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Emília P. Martins - One of the best experts on this subject based on the ideXlab platform.
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Occurrence data uncover patterns of allopatric divergence and interspecies interactions in the evolutionary history of Sceloporus lizards
Ecology and evolution, 2021Co-Authors: Julio A. Rivera, A. Michelle Lawing, Heather N. Rich, Michael S. Rosenberg, Emília P. MartinsAbstract:As shown from several long-term and time-intensive studies, closely related, sympatric species can impose strong selection on one another, leading to dramatic examples of phenotypic evolution. Here, we use occurrence data to identify clusters of sympatric Sceloporus lizard species and to test whether Sceloporus species tend to coexist with other species that differ in body size, as we would expect when there is competition between sympatric congeners. We found that Sceloporus species can be grouped into 16 unique bioregions. Bioregions that are located at higher latitudes tend to be larger and have fewer species, following Rapoport's rule and the latitudinal diversity gradient. Species richness was positively correlated with the number of biomes and elevation heterogeneity of each bioregion. Additionally, most bioregions show signs of phylogenetic underdispersion, meaning closely related species tend to occur in close geographic proximity. Finally, we found that although Sceloporus species that are similar in body size tend to cluster geographically, small-bodied Sceloporus species are more often in sympatry with larger-bodied Sceloporus species than expected by chance alone, whereas large-bodied species cluster with each other geographically and phylogenetically. These results suggest that community composition in extant Sceloporus species is the result of allopatric evolution, as closely related species move into different biomes, and interspecies interactions, with sympatry between species of different body sizes. Our phyloinformatic approach offers unique and detailed insights into how a clade composed of ecologically and morphologically disparate species are distributed over large geographic space and evolutionary time.
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Eye-Bulging Behavior in Lizards of the Genus Sceloporus: A Role in Chemical Communication?
Copeia, 2020Co-Authors: Morgan A. Herrmann, Emília P. Martins, Stephanie M. Campos, Cristina Romero-diazAbstract:We examined eye-bulging behavior in relation to scent-marking and chemosensory behavior in three species of iguanian lizards, Sceloporus jarrovii, S. tristichus, and S. virgatus, in a controlled en...
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evolutionary interactions between visual and chemical signals chemosignals compensate for the loss of a visual signal in male Sceloporus lizards
Journal of Chemical Ecology, 2016Co-Authors: Jake A Pruett, Emília P. Martins, Stephanie M. Campos, Jaime J Zunigavega, Helena A Soini, Milos V Novotny, Cuauhcihuatl Vitalgarcia, Diana K. HewsAbstract:Animals rely on multimodal signals to obtain information from conspecifics through alternative sensory systems, and the evolutionary loss of a signal in one modality may lead to compensation through increased use of signals in an alternative modality. We investigated associations between chemical signaling and evolutionary loss of abdominal color patches in males of four species (two plain-bellied and two colorful-bellied) of Sceloporus lizards. We conducted field trials to compare behavioral responses of male lizards to swabs with femoral gland (FG) secretions from conspecific males and control swabs (clean paper). We also analyzed the volatile organic compound (VOC) composition of male FG secretions by stir bar extraction and gas chromatography-mass spectrometry (GC-MS) to test the hypothesis that loss of the visual signal is associated with elaboration of the chemical signal. Males of plain-bellied, but not colorful-bellied species exhibited different rates of visual displays when exposed to swabs of conspecific FG secretions relative to control swabs. The VOC composition of male Sceloporus FG secretions was similar across all four species, and no clear association between relative abundances of VOCs and evolutionary loss of abdominal color patches was observed. The emerging pattern is that behavioral responses to conspecific chemical signals are species- and context-specific in male Sceloporus, and compensatory changes in receivers, but not signalers may be involved in mediating increased responsiveness to chemical signals in males of plain-bellied species.
