Khalid Ben Kaddour | Université Cadi Ayyad (original) (raw)
Papers by Khalid Ben Kaddour
Revue d'Écologie (La Terre et La Vie)
Sexual dimorphism, growth and maturation patterns of Testudo g. graeca in the Central Jbilets, Mo... more Sexual dimorphism, growth and maturation patterns of Testudo g. graeca in the Central Jbilets, Morocco.-Sexual size dimorphism and the growth and maturation patterns were studied in the Mediterranean Spur-thighed Tortoise (Testudo g. graeca), in the central Jbilets mountains (western Morocco). The number and width of scute growth annuli were respectively used as indicators of age at sexual maturity and of juvenile growth rates. Males reach their sexual maturity earlier than females but juvenile growth rates do not differ between sexes. Thence, when reaching sexual maturity males are smaller than females. However, important age and size inter-individual variations were observed at maturity. In both sexes, precocious individuals show high juvenile growth rates but reach a smaller body size at maturity than late individuals. Therefore, sexual maturity depends on juvenile growth rates. The important individual variations in age and size at maturity could reflect the plasticity of individual growth and maturation in response to changing environmental conditions.
Riassunto. Il Marocco è il paese dell'Africa settentrionale, così come del Mediterraneo oc-ci... more Riassunto. Il Marocco è il paese dell'Africa settentrionale, così come del Mediterraneo oc-cidentale, dall'erpetofauna più ricca e varia, di cui fanno parte anche 33 specie endemiche (ossia il 20% del totale di anfibi e rettili che ci vivono). Se da un lato si conosce bene la composizione attuale dell'erpetofauna marocchina, d'altra parte non si sa quasi nulla delle fluttuazioni all'interno delle popolazioni e negli areali di distribuzione che potrebbero interessare alcune specie a causa di cam-biamenti climatici e ambientali. La rapidità del declino delle specie più critiche rimane a tutti gli effetti sconosciuta. Tuttavia, è certo che diverse specie siano in declino, se non addirittura in grave rischio di estinzione. Inoltre una parte della fauna marocchina (soprattutto tra i rettili: le testuggini, i camaleonti, gli uro-mastici, i varani etc.) viene illegalmente venduta ai turisti, danneggiando così il patrimonio naturale del Marocco. Esistono sì delle leggi m...
Chelonian Conservation and Biology, 2008
... 1998. Sexual dimorphism in snakes: different reproductive roles favour different body plans. ... more ... 1998. Sexual dimorphism in snakes: different reproductive roles favour different body plans. Proceedings of the Royal Society B 265:15. ... 1999. Skeletochronology and mark-recapture assessments of growth in the North African agamid lizard, Agama impalearis. ...
Le surpâturage affecte l'ensemble des pays du Maghreb. Il modifie profondement la structure e... more Le surpâturage affecte l'ensemble des pays du Maghreb. Il modifie profondement la structure et le fonctionnement des ecosystemes situes sur les zones de parcours du betail. C'est une des causes probables de laregression importante des populations de tortue grecque (Testudo graeca graeca) en Afrique du Nord. Les consequences du surpâturage sur la biologie de la tortue sont complexes et ne se resument pas a une simple limitation des ressources trophiques pour l'animal...
Sexual dimorphism, growth and maturation patterns of Testudo g. graeca in the Central Jbilets, Mo... more Sexual dimorphism, growth and maturation patterns of Testudo g. graeca in the Central Jbilets, Morocco.-Sexual size dimorphism and the growth and maturation patterns were studied in the Mediterranean Spur-thighed Tortoise (Testudo g. graeca), in the central Jbilets mountains (western Morocco). The number and width of scute growth annuli were respectively used as indicators of age at sexual maturity and of juvenile growth rates. Males reach their sexual maturity earlier than females but juvenile growth rates do not differ between sexes. Thence, when reaching sexual maturity males are smaller than females. However, important age and size inter-individual variations were observed at maturity. In both sexes, precocious individuals show high juvenile growth rates but reach a smaller body size at maturity than late individuals. Therefore, sexual maturity depends on juvenile growth rates. The important individual variations in age and size at maturity could reflect the plasticity of individual growth and maturation in response to changing environmental conditions.
