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Eli Geffen - One of the best experts on this subject based on the ideXlab platform.
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alternative mating tactics in male chameleons Chamaeleo Chamaeleon are evident in both long term body color and short term courtship pattern
PLOS ONE, 2016Co-Authors: Tammy Kerenrotem, Noga Levy, Lior Wolf, Amos Bouskila, Eli GeffenAbstract:Alternative mating tactics in males of various taxa are associated with body color, body size, and social status. Chameleons are known for their ability to change body color following immediate environmental or social stimuli. In this study, we examined whether the differential appearance of male common chameleon during the breeding season is indeed an expression of alternative mating tactics. We documented body color of males and used computer vision techniques to classify images of individuals into discrete color patterns associated with seasons, individual characteristics, and social contexts. Our findings revealed no differences in body color and color patterns among males during the non-breeding season. However, during the breeding season males appeared in several color displays, which reflected body size, social status, and behavioral patterns. Furthermore, smaller and younger males resembled the appearance of small females. Consequently, we suggest that long-term color change in males during the breeding season reflects male alternative mating tactics. Upon encounter with a receptive female, males rapidly alter their appearance to that of a specific brief courtship display, which reflects their social status. The females, however, copulated indiscriminately in respect to male color patterns. Thus, we suggest that the differential color patterns displayed by males during the breeding season are largely aimed at inter-male signaling.
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male preference for sexual signalling over crypsis is associated with alternative mating tactics
Animal Behaviour, 2016Co-Authors: Tammy Kerenrotem, Noga Levy, Lior Wolf, Amos Bouskila, Eli GeffenAbstract:Changing body colour in animals generally reflects a conflict between two selection pressures, camouflage and social signalling. Chameleons are among the few organisms that resolve this conflict by rapid and temporary change in body colour for both background matching and social display. Male common chameleons, Chamaeleo Chamaeleon, employ two alternative mating tactics, dominants and subordinates, both of which are associated with long-term body colour patterns and instantaneous colour displays during social encounters. Hence, males present a good model in which to study the influence of mating tactic on the decision of whether to remain cryptic or to signal. We exposed individuals to two conflicting external stimuli: background manipulations, which challenge camouflage, and the presence of a female, which stimulates sexual signalling. No individuals of either mating tactic responded to background manipulation except when the shift was from green to brown background or vice versa. Ambient temperatures affected colour matching but not sexual signalling, while body temperature affected neither. Males ignored the background colour and prioritized being distinctive when encountering females. As such, males were more likely to engage in sexual signalling than crypsis. Subordinate sneakers signalled females more frequently than the dominant, female-guarding males, suggesting that sneakers rapidly signal females their intentions when the dominant is out of range. Conversely, dominant males may gain little by frequent signalling to the females they guard, while possibly gaining more by diverting this energy towards mate guarding. Our results suggest that specific male mating tactics strongly influence the decision to use crypsis or sexual signalling.
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Ontogenetic habitat shift and risk of cannibalism in the common chameleon (Chamaeleo Chamaeleon)
Behavioral Ecology and Sociobiology, 2006Co-Authors: Tammy Keren-rotem, Amos Bouskila, Eli GeffenAbstract:Ontogenetic habitat shifts have been documented in numerous fish and amphibians and in some reptiles. Intraspecific competition together with differential predation, prey size, social interactions, size-related thermal requirements, and morphological constraints on movement are often implicated in this ontogenetic habitat separation. In the current study, we combined field observation with experiments in seminatural arenas to test various hypotheses regarding the ontogenetic habitat shift that we have documented in the common chameleon. Juveniles (mean, 1 g) occupied low grasses and the adults (mean, 35 g) were found on bushes and trees. Overlap in habitat use between these two age classes was minimal. Our field experiments showed that juveniles actively avoid the presence of adults by concealment or flight. Adults readily attacked and consumed juveniles, regardless of their own mass. These results suggest that the risk of cannibalism towards juveniles is an important selective force behind the ontogenetic habitat shift observed in the common chameleon and may be important in other species too.
