huelva province. Both populations are thought to maintain reproductive isolation. However, we present new records obtained from two areas (the provinces of Malaga and Cadiz) which are outside their previously known range. Malaga province and Cadiz province are located between the two traditional reproductive areas. The new records were based on 16 interviews with shepherds as well as information provided by three naturalists. The aim of this work was to analyze the spatial distribution of areas favourable to the spur-thighed tortoise in the southern Iberian Peninsula, using different models with the same group of variables but with a different number of records: known records, new records and a combination of them. We obtained a distribution model for the species in Andalusia consistent with all observations, which was related to climatic stability, climatic disturbances, and spatial situation. This model presented three main favourable areas: two are coincident with the two known nuclei, and the other is situated in the southern part of the region, in the contiguous provinces of Cadiz and Malaga. We conclude that it is important to consider all the observations in the distribution models because records outside the traditional reproductive areas can include other environmental characteristics appropriate for the species.

Genetic patterns of a range expansion: The spur-thighed tortoise Testudo graeca graeca in southeastern Spain

Abstract In the present work we analyzed the genetic structure of the populations of the terrestrial tortoise Testudo graeca graeca in southeastern Spain, identified as a recent range expansion from North Africa. The study and interpretation of the species' genetic spatial pattern could provide clues to the processes related to the species' arrival and, because of its endangered status, is especially useful in implementing appropriate management measures. We used microsatellite markers to analyze 17 populations located in the coastal region of the species' range in southeastern Spain, and an external group of Algerian tortoises. Three genetic units with a high level of spatial coherence and moderate levels of admixture resulted from a cluster analysis, and an isolation-by-distance pattern covering the entire study area was detected. These results suggest that southeastern Spanish populations show a complex spatial genetic pattern resulting from their isolation from North African populations and their natural dispersal in this region. Finally, our work shows that conservation actions such as captive breeding, introductions or translocations, may have played a relevant role in the modification of the genetic structure of some populations in southeastern Spain. Therefore, these types of conservation measures should be carried out with more caution.

Specimen identification from time‐series photographs using plastron morphometry in Testudo graeca ibera

The spur-thighed tortoise Testudo graeca ibera Pallas, 1814 is a good example of a vulnerable long-lived CITES species, which is widely bred as a pet and can be easily reproduced in captivity. However, the high number of bred tortoises makes it difficult to monitor the international pet trade. Despite microchipping being widely recommended as an identification method, it is unsuitable for hatchlings and young tortoises because implanting the chip in chelonians can sometimes cause health problems. We believe that these disadvantages can be resolved by plastron photo documentation but this method is still not considered a valid alternative. The objective of this study was to find a method for identifying a specimen from a photograph database using morphometrics, an approach potentially more reliable than other fingerprinting methods currently used for tortoises. We propose a combined dissimilarity measure calculated from the relative differences in seam distances between two plastron photographs.

Habitat Selection by the Spur-thighed Tortoise Testudo graeca in a Multisuccessional Landscape: Implications for Habitat Management

As a result of human activities, natural Mediterranean landscapes (including agro-ecosystems) are characterised by a mosaic-like structure with habitat-patches at different successional stages. These systems have high biodiversity levels and are home to a large number of species protected by European laws whose habitats should be adequately managed. In the present work, we study habitat use from an applied point of view in the spur-thighed tortoise Testudo graeca, an endangered reptile present in semi-arid Mediterranean agro-ecosystems. Results show that, at a landscape scale, the species selects simplified vegetation structures and includes in its home range re-colonisation shrubland and small non-irrigated fields. Within the home range, habitat selection patterns vary and areas with higher vegetation cover and complexity are selected. Detected patterns are discussed in terms of the ecological requirements of the species and with a hierarchical view of resources and conditions. The implications of our findings for habitat management aimed at the conservation of the species are also discussed.

Long-term demographic fluctuations of the spur-thighed tortoise Testudo graeca in SW Spain

Long-term demographic fluctuations of the spur-thighed tortoise Testudo graeca in SW Spain

A protein titration hypothesis for the temperature-dependence of tissue CO2 content in reptiles and amphibians.