Environmental Conservation, 2012
SUMMARYArid Mediterranean regions that shelter unique biodiversity are threatened by increasing a... more SUMMARYArid Mediterranean regions that shelter unique biodiversity are threatened by increasing anthropogenic pressures, such as urbanization, overgrazing and climate change. In Morocco, one of the main bush species in arid areas, the jujube (Ziziphus lotus), suffers from officially promoted programmes of removal. The Moorish tortoise (Testudo graeca soussensis) is threatened by such habitat loss. Like most animals, the Moorish tortoise must navigate between microhabitats to find essential feeding resources and thermal refuges. This study combined radio-tracking of free-ranging individuals, microhabitat temperature monitoring and transects in a range of habitats. Tortoises were found to depend on the occurrence of large and relatively abundant bushes to escape lethal overheating. Thus, (1) current official encouragements for the destruction of the jujube bushes should be reappraised; (2) habitat restoration relying on replanting jujube bush should be encouraged; and (3) large-scale ...
– Accurate information on density, structure and vulnerability of wild populations occupies a cen... more – Accurate information on density, structure and vulnerability of wild populations occupies a central place in conservation biology. A mark-recapture study was carried out during the 2003 activity season in a population of Testudo graeca in the Central Jbilets (Morocco). Juveniles were poorly represented in our data set, suggesting that juvenile numbers are actually low in our population and/or that tortoises are easier to capture after the behavioural shift of the acquisition of sexual maturity. Although the studied population was localised in a severely over-grazed area, the estimated adult and sub-adult population density, six individu-als/ha, was relatively high comparatively to available estimates in other places. However, within three months of fieldwork, it was possible to capture most of the adults (60%), suggesting that Testudo graeca graeca populations are very sensitive to illegal and repeated harvesting. Long-term monitoring of the population is required to better appreciate the demographic trend of this population.
Riassunto. Il Marocco è il paese dell'Africa settentrionale, così come del Mediterraneo oc-cident... more Riassunto. Il Marocco è il paese dell'Africa settentrionale, così come del Mediterraneo oc-cidentale, dall'erpetofauna più ricca e varia, di cui fanno parte anche 33 specie endemiche (ossia il 20% del totale di anfibi e rettili che ci vivono). Se da un lato si conosce bene la composizione attuale dell'erpetofauna marocchina, d'altra parte non si sa quasi nulla delle fluttuazioni all'interno delle popolazioni e negli areali di distribuzione che potrebbero interessare alcune specie a causa di cam-biamenti climatici e ambientali. La rapidità del declino delle specie più critiche rimane a tutti gli effetti sconosciuta. Tuttavia, è certo che diverse specie siano in declino, se non addirittura in grave rischio di estinzione. Inoltre una parte della fauna marocchina (soprattutto tra i rettili: le testuggini, i camaleonti, gli uro-mastici, i varani etc.) viene illegalmente venduta ai turisti, danneggiando così il patrimonio naturale del Marocco. Esistono sì delle leggi marocchine, ed inter-nazionali (CITES), che proibiscono queste pratiche, ma i turisti spesso non le conoscono o fingono di ignorarle. D'altra parte, anche se questi animali " espor-tati " dal Marocco sono spesso sequestrati alle dogane degli aeroporti europei, diventa poi impossibile riportarli nei luoghi di cattura. A causa dell'entità delle minacce che incombono sulla biodiversità erpetologica, la valutazione dell'en-tità del declino e la salvaguardia delle specie che compongono la minacciata erpetofauna marocchina diventano una necessità assoluta. È in questo contesto che a partire da febbraio 2000 abbiamo impostato un programma di ricerca che cerca di capire l'evoluzione spazio-temporale di questi vertebrati ectotermi e di come gestirli. Questa ricerca, che è solo l'inizio di un complessivo prendersi ca-rico di questo patrimonio nazionale, è rivolta prioritariamente alle nostre specie più caratteristiche e a quelle endemiche. Durante questa conferenza esponiamo The Moroccan Herpetology " Basic research to the conservation of species "