Mariano Cuadrado - One of the best experts on this subject based on the ideXlab platform.
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mate guarding and social mating system in male common chameleons Chamaeleo Chamaeleon
Journal of Zoology, 2006Co-Authors: Mariano CuadradoAbstract:Male common chameleons Chamaeleo Chamaeleon actively followed the female closely as a typical mate guarding behaviour during the mating season. Guarding behaviour and spatial organization were studied in 34 radio-tagged males in a population in southern Spain during three summers. Timing and extent of guarding were highly variable among males. Overall, guarding started on 16 August (range 28 July‐ 5 September, n = 34) and ended on 4 September (range 21 August‐15 September, n = 24) lasting 13.4 days (range 0‐46 days, n = 30). Males showed a polygynous serial-type mating system where males sequentially guarded (and mated) several females during the breeding season but only one at a time. The number of guarded females (mean 2.8, range 0‐8, n = 34) and number of mates per male (mean 0.7, range 0‐3, n = 34) were also highly variable among males. In general, guarding males abandoned the females soon after mating in association with clear signs that females were no longer receptive. Males showed a remarkably complex spatial organization in close association with the home range of guarded females. Guarding behaviour resulted in territorial behaviour, and ‘stable’ as well as ‘mobile’ territories were recorded. In ‘stable’ territories, males defended non-overlapping areas where the home range of one female or more was included. Although monogamy was the predominant mating system recorded in this population, social polygyny occurred in all study years. Polygynous groups were only feasible because females aggregated in small-sized areas without apparent symptoms of intrasexual competition. Breeding asynchrony of females seems to influence this complex mating system as more competitive (large) males mated with large (early reproducing) females and small (late reproducing) ones (cf. Cuadrado, 1999). Most aggressive interactions were male‐male chasing of a solitary intruder by a guarding male. A removal experiment of guarding males revealed that newcomers were small-sized males, suggesting that an important fraction of males were acting as floaters searching for mating opportunities. Male characteristics (especially size and body weight) were the main factors influencing the spatial organization and the reproductive success of males in this population.
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comparison between tail and jugular venipuncture techniques for blood sample collection in common chameleons Chamaeleo Chamaeleon
Veterinary Journal, 2003Co-Authors: Mariano Cuadrado, Isabel Molinaprescott, Luis FloresAbstract:Abstract The most common technique used for collecting blood samples from chameleons, ventral tail caudal venipuncture (Reptile care. An Atlas of Diseases and Treatments, Vol. II, T.F.H. Publication, New Jersey, 1991) sometimes presents undesired effects. Here we compared tail versus jugular vein venipuncture techniques in the common chameleon. In the first experiment, we collected 0.25% of the chameleon’s body mass in blood from either tail or jugular sites in size-matched pairs of animals to check for secondary effects. In a second experiment, we measured white blood cells (WBC), red blood cells (RBC), total plasma protein and uric acid in blood samples collected from both sites in the same individual. We found few secondary effects following the use of either venipuncture site although skin darkening was observed in few specimens when using the ventral tail vein. Blood profiles were similar between samples. The repeatability of measurements was similar in RBC and WBC counts and remarkably low (
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reproduction of Chamaeleo Chamaeleon under contrasting environmental conditions
Herpetological Journal, 2002Co-Authors: Carmen Diazpaniagua, Mariano Cuadrado, M C Blazquez, Jose Antonio MateoAbstract:Reproductive characteristics of ChamaeleoChamaeleon are described and compared between a dry and a wet year. Nesting occurred in September and October, beginning later in the dry year when females also excavated their nests in longer (but not deeper) tunnels. Females were significantly smaller, with lower body mass, lower clutch mass and lower clutch size in the dry year. Relative clutch mass and body condition did not differ between the two years. Females laid a single clutch of 4-40 eggs, with a mean relative clutch mass of 60-70%. Clutch size was correlated with maternal size, being larger in the wet year, whereas egg variables were independent of maternal characteristics. Higher mortality rate was recorded in the dry than in the wet year. The observed variation in reproductive output maybe explained as a consequence oflower availability of food resources in the dry year, resulting in lower fecundity and survival of females.
