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There are notable examples of repeated evolution of ecomorphs within groups of closely related species, these are typically viewed as remarkable cases of natural selection. In most cases, directional selection for certain phenotypic traits under specific (and differing) environmental conditions is implicated. Differing ecomorphological forms for closely related species (or for populations within a species) have been documented for several lineages of South African dwarf chameleons (Bradypodion), although this pattern is not ubiquitous across the genus. Within one species, Bradypodion pumilum, two ecomorphs have been observed, these differ in terms of morphology, performance, ecology and habitat, yet genetic differences (mtDNA) were not apparent, with shared haplotypes across the ecomorphs. We investigated whether more sensitive genetic markers (eight microsatellite loci) would show population level structure between ecomorphs, which could indicate lack of gene flow across the ecological (habitat) boundary. Our results suggest that the two ecomorphs are distinct at a population level, implying that gene flow is absent or reduced and that the two ecomorphs are on separate evolutionary trajectories. Given that mtDNA could not detect population structure, we infer that the ecological boundary between ecomorphs is relatively recent in evolutionary history. The two ecomorphs are distinctive in terms of their morphology, ecology, habitat and functional traits, these differences are likely driven and maintained by reproductive isolation across the habitat boundary.

Although multiple paternity and sperm storage are common in squamates, neither has been conclusively demonstrated in the chameleons (Chamaeleonidae). To examine whether these traits are present in chameleons, the Cape Dwarf Chameleon (Bradypodion pumilum) was investigated. This viviparous species inhabits a temperate climate in southern Africa, has aseasonal breeding, and can produce multiple clutches annually. Given this reproductive schedule, we hypothesised that females may mate opportunistically and store sperm, and that single clutches may have multiple sires. To examine this, six females and their clutches were genotyped using microsatellite markers, and assessed for multiple paternity. In addition, 46 females were assessed for sperm storage structures and presence of sperm in the oviduct. Multiple paternity was found in all six clutches, based on the presence of multiple alleles at all loci that could not be assigned to the mother. No evidence of specialised sperm storage structures was found, but sperm was present in the lumen of the posterior oviduct in 74% of females. While sperm storage cannot be concluded with finality, it seems likely to occur, rather assuming that three out of four of the females in the sample had mated just prior to capture. Furthermore, two post-partum females retained sperm in the oviducts after the delivery of a clutch, but in the absence of additional copulation. Given that this species has aseasonal reproduction, if sperm is indeed stored long-term, this combination of traits would be advantageous given the lack of defined breeding season and presumably low rates of mate encounter.

The Cape Dwarf Chameleon, Bradypodion pumilum, is threatened by extensive habitat loss and transformation in the Western Cape Province of South Africa. As a result, the species exists as a collection of populations inhabiting an increasingly fragmented landscape within a critically endangered ecosystem. In this study we monitored microsatellite genetic variation in one of these populations of B. pumilum across a three-year period. From the results of a temporary site-vacancy of adult chameleons during the study, we anticipated a significant shift in microsatellite allele frequencies. Using data from eight highly polymorphic loci we detected differences in the allelic composition of chameleons inhabiting the study site between pre- and post-site-vacancy periods (AMOVA RST = 0.017; P = 0.019). Results suggest that recolonisation by immigrant chameleons, from an adjacent vegetation fragment connected to the study site by corridors, caused the recorded shifts in allelic frequencies. Pairwise tests of ...

Ecologically induced morphological variation has been identified as a mainstay in evolutionary theory. Species that inhabit different habitats are likely to display morphological and functional differences related to the exploitation of different dietary resources available in each habitat within limits imposed by trade-offs. Here, we examine two populations of the Cape Dwarf Chameleon, Bradypodion pumilum, from fynbos (heathland) and woodland to investigate whether head morphology and bite performance are related to diet within and between populations. Stomach contents are compared with prey availability to test whether chameleons are selective with respect to prey size, hardness and evasiveness. Our data show that for adult chameleons from the fynbos (Kogelberg; n = 44), mean and maximum prey size are tightly correlated with head morphology and performance. In woodland habitat (Stellenbosch; n = 52), only maximum prey size is correlated with head morphology and performance. Fynbos chameleons showed no preference with respect to prey hardness, while those from woodland ate less hard and/or sedentary prey than available, thus preferring items that were soft and/or evasive. Finally, fynbos chameleons have a diet of sedentary and/or evasive prey similar in proportions to that available. Our results suggest that diet is not directly related to selection on the head morphology and biting performance of B. pumilum in woodland habitat, but that it may be important for selection in fynbos due to a reduction in overall prey availability.