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Including Fossils in Phylogenetic Climate Reconstructions: A Deep Time Perspective on the Climatic Niche Evolution and Diversification of Spiny Lizards (Sceloporus).
The American naturalist, 2016Co-Authors: A. Michelle Lawing, Diana K. Hews, P. David Polly, Emília P. MartinsAbstract:AbstractFossils and other paleontological information can improve phylogenetic comparative method estimates of phenotypic evolution and generate hypotheses related to species diversification. Here, we use fossil information to calibrate ancestral reconstructions of suitable climate for Sceloporus lizards in North America. Integrating data from the fossil record, general circulation models of paleoclimate during the Miocene, climate envelope modeling, and phylogenetic comparative methods provides a geographically and temporally explicit species distribution model of Sceloporus-suitable habitat through time. We provide evidence to support the historic biogeographic hypothesis of Sceloporus diversification in warm North American deserts and suggest a relatively recent Sceloporus invasion into Mexico around 6 Ma. We use a physiological model to map extinction risk. We suggest that the number of hours of restriction to a thermal refuge limited Sceloporus from inhabiting Mexico until the climate cooled enough t...
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Information content is more important than sensory system or physical distance in guiding the long-term evolutionary relationships between signaling modalities in Sceloporus lizards
Behavioral Ecology and Sociobiology, 2013Co-Authors: Alison G. Ossip-klein, Jesualdo A. Fuentes, Diana K. Hews, Emília P. MartinsAbstract:Long-term signal evolution is shaped by a variety of selective pressures including the need to convey additional information or to improve message transfer to specific receivers or through multiple environments. Here, we test the relative importance of information and sensory modality in shaping the long-term evolution of multimodal signals in Sceloporus lizards. To broadcast identity at territorial boundaries, male Sceloporus use both visual motion (headbob) and chemical signals, whereas they use color (blue belly patches) to signal aggression. Using modern phylogenetic comparative methods, we found a negative correlation between evolutionary changes in visual motion (headbobs) and chemical (femoral pore) signals, but only indirect ties between the evolution of color and motion signals (both of which are perceived visually) through viviparity, and no evidence of an evolutionary link between color and chemical signals. We also find a negative correlation between arboreality and chemical signals. Thus, information content (in this case, broadcasting individual identity versus signaling aggression) appears to play a more important role than sensory modality or physical distance in guiding long-term signal evolution. Additional insights into the underlying evolutionary processes are described, illustrating the utility of a phylogenetic approach.
Diana K. Hews - One of the best experts on this subject based on the ideXlab platform.
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evolutionary interactions between visual and chemical signals chemosignals compensate for the loss of a visual signal in male Sceloporus lizards
Journal of Chemical Ecology, 2016Co-Authors: Jake A Pruett, Emília P. Martins, Stephanie M. Campos, Jaime J Zunigavega, Helena A Soini, Milos V Novotny, Cuauhcihuatl Vitalgarcia, Diana K. HewsAbstract:Animals rely on multimodal signals to obtain information from conspecifics through alternative sensory systems, and the evolutionary loss of a signal in one modality may lead to compensation through increased use of signals in an alternative modality. We investigated associations between chemical signaling and evolutionary loss of abdominal color patches in males of four species (two plain-bellied and two colorful-bellied) of Sceloporus lizards. We conducted field trials to compare behavioral responses of male lizards to swabs with femoral gland (FG) secretions from conspecific males and control swabs (clean paper). We also analyzed the volatile organic compound (VOC) composition of male FG secretions by stir bar extraction and gas chromatography-mass spectrometry (GC-MS) to test the hypothesis that loss of the visual signal is associated with elaboration of the chemical signal. Males of plain-bellied, but not colorful-bellied species exhibited different rates of visual displays when exposed to swabs of conspecific FG secretions relative to control swabs. The VOC composition of male Sceloporus FG secretions was similar across all four species, and no clear association between relative abundances of VOCs and evolutionary loss of abdominal color patches was observed. The emerging pattern is that behavioral responses to conspecific chemical signals are species- and context-specific in male Sceloporus, and compensatory changes in receivers, but not signalers may be involved in mediating increased responsiveness to chemical signals in males of plain-bellied species.