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Camouflage and escape decisions in the common chameleon Chamaeleo Chamaeleon
Biological Journal of the Linnean Society, 2001Co-Authors: Mariano Cuadrado, José Martín, Pilar LópezAbstract:In species with reduced locomotory abilities, camouflage seems to be far more important than other behavioural tactics (e.g. running) to elude predatory attacks. In this study, we examined the effects of camouflage on escape decisions in the common chameleon Chamaeleo Chamaeleon. The effectiveness of camouflage was assessed by the ability of humans to detect different sized chameleons placed on different backgrounds (vegetation of high and low density, defined here as open and dense bushes), both in the field and in photographs. Escape behaviour was analysed by simulating a predator attack (in our case, approach by a human). As expected, the probability of detection by a potential predator was size- and background dependent. In the field, detection time (but not distance) was significantly higher for chameleons of a given size perched on dense (Myoporum) than open (Retama) bushes. When using photographs, the probability of detection was higher for large (adult) chameleons perched on open (Retama or Nerium) bushes and lower for hatchlings perched on dense (Myoporum or Cupressus) bushes. Conspicuousness greatly influenced the escape tactics of individuals. Chameleons perched on more protected Myoporum allowed closest approach distances than those perched on less protectedRetama . In general, antipredatory responses (defined here as «first movement», «fleeing», «mouth opening» or «free falling») occurred significantly earlier in the trial sequence in chameleons perched on clear Retama than those perched in Myoporum. Two antipredatory responses were size-dependent: juveniles and adults exhibited «mouth opening» more frequently than hatchlings whereas «free falling» was more frequently recorded for hatchlings. Our results suggest that size and vegetation greatly influence the risk of detection by predators and this variation influences an individual's decision about when and how to escape.
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The Effects of Age and Size on Reproductive Timing in Female Chamaeleo Chamaeleon
Journal of Herpetology, 1999Co-Authors: Mariano Cuadrado, Jon LomanAbstract:Reproductive timing in relation to the size and age of individual female common Chame- leons (Chamaeleo Chamaeleon) was studied in a population in southern Spain. Thirty-one radio-tagged fe- males were observed during two summers, 1993 and 1995. The mating season (courting, pair formation, and copulation) lasted from late July to mid-September. Egg-laying was recorded from 25 September to 28 October, 34-40 d after copulation. Timing of reproduction varied between individual females, old and large females timing the reproductive events (i.e, mating and egg-laying) earlier than young and small ones. Specifically, timing was affected by size when age was controlled for but not the reverse. Four alternative explanations for delayed breeding of younger and smaller female chameleons are discussed: (1) late breeding could be a consequence of physiological constrains in the onset of maturation of younger females; (2) late breeding allows young females to secure more resources for reproduction thus achieving larger clutches; (3) young females avoid competition for attractive males from large females, and (4) if young females are less preferred, they may not be courted until males no longer are courting larger females. This happens when the latter become pregnant.
Charles R. Crumly - One of the best experts on this subject based on the ideXlab platform.