Terrestrial chelonians of arid regions are frequently faced with highly variable food quality and... more Terrestrial chelonians of arid regions are frequently faced with highly variable food quality and/or quantity and these problems could be aggravated in overgrazing areas. Then, it is crucial for species conservation to possess precise data on feeding ecology. In this paper, we provide the first quantitative data on Testudo graeca graeca feeding ecology, in the central Jbilets (Morocco). Diet composition was obtained by faecal analysis and compared to plant assemblages in the field. Interestingly, T. g. graeca seems rather a specialist herbivorous tortoise. The five main plant species found in faecal samples (Leontodon saxatilis (Asteraceae); Malva parviflora (Malvaceae); Astragalus cruciatus, Medicago hispida and Lotus arenarius (Fabaceae)) represent 70% of the identified material and are highly preferred whereas several other plant species, common in the field (e.g. Eryngium ilicifolium (Ombellifereae); Emex spinosus (Polygonaceae); Spergula flaccida Caryophyllaceae)) are actively avoided. Fabaceae made up 27% of the diet and may be important forbs in the diet of terrestrial tortoise owing to their high nutritional value. The diet composition of T. g. graeca suggests that diet overlap may occur between domestic ungulates and tortoises in overgrazed landscape and could generate a competition context. However, T. g. graeca seems to focus its foraging effort under the spiny shrubs where the impact of overgrazing is strongly attenuated.
SUMMARY. — Sexual dimorphism, growth and maturation patterns of Testudo g. graeca in the Central ... more SUMMARY. — Sexual dimorphism, growth and maturation patterns of Testudo g. graeca in the Central Jbilets, Morocco. — Sexual size dimorphism and the growth and maturation patterns were studied in the Mediterranean Spur-thighed Tortoise (Testudo g. graeca), in the central Jbilets mountains (western Morocco). The number and width of scute growth annuli were respectively used as indicators of age at sexual maturity and of juvenile growth rates. Males reach their sexual maturity earlier than females but juvenile growth rates do not differ between sexes. Thence, when reaching sexual maturity males are smaller than females. However, important age and size inter-individual variations were observed at maturity. In both sexes, precocious individuals show high juvenile growth rates but reach a smaller body size at maturity than late individuals. Therefore, sexual maturity depends on juvenile growth rates. The important individual variations in age and size at maturity could reflect the plasticity of individual growth and maturation in response to changing environmental conditions. RÉSUMÉ. — Le dimorphisme sexuel de taille (DST) et ses relations avec les patterns de croissance et de maturation ont été étudiés chez la Tortue mauresque (Testudo g. graeca), dans les Jbilets centrales (Maroc occidental). L'âge de maturité sexuelle et les taux de croissance ont été estimés à partir du nom-bre et de la largeur des anneaux de croissance ornant les écailles épidermiques de la carapace. La matu-rité sexuelle est plus précoce chez les mâles que chez les femelles bien qu'aucune différence du taux de croissance juvénile ne soit détectable selon le sexe. Les mâles atteignent ainsi à maturité sexuelle une taille plus petite que celle des femelles. Toutefois, il existe d'importantes variations individuelles dans l'âge et la taille à maturité. Chez les deux sexes, plus un individu montre une croissance juvénile rapide, plus il atteint la maturité sexuelle précocement et présente alors une taille plus faible. L'âge d'acquisi-tion de la maturité sexuelle semble ainsi essentiellement déterminé par la cinétique de croissance juvé-nile. Les variations individuelles importantes d'âge et de taille observées à la maturité sexuelle sem-blent refléter la plasticité de croissance et de maturation que présentent les individus en réponse aux conditions variables du milieu. Chez de nombreuses espèces animales, il existe des différences de taille marquées entre mâles et femelles adultes (
In most animal species, it is expected that females should exhibit a greater abdominal volume tha... more In most animal species, it is expected that females should exhibit a greater abdominal volume than males to hold the progeny, when compared with females, males should exhibit more developed attributes that enhance mobility. We tested this hypothesis in the Greek tortoise. In chelonians, a reduction of the openings in the shell improves protection against predation but also constrains the abdominal volume and limits the space available to move the limbs. As expected, our data show that the shell provides a larger abdominal volume relative to tortoise size in females than in males. In males, deep notches in the shell and a reduction of several plastron plates offer more freedom to the limbs and to the tail; these characteristics presumably enhance mating success. Further studies are necessary to assess the applicability of these results in other chelonians, notably freshwater and marine turtles.
