The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Kateřina Kintrová - One of the best experts on this subject based on the ideXlab platform.
-
specimen identification from time series photographs using plastron morphometry in Testudo Graeca ibera
Journal of Zoology, 2010Co-Authors: Lubomír Tichý, Kateřina KintrováAbstract: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.
-
Specimen identification from time‐series photographs using plastron morphometry in Testudo Graeca ibera
Journal of Zoology, 2010Co-Authors: Lubomír Tichý, Kateřina KintrováAbstract: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.
Fokla Zorgdrager - One of the best experts on this subject based on the ideXlab platform.
-
Mitochondrial haplotype diversity in the tortoise species Testudo Graeca from North Africa and the Middle East
BMC evolutionary biology, 2005Co-Authors: Antoinette C. Van Der Kuyl, Donato L. Ph. Ballasina, Fokla ZorgdragerAbstract:To help conservation programs of the endangered spur-thighed tortoise and to gain better insight into its systematics, genetic variation and evolution in the tortoise species Testudo Graeca (Testudines: Testudinidae) was investigated by sequence analysis of a 394-nucleotide fragment of the mitochondrial 12S rRNA gene for 158 tortoise specimens belonging to the subspecies Testudo Graeca Graeca, Testudo Graeca ibera, Testudo Graeca terrestris, and a newly recognized subspecies Testudo Graeca whitei. A 411-nucleotide fragment of the mitochondrial D-loop was additionally sequenced for a subset of 22 T. Graeca, chosen because of their 12S gene haplotype and/or geographical origin. Haplotype networks generated by maximum-likelihood and neighbor-joining analyses of both the separate and the combined sequence data sets suggested the existence of two main clades of Testudo Graeca, comprising Testudo Graeca from northern Africa and Testudo Graeca from the Turkey and the Middle East, respectively. Mitochondrial DNA haplotyping suggests that the tortoise subspecies of T. g. Graeca and T. g. ibera are genetically distinct, with a calculated divergence time in the early or middle Pleistocene. Other proposed subspecies could not clearly be recognized based upon their mt haplotypes and phylogenetic position, and were either part of the T. g. Graeca or of the T. g. ibera clade, suggesting that genetic evidence for the existence of most of the 15 proposed subspecies of T. Graeca is weak.
-
Mitochondrial haplotype diversity in the tortoise species Testudo Graeca from North Africa and the Middle East
BMC Evolutionary Biology, 2005Co-Authors: Antoinette C. Van Der Kuyl, Donato L. Ph. Ballasina, Fokla ZorgdragerAbstract:Background To help conservation programs of the endangered spur-thighed tortoise and to gain better insight into its systematics, genetic variation and evolution in the tortoise species Testudo Graeca (Testudines: Testudinidae) was investigated by sequence analysis of a 394-nucleotide fragment of the mitochondrial 12S rRNA gene for 158 tortoise specimens belonging to the subspecies Testudo Graeca Graeca , Testudo Graeca ibera , Testudo Graeca terrestris , and a newly recognized subspecies Testudo Graeca whitei . A 411-nucleotide fragment of the mitochondrial D-loop was additionally sequenced for a subset of 22 T. Graeca , chosen because of their 12S gene haplotype and/or geographical origin. Results Haplotype networks generated by maximum-likelihood and neighbor-joining analyses of both the separate and the combined sequence data sets suggested the existence of two main clades of Testudo Graeca , comprising Testudo Graeca from northern Africa and Testudo Graeca from the Turkey and the Middle East, respectively. Conclusion Mitochondrial DNA haplotyping suggests that the tortoise subspecies of T. g. Graeca and T. g. ibera are genetically distinct, with a calculated divergence time in the early or middle Pleistocene. Other proposed subspecies could not clearly be recognized based upon their mt haplotypes and phylogenetic position, and were either part of the T. g. Graeca or of the T. g. ibera clade, suggesting that genetic evidence for the existence of most of the 15 proposed subspecies of T. Graeca is weak.
Lubomír Tichý - One of the best experts on this subject based on the ideXlab platform.
-
specimen identification from time series photographs using plastron morphometry in Testudo Graeca ibera
Journal of Zoology, 2010Co-Authors: Lubomír Tichý, Kateřina KintrováAbstract: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.
-
Specimen identification from time‐series photographs using plastron morphometry in Testudo Graeca ibera
Journal of Zoology, 2010Co-Authors: Lubomír Tichý, Kateřina KintrováAbstract: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.
Antoinette C. Van Der Kuyl - One of the best experts on this subject based on the ideXlab platform.