Variation in phenotype between species or populations of the same species living in different habitats is often explained in an adaptive context with local habitat differences driving selection on morphological traits relevant in a given ecological context. Previous studies have demonstrated significant differences in limb and tail morphology between populations of the Cape Dwarf Chameleon (Bradypodion pumilum) living in closed vs. open habitats. However, the adaptive nature of the observed differences remains unclear. Here, we quantify the structural habitat use in two different populations, test whether the random habitat differs between the two sites and whether or not chameleons select perches randomly. Next, we test whether morphology is correlated with structural habitat use and test for differences in performance between populations. Our results demonstrate that habitats are structurally different, that chameleons in the two populations use perches of different diameters and that, in one of the populations, chameleons select relatively wider perches than available at random. Performance traits (hand and tail grip performance and sprint speed) are correlated with morphology (hand size, tail length and tibia length) and differ between sexes and populations. Moreover, performance is dependent on dowel size. These results suggest that differences in performance between populations are indeed adaptive and indicate the existence of true ecomorphs in chameleons of the genus Bradypodion. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104, 692–700.

An organism's phenotype is to some extent influenced by costs and benefits in terms of natural and sexual selection. The intensity of natural selection can in part be driven by habitat structure, which may result in varying levels of crypsis and/or selection on traits related to maximizing performance in that habitat. This may be countered by sexual selection, which can lead to sexual dimorphism in body size and/or the expression of conspicuous ornamentation relating to maximizing reproductive success. The intensity of these forces can also be different between the sexes, resulting in complex patterns of phenotypic variation. With this in mind, we examined morphological variation within the Cape Dwarf Chameleon, Bradypodion pumilum. The species inhabits two geographically disjunct habitat types and, in the present study, we demonstrate that chameleons from the two habitats show morphological differences. Large, conspicuous individuals inhabit closed vegetation, whereas small, drab individuals inhabit open vegetation. However, when morphological traits are size-adjusted, the open vegetation morph displays many traits that are larger for its body size than the closed vegetation morph, especially for characters related to locomotion (limbs) and bite force (head width). Sexual dimorphism is also present, although the degree and number of dimorphic characters was very different between the two morphs, with size-adjusted male-biased dimorphism much more pronounced in the closed morph. Overall, our findings suggest that natural selection in open habitats limits both body size and conspicuous characters, although sexual selection in closed habitats favours the development of ornamentation related to display. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 878–888.

Reptiles have an amazing diversity of life-history attributes ranging from the shortest- to longest-lived of vertebrate species. Estimating survival in wild populations is of key importance when understanding population dynamics and life-history evolution. However, data are lacking for a large and charismatic group of lizards, the chameleons. We conducted a Robust Design (RD) capture–mark–recapture (CMR) experiment on the Cape dwarf chameleon, Bradypodion pumilum, at two nested sites within the Cape Town Metropolitan Area, South Africa, in order to estimate survival and movement of adults in and around an isolated 3.5 ha patch of suitable habitat. Over a nine-week period, 97 individuals were identified in 379 captures from five primary capture sessions with three secondary events each. Analysis of CMR data provided evidence that smaller chameleons have a substantially lower survival per 10-day period than larger chameleons. RD analysis showed that males were more prone to temporary emigration than females, while open multi-strata analysis revealed that smaller chameleons more readily moved between the sites than larger chameleons. Our findings offer first important insights into chameleon survival and life-history dynamics, which suggest a more vagile subadult population and the possibility of male biased dispersal. Our results have implications for managing the conservation of threatened chameleon populations in highly fragmented urban habitats.