KEY WORDS. – Reptilia; Testudines; Testudinidae; body shape; body size; chelonian; sexual
dimorphism; Testudo graeca
SUMMARY Arid Mediterranean regions that shelter unique biodiversity are threatened by increasing ... more SUMMARY Arid Mediterranean regions that shelter unique biodiversity are threatened by increasing anthropo-genic pressures, such as urbanization, overgrazing and climate change. In Morocco, one of the main bush species in arid areas, the jujube (Ziziphus lotus), suffers from officially promoted programmes of removal. The Moorish tortoise (Testudo graeca soussensis) is threatened by such habitat loss. Like most animals, the Moorish tortoise must navigate between microhabitats to find essential feeding resources and thermal refuges. This study combined radio-tracking of free-ranging individuals, microhabitat temperature monitoring and transects in a range of habitats. Tortoises were found to depend on the occurrence of large and relatively abundant bushes to escape lethal overheating. Thus, (1) current official encouragements for the destruction of the jujube bushes should be reappraised; (2) habitat restoration relying on replanting jujube bush should be encouraged; and (3) large-scale monitoring of critical bush densities should be used to better organize conservation plans (protection and/or restoration of areas) for the Moorish tortoise.
Accurate information on density, structure and vulnerability of wild populations occupies a centr... more Accurate information on density, structure and vulnerability of wild populations occupies a central place in conservation biology. A mark-recapture study was carried out during the 2003 activity season in a population of Testudo graeca in the Central Jbilets (Morocco). Juveniles were poorly represented in our data set, suggesting that juvenile numbers are actually low in our population and/or that tortoises
Journal of Arid Environments, 2006
Terrestrial chelonians of arid regions are frequently faced with highly variable food quality and... more Terrestrial chelonians of arid regions are frequently faced with highly variable food quality and/or quantity and these problems could be aggravated in overgrazing areas. Then, it is crucial for species conservation to possess precise data on feeding ecology. In this paper, we provide the first quantitative data on Testudo graeca graeca feeding ecology, in the central Jbilets (Morocco). Diet composition was obtained by faecal analysis and compared to plant assemblages in the field. Interestingly, T. g. graeca seems rather a specialist herbivorous tortoise. The five main plant species found in faecal samples (Leontodon saxatilis (Asteraceae); Malva parviflora (Malvaceae); Astragalus cruciatus, Medicago hispida and Lotus arenarius (Fabaceae)) represent 70% of the identified material and are highly preferred whereas several other plant species, common in the field (e.g. Eryngium ilicifolium (Ombellifereae); Emex spinosus (Polygonaceae); Spergula flaccida Caryophyllaceae)) are actively avoided. Fabaceae made up 27% of the diet and may be important forbs in the diet of terrestrial tortoise owing to their high nutritional value. The diet composition of T. g. graeca suggests that diet overlap may occur between domestic ungulates and tortoises in overgrazed landscape and could ARTICLE IN PRESS www.elsevier.com/locate/jnlabr/yjare 0140-1963/$ -see front matter r (F. Lagarde).