-
Mitochondrial haplotype diversity in the tortoise species Testudo Graeca from North Africa and the Middle East
BMC evolutionary biology, 2005Co-Authors: Antoinette C. Van Der Kuyl, Donato L. Ph. Ballasina, Fokla ZorgdragerAbstract:To help conservation programs of the endangered spur-thighed tortoise and to gain better insight into its systematics, genetic variation and evolution in the tortoise species Testudo Graeca (Testudines: Testudinidae) was investigated by sequence analysis of a 394-nucleotide fragment of the mitochondrial 12S rRNA gene for 158 tortoise specimens belonging to the subspecies Testudo Graeca Graeca, Testudo Graeca ibera, Testudo Graeca terrestris, and a newly recognized subspecies Testudo Graeca whitei. A 411-nucleotide fragment of the mitochondrial D-loop was additionally sequenced for a subset of 22 T. Graeca, chosen because of their 12S gene haplotype and/or geographical origin. Haplotype networks generated by maximum-likelihood and neighbor-joining analyses of both the separate and the combined sequence data sets suggested the existence of two main clades of Testudo Graeca, comprising Testudo Graeca from northern Africa and Testudo Graeca from the Turkey and the Middle East, respectively. Mitochondrial DNA haplotyping suggests that the tortoise subspecies of T. g. Graeca and T. g. ibera are genetically distinct, with a calculated divergence time in the early or middle Pleistocene. Other proposed subspecies could not clearly be recognized based upon their mt haplotypes and phylogenetic position, and were either part of the T. g. Graeca or of the T. g. ibera clade, suggesting that genetic evidence for the existence of most of the 15 proposed subspecies of T. Graeca is weak.
-
Mitochondrial haplotype diversity in the tortoise species Testudo Graeca from North Africa and the Middle East
BMC Evolutionary Biology, 2005Co-Authors: Antoinette C. Van Der Kuyl, Donato L. Ph. Ballasina, Fokla ZorgdragerAbstract:Background To help conservation programs of the endangered spur-thighed tortoise and to gain better insight into its systematics, genetic variation and evolution in the tortoise species Testudo Graeca (Testudines: Testudinidae) was investigated by sequence analysis of a 394-nucleotide fragment of the mitochondrial 12S rRNA gene for 158 tortoise specimens belonging to the subspecies Testudo Graeca Graeca , Testudo Graeca ibera , Testudo Graeca terrestris , and a newly recognized subspecies Testudo Graeca whitei . A 411-nucleotide fragment of the mitochondrial D-loop was additionally sequenced for a subset of 22 T. Graeca , chosen because of their 12S gene haplotype and/or geographical origin. Results Haplotype networks generated by maximum-likelihood and neighbor-joining analyses of both the separate and the combined sequence data sets suggested the existence of two main clades of Testudo Graeca , comprising Testudo Graeca from northern Africa and Testudo Graeca from the Turkey and the Middle East, respectively. Conclusion Mitochondrial DNA haplotyping suggests that the tortoise subspecies of T. g. Graeca and T. g. ibera are genetically distinct, with a calculated divergence time in the early or middle Pleistocene. Other proposed subspecies could not clearly be recognized based upon their mt haplotypes and phylogenetic position, and were either part of the T. g. Graeca or of the T. g. ibera clade, suggesting that genetic evidence for the existence of most of the 15 proposed subspecies of T. Graeca is weak.
Ana C. Andreu - One of the best experts on this subject based on the ideXlab platform.
-
Long‐term demographic fluctuations of the spur‐thighed tortoise Testudo Graeca in SW Spain
Ecography, 2008Co-Authors: Carmen Díaz-paniagua, Claudia Keller, Ana C. AndreuAbstract:We assessed the dynamics of a population of spur-thighed tortoises, Testudo Graeca, placed under long-term protection from human interference. We estimated demographic parameters and constructed vertical life tables based on age structures for two different study periods separated by a 12-yr interval. Average age at maturity was 6.9 yr for males and 8.5 yr for females. Clutch size varied with female size, but tended to be constant among years. Average annual female fecundity over 9 yr was 8.4 eggs and decreased significantly in years of high rainfall. Females seemed to reproduce yearly, but with a constantly low output, probably maximising both their long-term reproductive potential and the probability of producing offspring during favourable years for hatchling survival. Adult survival was high and constant between periods. Juvenile survivorship from egg to 6 yr and recruitment into the 5-8-yr-old cohorts were significantly higher in the second period. Life tables indicated a predominantly negative demographic trend for the first period, with an average population increase rate of 0.977, and an overall positive tendency for the second period, with an average increase rate of 1.091. These figures suggest that the population experienced a variation that was closer to the maximum estimates for the first period, mediated mainly by an increase in juvenile recruitment. The data indicate that, besides high adult survival rates, occasional high juvenile recruitment bouts may have an important regulatory effect on the population dynamics of Testudo Graeca.