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Including Fossils in Phylogenetic Climate Reconstructions: A Deep Time Perspective on the Climatic Niche Evolution and Diversification of Spiny Lizards (Sceloporus).
The American naturalist, 2016Co-Authors: A. Michelle Lawing, Diana K. Hews, P. David Polly, Emília P. MartinsAbstract:AbstractFossils and other paleontological information can improve phylogenetic comparative method estimates of phenotypic evolution and generate hypotheses related to species diversification. Here, we use fossil information to calibrate ancestral reconstructions of suitable climate for Sceloporus lizards in North America. Integrating data from the fossil record, general circulation models of paleoclimate during the Miocene, climate envelope modeling, and phylogenetic comparative methods provides a geographically and temporally explicit species distribution model of Sceloporus-suitable habitat through time. We provide evidence to support the historic biogeographic hypothesis of Sceloporus diversification in warm North American deserts and suggest a relatively recent Sceloporus invasion into Mexico around 6 Ma. We use a physiological model to map extinction risk. We suggest that the number of hours of restriction to a thermal refuge limited Sceloporus from inhabiting Mexico until the climate cooled enough t...
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Information content is more important than sensory system or physical distance in guiding the long-term evolutionary relationships between signaling modalities in Sceloporus lizards
Behavioral Ecology and Sociobiology, 2013Co-Authors: Alison G. Ossip-klein, Jesualdo A. Fuentes, Diana K. Hews, Emília P. MartinsAbstract:Long-term signal evolution is shaped by a variety of selective pressures including the need to convey additional information or to improve message transfer to specific receivers or through multiple environments. Here, we test the relative importance of information and sensory modality in shaping the long-term evolution of multimodal signals in Sceloporus lizards. To broadcast identity at territorial boundaries, male Sceloporus use both visual motion (headbob) and chemical signals, whereas they use color (blue belly patches) to signal aggression. Using modern phylogenetic comparative methods, we found a negative correlation between evolutionary changes in visual motion (headbobs) and chemical (femoral pore) signals, but only indirect ties between the evolution of color and motion signals (both of which are perceived visually) through viviparity, and no evidence of an evolutionary link between color and chemical signals. We also find a negative correlation between arboreality and chemical signals. Thus, information content (in this case, broadcasting individual identity versus signaling aggression) appears to play a more important role than sensory modality or physical distance in guiding long-term signal evolution. Additional insights into the underlying evolutionary processes are described, illustrating the utility of a phylogenetic approach.
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sex and species differences in plasma testosterone and in counts of androgen receptor positive cells in key brain regions of Sceloporus lizard species that differ in aggression
General and Comparative Endocrinology, 2012Co-Authors: Diana K. Hews, Erina Hara, Maurice C AndersonAbstract:Abstract We studied neuroendocrine correlates of aggression differences in adults of two Sceloporus lizard species. These species differ in the degree of sex difference in aggressive color signals (belly patches) and in aggression: Sceloporus undulatus (males blue, high aggression; females white, low aggression) and Sceloporus virgatus (both sexes white, lower aggression). We measured plasma testosterone and counted cells expressing androgen receptor-like immunoreactivity to the affinity-purified polyclonal AR antibody, PG-21, in three brain regions of breeding season adults. Male S. undulatus had the highest mean plasma testosterone and differed significantly from conspecific females. In contrast, there was no sex difference in plasma testosterone concentrations in S. virgatus . Male S. undulatus also had the highest mean number of AR-positive cells in the preoptic area: the sexes differed in S. undulatus but not in S. virgatus , and females of the two species did not differ. In the ventral medial hypothalamus, S. undulatus males had higher mean AR cell counts compared to females, but again there was no sex difference in S. virgatus . In the habenula, a control brain region, the sexes did not differ, and although the sex by species interaction significant was not significant, there was a trend ( p = 0.050) for S. virgatus to have higher mean AR cell counts than S. undulatus . Thus hypothalamic AR cell counts paralleled sex and species differences in aggression, as did mean plasma testosterone levels in these breeding-season animals.