Revue d'Écologie (La Terre et La Vie)
Sexual dimorphism, growth and maturation patterns of Testudo g. graeca in the Central Jbilets, Mo... more Sexual dimorphism, growth and maturation patterns of Testudo g. graeca in the Central Jbilets, Morocco.-Sexual size dimorphism and the growth and maturation patterns were studied in the Mediterranean Spur-thighed Tortoise (Testudo g. graeca), in the central Jbilets mountains (western Morocco). The number and width of scute growth annuli were respectively used as indicators of age at sexual maturity and of juvenile growth rates. Males reach their sexual maturity earlier than females but juvenile growth rates do not differ between sexes. Thence, when reaching sexual maturity males are smaller than females. However, important age and size inter-individual variations were observed at maturity. In both sexes, precocious individuals show high juvenile growth rates but reach a smaller body size at maturity than late individuals. Therefore, sexual maturity depends on juvenile growth rates. The important individual variations in age and size at maturity could reflect the plasticity of individual growth and maturation in response to changing environmental conditions.
Riassunto. Il Marocco è il paese dell'Africa settentrionale, così come del Mediterraneo oc-ci... more Riassunto. Il Marocco è il paese dell'Africa settentrionale, così come del Mediterraneo oc-cidentale, dall'erpetofauna più ricca e varia, di cui fanno parte anche 33 specie endemiche (ossia il 20% del totale di anfibi e rettili che ci vivono). Se da un lato si conosce bene la composizione attuale dell'erpetofauna marocchina, d'altra parte non si sa quasi nulla delle fluttuazioni all'interno delle popolazioni e negli areali di distribuzione che potrebbero interessare alcune specie a causa di cam-biamenti climatici e ambientali. La rapidità del declino delle specie più critiche rimane a tutti gli effetti sconosciuta. Tuttavia, è certo che diverse specie siano in declino, se non addirittura in grave rischio di estinzione. Inoltre una parte della fauna marocchina (soprattutto tra i rettili: le testuggini, i camaleonti, gli uro-mastici, i varani etc.) viene illegalmente venduta ai turisti, danneggiando così il patrimonio naturale del Marocco. Esistono sì delle leggi m...
Chelonian Conservation and Biology, 2008
... 1998. Sexual dimorphism in snakes: different reproductive roles favour different body plans. ... more ... 1998. Sexual dimorphism in snakes: different reproductive roles favour different body plans. Proceedings of the Royal Society B 265:15. ... 1999. Skeletochronology and mark-recapture assessments of growth in the North African agamid lizard, Agama impalearis. ...
Le surpâturage affecte l'ensemble des pays du Maghreb. Il modifie profondement la structure e... more Le surpâturage affecte l'ensemble des pays du Maghreb. Il modifie profondement la structure et le fonctionnement des ecosystemes situes sur les zones de parcours du betail. C'est une des causes probables de laregression importante des populations de tortue grecque (Testudo graeca graeca) en Afrique du Nord. Les consequences du surpâturage sur la biologie de la tortue sont complexes et ne se resument pas a une simple limitation des ressources trophiques pour l'animal...
Sexual dimorphism, growth and maturation patterns of Testudo g. graeca in the Central Jbilets, Mo... more Sexual dimorphism, growth and maturation patterns of Testudo g. graeca in the Central Jbilets, Morocco.-Sexual size dimorphism and the growth and maturation patterns were studied in the Mediterranean Spur-thighed Tortoise (Testudo g. graeca), in the central Jbilets mountains (western Morocco). The number and width of scute growth annuli were respectively used as indicators of age at sexual maturity and of juvenile growth rates. Males reach their sexual maturity earlier than females but juvenile growth rates do not differ between sexes. Thence, when reaching sexual maturity males are smaller than females. However, important age and size inter-individual variations were observed at maturity. In both sexes, precocious individuals show high juvenile growth rates but reach a smaller body size at maturity than late individuals. Therefore, sexual maturity depends on juvenile growth rates. The important individual variations in age and size at maturity could reflect the plasticity of individual growth and maturation in response to changing environmental conditions.