-
Microsatellite markers reveal multiple paternity and sperm storage in the Mediterranean spur-thighed tortoise, Testudo Graeca
Canadian Journal of Zoology, 2004Co-Authors: Séverine Roques, Carmen Díaz-paniagua, Ana C. AndreuAbstract:The spur-thighed tortoise (Testudo Graeca) is a terrestrial species in which multiple mating is frequently observed. We assessed the probability of multiple paternity in clutches (n = 15) laid by eight females, including successive clutches. Paternity was determined by microsatellite analyses at three loci. A large number of alleles per locus (n = 15–22) provided high probabilities of detecting multiple paternity, particularly at all loci combined (P = 0.989). Multiple paternity was found in 20% of the clutches in which offspring displayed more than two paternal alleles. However, this frequency may have been underestimated, given the small clutch sizes and the few loci used. Also, T. Graeca is able to store sperm from single or multiple matings and can use it to fertilize subsequent clutches of eggs, as indicated by the fact that the second clutch of a captive female was sired by a different male and that clutches of another female were multiply sired by the same males. These results confirm that multiple...
-
long term demographic fluctuations of the spur thighed tortoise Testudo Graeca in sw spain
Ecography, 2001Co-Authors: Carmen Diazpaniagua, Claudia Keller, Ana C. AndreuAbstract:We assessed the dynamics of a population of spur-thighed tortoises, Testudo Graeca, placed under long-term protection from human interference. We estimated demographic parameters and constructed vertical life tables based on age structures for two different study periods separated by a 12-yr interval. Average age at maturity was 6.9 yr for males and 8.5 yr for females. Clutch size varied with female size, but tended to be constant among years. Average annual female fecundity over 9 yr was 8.4 eggs and decreased significantly in years of high rainfall. Females seemed to reproduce yearly, but with a constantly low output, probably maximising both their long-term reproductive potential and the probability of producing offspring during favourable years for hatchling survival. Adult survival was high and constant between periods. Juvenile survivorship from egg to 6 yr and recruitment into the 5-8-yr-old cohorts were significantly higher in the second period. Life tables indicated a predominantly negative demographic trend for the first period, with an average population increase rate of 0.977, and an overall positive tendency for the second period, with an average increase rate of 1.091. These figures suggest that the population experienced a variation that was closer to the maximum estimates for the first period, mediated mainly by an increase in juvenile recruitment. The data indicate that, besides high adult survival rates, occasional high juvenile recruitment bouts may have an important regulatory effect on the population dynamics of Testudo Graeca.
-
Mitochondrial DNA haplotyping of Testudo Graeca on both continental sides of the Straits of Gibraltar.
The Journal of heredity, 2000Co-Authors: Y Álvarez, Carmen Díaz-paniagua, Ana C. Andreu, José Antonio Mateo, A Diez, Jm BautistaAbstract:Testudo Graeca is an endangered species of tortoise that inhabits Mediterranean areas of Africa, Asia, and Europe. Western populations are found on both sides of the Straits of Gibraltar. The effects of geographical isolation on genetic divergence were assessed by the sequence analysis of two mitochondrial DNA regions of the 12S rRNA and cytochrome b genes. Four different haplotypes were identified. A single haplotype was shared by all Spanish and some east Moroccan specimens. Two haplotypes were unique to the west Moroccan T. Graeca populations and allowed the clear discrimination between individual specimens found west of the Moulouya River. Phylogenetic analysis based on the estimation of nucleotide sequence distances of the haplotypes suggests an African origin for the Spanish populations and a subspecies status for the west Moroccan pool.
-
Survival Rates and Causes of Mortality of Testudo Graeca Hatchlings in Southwestern Spain
Journal of Herpetology, 1998Co-Authors: Claudia Keller, Carmen Díaz-paniagua, Ana C. AndreuAbstract:We assessed mortality causes and survival rates for 59 free ranging Testudo Graeca hatchlings. Individuals were followed for varying lengths of time from emergence from the nest in August-September to April using thread-trailing. Hatchlings died from unknown causes, mainly soon after emergence and belonged mainly to clutches which contained also unhatched eggs. Other causes of mortality were predation, car traffic, and trampling by large ungulates during the activity season (autumn and spring). Predation was low, and available data on potential predator diets also indicate low predation upon hatchlings. We found seasonal differences in survival; highest survival was in winter and lowest in spring. The overall survival rate for the 8 mo period was 0.39. Mortality causes registered during continuous monitoring were similar to anecdotal observations recorded over an 11 yr period.