Dominican House Wren (Troglodytes aedon rufescens) holding a juvenile Puerto Rican crested anole (Anolis cristatellus). Photo by M.P. van den Burg.
New literature alert!
Predation on the nonnative Puerto Rican crested anole (Anolis cristatellus) by the Dominican House Wren (Troglodytes aedon rufescens) on the Commonwealth of Dominica
In The Wilson Journal of Ornithology
van den Burg & Brisbane
Abstract
Predation on vertebrate species by insect-eating birds is rarely recorded, with only one report for the House Wren (Troglodytes aedon). On 4 January 2019, we observed a Dominican House Wren (T. a. rufescens) consume a juvenile of the nonnative Puerto Rican crested anole (Anolis cristatellus) in Roseau, Commonwealth of Dominica. This observation suggests the Dominican House Wren could additionally prey on the endemic Dominican anole (Anolis oculatus). This record aids our understanding of the ecosystem-wide impact of the A. cristatellus invasion.
Cockroach positioned on head of Anolis fuscoauratus, on 29 March 2019 in the Ecuadorian Amazon. Photo by Javier Aznar González de Rueda
New literature alert!
Lachryphagy by cockroaches: reptile tears to increase reproductive output?
In Neotropical Biodiversity
van den Burg & Aznar González de Rueda
Abstract
Lachryphagy, or tear-feeding, is generally considered as supplementary feeding by invertebrates with a long proboscis to acquire essential nutrients. Commonly reported vertebrate host species of lachrypaghic interactions are humans and birds, and in reptiles concern large species: turtles and crocodiles, with one report from an iguanid host. Here, we report tear-feeding by a cockroach, a species lacking a proboscis, on a small squamate species, Anolis fuscoauratus. We address how the nutritional needs for the reproductive cycle may force cockroaches to explore any dietary source with essential nutrients. In addition to birds, our report adds Anolis as invertebrate predators that are visited by lachryphagous invertebrates, interactions that may be restricted to nights to reduce predation risk for the feeding invertebrates. This report extends tear-feeding behavior to proboscis-lacking invertebrates, and to small squamate hosts, and demonstrates that lachryphagy on reptilian hosts is not restricted to diurnal occurrence. Overall, this observation suggests that similar interactions could be far more frequent.
Female (top) and male (bottom) brown anole. Photo courtesy Bob Reed
New literature alert!
Sex-Specific Population Differences in Resting Metabolism Are Associated with Intraspecific Variation in Sexual Size Dimorphism of Brown Anoles
In Physiological and Biochemical Zoology
Curlis, Cox, & Cox
Abstract
Sexual size dimorphism can vary in direction and magnitude across populations, but the extent to which such intraspecific variation is associated with sex and population differences in underlying metabolic processes is unclear. We compared resting metabolic rates (RMRs) of brown anole lizards (Anolis sagrei) from two island populations in the Bahamas (Eleuthera and Great Exuma) that differ in the magnitude of male-biased sexual size dimorphism. Whereas females from each population exhibit similar growth rates and body sizes, males from Great Exuma grow more quickly and attain larger body sizes than males from Eleuthera. We found that these population differences in growth of males persisted in captivity. Therefore, we predicted that males from each population would differ in RMR, whereas females would not. Consistent with this prediction, we found that RMR of males from Eleuthera was higher than that of males from Great Exuma, particularly at higher temperatures. As predicted, RMR of females did not differ between populations. Despite this apparent sex-specific trade-off between growth rate and RMR at the population level, we found a positive relationship between growth rate and RMR at the individual level. The fact that Great Exuma males maintain lower RMR than Eleuthera males, despite their greater absolute growth rates and the positive relationship between RMR and growth rate across individuals, suggests that Great Exuma males may have lower baseline metabolic demands and/or greater growth efficiency than Eleuthera males. Our results call attention to sex-specific divergence in metabolism as a potential mechanism for intraspecific divergence in sexual size dimorphism.