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Paedomorphosis and skull structure in Malagasy Chamaeleons (Reptilia: Chamaeleoninae)
Journal of Zoology, 1997Co-Authors: Olivier Rieppel, Charles R. CrumlyAbstract:The phylogenetic analysis of skull characteristics, along with data derived from lung and hemipenial morphology, does not support monophyly of the predominantly terrestrial Chamaeleons, Brookesiinae (Brookesia plus Rhampholeon), as sister-taxon of a monophyletic clade of arboreal Chamaeleons, the Chamaeleoninae. Instead, the phylogenetic interrelationships of Chamaeleonine lizards are (Brookesia (“Rhampholeon” (Bradypodion, Chamaeleo)). The monophyly of the genus Rhampholeon is not demonstrated. The arboreal Chamaeleons form a monophyletic group comprising two genera, Bradypodion and Chamaeleo. Bradypodion may be placed as sister-group of the genus Chamaeleo, but its phyletic position and monophyly cannot at present be corroborated. This study documents that there is a high degree of intraspecific variability in skull characters which may be due to paedomorphic reduction in the skull, especially of small species. Characters affected by a variable degree of ossification include the separation of a prefrontal fontanelle, the contact of the squamosal with the parietal, the size and position of the fenestra vestibuli, the degree of ossification in the basicranial rim of the fenestra, the extent of ossification of the pterygoid wing, and the shape of the skull roof as indicated by the bones forming the dorsal margin of the orbit. The closure of the lateral aperture of the occipital recess might indicate that miniaturization, and concomitant paedomorphosis, may have played a role in the initial phases of Chamaeleonine phylogeny.
Amos Bouskila - One of the best experts on this subject based on the ideXlab platform.
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alternative mating tactics in male chameleons Chamaeleo Chamaeleon are evident in both long term body color and short term courtship pattern
PLOS ONE, 2016Co-Authors: Tammy Kerenrotem, Noga Levy, Lior Wolf, Amos Bouskila, Eli GeffenAbstract:Alternative mating tactics in males of various taxa are associated with body color, body size, and social status. Chameleons are known for their ability to change body color following immediate environmental or social stimuli. In this study, we examined whether the differential appearance of male common chameleon during the breeding season is indeed an expression of alternative mating tactics. We documented body color of males and used computer vision techniques to classify images of individuals into discrete color patterns associated with seasons, individual characteristics, and social contexts. Our findings revealed no differences in body color and color patterns among males during the non-breeding season. However, during the breeding season males appeared in several color displays, which reflected body size, social status, and behavioral patterns. Furthermore, smaller and younger males resembled the appearance of small females. Consequently, we suggest that long-term color change in males during the breeding season reflects male alternative mating tactics. Upon encounter with a receptive female, males rapidly alter their appearance to that of a specific brief courtship display, which reflects their social status. The females, however, copulated indiscriminately in respect to male color patterns. Thus, we suggest that the differential color patterns displayed by males during the breeding season are largely aimed at inter-male signaling.
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male preference for sexual signalling over crypsis is associated with alternative mating tactics
Animal Behaviour, 2016Co-Authors: Tammy Kerenrotem, Noga Levy, Lior Wolf, Amos Bouskila, Eli GeffenAbstract:Changing body colour in animals generally reflects a conflict between two selection pressures, camouflage and social signalling. Chameleons are among the few organisms that resolve this conflict by rapid and temporary change in body colour for both background matching and social display. Male common chameleons, Chamaeleo Chamaeleon, employ two alternative mating tactics, dominants and subordinates, both of which are associated with long-term body colour patterns and instantaneous colour displays during social encounters. Hence, males present a good model in which to study the influence of mating tactic on the decision of whether to remain cryptic or to signal. We exposed individuals to two conflicting external stimuli: background manipulations, which challenge camouflage, and the presence of a female, which stimulates sexual signalling. No individuals of either mating tactic responded to background manipulation except when the shift was from green to brown background or vice versa. Ambient temperatures affected colour matching but not sexual signalling, while body temperature affected neither. Males ignored the background colour and prioritized being distinctive when encountering females. As such, males were more likely to engage in sexual signalling than crypsis. Subordinate sneakers signalled females more frequently than the dominant, female-guarding males, suggesting that sneakers rapidly signal females their intentions when the dominant is out of range. Conversely, dominant males may gain little by frequent signalling to the females they guard, while possibly gaining more by diverting this energy towards mate guarding. Our results suggest that specific male mating tactics strongly influence the decision to use crypsis or sexual signalling.