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Field presentation of male secretions alters social display in Sceloporus virgatus but not S. undulatus lizards
Behavioral Ecology and Sociobiology, 2011Co-Authors: Diana K. Hews, Erina Hara, Priya Date, Michael J. CastellanoAbstract:Lizards have communicative displays involving primarily vision and chemicals, and recent work suggests trade-offs between these two modalities. In reptiles, little work assesses effects of conspecific chemicals on subsequent signaling behavior. Here, we studied responses to conspecific secretions in two Sceloporus species differing in visual signaling: male Sceloporus undulatus have blue abdominal patches used in aggressive territorial encounters, while Sceloporus virgatus males have evolutionarily lost the patches and have low rates of aggressive display. We measured behavior of free-ranging males following presentation of swabs with conspecific male chemicals from femoral glands and the cloaca, or of clean swabs. For male S. undulatus (blue), neither likelihoods nor rates of behavioral responses differed between swab treatments. In contrast, male S. virgatus (white) presented with secretions had significantly higher likelihood of performing head bob, push-up, and shudder displays, than males in control swab trials. Rates of behavior also differed for S. virgatus, with higher rates of push-up display and tongue flick in trials with conspecific chemicals, but rates of other displays, number of moves, and mean total distance moved did not differ between treatments. Male S. undulatus moved significantly greater distances than S. virgatus, independent of treatment. In sum, male S. virgatus responded to conspecific male chemicals by increasing their low rates of display behavior, whereas male S. undulatus did not alter their already high rates of display or movement following chemical exposure. Chemical signals may play a different role in social signaling in the species with the loss of the abdominal color signal.
Adam D. Leaché - One of the best experts on this subject based on the ideXlab platform.
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characterization of a pericentric inversion in plateau fence lizards Sceloporus tristichus evidence from chromosome scale genomes
G3: Genes Genomes Genetics, 2021Co-Authors: Ana M Bedoya, Adam D. LeachéAbstract:Spiny lizards in the genus Sceloporus are a model system among squamate reptiles for studies of chromosomal evolution. While most pleurodont iguanians retain an ancestral karyotype formula of 2n = 36 chromosomes, Sceloporus exhibits substantial karyotype variation ranging from 2n = 22 to 46 chromosomes. We present two annotated chromosome-scale genome assemblies for the Plateau Fence Lizard (Sceloporus tristichus) to facilitate research on the role of pericentric inversion polymorphisms on adaptation and speciation. Based on previous karyotype work using conventional staining, the S. tristichus genome is characterized as 2n = 22 with six pairs of macrochromosomes and five pairs of microchromosomes and a pericentric inversion polymorphism on chromosome 7 that is geographically variable. We provide annotated, chromosome-scale genomes for two lizards located at opposite ends of a dynamic hybrid zone that are each fixed for different inversion polymorphisms. The assembled genomes are 1.84-1.87 Gb (1.72 Gb for scaffolds mapping to chromosomes) with a scaffold N50 of 267.5 Mb. Functional annotation of the genomes resulted in ∼15K predicted gene models. Our assemblies confirmed the presence of a 4.62-Mb pericentric inversion on chromosome 7, which contains 62 annotated coding genes with known functions. In addition, we collected population genomics data using double digest RAD-sequencing for 44 S. tristichus to estimate population structure and phylogeny across the Colorado Plateau. These new genomic resources provide opportunities to perform genomic scans and investigate the formation and spread of pericentric inversions in a naturally occurring hybrid zone.