Ecological Opportunity from Innovation, not Islands, Drove the Anole Lizard Adaptive Radiation
In Systematic Biology
Burress & Muñoz
Abstract
Islands are thought to facilitate adaptive radiation by providing release from competition and predation. Anole lizards are considered a classic example of this phenomenon: different ecological specialists (‘ecomorphs’) evolved in the Caribbean Greater Antilles (Cuba, Hispaniola, Jamaica, and Puerto Rico), resulting in convergent assemblages that are not observed in mainland Latin America. Yet, the role of islands in facilitating adaptive radiation is more often implied than directly tested, leaving uncertain the role of biogeography in stimulating diversification. Here, we assess the proposed “island effect” on anole diversification using Bayesian phylogenetic comparative methods that explicitly incorporate rate heterogeneity across the tree and demonstrate two cases of would-be false positives. We discovered that rates of speciation and morphological evolution of island and mainland anoles are equivalent, implying that islands provide no special context for exceptionally rapid diversification. Likewise, rates of evolution were equivalent between island anoles that arose via in situ versus dispersal-based mechanisms, and we found no evidence for island-specific rates of speciation or morphological evolution. Nonetheless, the origin of Anolis is characterized by a speciation pulse that slowed over time – a classic signature of waning ecological opportunity. Our findings cast doubt on the notion that islands catalyzed the anole adaptive radiation and instead point to a key innovation, adhesive toe pads, which facilitated the exploitation of many arboreal niches sparsely utilized by other iguanian lizards. The selective pressures responsible for arboreal niche diversification differ between islands and the mainland, but the tempo of diversification driven by these discordant processes is indistinguishable.
Transcriptomic Analysis of Skin Color in Anole Lizards
In Genome Biology and Evolution
de Mello, Hime, & Glor
Abstract
Color and color pattern are critical for animal camouflage, reproduction, and defense. Few studies, however, have attempted to identify candidate genes for color and color pattern in squamate reptiles, a colorful group with over 10,000 species. We used comparative transcriptomic analyses between white, orange and yellow skin in a color-polymorphic species of anole lizard to: (i) identify candidate color and color-pattern genes in squamates, and (ii) assess if squamates share an underlying genetic basis for color and color pattern variation with other vertebrates. Squamates have three types of chromatophores that determine color pattern: guanine-filled iridophores, carotenoid- or pteridine-filled xanthophores/erythrophores, and melanin-filled melanophores. We identified 13 best candidate squamate color and color-pattern genes shared with other vertebrates: six genes linked to pigment synthesis pathways, and seven genes linked to chromatophore development and maintenance. In comparisons of expression profiles between pigment-rich and white skin, pigment-rich skin upregulated the pteridine pathway as well as xanthophore/erythrophore development and maintenance genes; in comparisons between orange and yellow skin, orange skin upregulated the pteridine and carotenoid pathways as well as melanophore maintenance genes. Our results corroborate the predictions that squamates can produce similar colors using distinct color-reflecting molecules, and that both color and color-pattern genes are likely conserved across vertebrates. Furthermore, this study provides a concise list of candidate genes for future functional verification, representing a first step in determining the genetic basis of color and color pattern in anoles.
Anolis carolinensis from http://www.mascotissimo.com/wp-content/uploads/2008/02/anolis_carolinensis.jpg
New literature alert!
The Effect of Long Term Captivity on Stress Levels in Anolis carolinensis Lizards
In Journal of Applied Animal Welfare Science
Borgmans, Palme, Sannen, Vervaecke, & Van Damme
Abstract
The effect of long term captivity is a factor that is important for all research utilizing wild caught animals. Despite the fact that it can be considered to be one of the most fundamental potential sources of stress in captivity, it has received a low amount of interest in recent research on lizards. Given the wide variety in ecology and life history among lizards species, it would make sense to investigate the effect of long term captivity on wild caught lizards on a broader scale. In this study we investigated the effect of long term captivity (four months) on the physiology and behavior of male and female Anolis carolinensis lizards. Our results showed no negative effects of four months of captivity on physiological and behavioral measurements in male A carolinensis lizards. Similar results for females were found for all measurements except body mass and tail width. Here our results indicated a potential negative effect of four months of captivity on body mass and tail width in females.
Size but not relatedness drives the spatial distribution of males within an urban population of Anolis carolinensis lizards
In Ecology and Evolution
Weber, Anthony, and Lailvaux
Abstract
The way that individuals are spatially organized in their environment is a fundamental population characteristic affecting social structure, mating system, and reproductive ecology. However, for many small or cryptic species, the factors driving the spatial distribution of individuals within a population are poorly understood and difficult to quantify. We combined microsatellite data, remote sensing, and mark–recapture techniques to test the relative importance of body size and relatedness in determining the spatial distribution of male Anolis carolinensis individuals within a focal population over a five‐year period. We found that males maintain smaller home ranges than females. We found no relationship between male body size and home range size, nor any substantial impact of relatedness on the geographic proximity. Instead, the main driver of male spatial distribution in this population was differences in body size. We also found no evidence for offspring inheritance of their parent’s territories. Males were never sampled within their father’s territory providing strong support for male‐biased dispersal. This study introduces a novel approach by combining standard mark release capture data with measures of pairwise relatedness, body size, and GPS locations to better understand the factors that drive the spatial distribution of individuals within a population.