The Cape Dwarf Chameleon (Bradypodion pumilum) is an endemic South African species that is currently threatened by habitat loss and fragmentation of its natural habitat through urbanization and agriculture. To conduct studies that will assist in understanding these anthropogenic effects on gene flow, population structure, and genetic diversity, we developed eight microsatellite loci using an enrichment protocol. Number of alleles ranged from 5 to 26 with observed heterozygosities of 0.279–0.930. Several loci did not meet HW expectations, but this may be a result of extreme demographic fluctuations that have been noted for this species. These loci will prove useful to examine the population genetics of these threatened reptiles and for providing information that will be used for generating and updating conservation assessments.

The use of automated grape harvesters in the Cape Wine Growing region has resulted in controversy regarding their effect on the chameleon Bradypodion pumilum. We investigated densities of B. pumilum during harvesting at a vineyard near Stellenbosch, South Africa. During dedicated surveys, no chameleons were found in vines, while vegetation surrounding the vines contained densities as high as 1.3 chameleons per 100 m of survey. In addition, the force required to remove ripe grapes was investigated and found to be substantially lower than that required to dislodge a chameleon. We conclude that the effect of automated grape harvesting on chameleons is negligible.

Arboreal lizards are extremely effective at moving in structurally complex habitats, including surfaces of varying diameter and incline. Chameleons exemplify this by exhibiting a number of morphological specializations for moving in these habitats, including the use of prehensile feet and tail to grasp branches. Despite their unique morphology and behaviour, little is known about how locomotor movements vary between species. In addition, some species, such as the Cape Dwarf Chameleon, Bradypodion pumilum, consist of two morphs that differ in ecology, morphology, and behaviour. The two morphs can be found in either closed canopy woodland habitat or relatively open fynbos habitat. The morph that occupies the woodland habitat tends to be larger and utilizes larger diameter perches. Although their ecological and morphological divergence is established, whether this translates into differences in three-dimensional kinematics of locomotion is not known. Given the potentially strong selective pressures from structurally different habitats, kinematic differences might reveal the functional basis of incipient speciation. We determined that the two morphs diverge significantly in multidimensional kinematic space, and that this occurs for the forelimb and hindlimb independently. These differences outweigh the effects of substrate within each morph, although the differences between morphs were more pronounced on the vertical treatments.

Traditionally, studies of intrasexual selection have focused on single traits that are more exaggerated in males. Relatively little is known about systems in which traits are larger in females or the role of multiple traits in male contests. We used a tournament design in which each male encounters a series of different opponents, in conjunction with the structured Bradley–Terry model, to examine the role of multiple male traits in contests between male Cape dwarf chameleons, Bradypodion pumilum. Females are larger but males have relatively longer tails, larger and more ornamented heads and a larger central flank patch, all of which are emphasized during agonistic displays. We found no evidence that larger body size confers an advantage in male contests, despite high levels of aggression and escalated encounters. However, both the height of the casque (head ornament) and relative area of the flank patch were positively associated with fighting ability, and not correlated with each other, suggesting that they may represent independent sources of information about an opponent's ability. We discuss these results in relation to the role of male contest competition in the evolution of multiple male signals and sexual dimorphism in dwarf chameleons. In addition, we show that the use of tournament designs, in conjunction with the structured Bradley–Terry model, has important advantages over traditional designs and methods of analysing animal contests.

Conflict between the sexes has traditionally been studied in terms of costs of mating to females and female resistance. However, courting can also be costly to males, especially when females are larger and aggressively resist copulation attempts. We examined male display intensity towards females in the Cape dwarf chameleon, Bradypodion pumilum , in which females are larger than males and very aggressive. We assessed whether aggressive female rejection imposes potential costs on males and whether males vary their display behaviour with intensity of female rejection, female size or relative size differences. Males persisted in courtship after initial female rejection in 84% of trials, and were bitten in 28% of trials. Attempted mounts were positively associated with males being bitten. Males reduced courtship with increased intensity of female rejection. Male courtship behaviour also varied with female size: males were more likely to court and approach smaller females, consistent with the hypothesis that larger females can inflict more damage. These results suggest that, in addition to assessing female willingness to mate, male dwarf chameleons may use courtship displays to assess potential costs of persistence, including costs associated with aggressive female rejection, weighed against potential reproductive pay-offs associated with forced copulation.

