RESUMO
We describe the new species Norops arenal sp. nov. from Parque Nacional Volcán Arenal, north-central Costa Rica. In external morphology and genetic similarity of the 16S DNA barcode, Norops arenal is most similar to N. altae, N. fortunensis, N. fuscoauratus, N. gruuo, N. kemptoni, N. monteverde, N. pseudokemptoni, and N. tenorioensis. In morphology it shares with these species the following characteristics: (1) short hind limbs; (2) a single elongate prenasal scale; (3) tiny, smooth, often juxtaposed body scales; and (4) a slender habitus, often delicate. Norops arenal differs from these species, among several scalation details, by having a blackish central area in the male dewlap in life and in preservative (vs. no suffusion of black pigment on male dewlap in the other species), and a small red female dewlap in life (vs. dirty white, cream colored, or orange); extremely short hind legs with the tip of fourth toe of the adpressed hind leg reaching only to level of shoulder (vs. usually at least to level of ear in the other species); a short tail with a tail length/SVL ratio of 1.53 in single specimen with complete tail (vs. this ratio >1.6 in the other species); and a tiny size with 41.5 mm in single known adult male and 38.5 mm in single known adult female (vs. SVL of adults usually >42.0 mm). It further differs from N. altae, N. fuscoauratus, N. gruuo, N. pseudokemptoni, and N. tenorioensis by having a unilobed hemipenis (vs. bilobed in these five species).
Assuntos
Lagartos , Animais , Costa Rica , Feminino , MasculinoRESUMO
BACKGROUND: Recent studies have begun to reveal the complex evolutionary and biogeographic histories of mainland anoles in Central America, but the origins and relationships of many taxa remain poorly understood. One such group is the Anolis (Norops) crassulus species subgroup, which contains ten morphologically similar highland taxa, the majority of which have restricted distributions. The nominal taxon A. crassulus has a disjunct distribution from Chiapas, Mexico, through Guatemala, in the highlands of El Salvador, and in the Chortís Highlands of Honduras. We test the relationships of these species using multiple mitochondrial and nuclear loci in concatenated and multispecies coalescent frameworks, in an effort to both resolve long-standing taxonomic confusion and present new insights into the evolution and biogeography of these taxa. RESULTS: Sequences of multiple mitochondrial and nuclear loci were generated for eight of the ten species of the Anolis crassulus species subgroup. We analyzed phylogenetic relationships and estimated divergence times and ancestral ranges of the subgroup, recovering a monophyletic subgroup within Anolis. Within the nominal taxon Anolis crassulus, we recovered multiple genetically distinct lineages corresponding to allopatric populations, and show that the Chortís Highland lineage split from the others over 13 MYA. Additionally, distinct mitochondrial lineages are present within the taxa A. heteropholidotus and A. morazani, and importantly, samples of A. crassulus and A. sminthus previously used in major anole phylogenetic analyses are not recovered as conspecific with those taxa. We infer a Chortís Highland origin for the ancestor of this subgroup, and estimate cladogenesis of this subgroup began approximately 22 MYA. CONCLUSIONS: Our results provide new insights into the evolution, biogeography, and timing of diversification of the Anolis crassulus species subgroup. The disjunctly distributed Anolis crassulus sensu lato represents several morphologically conserved, molecularly distinct anoles, and several other species in the subgroup contain multiple isolated lineages.