Environmental Conservation, 2012
SUMMARYArid Mediterranean regions that shelter unique biodiversity are threatened by increasing a... more SUMMARYArid Mediterranean regions that shelter unique biodiversity are threatened by increasing anthropogenic pressures, such as urbanization, overgrazing and climate change. In Morocco, one of the main bush species in arid areas, the jujube (Ziziphus lotus), suffers from officially promoted programmes of removal. The Moorish tortoise (Testudo graeca soussensis) is threatened by such habitat loss. Like most animals, the Moorish tortoise must navigate between microhabitats to find essential feeding resources and thermal refuges. This study combined radio-tracking of free-ranging individuals, microhabitat temperature monitoring and transects in a range of habitats. Tortoises were found to depend on the occurrence of large and relatively abundant bushes to escape lethal overheating. Thus, (1) current official encouragements for the destruction of the jujube bushes should be reappraised; (2) habitat restoration relying on replanting jujube bush should be encouraged; and (3) large-scale ...
– Accurate information on density, structure and vulnerability of wild populations occupies a cen... more – Accurate information on density, structure and vulnerability of wild populations occupies a central place in conservation biology. A mark-recapture study was carried out during the 2003 activity season in a population of Testudo graeca in the Central Jbilets (Morocco). Juveniles were poorly represented in our data set, suggesting that juvenile numbers are actually low in our population and/or that tortoises are easier to capture after the behavioural shift of the acquisition of sexual maturity. Although the studied population was localised in a severely over-grazed area, the estimated adult and sub-adult population density, six individu-als/ha, was relatively high comparatively to available estimates in other places. However, within three months of fieldwork, it was possible to capture most of the adults (60%), suggesting that Testudo graeca graeca populations are very sensitive to illegal and repeated harvesting. Long-term monitoring of the population is required to better appreciate the demographic trend of this population.
Riassunto. Il Marocco è il paese dell'Africa settentrionale, così come del Mediterraneo oc-cident... more Riassunto. Il Marocco è il paese dell'Africa settentrionale, così come del Mediterraneo oc-cidentale, dall'erpetofauna più ricca e varia, di cui fanno parte anche 33 specie endemiche (ossia il 20% del totale di anfibi e rettili che ci vivono). Se da un lato si conosce bene la composizione attuale dell'erpetofauna marocchina, d'altra parte non si sa quasi nulla delle fluttuazioni all'interno delle popolazioni e negli areali di distribuzione che potrebbero interessare alcune specie a causa di cam-biamenti climatici e ambientali. La rapidità del declino delle specie più critiche rimane a tutti gli effetti sconosciuta. Tuttavia, è certo che diverse specie siano in declino, se non addirittura in grave rischio di estinzione. Inoltre una parte della fauna marocchina (soprattutto tra i rettili: le testuggini, i camaleonti, gli uro-mastici, i varani etc.) viene illegalmente venduta ai turisti, danneggiando così il patrimonio naturale del Marocco. Esistono sì delle leggi marocchine, ed inter-nazionali (CITES), che proibiscono queste pratiche, ma i turisti spesso non le conoscono o fingono di ignorarle. D'altra parte, anche se questi animali " espor-tati " dal Marocco sono spesso sequestrati alle dogane degli aeroporti europei, diventa poi impossibile riportarli nei luoghi di cattura. A causa dell'entità delle minacce che incombono sulla biodiversità erpetologica, la valutazione dell'en-tità del declino e la salvaguardia delle specie che compongono la minacciata erpetofauna marocchina diventano una necessità assoluta. È in questo contesto che a partire da febbraio 2000 abbiamo impostato un programma di ricerca che cerca di capire l'evoluzione spazio-temporale di questi vertebrati ectotermi e di come gestirli. Questa ricerca, che è solo l'inizio di un complessivo prendersi ca-rico di questo patrimonio nazionale, è rivolta prioritariamente alle nostre specie più caratteristiche e a quelle endemiche. Durante questa conferenza esponiamo The Moroccan Herpetology " Basic research to the conservation of species "
