Reproductive Tradeoffs and Phenotypic Selection Change with Body Condition, but Not with Predation Regime, across Island Lizard Populations

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On September 8, 2021

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A Brown Anole (Anolis sagrei)--the species of focus in the below study by Cox et al. (2021)--displays a gorgeous bright-orange dewlap. Credit Wikimedia Commons (https://commons.wikimedia.org/wiki/File:Brown_Anole_male_(Anolis_sagrei)_-_Introduced_(24416281378).jpg).

A Brown Anole (Anolis sagrei)–the species of focus in the study by Cox et al. (2021)–displays a gorgeous bright-orange dewlap. Credit Wikimedia Commons.

New literature alert!

Reproductive tradeoffs and phenotypic selection change with body condition, but not with predation regime, across island lizard populations

In Journal of Evolutionary Biology

Abstract:

Tradeoffs between reproduction and survival are central to life-history theory and are expected to shape patterns of phenotypic selection, but the ecological factors structuring these tradeoffs and resultant patterns of selection are generally unknown. We manipulated reproductive investment and predation regime in island populations of brown anole lizards (Anolis sagrei) to test (1) whether previously documented increases in the survival of experimentally non-reproductive females (OVX = ovariectomy) reflect the greater susceptibility of reproductive females (SHAM = control) to predation, and (2) whether phenotypic selection differs as a function of reproductive investment and predation regime. OVX females exceeded SHAM controls in growth, mass gain, and body condition, indicating pronounced energetic costs of reproduction. Although mortality was greatest in the presence of bird and snake predators, differences in survival between OVX and SHAM were unrelated to predation regime, as were patterns of natural selection on body size. Instead, we found that body condition at the conclusion of the experiment differed significantly across populations, suggesting that local environments varied in their ability to support mass gain and positive energy balance. As mean body condition improved across populations, the magnitude of the survival cost of reproduction increased, linear selection on body size shifted from positive to negative, and quadratic selection shifted from stabilizing to weakly disruptive. Our results suggest that reproductive tradeoffs and patterns of phenotypic selection in female brown anoles are more sensitive to inferred variation in environmental quality than to experimentally induced variation in predation.

Undergraduate Research Turned National Geographic Expedition

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On September 6, 2021

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In a recent publication in the Journal of Tropical Ecology, we found that the herpetofauna communities of Virgin Islands National Park, on the island of St. John, USVI, were resistant to the large disturbances of hurricanes Irma and Maria, showing no significant change in habitat associations eight months post-hurricane. These findings were born from undergraduate research that grew, due to ample encouragement and funding from the National Geographic Society, into an in-depth examination of community recovery from some of the nastiest storms to hit the Caribbean region.

Anolis stratulus dewlapping. Photo by Sam DiGiulio

I started this work in 2016 as a third-year undergraduate at Northern Michigan University (NMU). My research partner, Sam DiGiulio, and I jumped at the chance to enroll in Dr. Jill Leonard’s class, Field Marine Biology, which took students on a spring-break field excursion to St. John, USVI. During our stay at the Virgin Islands Environmental Resource Station (VIERS), we experienced the biodiversity of Caribbean coral reefs, observed marine sampling techniques, and learned how terrestrial processes affect marine environments. As an additional component to the class, Sam and I designed an independent research project to carry out during our time on St. John. Due our shared passion for herpetofauna, we decided to implement a herpetological inventory of Virgin Islands National Park (VINP), following up on work done by the US Geological Survey (USGS) in 2001 (Rice et al. 2001). The initial goal of our survey was to provide the National Park Service (NPS) with a report that would act as a snapshot of the herp communities 15 years after the USGS survey, but it ended up being a lot more than that.