Assuntos
Ecossistema , Lagartos/classificação , Filogeografia , Animais , Teorema de Bayes , América Central , DNA Mitocondrial/genética , Loci Gênicos , Lagartos/genética , Nepovirus , Filogenia , Análise de Sequência de DNA , Especificidade da Espécie , Fatores de TempoRESUMO
Whether or not sexually selected traits consistently exhibit positive allometry (i.e. are disproportionately large in larger individuals) is an ongoing debate. Multiple models and exceptions to this rule suggest that the underlying drivers of sexual trait allometry are nuanced. Here, we compare allometries of sexual and non-sexual traits of a species (Anolis aquaticus) within a well-studied lizard genus to test the competing hypotheses that sexual traits are, or are not, defined by positive allometry. We further consider the relationships of trait functions, which are relatively well understood in the genus Anolis, and allometry to identify potential drivers of allometric patterns. In particular, we explore how trait allometries interact to influence total organism function and generate sexual dimorphism. We quantified size (of targeted traits) and color of a sexual signal (the dewlap) in Anolis aquaticus in the field. The dewlap conveyed information relevant to intra-sexual combat and exhibited positive allometry. Overall, our results suggest that using single-trait allometries as indicators of past selection provides only an incomplete understanding of trait evolution. Although the function of positive allometry in some individual sexual signals (e.g. those conveying "super-honest" information) may be straightforward, we illustrate how scaling relationships interact synergistically to influence the function of phenotypes and propose avenues for future research.
Assuntos
Tamanho Corporal , Lagartos/anatomia & histologia , Caracteres Sexuais , Pele/anatomia & histologia , Animais , Cor , Costa Rica , Feminino , Masculino , Seleção GenéticaRESUMO
The Cerrado is a wide Neotropical savanna with tremendously high endemic diversity. Yet, it is not clear what the prevalent processes leading to such diversification are. We used the Cerrado-endemic lizard Norops meridionalis to investigate the main abiotic factors that promoted genetic divergence, the timings of these divergence events, and how these relate to cryptic diversity in the group. We sequenced mitochondrial and nuclear genes from 21 sites of N. meridionalis to generate species tree, divergence time estimations, and estimate species limits. We also performed population-level analysis and estimated distribution models to test the roles of niche conservatism and divergence in the group diversification. We found that N. meridionalis is composed by at least five cryptic species. Divergence time estimations suggest that the deepest branches split back into the early-mid Miocene, when most of the geophysical activity of the Cerrado took place. The deep divergences found in N. meridionalis suggest that beta anoles invaded South America much earlier than previously thought. Recent published evidence supports this view, indicating that the Panama gap closed as early as 15 mya, allowing for an early invasion of Norops into South America. The spatial pattern of diversification within N. meridionalis follows a northwest-southeast direction, which is consistent across several species of vertebrates endemic to the Cerrado. Also, we found evidence for non-stationary isolation by distance, which occurs when genetic differentiation depends on space. Our preliminary data in two out of five lineages suggest that niche conservatism is an important mechanism that promoted geographic fragmentation in the group.
Assuntos
Especiação Genética , Lagartos/classificação , Lagartos/genética , Animais , Brasil , Variação Genética , Pradaria , Filogenia , Filogeografia , Análise de Sequência de DNARESUMO
The breast-shoulder apparatus (BSA) is a structurally and kinematically complex region of lizards. Compared with the pelvic region it has received little attention, even though its morphological variation is known to be extensive. This variability has seldom been the focus of functional explanation, possibly because the BSA has been difficult to explore as a composite entity. In this study we apply geometric morphometric techniques to the analysis of the BSA in an attempt to more fully understand its configuration in relation to differential use in locomotion. Our approach centers upon the Jamaican radiation of anoline lizards (genus Norops) as a tractable, small monophyletic assemblage consisting of species representing several ecomorphs. We hypothesized that the different species and ecomorphs would exhibit variation in the configuration of the BSA. Our findings indicate that this is so, and is expressed in the component parts of the BSA, although it is subtle except for Norops valencienni (twig ecomorph), which differs greatly in morphology (and behavior) from its island congeners. We further found similarities in the BSA of N. grahami, N. opalinus (both trunk-crown ecomorphs), and N. garmani (crown giant). These outcomes are promising for associating morphology with ecomorphological specialization and for furthering our understanding of the adaptive response of the BSA to demands on the locomotor system.
