Anolis Species Research Articles

Natural hybridization between two species of green Anoles: morphological and genetic evidence

Anoles are a group of lizards that offer a wide range of opportunities to study different biological topics. In this work, we examined some aspects of the morphology from 139 individuals of green anoles collected in urban parks of Santo Domingo and the Distrito Nacional. We investigated evidence of hybridization between the two Hispaniola endemic species Anolis chlorocyanus and A. cyanostictus and the introduced species A. porcatus. We categorized the individuals in pure species and intermediates based on their phenotype. Additionally, mitochondrial 16S sequence data was generated from the collected specimens, to compare molecular and phenotypic species assignments. We consider the general congruence between both data sets in most but inconsistency in a few specimens as evidence for hybridization between the two endemic species. However, we did not find evidence of hybridization between any of these species and the introduced species A. porcatus. Nevertheless, the continuous expansion of the distribution of this invasive species possibly will have drastic negative consequences for the populations of the endemic species.

The highest kingdom of Anolis: Thermal biology of the Andean lizard Anolis heterodermus (Squamata: Dactyloidae) over an elevational gradient in the Eastern Cordillera of Colombia

Vertebrate ectotherms may deal with changes of environmental temperatures by behavioral and/or physiological mechanisms. Reptiles inhabiting tropical highlands face extreme fluctuating daily temperatures, and extreme values and intervals of fluctuations vary with altitude. Anolis heterodermus occurs between 1800m to 3750m elevation in the tropical Andes, and is the Anolis species found at the highest altitude known. We evaluated which strategies populations from elevations of 2200m, 2650m and 3400m use to cope with environmental temperatures. We measured body, preferred, critical maximum and minimum temperatures, and sprint speed at different body temperatures of individuals, as well as operative temperatures. Anolis heterodermus exhibits behavioral adjustments in response to changes in environmental temperatures across altitudes. Likewise, physiological traits exhibit intrapopulation variations, but they are similar among populations, tended to the "static" side of the evolution of thermal traits spectrum. The thermoregulatory behavioral strategy in this species is extremely plastic, and lizards adjust even to fluctuating environmental conditions from day to day. Unlike other Anolis species, at low thermal quality of the habitat, lizards are thermoconformers, particularly at the highest altitudes, where cloudy days can intensify this strategy even more. Our study reveals that the pattern of strategies for dealing with thermal ambient variations and their relation to extinction risks in the tropics that are caused by global warming is perhaps more complex for lizards than previously thought.

Appendicular morphology and locomotor performance of two morphotypes of continental anoles: Anolis heterodermus and Anolis tolimensis.

Anolis lizards have been a model of study in ecomorphology in the Caribbean islands because species with the same type of microhabitat share similar morphological features. But despite their great diversity, little is known about continental species. We analyzed the relationship between the anatomical characteristics of the appendicular skeleton and the locomotor performance of two Anolis species found in Colombia that have different use of habitat. Anolis heterodermus, a strictly arboreal species, was compared with Anolis tolimensis, which inhabits the lower strata of vegetation. These two species differ in their body plan not only in body shape and external morphological features, but also in the skeleton and appendicular musculature. The results highlight the muscle and bone specializations associated with the use of habitat in this genus, such as the presence of more robust bones to enlarge the surface of muscle insertion, the thickening and loss of carpal parts, thickening of tendons associated with the manus, and greater development of muscle mass in the forelimbs by A.heterodermus with respect to A.tolimensis. These differences are related to the use of the microhabitat and the locomotor style of each species.

Morphological evidence of sexual dimorphism in a Continental anole species of southeastern of Mexico