There is not much better field work than that in VINP. We hiked the trails and conducted visual encounter surveys; documenting the anoles, dwarf geckos (Sphaerodactylus macrolepis), and the occasional green iguana (Iguana iguana). Each transect we walked was classified by one of five landcover types (moist forest, dry forest, scrub, estuarine, and gut – small areas that hold freshwater for extended periods), per the USGS inventory. We also set out to the trails at night to conduct vocalization surveys for the island’s frog species. VINP is home to 19 species of reptile and amphibian, though this number fluctuates as populations of introduced species wink in and out. St. John is the smallest of the US Virgin Islands and does not host some of the rarer endemic species like St. Croix, such as Anolis acutus, or Ameiva polops, or hold the diversity found on Puerto Rico. However, that doesn’t make its residents any less charming, and with over 56% of the island of St. John included within VINP, there are ample places to observe them.

Anolis cristatellus. Photo by Sam DiGiulio

The most common anole on the island is the Puerto Rican crested anole (Anolis cristatellus). We observed all age classes, sizes, and crest shapes of these lizards and in every habitat type on the island. It was a treat to see two huge males duke it out on a tree trunk, head bobbing, dewlapping, and charging at one another, turning almost black, as opposed to their usual brown hues. The fight ended with one tossing the other off the trunk with its mouth.

We were also fortunate to find some of the rarer island residents, flipping just the right logs and rocks to reveal blind snakes (Antillotyphlops richardii) and a Virgin Islands worm lizard (Amphisbaena fenestrata). We conducted our surveys anywhere that we could hitch a ride with the class, or with staff from VIERS as they traveled to and from town for camp supplies. Even without our own vehicle, we were able to cover much of the park on foot in the course of the week and after returning to NMU for the end of the semester, we wrote up the report for the NPS, and presented the data at several scientific conferences.

Come September of 2017, category 5 Hurricanes Irma and Maria struck St. John within the course of two weeks. The forests and infrastructure of the islands sustained serious damage. Countless trees had fallen, and those that were still standing were completely defoliated. I anxiously stayed informed about the damage, but it wasn’t until November of 2017 that we talked about the potential of returning to resurvey the herps of VINP. Jill pointed us in the direction of the program. With encouragement from our advisor, we applied for a National Geographic Society’s Early Careers grant and in March of 2018 we received the funds necessary to return to St. John to re-conduct our herp survey.

Early that summer, Sam and I arrived back on St. John. This time, we were able to secure a vehicle and cover even more of the park, in addition to resurveying the areas that we had visited in 2016. We hit the ground running, first by revisiting our previous survey areas to ensure we repeated the same procedures as 2016. As we had arrived nine months after the storms hit, there were already plenty of signs of recovery. Canopy gaps created by the storms were being filled by early successional growth. Vines covered fallen trees and standing trees were quickly replacing lost leaves. The red mangroves were very slowly sprouting new shoots and leaves from the standing skeletons of prop roots. Clean-up operations and construction projects were coming along in the developed areas of the island. Unfortunately, VINP infrastructure had yet to be repaired, and VIERS had been destroyed. As of writing this post in 2021, the incredible education center is still not functional. However, as we traversed the trails and conducted our visual encounter surveys, the herps of the island appeared to be rather unperturbed.

Anolis pulchellus. Photo by Sam DiGiulio

While the vegetation structure appeared different from our initial surveys in 2016, community composition and the landcover types in which they were found  remained unchanged. Puerto Rican crested anoles remained the most abundant species across the landcover types, taking full advantage of the coarse woody debris as display platforms to show off their dewlaps. The male anoles retained their cantankerous attitude towards conspecifics; this time around, we observed two dueling sharp-mouth anoles (Anolis pulchellus). These anoles are much lighter than the bulky crested anoles, favoring grasses and shrubbery to perch, allowing their background to more easily match their greenish hues. As diligently as we searched, we were unable to find more blind snakes and worm lizards, although this was no surprise due to the rarity of specimens recorded in previous surveys. Sufficient planning allowed the 2018 surveys to unfold even more smoothly than in 2016, and after canvasing the national park, we headed home to work through our results.