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Mitochondrial DNA Variation, but Not Nuclear DNA, Sharply Divides Morphologically Identical Chameleons along an Ancient Geographic Barrier
2013Co-Authors: Dan Bar Yaacov, Amos Bouskila, Karmit Arbel-thau, Yael Zilka, Ofer Ovadia, Dan MishmarAbstract:The Levant is an important migration bridge, harboring border-zones between Afrotropical and palearctic species. Accordingly, Chameleo chameleon, a common species throughout the Mediterranean basin, is morphologically divided in the southern Levant (Israel) into two subspecies, Chamaeleo Chamaeleon recticrista (CCR) and C. c. musae (CCM). CCR mostly inhabits the Mediterranean climate (northern Israel), while CCM inhabits the sands of the north-western Negev Desert (southern Israel). AFLP analysis of 94 geographically well dispersed specimens indicated moderate genetic differentiation (PhiPT = 0.097), consistent with the classical division into the two subspecies, CCR and CCM. In contrast, sequence analysis of a 637 bp coding mitochondrial DNA (mtDNA) fragment revealed two distinct phylogenetic clusters which were not consistent with the morphological division: one mtDNA cluster consisted of CCR specimens collected in regions northern of the Jezreel Valley and another mtDNA cluster harboring specimens pertaining to both the CCR and CCM subspecies but collected southern of the Jezreel Valley. AMOVA indicated clear mtDNA differentiation between specimens collected northern and southern to the Jezreel Valley (PhiPT = 0.79), which was further supported by a very low coalescent-based estimate of effective migration rates. Whole chameleon mtDNA sequencing (,17,400 bp) generated from 11 well dispersed geographic locations revealed 325 mutations sharply differentiating the two mtDNA clusters, suggesting a long allopatric history further supported by BEAST. This separation correlated temporally with the existence of an at least 1 million year ol
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Mitochondrial DNA Variation, but Not Nuclear DNA, Sharply Divides Morphologically Identical Chameleons along an Ancient Geographic Barrier
2012Co-Authors: Dan Bar Yaacov, Amos Bouskila, Karmit Arbel-thau, Yael Zilka, Ofer Ovadia, Dan MishmarAbstract:The Levant is an important migration bridge, harboring border-zones between Afrotropical and palearctic species. Accordingly, Chameleo chameleon, a common species throughout the Mediterranean basin, is morphologically divided in the southern Levant (Israel) into two subspecies, Chamaeleo Chamaeleon recticrista (CCR) and C. c. musae (CCM). CCR mostly inhabits the Mediterranean climate (northern Israel), while CCM inhabits the sands of the north-western Negev Desert (southern Israel). AFLP analysis of 94 geographically well dispersed specimens indicated moderate genetic differentiation (PhiPT = 0.097), consistent with the classical division into the two subspecies, CCR and CCM. In contrast, sequence analysis of a 637 bp coding mitochondrial DNA (mtDNA) fragment revealed two distinct phylogenetic clusters which were not consistent with the morphological division: one mtDNA cluster consisted of CCR specimens collected in regions northern of the Jezreel Valley and another mtDNA cluster harboring specimens pertaining to both the CCR and CCM subspecies but collected southern of the Jezreel Valley. AMOVA indicated clear mtDNA differentiation between specimens collected northern and southern to the Jezreel Valley (PhiPT = 0.79), which was further supported by a very low coalescent-based estimate of effective migration rates. Whole chameleon mtDNA sequencing (∼17,400 bp) generated from 11 well dispersed geographic locations revealed 325 mutations sharply differentiating the two mtDNA clusters, suggesting a long allopatric history further supported by BEAST. This separation correlated temporally with the existence of an at least 1 million year old marine barrier at the Jezreel Valley exactly where the mtDNA clusters meet. We discuss possible involvement of gender-dependent life history differences in maintaining such mtDNA genetic differentiation and suggest that it reflects (ancient) local adaptation to mitochondrial-related traits.