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characterization of a large pericentric inversion in plateau fence lizards Sceloporus tristichus evidence from chromosome scale genomes
bioRxiv, 2020Co-Authors: Adam D. Leaché, Ana M BedoyaAbstract:Spiny lizards in the genus Sceloporus are a model system among squamate reptiles for studies of chromosomal evolution. While most pleurodont iguanians retain an ancestral karyotype formula of 2n=36 chromosomes, Sceloporus exhibits substantial kary- otype variation ranging from 2n=22 to 2n=46 chromosomes. In this study, we present two annotated chromosome-scale genome assemblies for the Plateau Fence Lizard (Sceloporus tristichus) in order to facilitate research on the role of pericentric inversion polymorphisms on adaptation and speciation. Based on previous karyotype work using conventional staining, the S. tristichus genome is characterized as 2n=22 with 6 pairs of macrochromosomes and 5 pairs of microchromosomes with a large pericentric inversion polymorphism on chromosome seven that is geographically variable. We provide annotated, chromosome-scale genomes for two lizards located at opposite ends of a dynamic hybrid zone that are each fixed for different inversion polymorphisms. The assembled genomes are 1.84 to 1.87 Gb (1.72 Gb for scaffolds mapping to chromosomes) with a scaffold N50 of 267.5 Mb. Functional annotation of the genomes resulted in 65,417 annotated genes, 16,426 of which were deduced to have a function. We confirmed the presence of a 4.62 Mb pericentric inversion on chromosome seven, which contains 59 annotated coding genes with known functions. These new genomic resources provide opportunities to perform genomic scans and investigate the formation and spread of pericentric inversions in a naturally occurring hybrid zone. Key words: chromosome rearrangement, de novo assembly, hybrid zone, pericentric inversion, phrynosomatidae, Sceloporus, genome sequencing.
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phylogenomics of a rapid radiation is chromosomal evolution linked to increased diversification in north american spiny lizards genus Sceloporus
BMC Evolutionary Biology, 2016Co-Authors: Adam D. Leaché, Barbara L Banbury, Charles W Linkem, Adrian Nietomontes De OcaAbstract:Background Resolving the short phylogenetic branches that result from rapid evolutionary diversification often requires large numbers of loci. We collected targeted sequence capture data from 585 nuclear loci (541 ultraconserved elements and 44 protein-coding genes) to estimate the phylogenetic relationships among iguanian lizards in the North American genus Sceloporus. We tested for diversification rate shifts to determine if rapid radiation in the genus is correlated with chromosomal evolution.
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Species trees for spiny lizards (genus Sceloporus): identifying points of concordance and conflict between nuclear and mitochondrial data.
Molecular phylogenetics and evolution, 2009Co-Authors: Adam D. LeachéAbstract:Spiny lizards (genus Sceloporus) represent one of the most diverse and species rich clades of squamate reptiles in continental North America. Sceloporus contains 90+ species, which are partitioned into 21 species groups containing anywhere from one to 15 species. Despite substantial progress towards elucidating the phylogeographic patterns for many species of Sceloporus, efforts to resolve the phylogenetic relationships among the major species groups remain limited. In this study, the phylogenetic relationships of 53 species of Sceloporus, representing all 21 species groups, are estimated based on four nuclear genes (BDNF, PNN, R35, RAG-1; >3.3 kb) and contrasted with a new mitochondrial DNA genealogy based on six genes (12S, ND1, ND4, and the histidine, serine, and leucine tRNA genes; >2.5 kb). Species trees estimated from the nuclear loci using data concatenation or a coalescent-based inference method result in concordant topologies, but the coalescent approach provides lower resolution and support. When comparing nuclear versus mtDNA-based topologies for Sceloporus species groups, conflicting relationships outnumber concordant relationships. Incongruence is not restricted to weak or unresolved nodes as might be expected under a scenario of rapid diversification, but extends to conflicts involving strongly support clades. The points of concordance and conflict between the nuclear and mtDNA data are discussed, and arguments for preferring the species trees estimated from the multilocus nuclear data are presented.