As a conclusion to our expedition, we determined that the reptile and amphibian communities of VINP had no observable changes in community composition, or landcover associations after hurricanes Irma and Maria. Interestingly, the communities appear resistant to large disturbances, indicating that they are either able to survive and adapt to the habitat changes, or underwent rapid population growth. Because the hurricanes struck the island over the course of just two weeks, they may have been perceived as a single disturbance event for the island fauna.

While the herpetofauna communities appeared to survive the hurricanes intact, they remain under pressure from many other threats, including invasive species like rats (Rattus rattus) and Indian mongoose (Herpestes auropunctatus), increasing human impact in VINP, and climate change. We recommend a regular monitoring program that would allow managers to observe abundance and population changes of both the herpetofauna species and invasive predators on the island, and give further insight to how these animals deal with disturbances, especially in a time of global biodiversity loss.

The findings from this study were recently published in the Journal of Tropical Ecology (Richter et al. 2021). What started as a class project was able to grow into grant writing, presentation, and publication opportunities that have helped me gain critical skills I’ll be using while pursuing my master’s degree at the University of Georgia’s Warnell School of Forestry and beyond. This work would not have been possible without the encouragement and guidance of our advisors and coauthors, and serves as an example of the advances that can be made by investing in undergraduate research.


Rice KG, Waddle JH, Crockett ME, Carthy RR and Percival HF (2005) Herpetofaunal Inventories of the National Parks of South Florida and the Caribbean. U.S. Geological Survey Professional Paper 1631. Open-File Report 2005-1301: 2, 1-45.

Richter, C. J., S. M. DiGiulio, C. D. Marshall, and J. B. K. Leonard. 2021. Herpetofaunal community response to hurricanes Irma and Maria in Virgin Islands National Park. Journal of Tropical Ecology 37(4): 185-192.


What Determines Paternity in Wild Lizards? A Spatiotemporal Analysis of Behavior and Morphology

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On September 3, 2021

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Using a fine-toothed genetic comb, Johnson et al. (2021) investigated the mating system of Anolis cristatellus (pictured above; photo credit Aryeh H. Miller) to better understand both female mate choice and male competition in an explicit spatiotemporal context.

New literature alert!

What Determines Paternity in Wild Lizards? A Spatiotemporal Analysis of Behavior and Morphology

In Integrative and Comparative Biology

Johnson, Kamath, Kirby, Fresquez, Wang, Stehle, Templeton, and Losos

Abstract:

Mating behavior in animals can be understood as a sequence of events that begins with individuals encountering one another and ends with the production of offspring. Behavioral descriptions of animal interactions characterize early elements of this sequence, and genetic descriptions use offspring parentage to characterize the final outcome, with behavioral and physiological assessments of mates and mechanisms of copulation and fertilization comprising intermediate steps. However, behavioral and genetic descriptions of mating systems are often inconsistent with one another, complicating expectations for crucial aspects of mating biology, such as the presence of multiple mating. Here, we use behavioral and genetic data from a wild population of the lizard Anolis cristatellus to characterize female multiple mating and the potential for sexual selection through female mate choice in this species. We find that 48% of sampled females bore offspring sired by multiple males. Moreover, spatiotemporal proximity between males and females was associated with whether a male sired a female’s offspring, and if yes, how many offspring he sired. Additionally, male body size, but not display behavior, was associated with reproductive outcomes for male–female pairs. While much remains to be learned about the mechanisms of mating and targets of sexual selection in A. cristatellus, it is clear that female multiple mating is a substantial component of this species’ mating system in nature.

#DidYouAnole – Anolis roquet

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On September 3, 2021

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From an island made up of other islands, is an anole species with lots of subspecies. Not entirely the same, but sort of.