Whole-body CO2 stores are known to increase with cooling in reptiles and amphibians (-[CO2]/T ). The aim of this study was to determine the mechanism(s) producing this inverse relationship. The [CO2]/T coefficients were determined for eight reptilian and one amphibian species and were found to differ by a factor of approximately 10, from -0.21 mmol kg-1 &deg;C-1 in the Mediterranean spur-thighed tortoise Testudo graeca to -0.02 mmol kg-1 &deg;C-1 in the bullfrog Rana catesbeiana. The [CO2]/T coefficients were correlated with values in the literature for in vivo plasma pH/T coefficients ([CO2]/T=-0.18&shy;8.24pH/T; r2=0.87). Plasma electrolyte concentrations (Na+, K+, Ca2+, Mg2+, Cl-, inorganic phosphate, SO42- and lactate), [protein], [CO2], PCO2 and pH were measured in chronically cannulated resting black racer snakes Coluber constrictor. When the temperature was reduced from 30 to 10 &deg;C, pH increased slightly (by -0.0028 pH units &deg;C-1), PCO2 decreased by 7 mmHg, [CO2] increased by 3.2 mmol l-1 and [HPO42-+H2PO4-] increased by 0.7 mmol l-1. Concentrations of protein and of the remaining electrolytes were not significantly different (P>0.05) at 30 and 10 &deg;C. Net plasma protein charge, calculated from the principle of electroneutrality (the sum of the cations in mequiv = the sum of anions in mequiv), was -0.48 mequiv g-1 protein at 30 &deg;C and -0.38 mequiv g-1 protein at 10 &deg;C. This 21 % decrease was attributed to the increases in [CO2] (i.e. carbonic acid) and inorganic phosphate concentration. Between 30 and 10 &deg;C, skeletal muscle pH and [CO2] in C. constrictor increased (by -0.009 units &deg;C-1 and -0.125 mmol kg-1 &deg;C-1, respectively), [Na+] and [Cl-] each decreased by approximately 12 mequiv l-1, and [K+] and the percentage of water did not change significantly. It is concluded that the increase in whole-body CO2 stores with cooling in reptiles and amphibians results from the passive effects of temperature changes upon the ionization constants of proteins and the active adjustment of PCO2 (ventilatory regulation), so that -pK is greater than -pH. Active transmembrane ion-exchange processes do not appear to be involved.

Seed Consumption and Dispersal by the Spur-Thighed Tortoise Testudo graeca

Seeds belonging to 34 species, mainly Poaceae, Asteraceae and Juncaceae, were identified in a sample of 170 faecal pellets of Testudo graeca L. from Dofiana Biological Reserve, Huelva province, Spain. The effect of the digestion of these chelonians on the seeds of Spergula arvensis, Hypochaeris glabra, Rumex bucephalophorus, Ornithopus sativus, Briza maxima and Lavandula stoechas was studied. The average period of retention in the digestive tract was found to be 5.3 d and the percentage of recovered seeds in the faeces was 19.3 (6.5-34.2). All seeds germinated, except in H. glabra and L. stoechas, suggesting that T. graeca is a disperser for these species. Seeds of S. arvensis that pass through the digestive tract of the tortoise show increased germination compared with controls.

Temperature, activity and field sighting in the mediterranean spur-thighed or common garden tortoise Testudo graeca L

Daylight observations on NW African and W Turkish populations of the Mediterranean spur-thighed tortoise Testudo graeca L. showed that activity, depending upon maturity, sex and size, is influenced by air temperature and sunshine. Tortoises are active above 18°C while refuge from sunshine during the middle of the day occurs above 28°C. Morning basking increases body temperature, which under glass in S England was shown to be thermoregulated at about 35°C. With movements in and out of sunshine, most heat is dissipated through the plastron. Field sighting frequency (no.man-h −1) as a relative index of abundance in low density populations is influenced by activity and behaviour type. This is discussed with regard to tortoise detection being increased by locomotory rustling and mating sounds in thick vegetation.