02224nas a2200217 4500008004100000245007300041210006900114260001200183300001200195490000800207520156100215653001401776653001301790653002201803653002101825653001001846653001201856100002001868700001501888856010301903 2003 eng d00aSexual dimorphism of body size and shell shape in European tortoises0 aSexual dimorphism of body size and shell shape in European torto c2003/// a353-3650 v2603 aAdult body size and shape were examined in almost 1400 individuals of the tortoises Testudo graeca, T. hermanni and T. marginata from Greece. The size at maturity was greater in females than in males in all three species. Maximum and mean adult sizes were also greater in females than in males in T. graeca and T. hermanni. Males grew to a larger size than females in T. marginata, and mean adult size was similar in the sexes in this species. Sexual dimorphism of shape (adjusted for size covariate) was shown in most of the characters examined, and the degree of this dimorphism differed significantly among the three species. Differences were related to their contrasting courtship behaviours: horizontal head movements and severe biting in T. marginata, vertical head bobs and carapace butting in T. graeca, and mounting and tail thrusting in T. hermanni. There was no difference in the frequency of observations of courtship or fighting among the three species, but courtship was about 10 times more common than combat in males. All species showed greatest courtship activity in autumn; copulation was rarely observed in T. hermanni (only 0.36% of courting males) and not seen in the other species in the field. Observations made throughout the activity season indicated that feeding was equally common in males and females in all three species. Differences in shape were more likely to be the result of sexual selection than of natural selection for fecundity. Detailed predictions are made for sexual dimorphism of other characters in these species.10aCourtship10aReptilia10aSexual dimorphism10asexual selection10aShape10aTestudo1 aWillemsen, R.E.1 aHailey, A. uhttps://icgf.myspecies.info/content/sexual-dimorphism-body-size-and-shell-shape-european-tortoises02061nas a2200217 4500008004100000245010400041210006900145260001200214300001200226490000600238520136000244653001001604653001701614653001301631653001201644653002101656653001301677100002001690700001501710856011801725 1999 eng d00aA latitudinal cline of dark plastral pigmentation in the tortoise Testudo hermanni in Greece0 alatitudinal cline of dark plastral pigmentation in the tortoise  c1999/// a125-1320 v93 aThe area of dark pigmentation on the plastron of the tortoise Testudo hermanni shows a latitudinal cline over about 400 km in Greece, with populations in the south being darker. The carapace did not show the clinal trend, and pigmentation was not significantly related to longitude or altitude. We examined several possible explanations for the cline, including an effect of incubation temperature, random genetic variation, and adaptation to several environmental variables. The most likely explanation is selection for thermoregulation, with decreased dark pigmentation in the north reducing heat loss to the substrate by infra red radiation during activity. This hypothesis was supported by data on body (T(b)) and substrate (T(s)) temperatures in populations from northern, central and southern Greece. T(b) was generally above T(s), showing that heat would generally be lost rather than gained through the plastron, and the mean difference T(b)-T(s) was greatest in the north: +6.6 °C, compared to +2.4 °C in the south. Mean T(b) was lowest in the south (26.9°C, compared to 29.3°C in the north) and the slope of T(b) on T(s) was about 1 (compared to 0.5 in the north). Thermoregulation in southern Greece is similar to that of tropical tortoises, with avoidance of overheating being the major problem, rather than elevation of T(b) for activity.10aCline10aPigmentation10aReptilia10aTestudo10athermoregulation10aTortoise1 aWillemsen, R.E.1 aHailey, A. uhttps://icgf.myspecies.info/content/latitudinal-cline-dark-plastral-pigmentation-tortoise-testudo-hermanni-greece02354nas a2200229 4500008004100000245011400041210006900155260001200224300001200236490000800248520157600256653001401832653002501846653001101871653002801882653001301910653001601923653002101939100002001960700001501980856012901995 1999 eng d00aVariation of adult body size of the tortoise Testudo hermanni in Greece: Proximate and ultimate causes0 aVariation of adult body size of the tortoise iTestudo hermanni i c1999/// a379-3960 v2483 aSeventeen populations of T. hermanni in Greece differed substantially in mean adult body size, over a range of about one and a half times in length and three times in mass. Females were the larger sex in all populations; the degree of sexual size dimorphism did not vary with mean body size. The proximate cause of the variation of body size among populations was differences in the duration of growth, rather than egg or hatchling size or the growth rates of juveniles. The age at maturity (á) increased with body size in the 17 populations, while the Bertalanffy growth constant (k) decreased with body size. The quantities áM and M/k (where M is the instantaneous mortality rate) were invariant with body size, suggesting that differences between populations were adaptive rather than the result of short-term disturbance. Body size was greater in cooler areas, and increased with both latitude and altitude. This pattern is opposite to that found in most ectotherms (the reverse Bergmann's rule), and to that which occurs between tortoise species. Several hypotheses about the possible ultimate causes of variation of body size were rejected, including adaptation to long-term habitat disturbance (land use), character displacement, social factors, energetics, thermoregulation, r-K selection, the length of the season available for incubation, or differences in juvenile mortality. The most likely ultimate cause of size variation between sites is differences in adult mortality, the correlation with environmental temperature being through the frequency of fires.10aBody size10aGeographic