This week’s anole is Anolis roquet, and its six subspecies. Also called the Martinique anole or savannah anole, it is endemic to the island and the subspecies are visibly different in the specific geographic regions they inhabit there. This means that much like Anolis oculatus, they are a great example of intraspecific variation. Male Martinique anoles typically have an SVL of 86mm and females are around 66mm.

The nominate subspecies (originally described) Anolis roquet roquet, can be found in wooded habitats near the penisula on the island, and is usually green in colour with spotting or stripes (in females).


Photo: Erika Mitchell, iNaturalist

Anolis roquet caracoli can also be found in similar habitat, but prefers more dense forest and is on the Caravelle Peninsula itself. Males of this subspecies have a more marbled pattern, while females have dorsal striping. Both are usually brown.


Photo: Erika Mitchell, iNaturalist

Moving to north coast, we find Anolis roquet majolgris, an olive-to-brown coloured subspecies. This anole tends to be darker; while the females also feature dorsal striping like those of the other subspecies, the males have small scattered spotted patterning and may have white blotches around their heads (Anderson et al, 2016).

Northwest, on the elevations of Mt. Pelée, is the montane subspecies, Anolis roquet summus. As its rainforest habitat would suggest, this anole is mostly a bold green. Males have a dark marbled and spotted pattern on their backs and sides and females have a chevron dorsal stripes and may have faint lateral mottled patterning.

Photo by Thomas Ackermann.

A tan to brown subspecies occupies the west coast, with males that feature a stripe pattern that most likely inspired its epithet, Anolis roquet zebrilus. The females are more drab and less boldly striped.

Photo can be found here.

Last but not least is Anolis roquet salinei, the southeasternmost subspecies. These anoles are olive to yellow-green and brown. Males have black bars on their back and splotches on their heads, while females have dark mottled patterning.

Photo: Erika Mitchell, iNaturalist

Both males and females have dewlaps with the males being larger and more brightly coloured. Recently, an adult male was discovered at a port in Dominica, likely having come in with a shipment. It was captured and recorded.

Lovely Photos of Green Anoles

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On August 27, 2021

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Javier Lobon Rovira, a graduate student working on geckos, decided to up his game and pay attention to anoles. Here’s what resulted! The lizards were found on 24th of August in the surroundings of Gainesville, Florida, displaying from a tree branch around one meter high. He found a second specimen close by sleeping at night on a small bush close to a water pond.

#DidYouAnole – Anolis gingivinus

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On August 26, 2021

In All Posts


Photo: Kerry Ross, iNaturalist

Hello and welcome to my first post since officially starting as a grad student!
I think I’ve got my schedule down and we can get back to regular weekly anoles. Love that for us!

This week’s anole, Anolis gingivinus is also called the Anguilla Bank anole or Anguilla anole and is endemic to Anguilla and its satellite islands.
The Anguillan anole is reported to adapt well to anthropogenic effects on its habitat (Hailey et al, 2011) and to different niches, although its ecomorph affinities lie closest to being trunk-ground. They also seem to be abundant despite being heavily preyed on by American kestrels.


Photo: John Sullivan, iNaturalist

Male Anguillan anoles have an average SVL of 72mm and females have an average of 53mm. They are usually olive to greyish in colour with bright orange dewlaps, and have bold dorsal and lighter flank stripes. They also occasionally sport some green on their lower halves and males may have darker marbled spotting along their bodies. Anolis gingivinus are insectivorous but like many other anoles will eat smaller lizards.


Photo: Rozilber, iNaturalist

Why Are There More Anoles Here?

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On August 11, 2021

In All Posts, New Research

New Paper: Disentangling Controls on Animal Abundance: Prey Availability, Thermal Habitat, and Microhabitat Structure

DOI:  https://doi.org/10.1002/ece3.7930

Above: Male Anolis bicaorum, endemic to the island of Utila (photo credit Tom Brown).