Terrestrial chelonians of arid regions are frequently faced with highly variable food quality and... more Terrestrial chelonians of arid regions are frequently faced with highly variable food quality and/or quantity and these problems could be aggravated in overgrazing areas. Then, it is crucial for species conservation to possess precise data on feeding ecology. In this paper, we provide the first quantitative data on Testudo graeca graeca feeding ecology, in the central Jbilets (Morocco). Diet composition was obtained by faecal analysis and compared to plant assemblages in the field. Interestingly, T. g. graeca seems rather a specialist herbivorous tortoise. The five main plant species found in faecal samples (Leontodon saxatilis (Asteraceae); Malva parviflora (Malvaceae); Astragalus cruciatus, Medicago hispida and Lotus arenarius (Fabaceae)) represent 70% of the identified material and are highly preferred whereas several other plant species, common in the field (e.g. Eryngium ilicifolium (Ombellifereae); Emex spinosus (Polygonaceae); Spergula flaccida Caryophyllaceae)) are actively avoided. Fabaceae made up 27% of the diet and may be important forbs in the diet of terrestrial tortoise owing to their high nutritional value. The diet composition of T. g. graeca suggests that diet overlap may occur between domestic ungulates and tortoises in overgrazed landscape and could generate a competition context. However, T. g. graeca seems to focus its foraging effort under the spiny shrubs where the impact of overgrazing is strongly attenuated.
SUMMARY. — Sexual dimorphism, growth and maturation patterns of Testudo g. graeca in the Central ... more SUMMARY. — Sexual dimorphism, growth and maturation patterns of Testudo g. graeca in the Central Jbilets, Morocco. — Sexual size dimorphism and the growth and maturation patterns were studied in the Mediterranean Spur-thighed Tortoise (Testudo g. graeca), in the central Jbilets mountains (western Morocco). The number and width of scute growth annuli were respectively used as indicators of age at sexual maturity and of juvenile growth rates. Males reach their sexual maturity earlier than females but juvenile growth rates do not differ between sexes. Thence, when reaching sexual maturity males are smaller than females. However, important age and size inter-individual variations were observed at maturity. In both sexes, precocious individuals show high juvenile growth rates but reach a smaller body size at maturity than late individuals. Therefore, sexual maturity depends on juvenile growth rates. The important individual variations in age and size at maturity could reflect the plasticity of individual growth and maturation in response to changing environmental conditions. RÉSUMÉ. — Le dimorphisme sexuel de taille (DST) et ses relations avec les patterns de croissance et de maturation ont été étudiés chez la Tortue mauresque (Testudo g. graeca), dans les Jbilets centrales (Maroc occidental). L'âge de maturité sexuelle et les taux de croissance ont été estimés à partir du nom-bre et de la largeur des anneaux de croissance ornant les écailles épidermiques de la carapace. La matu-rité sexuelle est plus précoce chez les mâles que chez les femelles bien qu'aucune différence du taux de croissance juvénile ne soit détectable selon le sexe. Les mâles atteignent ainsi à maturité sexuelle une taille plus petite que celle des femelles. Toutefois, il existe d'importantes variations individuelles dans l'âge et la taille à maturité. Chez les deux sexes, plus un individu montre une croissance juvénile rapide, plus il atteint la maturité sexuelle précocement et présente alors une taille plus faible. L'âge d'acquisi-tion de la maturité sexuelle semble ainsi essentiellement déterminé par la cinétique de croissance juvé-nile. Les variations individuelles importantes d'âge et de taille observées à la maturité sexuelle sem-blent refléter la plasticité de croissance et de maturation que présentent les individus en réponse aux conditions variables du milieu. Chez de nombreuses espèces animales, il existe des différences de taille marquées entre mâles et femelles adultes (
In most animal species, it is expected that females should exhibit a greater abdominal volume tha... more In most animal species, it is expected that females should exhibit a greater abdominal volume than males to hold the progeny, when compared with females, males should exhibit more developed attributes that enhance mobility. We tested this hypothesis in the Greek tortoise. In chelonians, a reduction of the openings in the shell improves protection against predation but also constrains the abdominal volume and limits the space available to move the limbs. As expected, our data show that the shell provides a larger abdominal volume relative to tortoise size in females than in males. In males, deep notches in the shell and a reduction of several plastron plates offer more freedom to the limbs and to the tail; these characteristics presumably enhance mating success. Further studies are necessary to assess the applicability of these results in other chelonians, notably freshwater and marine turtles.