Abstract. Badillo-Saldaña LM, García-Rosales A, Lara-Tufiño JD, Ramírez-Bautista A. 2019. Morphological evidence of sexual dimorphism in a Continental anole species of southeastern Mexico. Biodiversitas 20: 3347-3351. Intersexual differences (sexual dimorphism; SD) have been observed in many traits of vertebrate and invertebrate species. These differences evolved as a response to ecological factors, such as the display of morphological and behavioral attributes during reproduction, territorial defense, or differential use of resources. However, some species of lizards do not show high SD, as is the case of some slender small body-sized anoles of the Caribbean Islands. Despite extensive knowledge about SD in island anoles, SD has not been evaluated for most mainland species. Therefore, the goal of this study was to evaluate the SD of a small body-sized species (Anolis unilobatus) throughout its distribution in Mexico, making use of eight morphological characteristics and multivariate analyses. The results showed that snout-vent (SVL) and forearm (FAL) lengths of males are larger than those of females. This could be explained by males being more territorial, so larger size will make them more successful in defending their territory from other males. Therefore, the difference in SVL and FAL between males and females of this species could be related to defense of their territory. The differences observed in morphological structures between males and females could thus support the hypothesis of sexual selection.

The distribution of non-native Anolis lizards on Saint Lucia, Lesser Antilles

Anolis lizards are common throughout the islands of the West Indies, often with several species existing in sympatry by demonstrating conspicuous niche separation. With increasing occurrences of Anolis species being introduced to islands outside of their natural range, there is potential for significant disturbance to natural Anolis communities and particularly to endemic species that have evolved in the absence of congeners. Here we report on the status of non-native Anolis lizards now present on the island of Saint Lucia, historically a single species island, and discuss the potential impact these introductions may have on endemic Anolis luciae. Through systematic visual encounter surveys and opportunistic sightings we present evidence for the widespread dispersal of Watts' anole (A. wattsi), indications of range expansion of Barbados anole (A. extremus), and the arrival and dispersal of a third species, the Cuban brown anole (A. sagrei). Our data suggest the presence of at least two of these species may be having a detrimental impact on the abundance of A. luciae, particularly in disturbed habitats.

Evolutionary lability in Hox cluster structure and gene expression in Anolis lizards.

Hox genes orchestrate development by patterning the embryonic axis. Vertebrate Hox genes are arranged in four compact clusters, and the spacing between genes is assumed to be crucial for their function. The genomes of squamate reptiles are unusually rich and variable in transposable elements (TEs), and it has been suggested that TE invasion is responsible for the Hox cluster expansion seen in snakes and lizards. Using de novo TE prediction on 17 genomes of lizards and snakes, I show that TE content of Hox clusters are generally 50% lower than genome‐wide TE levels. However, two distantly related lizards of the species‐rich genus Anolis have Hox clusters with a TE content that approaches genomic levels. The age distribution of TEs in Anolis lizards revealed that peaks of TE activity broadly coincide with speciation events. In accordance with theoretical models of Hox cluster regulation, I find that Anolis species with many TEs in their Hox clusters show aberrant Hox gene expression patterns, suggesting a functional link between TE accumulation and embryonic development. These results are consistent with the hypothesis that TEs play a role in developmental processes as well as in evolutionary diversifications.

Biogeography, Systematics, and Ecomorphology of Pacific Island Anoles

: Anoles are regarded as important models for understanding dynamic processes in ecology and evolution. Most work on this group has focused on species in the Caribbean Sea, and recently in mainland South and Central America. However, the Eastern Tropical Pacific (ETP) is home to seven species of anoles from three unique islands (Islas Cocos, Gorgona, and Malpelo) that have been largely overlooked. Four of these species are endemic to single islands (Norops townsendi on Isla Cocos, Dactyloa agassizi on Isla Malpelo, D. gorgonae and N. medemi on Isla Gorgona). Herein, we present a phylogenetic analysis of anoles from these islands in light of the greater anole phylogeny to estimate the timing of divergence from mainland lineages for each species. We find that two species of solitary anoles (D. agassizi and N. townsendi) diverged from mainland ancestors prior to the emergence of their respective islands. We also present population-wide morphological data suggesting that both display sexual size dimorphism, similar to single-island endemics in the Caribbean. All lineages on Isla Gorgona likely arose during past connections with South America, and ecologically partition their habitat. Finally, we highlight the importance of conservation of these species and island fauna in general.

Host Associations of Culex (Melanoconion) atratus (Diptera: Culicidae) and Culex (Melanoconion) pilosus from Florida, USA.