Why are there more anoles in this plot? This is the question that we continually asked ourselves whilst setting up our 2018 survey plots on the small island of Utila, Honduras, home of the endemic Anolis bicaorum (pictured above). So in 2019 we set out from Heathrow airport, kitted up with A LOT of equipment, for our second field season, based at Kanahau Utila Research and Conservation Facility, with one of the goals being to look into just that (see previous Anole Annals posts on Utila and its anoles).

Above Left: Getting ready to leave Heathrow (photo: Adam Algar). Above Right: Miraculously all the field kit all safely arrived at Houston stopover.

We all know that such factors as the thermal environment, prey resources and structural habitat play important roles in the lives of our beloved anoles. And we also know that you can go to one spot and be overrun with anoles, but go to a seemingly similar spot nearby and find none (usually when the field season is drawing to a close and you still don’t have a large enough sample size). But how are these aspects of anole biology linked? Specifically what determines their abundance, and its variation, at fine scales? While ecological niche theory is well developed, empirical evidence for which factors are most important, and how they interact, is still rare for many taxa, including anoles. Given rapid environmental change, understanding the drivers and mechanisms governing abundance is now more important than ever.

We measured the abundance of the endemic Anolis bicaorum across thirteen 20x20m plots along a tropical habitat gradient, using standard mark-recapture methods, based on Heckel & Roughgarden (1979). Within these plots, we also measured factors relating to the thermal habitat suitability (using 3D printed models fitted with iButtons), structural habitat (perch surveys), canopy cover (leaf area index) and prey availability (arthropod biomass and diversity). We then used N-mixture models and path analysis to disentangle direct and indirect effects of these factors on anole abundance.

Above Left: Emma setting up 3D printed anole thermal models. Above Right: Tom out collecting 3D printed anole replica models (photo credits Adam Algar).

We first decided on several measures for each niche factor which could determine the suitability of the habitat for the anoles. For the thermal environment, we first determined the thermal preference (Tpref) range of A. bicaorum, following Battles and Kolbe (2018). We then calculated two indices to quantify the thermal habitat quality of each plot. The first was the percent of model hours that operative temperatures (from 3D models) were within the Tpref range over the 36-hour study period for each plot. The second was the total number of degrees (°C) that the models deviated from the Tpref range across all models throughout the survey period for each plot, which included the total degrees, the degrees above and degrees below the Tpref range.

Above: Many of the anoles were “side-eye” pros

As a measure of structural microhabitat quality we determined both perch availability by counting surveys and the plot basal area (a measure of stand density), across all tree trunks, palm stems and fence posts in the plot.

Above:  A. bicaorum predating on an unidentified spider (Araneae).

For prey availability, we measured arthropod biomass (g) and diversity (Simpson and Shannon’s) from a combination of leaf litter sieving and sweep-net samples taken in each plot. Sweep-net and leaf-litter samples were combined for plot level analyses.

We also measured mean leaf area index (LAI) in each plot using an Accupar LP80 ceptometer. LAI is the one-sided area of leaves per unit ground area and is a measure of canopy density; it is expected to influence thermal environment via the interception of solar radiation (Campbell & Normal 1998; Algar et al 2018).

After we determined reasonable measures of habitat suitability for each factor, we examined univariate relationships between A. bicaorum abundance and each of our habitat variables (percent of time within Tpref, deviation from Tpref, perch number, basal area, arthropod biomass, arthropod diversity and LAI) by including each predictor as a covariate in a multinomial-Poisson mixture model of abundance. The results of the most significant and strongest relationships can be seen in the figure below.

Above: Relationships between Anolis bicaorum abundance and individual niche metrics in forest plots across Utila, Honduras. Relationships were estimated using multinomial Poisson mixture models with a constant detection rate across plots. All variables are scaled to a mean of zero and unit variance; (a) reflects thermal habitat quality, (b) reflects structural habitat quality, (c) reflects prey availability and (d) reflects canopy cover.