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Chromosome Evolution and Diversification in North American Spiny Lizards (Genus Sceloporus)
Cytogenetic and genome research, 2009Co-Authors: Adam D. Leaché, J.w. SitesAbstract:The genus Sceloporus is a diverse clade of lizards that exhibits substantial variation in chromosome numbers and sex chromosome heteromorphisms, 2 features of the genome that are static among most other pleurodont iguanian lizards. Evolutionary changes to the fundamental number of chromosomes are hypothesized to be a primary factor responsible for driving the diversification of Sceloporus. We explore the patterns of chromosome evolution in Sceloporus using a combination of ancestral state estimations and species diversification tests. Phylogenetic relationships and divergence times within Sceloporus (53 species representing all 19 species groups) are estimated using 4 nuclear genes (>3.3 kb) and relaxed-clock analyses that incorporate a fossil calibration on the root of the tree. We test the hypothesis that chromosome evolution is correlated with shifts in species diversification using cross-validation predictive densities, a new Bayesian approach for modeling the number of species that are predicted to have evolved in the absence of a certain historical event (e.g., a change in chromosome numbers). Results of the cross-validation predictive densities approach indicate that chromosomal evolution is correlated with significantly higher species diversity than predicted under the background rate of diversification in Sceloporus. We conclude by discussing the future of comparative cytogenetic investigations in Sceloporus.
Stephen M. Reilly - One of the best experts on this subject based on the ideXlab platform.
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Sprawling locomotion in the lizard Sceloporus clarkii: speed modulation of motor patterns in a walking trot.
Brain behavior and evolution, 1998Co-Authors: Stephen M. ReillyAbstract:Previous kinematic analyses in Sceloporus clarkii have shown that increased speed during trotting is attained by retracting the femur relatively faster (decreasin
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Sprawling locomotion in the lizard Sceloporus clarkii: quantitative kinematics of a walking trot
The Journal of Experimental Biology, 1997Co-Authors: Stephen M. Reilly, Michael J. DelanceyAbstract:Although the hindlimb is widely considered to provide the propulsive force in lizard locomotion, no study to date has investigated the kinematic patterns of the lizard hindlimb during running for more than one stride for a single individual. The quantitative kinematics of the hindlimb, pelvis and backbone are described here for two individuals of the lizard Sceloporus clarkii using a fast walking trot on a treadmill moving at a constant speed of 0.833 m s-1. Pelvic rotation, femoral retraction, knee flexion and posterior movement of the foot all begin before the foot hits the substratum and, thus, there is a terminal portion of the swing phase during which the limb is retracting. Pelvic rotation (to the opposite side), femoral protraction and knee flexion all begin before the foot leaves the substratum. The foot, however, continues to move posteriorly into the early swing phase. Thus, limb retraction and protraction movements do not directly correlate with footfall phases. Axial bending involves a rough standing wave with two nodes, one centered on each limb girdle. In Sceloporus clarkii, the foot clearly remains lateral to the knee and, thus, has a more sprawling posture than that of any other vertebrate studied to date. Therefore, the generalization that the 9lacertilian9 foot passes under the knee joint is no longer supported. The kinematics of sprawling locomotion in Sceloporus clarkii are compared and contrasted with the general understanding of lizard locomotion based on qualitative work to date. Comparisons with other tetrapods reveal a fundamental functional dichotomy in hindlimb retraction mechanics in salamanders and mammals versus lizards that may be related to a key morphological difference in the saurian caudifemoralis muscle.
Aurelio Ramírez-bautista - One of the best experts on this subject based on the ideXlab platform.