Characterizing the host-use patterns of mosquitoes is an essential component of understanding the transmission dynamics of mosquito-vectored pathogens. The host associations of two species of the medically important Culex subgenus Melanoconion, Culex atratus, and Culex pilosus are unknown or unclear, respectively. Both species have wide neotropical distributions. In the United States of America (USA), Culex pilosus occurs throughout the southeastern coastal plain, while Culex atratus is restricted to the southern Florida Peninsula. Using PCR-based blood meal analysis, we investigated the host associations of Culex atratus and Culex pilosus that were collected from Everglades National Park, Florida, USA We identified the host species of 208 Culex atratus and 168 Culex pilosus. Both species were narrowly associated with reptilian host species, particularly native and non-native lizards of the genus Anolis. Sampled Culex atratus exclusively fed on reptilian hosts, with >99% of blood meals derived from Anolis lizards. Culex pilosus fed predominantly from reptiles, but avian and mammalian blood meals were also detected. Of these, 92% of blood meals were derived from Anolis species. For both species, Anolis sagrei, an invasive exotic lizard in Florida, was the most frequently detected host species. These data indicate that Culex atratus and Culex pilosus are specialists of reptilian hosts, particularly Anolis lizards.

Genetic reconstruction of the invasion history of Anolis wattsi in Trinidad with a comment on the importance of ecological similarity to invasion success

Human activities have reshaped patterns of island biogeography for many groups of amphibians and reptiles. In Trinidad, an island in the West Indies with only one native Anolis lizard species, four additional anole species have been introduced since the 1800s. The most recent introduction, Anolis wattsi, native to Antigua, has become established despite the presence of multiple species of resident anoles. We used genetic data (mitochondrial DNA) to infer the geographic origin and genetic structure of introduced A. wattsi on Trinidad. We then gathered published data to compare eco-morphological traits of all anole species currently established on the island. We found three mtDNA haplotypes in Trinidad that clustered with two different clades from the northern part of the native range in Antigua, rejecting the hypothesis that the lizards originated in the pineapple-growing region of the south. However, a lack of fine-scale population structure precluded precise identification of the origin in Antigua of haplotypes introduced to Trinidad. Compared to the other anole species on Trinidad, A. wattsi is smaller, perches lower, and has a higher field body temperature. Thus, the successful establishment and spread of A. wattsi should not be surprising given the success of two previous introductions of anole species that were more similar ecomorphologically to the native species and each other, and the fact that Trinidad has relatively few anole species for its size.

DIETARY ANALYSIS OF THREE SPECIES OF THE GENUS Anolis (SAURIA: DACTYLOIDAE) IN “LOS TUXTLAS,” VERACRUZ, MEXICO

Anoles have been studied by researchers to a greater extent than any other group of lizards. Their high diversity has led them to colonize a variety of niches, making them an ideal model group for evaluating ecological hypotheses such as dietary niche overlap. This work analyzes the stomach contents of 73 individuals from three species of the genus Anolis: A. barkeri (34), A. sericeus (17), and A. tropidonotus (22) occurring in the vicinity of Los Tuxtlas, Veracruz. Analyses performed included Shannon’s index in its log form to calculate dietary diversity, the Jaccard index to estimate the dissimilarity of the species’ diets, and Schoener’s index to measure dietary overlap. The results suggest that A. barkeri (10.08) hast the most generalist diet, followed by A. sericeus (8.75) and A. tropidonotus (5.78). Schoener’s index showed a considerable amount of diet overlap between A. barkeri and A. sericeus (0.76). We conclude that the three focal species show a generalist feeding behavior in times of abundant prey, such as the rainy season in which this study was conducted. This may lead to the elusion of intra-generic competition, explaining why we did not observe dietary niche displacement between these three species of Anolis.

Parallel increases in grip strength in two species of Anolis lizards after a major hurricane on Dominica

AbstractA recent study showed that hurricanes can act as selective agents affecting the phenotype of anole populations subjected to these extreme climatic events. Specifically, Anolis lizards that survived hurricanes were shown to have larger toepads than those that did not. To test whether hurricanes more generally impact populations of Anolis lizards, we collected data on toepad size, lamella number and grip strength for two species of Anolis on the island of Dominica in 2018 and compared them with data collected in 2016 before Hurricane Maria devastated the island. Our results show that populations of both species showed higher clinging forces in 2018, consistent with our predictions that lizards that are better clingers would be more likely to survive hurricanes. Unexpectedly, the increase in clinging force was not accompanied by an increase in toepad size or lamella number, suggesting that the increase in clinging strength is more likely driven by changes at the level of the setae microstructure. While the mechanism driving this pattern cannot be determined until future before/after hurricane comparisons are made, our data provide further evidence that hurricanes may be a previously overlooked driver of form and function in Anolis lizards.