Assuntos
Osso e Ossos/anatomia & histologia , Lagartos/anatomia & histologia , Ombro/anatomia & histologia , Animais , Evolução Biológica , Fenômenos Biomecânicos , Osso e Ossos/fisiologia , Clavícula/anatomia & histologia , Clavícula/fisiologia , Feminino , Lagartos/fisiologia , Locomoção , Masculino , Filogenia , Análise de Componente Principal , Escápula/anatomia & histologia , Escápula/fisiologia , Fatores Sexuais , Ombro/fisiologia , Especificidade da Espécie , Coluna Vertebral/anatomia & histologia , Coluna Vertebral/fisiologia , Tórax/anatomia & histologia , Tórax/fisiologiaRESUMO
Predation is one of the major selective agents influencing evolution of color patterns. Cryptic color patterns decrease detection probability by predators, but their concealing function depends on the background against which patterns are seen; therefore, habitat use and color patterns are tightly linked. in many anole species, females exhibit variation in dorsal color patterns; the drab and perhaps cryptic colors of the patterns suggest a predator avoidance function behind this polymorphism. We tested whether these different color patterns experience different predation rates depending on their micro- habitat. We expected each pattern to form at least one optimal combination with a typically used micro-habitat that would result in lower predation compared to other morphs in the same micro-habitat. We tested this hypothesis for anoles at La Selva, Costa Rica, using clay models resembling a common species at this site: Norops humilis. The first experiment tested for variation in predation on various substrates. We included leaf litter, live leaves, and two size classes of woody stems, using 44 models for each pattern substrate combination. A second experiment tested effects of perch height (10 and 60cm) and diameter (<2cm and >5cm), with 50 models for each pattern perch combination. We found differences in predation rates between the morphs depending on their micro-habitat. Specifically, the striped morph had a significant advantage over the others on green leaves. in the second experiment, striped morphs showed significantly lower predation on low than on high perches, irrespective of perch diameter. Reticulated models had an advantage over other morphs on thin stems for the first experiment, where models were placed about 60cm high. Diameter did not have a significant effect on predation for reticulated morphs when height classes were combined. Dotted models did not experience an advantage over the other morphs in any of the treatments. in leaf litter and on thick perches no morph had any advantage over another, and leaf litter predation rates were generally low. These results support a role for predation in maintaining multiple female morphs within small Costa Rican anoles, such as N. humilis.
En los animales, los patrones dorsales de coloración a menudo se asocian con la protección contra la depredación. Con el fin de analizar el papel que tienen los micro-hábitat en la depredación de lagartijas hembras que presentan variaciones en los patrones de coloración dorsal (colores grises, crípticos), se realizó en la Estación Biológica La Selva, Costa Rica un estudio con el objetivo de comprobar si los patrones de diferentes colores provocan cambios en las tasas de depredación en función de a su micro-hábitat; se esperaba que cada patrón formara una combinación óptima utilizando el micro-habitat y que permitiera de esta manera reducir los niveles de depredación. Para evidenciar esta hipótesis se utilizaron modelos de arcilla que asemejan a la especie Norops humilis propia del lugar. Se realizaron dos estudios, el primero analizó modelos colocados en cuatro sustratos diferentes: hojarasca, hojas vivas y dos clases de tamaño de tallos leñosos, los cuales representaban cada hábitat donde es posible observar esta especie. Un segundo experimento estudió el efecto de la altura y el diámetro de la percha en la depredación, para ello se colocaron los modelos sobre tallos de diferentes alturas y diámetros. Fue posible observar en el primer experimento que el morfo rayado tuvo una ventaja significativa sobre los demás morfos en las hojas verdes y que los modelos reticulados tuvieron una ventaja sobre otros morfos en tallos delgados. El segundo estudio mostró que los morfos rayados tienen una tasa de depredación baja en perchas altas, independientemente del diámetro de la percha. Fue posible comprobar que los morfos punteados no experimentaron ventaja sobre otros morfos en ninguno de los dos estudios.