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No Sexual Size-Dimorphism In the Eastern Spiny Lizard, Sceloporus spinosus, from Guadalcázar, San Luis Potosi, Mexico
The Southwestern Naturalist, 2013Co-Authors: Aurelio Ramírez-bautista, Geoffrey R Smith, Adrian Leyte-manrique, Uriel Hernández-salinasAbstract:Abstract Sexual dimorphism in the genus Sceloporus has historically been relatively well studied; however, there is little understanding of how patterns of sexual size dimorphism might vary within species and how that might affect our ability to generalize about the evolution of sexual size-dimorphism in Sceloporus and other organisms. We examined sexual size-dimorphism in a population of Sceloporus spinosus from Guadalcazar, San Luis Potosi, Mexico. Males (n = 85) and females (n = 63) showed no significant sexual dimorphism in size of the body, head, or legs. In combination with the results of other studies on sexual dimorphism in S. spinosus and closely related species of Sceloporus, our results suggest that there can be variation in sexual size-dimorphism within and among species that can limit the ability to make broad generalizations about the phylogenetic patterns of sexual dimorphism in Sceloporus.
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Did sexually dimorphic dorsal coloration evolve by a pre-existing bias in males in the lizard Sceloporus minor?
Evolutionary Ecology, 2012Co-Authors: Barry P. Stephenson, Aurelio Ramírez-bautistaAbstract:Theory and empirical evidence indicate that male secondary sex traits can evolve by co-option of pre-existing biases in females. However, relatively few studies have explored whether male pre-existing biases could drive the evolution of traits important in male contests. Male spiny lizards ( Sceloporus ) are characterized by the expression of sexually dimorphic blue throat and abdominal patches. These features are revealed to conspecifics during social interactions, and variation in ventral color can predict the outcome of male contests in some species of spiny lizards. In Sceloporus minor , males in some populations also express bright blue color on the dorsal surfaces. Given the significance of blue color in intrasexual signaling in other species of Sceloporus , blue dorsal color may have evolved in S. minor by co-option of a male sensory bias for the color blue. We tested this hypothesis in a population that exhibits an ancestral phenotype for male dorsal color (brown/orange), and lacks males with bright blue dorsal coloration. Resident territorial males were presented with one of three types of intruder males manipulated in dorsal color by painting. Orange males mimicked the ancestral dorsal phenotype found at the study site; blue males resembled those from a population with the derived (blue) form of this trait; and green males represented a novel stimulus control. If blue dorsal color evolved in S. minor in part due to co-option of a male sensory bias, we predicted that resident males would exhibit either increased or decreased levels of aggression to blue intruders relative to controls. We found no difference in resident aggressive behavior across all treatments, thus failing to support the predictions of a pre-existing bias. We discuss these findings in the context of social behavior in Sceloporus , and propose directions for further study in this species.
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Reproductive Characteristics of the Spiny Lizards, Sceloporus horridus and Sceloporus spinosus (Squamata: Phrynosomatidae) from México
Journal of Herpetology, 2002Co-Authors: Martha A. Valdéz-gonzález, Aurelio Ramírez-bautistaAbstract:Abstract We studied the reproductive characteristics of the spiny lizards, Sceloporus horridus and Sceloporus spinosus (Phrynosomatidae). The specimens (N = 102) of S. horridus came from the state of Morelos and Guerrero, and individuals of S. spinosus (N = 87) came from Puebla, Mexico. Male S. horridus exhibited a peak of reproductive activity during early spring and early summer and male S. spinosus during spring and autumn. Females of both species showed a reproductive peak during the summer. Vitellogenesis of S. horridus began in late March and of S. spinosus in late January, and ovulation in both species occurred during spring and early summer. Mean snout–vent length (SVL) of sexually mature females (based on the largest 50%) was higher in S. spinosus (x ± SE = 98.6 ± 1.85) than in S. horridus (91.4 ± 1.32, P < 0.05). Mean clutch size (vitellogenic follicles + oviductal eggs) for S. spinosus was higher (18.5 ± 1.5, N = 18) than for S. horridus (14.8 ± 0.91, N = 30, P < 0.05). There was no significan...