Predicting Climate-Induced Distributional Shifts for Puerto Rican Anoles

With some 400 known species, the lizard genus Anolis is one of the most species-rich groups of terrestrial vertebrates in the world. Widely distributed, they occur throughout Central and South America, the West Indies, and the southeastern United States. Although anoles have emerged as paradigmatic species in ecology and evolution, relatively little research has addressed the effects of climate change on their distributions. Over the past 40 years, Puerto Rico has experienced steady increases in ambient temperature with mean maximum temperatures rising by as much as 2°C. Using distribution data from the Puerto Rico Gap Analysis, WorldClim bioclimatic variables, and MaxEnt niche modeling software, we projected potential changes in the distribution of ten species of Puerto Rican anoles for 2050 and 2070. All of our models used either the HadGEM2-AO or the MRI-CGCM3 Global Climate Model, each paired with the IPCC's Representative Concentration Pathways (RCPs). RCP4.5 was chosen as it represents a scenario in which greenhouse gas concentrations rise in the Earth's atmosphere until the year 2040 and then begin to decline. RCP8.5 was chosen as it represents a likely scenario of continued high greenhouse gas emissions through 2100 and acts as the IPCC's worst-case scenario of warming. Under HadGEM2-AO RCP8.5 for 2050, Anolis krugi, A. evermanni, and A. gundlachi are the most negatively impacted species, while for MRI-CGCM3 RCP8.5 for 2050, the most negatively impacted species are A. cuvieri, A. gundlachi, and A. evermanni. The models also predict mean reductions in most suitable habitat across all ten species of Anolis, ranging from –29.4% by 2050 to –39.6% by 2070 under HadGEM2-AO RCP8.5, and from –10.6% by 2050 to –28.5% by 2070 under MRI-CGCM3 RCP8.5. Our study provides insights into the potential impact of continued climate change on Puerto Rican anoles, and most likely other West Indian species of Anolis, and has important implications for future conservation efforts.

Importancia del género Anolis (Lacertilia: Dactyloidae), como indicadores del estado del hábitat, en bosque pluvial tropical del Chocó

El objetivo fue cuantificar el valor de las especies del género Anolis como indicadores ecológicos del estado de conservación de los hábitats usados por estas especies en una zona de bosque tropical en el departamento del Chocó. El método de relevamiento por encuentro visual, fue empleado para establecer especies con mayor abundancia relativa en determinado sitio con distintos grados de cobertura vegetal, el patrón “A” son especies indicadoras de altos niveles de intervención donde se destacó Anolis chloris con el 88.2% de abundancia relativa, patrón “B” se referencia a las especies indicadoras de niveles medios de intervención, donde A. latifrons con el 75% de los individuos fueron registrados en este nivel de tolerancia y el patrón “C”, hace referencia a especies que se encuentran en áreas boscosas con un alto nivel de conservación de su estado natural, donde las especies A. anchicayae (92.8%) y A. notopholis (exclusiva) fueron las más importantes., en cuanto al indice de Valor Indicador Ecológico “IndVal”, se reportaron cuatro especies indicadoras, con una diferencia estadísticamente significativa entre especies; A. anchicayae (IndVal: 92.9%), para áreas de bosque con muchos años de regeneración natural, A. chloris (IndVal: 88.2%), A. maculiventris (IndVal: 65.2%) y A. granuliceps (IndVal: 50.8%). Además, se realizo un análisis de similitud y complementariedad entres las diferentes coberturas, indicando el recambio y la exclusividad de especies entre las mismas y posteriormente se graficaron curvas de rango- abundancia. Los resultados sugerir a los Anolis como grupo indicador del estado de conservación de los bosques tropicales del Chocó.