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Ontogenetic habitat shift and risk of cannibalism in the common chameleon (Chamaeleo Chamaeleon)
Behavioral Ecology and Sociobiology, 2006Co-Authors: Tammy Keren-rotem, Amos Bouskila, Eli GeffenAbstract:Ontogenetic habitat shifts have been documented in numerous fish and amphibians and in some reptiles. Intraspecific competition together with differential predation, prey size, social interactions, size-related thermal requirements, and morphological constraints on movement are often implicated in this ontogenetic habitat separation. In the current study, we combined field observation with experiments in seminatural arenas to test various hypotheses regarding the ontogenetic habitat shift that we have documented in the common chameleon. Juveniles (mean, 1 g) occupied low grasses and the adults (mean, 35 g) were found on bushes and trees. Overlap in habitat use between these two age classes was minimal. Our field experiments showed that juveniles actively avoid the presence of adults by concealment or flight. Adults readily attacked and consumed juveniles, regardless of their own mass. These results suggest that the risk of cannibalism towards juveniles is an important selective force behind the ontogenetic habitat shift observed in the common chameleon and may be important in other species too.
Tammy Kerenrotem - One of the best experts on this subject based on the ideXlab platform.
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alternative mating tactics in male chameleons Chamaeleo Chamaeleon are evident in both long term body color and short term courtship pattern
PLOS ONE, 2016Co-Authors: Tammy Kerenrotem, Noga Levy, Lior Wolf, Amos Bouskila, Eli GeffenAbstract:Alternative mating tactics in males of various taxa are associated with body color, body size, and social status. Chameleons are known for their ability to change body color following immediate environmental or social stimuli. In this study, we examined whether the differential appearance of male common chameleon during the breeding season is indeed an expression of alternative mating tactics. We documented body color of males and used computer vision techniques to classify images of individuals into discrete color patterns associated with seasons, individual characteristics, and social contexts. Our findings revealed no differences in body color and color patterns among males during the non-breeding season. However, during the breeding season males appeared in several color displays, which reflected body size, social status, and behavioral patterns. Furthermore, smaller and younger males resembled the appearance of small females. Consequently, we suggest that long-term color change in males during the breeding season reflects male alternative mating tactics. Upon encounter with a receptive female, males rapidly alter their appearance to that of a specific brief courtship display, which reflects their social status. The females, however, copulated indiscriminately in respect to male color patterns. Thus, we suggest that the differential color patterns displayed by males during the breeding season are largely aimed at inter-male signaling.
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male preference for sexual signalling over crypsis is associated with alternative mating tactics
Animal Behaviour, 2016Co-Authors: Tammy Kerenrotem, Noga Levy, Lior Wolf, Amos Bouskila, Eli GeffenAbstract:Changing body colour in animals generally reflects a conflict between two selection pressures, camouflage and social signalling. Chameleons are among the few organisms that resolve this conflict by rapid and temporary change in body colour for both background matching and social display. Male common chameleons, Chamaeleo Chamaeleon, employ two alternative mating tactics, dominants and subordinates, both of which are associated with long-term body colour patterns and instantaneous colour displays during social encounters. Hence, males present a good model in which to study the influence of mating tactic on the decision of whether to remain cryptic or to signal. We exposed individuals to two conflicting external stimuli: background manipulations, which challenge camouflage, and the presence of a female, which stimulates sexual signalling. No individuals of either mating tactic responded to background manipulation except when the shift was from green to brown background or vice versa. Ambient temperatures affected colour matching but not sexual signalling, while body temperature affected neither. Males ignored the background colour and prioritized being distinctive when encountering females. As such, males were more likely to engage in sexual signalling than crypsis. Subordinate sneakers signalled females more frequently than the dominant, female-guarding males, suggesting that sneakers rapidly signal females their intentions when the dominant is out of range. Conversely, dominant males may gain little by frequent signalling to the females they guard, while possibly gaining more by diverting this energy towards mate guarding. Our results suggest that specific male mating tactics strongly influence the decision to use crypsis or sexual signalling.