variation10agrowth10aLife history invariants10aReptilia10atemperature10aTestudo hermanni1 aWillemsen, R.E.1 aHailey, A. uhttps://icgf.myspecies.info/content/variation-adult-body-size-tortoise-testudo-hermanni-greece-proximate-and-ultimate-causes02168nas a2200229 4500008004100000245012800041210006900169260001200238300001000250490000800260520139000268653001401658653001601672653001701688653001501705653001301720653001801733653002101751100002001772700001501792856013101807 2001 eng d00aVariation in adult survival rate of the tortoise Testudo hermanni in Greece: Implications for evolution of body size0 aVariation in adult survival rate of the tortoise iTestudo herman c2001/// a43-530 v2553 aAdult annual survival rates estimated by mark-recapture for eight Greek populations of the tortoise Testudo hermanni were in the range 0.80-1.0 (mean 0.886). Estimates from growth rings for the same populations were in a similar range (0.84-0.95, mean 0.899). The average survival rate from the two methods was significantly positively related to mean adult body size (r = 0.815) and negatively related to effective temperature (r = -0.880). A life table model was used to investigate the consequences of adult survival rate for optimum age at maturity and mean adult size of females. The basis of the model was the trade-off between increased reproduction from large adult size, and decreased survival to maturity from delayed age at maturity. The model showed that the observed variation in adult survival rates was more than sufficient to account for the variation of adult size among populations. The model thus predicted an even greater range of mean adult size than that observed. A negative correlation between growth rate and adult survival rate or age at maturity, as observed, was needed to fit the size data. The model supports the hypothesis that variation in adult size of T. hermanni in Greece is adaptive (rather than a non-adaptive environmental or phylogenetic effect) and due to variation in adult survival rates (rather than other factors such as juvenile survival).10aBody size10aGrowth rate10alife history10aLife table10aReptilia10aSurvival rate10aTestudo hermanni1 aWillemsen, R.E.1 aHailey, A. uhttps://icgf.myspecies.info/content/variation-adult-survival-rate-tortoise-testudo-hermanni-greece-implications-evolution-body02043nas a2200217 4500008004100000245008100041210006900122260001200191300001200203490000700215520134900222653002001571653001301591653001101604653001901615653002101634653002201655100002001677700001501697856011301712 2002 eng d00aBody mass condition in greek tortoises: Regional and interspecific variation0 aBody mass condition in greek tortoises Regional and interspecifi c2002/// a105-1140 v123 aBody mass and length data from large samples of wild Testudo graeca, T. hermanni and T. marginata in Greece were used to assess body mass condition. Mass-length relationships differed significantly between the sexes (females being heavier) and among the species (T. marginata being least heavy). Mass-length relationships for each species and sex were used to calculate the condition index (CI) log (M/M?), where M is observed mass and M? is mass predicted from length, which is equal to residuals from the regression of log M on log length. It was possible to use the empirical mass-length relationships from one population of T. hermanni to calculate CI in other populations of substantially different adult size. The seasonal pattern of the CI varied with latitude, with a sharper and later peak further north, and habitat, declining more in summer at a xeric coastal site. The seasonal patterns of CI in T. graeca and T. marginata were similar, with sharper and later peaks compared to T. hermanni. These seasonal patterns of CI were related to differences in activity and food availability among species and sites. The variability of the CI was similar in all three species, with most values between -0.1 and +0.1; seasonal variation was of relatively low amplitude, with a range of about 0.05 between the highest and lowest monthly means.10aCondition index10aReptilia10aseason10aTestudo graeca10aTestudo hermanni10aTestudo marginata1 aWillemsen, R.E.1 aHailey, A. uhttps://icgf.myspecies.info/content/body-mass-condition-greek-tortoises-regional-and-interspecific-variation01961nas a2200241 4500008004100000245013900041210006900180260001200249300001200261490000800273520114000281653002401421653001201445653000901457653002601466653001301492653001401505653002101519653001301540100001501553700002001568856013101588 2000 eng d00aPopulation density and adult sex ratio of the tortoise Testudo hermanni in Greece: Evidence for intrinsic population regulation0 aPopulation density and adult sex ratio of the tortoise iTestudo  c2000/// a325-3380 v2513 aThe idea that the size of animal populations may be regulated by factors intrinsic to them, such as behaviour, has a long history in ecology. Although this idea is now rejected as a general mechanism, it may apply in some species where females are damaged during courtship attempts, such as the Mediterranean tortoise Testudo hermanni. The sex ratios (adult males: adult females) of most dense Greek populations were more extreme (over 1.5:1) than could be accounted for by the earlier age at maturity of males, and some ranged to over 6:1. The sex ratio was correlated with the population density of adult males and the frequency of courtship attempts on females, and negatively correlated with the longevity of females. A high population density of males limits the density of adult females. This intrinsic regulation of population size is a consequence, rather than a goal, of a particular type of courtship behaviour (persistent thrusts by the male using a tail with a sharp terminal spur) in T. hermanni. Existing population densities at many Greek sites are probably unnaturally high, owing to the reduction of natural predators.10aCourtship behaviour10adensity10aKAPE10aPopulation regulation10aReptilia10aSex ratio10aTestudo hermanni10aTortoise1 aHailey, A.1 aWillemsen, R.E. uhttps://icgf.myspecies.info/content/population-density-and-adult-sex-ratio-tortoise-testudo-hermanni-greece-evidence-intrinsic