Malaria Infection is Lower in Invasive Anoles than Native Anoles in Central Florida, USA

Florida is home to the largest number of invasive reptile species, including the abundant Anolis sagrei, of any U.S. state. This lizard species has largely displaced the native Anolis carolinensis because of its superior competitive ability and tolerance of urbanized habitats. One facet of the invasion of A. sagrei that has not received attention in the literature is its interactions with parasites, including the malaria protozoan Plasmodium. We studied the relative prevalence of Plasmodium floridense in two Anolis species at three sympatric sites in central Florida to determine the factors that affect the parasite's prevalence, incidence, and effects on blood cell counts. After catching lizards and making blood smears, we examined slides for the presence of Plasmodium and counted relative erythrocyte/ leukocyte ratios. Of the 101 lizards sampled, 31% of A. carolinensis were positive for P. floridense, as opposed to only 11% for A. sagrei. Date of capture was also an important factor, with June having the highest prevalence and March the lowest. Erythrocyte to leukocyte ratios differed with infection, averaging 3.15 ± 1.28 SD in infected lizards versus 4.28 ± 1.03 in uninfected lizards. Reduced infection by blood parasites may have been one of the many factors that allowed A. sagrei to successfully invade Florida and to become the superior competitor throughout its range. Additional studies of the effects of Plasmodium infection on competitive ability and fitness are needed to determine whether infection is a major contributor to invasion success.

Diurnal colour change in a sexually dimorphic trait in the Andean lizard Anolis heterodermus (Squamata: Dactyloidae)

ABSTRACTSexual dimorphism in body size, shape and colour is widespread in lizards as well as in other taxa. In the context of sexual selection, these sex differences are commonly manifested as exaggerated male traits, which are selected by females to assess the quality of males. However, differences in sex by environment interactions can also lead to sexual dimorphism. The genus of Anolis lizards is particularly well known for sharp sexual dimorphism in dewlap colour and size; however, this is not the case in all anole species. Using digital image analyses, I assessed the existence of sexual differences in the diurnal change in colour and size of a conspicuous patch on the tail of the lizard Anolis heterodermus Duméril 1851. Results showed that the tail patch of both males and females changed in colour, but not size, from red to blue throughout the day in a similar fashion. This process took almost half a day to complete and occurred in the absence of conspecifics, suggesting that the change itself may not have an active role in social communication. However, the colour patches of males were consistently larger. The cause of the substantial variation in colour and size of the tail patch of A. heterodermus is still unknown and deserves more research. This study highlights the importance of continuous wildlife observations to identify life history traits that may be important in animal behaviour but are challenging to observe in nature.

The need for speed: functional specializations of locomotor and feeding muscles in Anolis lizards.

Muscles often perform diverse mechanical roles within an organism. Tuning of contractile properties may therefore provide an opportunity for muscles to better perform their different roles and impact their associated whole-organism performance. Here, we examined the muscle contractile physiology of a jaw and a leg muscle in five Anolis species to determine whether consistent physiological differences are found in these muscles. We found that these jaw and leg muscles exhibited consistent patterns of variation across species, which may be related to the functional use of each muscle. In particular, we found that each muscle had differentially increased different measures of muscle speed. Although the jaw muscles had faster peak contractile velocities than the leg muscles, the leg muscles had faster twitch times and faster contractile velocities under intermediate loads. We also found that the jaw muscles exerted higher specific tensions and had a greater curvature to their force-velocity relationship. The consistent patterns across five species suggest that these jaw and leg muscles have specialized in different ways. Examination of these contractile property variations may help illuminate important features relating to performing their individual functional roles.

A Cryptic New Species of Anole (Squamata: Dactyloidae) from the Lenca Highlands of Honduras, Previously Referred to as Norops crassulus (Cope, 1864)

We describe a cryptic new species of Norops Wagler, 1830, Norops caceresae, from mixed transitional and broadleaf cloud forest formations in the Lenca Highlands of southwestern Honduras. This population was previously considered conspecific with Norops crassulus (Cope, 1864) of Guatemala, El Salvador, and Mexico, despite it being entirely disjunct (> 100 km) from any of those populations. Recent molecular work revealed consistent, deep mitochondrial and nuclear distinctiveness between this population and all other anoles of the N. crassulus species group, prompting a thorough morphological investigation of this population. This new species is most similar in external morphology to N. crassulus sensu stricto, but is readily distinguished by molecular distinctiveness, distribution, and morphology.