KEY WORDS. – Reptilia; Testudines; Testudinidae; body shape; body size; chelonian; sexual
dimorphism; Testudo graeca
SUMMARY Arid Mediterranean regions that shelter unique biodiversity are threatened by increasing ... more SUMMARY Arid Mediterranean regions that shelter unique biodiversity are threatened by increasing anthropo-genic pressures, such as urbanization, overgrazing and climate change. In Morocco, one of the main bush species in arid areas, the jujube (Ziziphus lotus), suffers from officially promoted programmes of removal. The Moorish tortoise (Testudo graeca soussensis) is threatened by such habitat loss. Like most animals, the Moorish tortoise must navigate between microhabitats to find essential feeding resources and thermal refuges. This study combined radio-tracking of free-ranging individuals, microhabitat temperature monitoring and transects in a range of habitats. Tortoises were found to depend on the occurrence of large and relatively abundant bushes to escape lethal overheating. Thus, (1) current official encouragements for the destruction of the jujube bushes should be reappraised; (2) habitat restoration relying on replanting jujube bush should be encouraged; and (3) large-scale monitoring of critical bush densities should be used to better organize conservation plans (protection and/or restoration of areas) for the Moorish tortoise.
Accurate information on density, structure and vulnerability of wild populations occupies a centr... more Accurate information on density, structure and vulnerability of wild populations occupies a central place in conservation biology. A mark-recapture study was carried out during the 2003 activity season in a population of Testudo graeca in the Central Jbilets (Morocco). Juveniles were poorly represented in our data set, suggesting that juvenile numbers are actually low in our population and/or that tortoises
Journal of Arid Environments, 2006
Terrestrial chelonians of arid regions are frequently faced with highly variable food quality and... more Terrestrial chelonians of arid regions are frequently faced with highly variable food quality and/or quantity and these problems could be aggravated in overgrazing areas. Then, it is crucial for species conservation to possess precise data on feeding ecology. In this paper, we provide the first quantitative data on Testudo graeca graeca feeding ecology, in the central Jbilets (Morocco). Diet composition was obtained by faecal analysis and compared to plant assemblages in the field. Interestingly, T. g. graeca seems rather a specialist herbivorous tortoise. The five main plant species found in faecal samples (Leontodon saxatilis (Asteraceae); Malva parviflora (Malvaceae); Astragalus cruciatus, Medicago hispida and Lotus arenarius (Fabaceae)) represent 70% of the identified material and are highly preferred whereas several other plant species, common in the field (e.g. Eryngium ilicifolium (Ombellifereae); Emex spinosus (Polygonaceae); Spergula flaccida Caryophyllaceae)) are actively avoided. Fabaceae made up 27% of the diet and may be important forbs in the diet of terrestrial tortoise owing to their high nutritional value. The diet composition of T. g. graeca suggests that diet overlap may occur between domestic ungulates and tortoises in overgrazed landscape and could ARTICLE IN PRESS www.elsevier.com/locate/jnlabr/yjare 0140-1963/$ -see front matter r (F. Lagarde).