Using Google Trends to Determine Current, Past, and Future Trends in the Reptile Pet Trade
In Animals
Jose W. Valdez
Abstract
Reptiles are one of the most popular exotic pets in the world, with over a third of all described species currently being traded. However, the most commonly available reptiles are typically non-threatened, captive-bred, and/or domestically obtained, which means they are also largely unregulated and unmonitored, resulting in a large portion of the reptile pet trade remaining unknown. In this study, the past, current, and future trends of the most popular reptiles in the pet trade were examined. Google Trends was used to determine the global popularity of the most popular pets from 2004 to 2020 and compared to the results from an online survey sent to individuals involved in the reptile trade. The most popular pets from the previous five years were also compared globally across regions and countries. The results determined that the most popular reptile species during the last decade is by far bearded dragons, followed by ball pythons and leopard geckos. Although the survey results were similar when asked what the top reptiles were, most respondents named ball pythons as the most popular reptile. However, when asked what reptiles had lost the most popularity during the previous decade, the survey respondents named green iguanas, Burmese pythons, chameleons, red-eared sliders, and green anoles, concurring with what was found with Google Trends. The reptiles thought to be more popular in the upcoming decade by the survey participants were blue-tongued skinks, tegus, uromastyx, crested geckos, and ball pythons—most of which did indeed show an increase in popularity during the last decade, as indicated with Google Trends. The results from Google Trends demonstrated that ball pythons and crested geckos have increased their popularity more than any other reptile in the last two decades. Reptile popularity also differed between countries, with bearded dragons the most popular reptile in Australia, Western Europe, the U.S., and Canada. Leopard geckos were the most popular reptile in Italy and Turkey, and ball pythons were the reptile of choice in Mexico, Indonesia, and India. The general finding of this study is that the reptiles declining in popularity were mostly wild-caught or restricted due to regulations, while current and future species were captive-bred and available in many varieties or morphs. The most popular species were also docile, medium-sized, and easy to handle, with relatively simple care requirements. This study demonstrates that Google Trends can be a useful tool for determining relative popularity among reptiles, or any other pet group, with results closely mirroring those obtained through direct surveying of people involved in the pet trade. However, unlike surveys, this analysis is quick, quantifiable, and can show what is popular and in-demand not only at the global level but at much finer scales. Thus, Google Trends can be a valuable tool in many research applications, especially in topics that may otherwise be difficult to monitor and quantify.
By Peter van der Sluijs – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=33133626
New literature alert!
Detection of Anolis carolinensis using drone images and a deep neural network: an effective tool for controlling invasive species
In Biological Invasions
Aota, Ashizawa, Mori, Toda, and Chiba
Abstract
Invasive species greatly disrupt island ecosystems, risk assessment and the conservation of native ecosystems have therefore become pressing concerns. However, the cost of monitoring invasive species by humans is often high. In this study, we developed a system to detect an invasive lizard species, Anolis carolinensis, that threatens the native insect ecosystem of the Ogasawara Islands in Japan. Surveying these forest lizards requires specialized field observers, a challenge that prevents the government of Japan from efficient conservation and management of this ecosystem. The proposed system detects these lizards in drone images using a type of machine learning called deep neural network. Data were collected using a drone on Ani-jima in the Ogasawara Islands, and the trained network shows approximately 70% precision of detecting A. carolinensis. This study shows the combination of remote sensing and machine learning have the potential to contribute to an efficient and effective approach to conserving ecosystems.
Table 2 from Hsu et al. showing the survival rates of lizard eggs exposed to saltwater
New literature alert!
Trans-marine dispersal inferred from the saltwater tolerance of lizards from Taiwan
In PLOS ONE
Hsu, Lin, Liao, Hsu, and Huang
Abstract
Dehydration and hypersalinity challenge non-marine organisms crossing the ocean. The rate of water loss and saltwater tolerance thus determine the ability to disperse over sea and further influence species distribution. Surprisingly, this association between physiology and ecology is rarely investigated in terrestrial vertebrates. Here we conducted immersion experiments to individuals and eggs of six lizard species differently distributed across Taiwan and the adjacent islands to understand if the physiological responses reflect the geographical distribution. We found that Plestiodon elegans had the highest rate of water loss and the lowest saltwater tolerance, whereas Eutropis longicaudata and E. multifasciata showed the lowest rate of water loss and the highest saltwater tolerance. Diploderma swinhonis, Hemidactylus frenatus, and Anolis sagrei had medium measurements. For the eggs, only the rigid-shelled eggs of H. frenatus were incubated successfully after treatments. While, the parchment-shelled eggs of E. longicaudata and D. swinhonis lost or gained water dramatically in the immersions without any successful incubation. Combined with the historical geology of the islands and the origin areas of each species, the inferences of the results largely explain the current distribution of these lizards across Taiwan and the adjacent islands, pioneerly showing the association between physiological capability and species distribution.