Foraging mode is an important aspect of life history, often associated with traits such as locomotor mode, energy budget, risk of predation and reproductive effort. Because of these life-history associations, classification of foraging mode can be conceptually useful. Lizards figured prominently in the historical development of foraging mode concepts, yet our current understanding is dominated by only two lizard families which are good examples of the two extreme modes, sit-and-wait vs. active foraging. A great deal of lizard phylogenetic diversity remains unrepresented. Chameleons are a highly derived lizard taxon for which we have very little behavioural or ecological data, and no foraging mode data. Because chameleons are so unusual, it is not possible to predict where they will fit within the bimodal paradigm. I studied time budget and foraging mode in the Cape dwarf chameleon, Bradypodion pumilum, in Stellenbosch, South Africa. Several approaches were taken to assess foraging behaviour. First, lag-sequential analysis was applied to compare rates behaviours associated with observed eating events, which did not support a sit-and-wait foraging mode. Second, the number of moves per minute (MPM) and per cent time moving (%TM) were compared with those of other lizard taxa from the literature. Foraging in B. pumilum was found to be most consistent with an active foraging mode, although the MPM is unusually low. Thus I propose classification of B. pumilum as a cruise forager. Sufficient data are available to define a discriminant function for active vs. sit-and-wait modes among lizard speries, which classifys B. pumilum as active and additionally lends statistical support for good separation between foraging modes. These findings are discussed in relation to the evolution of foraging modes in chameleons and other lizard families. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 84, 797–808.

Summary Temperature is an extrinsic factor which influences reptile behavior given that their physiology is dependent on environmental temperature. Understanding the impact of temperature on performance traits is important as it may affect the ecology and fitness of ectothermic animals such as reptiles. Here we examine the temperature dependence of performance in two species of South African Dwarf chameleon (Bradypodion), a semi-arid and a mesic adapted species. Ecologically relevant performance traits were tested at different temperatures to evaluate their thermal dependence and temperature-performance breadths for 80% and 90% of each performance trait were calculated. Our results show distinct differences in the thermal dependence of speed versus force-related performance traits. Moreover, our results show that the semi-arid species is better adapted to higher temperatures and as such has better chances to cope with the predicted increases in temperature. The mesic-adapted species seems to be more sensitive to an increase in temperature and could therefore potentially be threatened by predicted future climate change. However, further studies investigating the potential for acclimation in chameleons are needed to better understand how animals may respond to predicted future climate change.

Game theory models of animal contests make many non-mutually exclusive predictions, complicating empirical tests. These predictions regard the relationship between contest parameters and fighting ability, for which body size is usually used as a proxy. However, in many systems, body size may be a limited proxy since multiple traits and contextual factors such as experience influence fighting ability. Using contests between male Cape dwarf chameleons, Bradypodion pumilum , I test alternative game theory models of extended contests. I show how the most likely candidate model can be identified through a process of elimination, based on tests of key predictions. In addition, I present a measure of fighting ability based on multiple traits that allows ability to change as experience changes. In dwarf chameleons, persistence is based on loser thresholds rather than assessment of relative ability, ruling out the sequential assessment model. Winners and losers do not match behaviours in early parts of the contest, arguing against all types of war of attrition models. Although the cumulative assessment model remained as the most likely candidate model, not all specific predictions of this model were upheld.

The external morphology of the hemipenes of squamate reptiles is often complex and has been widely employed in systematic studies. Little is known, however, of the development of these patterns and thus of the potential polarity of the character states used in systematic studies. Analysis of three developmental stages of the hemipenes of the chameleon Bradypodion pumilum using scanning electron microscopy reveals that the complexity of pattern emerges gradually. Initially the hemipenial anlagen appear as simple, external lobes that develop in close association with the cloaca. By stage 38 a shallow sulcus spermaticus is evident and calices have begun to appear. By stage 41 embryos possess a deep, protected sulcus and two pairs of distal lobes. These lobes will eventually differentiate into semicircular disks (rotulae) with serrated margins that are characteristic of many members of the family. The complex external morphology of the hemipenes that is of significance in systematic studies and of assumed importance in copulatory mechanics may not be expressed until sexual maturity is reached.