Detection and phylogenetic analysis of adenoviruses occurring in a single anole species.

Adenoviruses (AdVs) infect a wide range of hosts, and they have undergone recent and ancient host transfers multiple times. In reptiles, AdVs have been found in many captive individuals, and have been implicated in morbidity and mortality in several species. Yet the pathogenicity, transmission, phylogenetic distribution, and source of AdVs in the environment are still unknown. We therefore chose to opportunistically sample deceased captive Anolis sagrei individuals that were collected from different populations in the Bahamas and the Cayman Islands, as well as fecal samples from one island population, to explore the disease dynamics and diversity of adenovirus infecting A. sagrei populations. We found that adenovirus infection was present in our captive colony at low prevalence (26%), and was likely not the primary cause of observed morbidity and mortality. Among the 10 individuals (out of 38 sampled) which tested positive for adenovirus, we identified four adenovirus clades, several of which are distantly related, despite the close relationships of the A. sagrei host populations. These results suggest that while adenovirus may not be highly prevalent in the wild, it is present at low levels across much of the range of A. sagrei. It may undergo frequent host switching across both deep and shallow host divergences.

Factors affecting interspecific differences in genetic divergence among populations of Anolis lizards in Cuba

BackgroundGeographical patterns and degrees of genetic divergence among populations differ between species, reflecting relative potentials for speciation or cladogenesis and differing capacities for environmental adaptation. Identification of factors that contribute to genetic divergence among populations is important to the understanding of why some species exhibit greater interpopulation genetic divergence. In this study, we calculated the mean pairwise genetic distances among populations as species’ average genetic divergence by a phylogeny using nuclear and mitochondrial genes of 303 individuals from 33 Cuban Anolis species and estimated species ages by another phylogeny using nuclear and mitochondrial genes of 51 Cuban and 47 non-Cuban Anolis species. We identified factors that influence species’ differences in genetic divergence among 26 species of Anolis lizards from Cuba. Species ages, environmental heterogeneity within species ranges, and ecomorph types were considered as factors affecting average genetic divergences among populations.ResultsThe phylogenies presented in this study provide the most comprehensive sampling of Cuban Anolis species to date. The phylogeny showed more conservative evolution of Anolis ecomorphs within Cuba and identified twig anoles as a monophyletic group. Subsequent Phylogenetic Generalized Least Squares (PGLS) analyses showed that species age was positively correlated with species’ average genetic divergence among populations.ConclusionAlthough previous studies have focused on factors affecting genetic divergence within species, the present study showed for the first time that species differences in genetic divergence could be largely affected by species age.

The Lizards, Crocodiles, and Turtles of Honduras. Systematics, Distribution, and Conservation

I discuss the taxonomy, distribution, and conservation of the lizards, crocodiles, and turtles occurring in the Central American country of Honduras. This is the fourth and final work in this series documenting the amphibians and reptiles of that country. I propose three new species: one of Laemanctus and two of the Sceloporus malachiticus species complex of the S. formosus group. I also suggest several other taxonomic changes, including elevating Laemanctus waltersi, Leiocephalus varius, Sceloporus schmidti, and Kinosternon albogulare to valid species. I also place Ctenosaura praeocularis in the synonymy of C. quinquecarinata and Laemanctus serratus mccoyi in the synonymy of L. serratus. All of those decisions are documented with specimens examined (with the exception of L. s. mccoyi) and data and were reviewed by experts on those groups. Several geographically wide-ranging species appear to represent more than one species (i.e., Phyllodactylus tuberculosus, Sphaerodactylus continentalis, Basiliscus vittatus). Also discussed is the uncontested, illegal forest destruction occurring throughout the country, including in areas designated as national parks and other types of reserves. The reader is urged to refer to the materials and methods section for an explanation of the procedures used in this work. In total, 107 species of lizards, 2 species of crocodiles, and 17 species of turtles are discussed. Full species accounts of 86 nominal forms are included herein, since a recent review of the anoles had included full species accounts for 39 of those species (one anole species recently added not included in a species account).