We used these models to select a subset of these variables (one representing habitat structure, one prey availability, and one thermal quality) for subsequent path analysis; we also included LAI as the sole measure for canopy cover. We used the path analysis to evaluate the relative strength of direct and indirect effects on abundance. As we could not estimate indirect paths within a single multinomial-Poisson mixture model, we estimated abundance for the path analysis from a multinomial Poisson mixture model that included no environmental covariates, held detection rate constant, and permitted abundance to vary by plot. The results of the path analysis can be seen in the figure below.

Above: Direct and indirect effects of niche axes on A. bicaorum abundance. (a) Values are standardized path coefficients; line width is proportional to the strength of the effect, solid lines indicate statistically significant pathways. ε, unexplained variation. (b) The total effects of covariates on abundance. NP: number of perches; PB: prey biomass; LAI: mean leaf area index; TP: time within Tpref range.

Our results showed that thermal habitat quality and prey biomass both had positive direct effects on anole abundance. However, thermal habitat quality also influenced prey biomass, leading to a strong indirect effect on abundance. Thermal habitat quality was primarily a function of canopy density, measured as leaf area index (LAI). Despite having little direct effect on abundance, LAI had a strong overall effect mediated by thermal quality and prey biomass.

We have demonstrated the interconnectedness of abiotic and biotic components that determine habitat quality and animal abundance. Rather than identify a single strong control on abundance, we found key abiotic factors (canopy cover and thermal environment) affect abundance through multiple pathways and have effects that are mediated by biotic interactions and the niche of the focal species. In particular, our results suggest alignment of thermal niches across multiple trophic levels results in strong indirect effects of thermal environment on anole abundance. Losses of thermal habitat quality, particularly due to canopy loss, may thus have greater effects than appreciated when only direct effects are considered.

Our results demonstrate the role of multidimensional environments and niche interactions in determining animal abundance and highlight the need to consider interactions between thermal niches and trophic interactions to understand variation in abundance, rather than focusing solely on changes in the physical environment. Identifying the factors responsible for population change along habitat gradients will improve our understanding of how multidimensional environments and niches interact to determine population abundance. Which is more important than ever in this ever-changing world.

You can read the full paper here.

If you have any questions or just an interest in the work, please feel free to contact me emma.a.higgins@hotmail.com.

I would also just like to thank everyone again who was involved in this project, it was a lot of hard work, but great fun and it couldn’t have been done without the team effort.

Above: Part of the field team, helping process what is certainly not an anole, whilst setting up survey plots (photo credit Adam Algar).

 

References

Algar, A.C. et al. 2018. Remote sensing restores predictability of ectotherm body temperature in the world’s forests. – Glob. Ecol. Biogeogr. 27: 1412-1425. https://doi.org/10.1111/geb.12811

Campbell, G. S., and J. M. Norman. 1998. An introduction to environmental biophysics. 2nd edition. -Springer-Verlag, New York.

Battles, A.C. and Kolbe, J.J. 2018. Miami heat: Urban heat islands influence the thermal suitability of habitats for ectotherms. – Glob. Change Biol. 25: 562–576. https://doi.org/10.1111/gcb.14509

Heckel, D.G. and Roughgarden, J., 1979. A Technique For estimating the Size of Lizard Populations .Published by : Wiley on behalf of the Ecological Society of America Stable URL : http://www.jstor.org/stable/1936865 References Linked refere 60, 966–975.

 

Lizards with Sticky Toepads Rule the Trees

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On August 7, 2021

In All Posts

AUGUST 6TH, 2021 POSTED BY 

Lizards with sticky toepads have a greater clinging ability. Above, the tree canopy specialist American green anole (Anolis carolinensis). (Credit: Getty Images)

Data from 2,600 lizard species worldwide indicate that those with sticky toepads prevail.

Many lizards are phenomenal climbers. Their sharp, curved claws are ideal for clinging to tree trunks, rocks, and other rough surfaces. However, in the precarious world of tree tops—filled with slippery leaves and unstable branches—three peculiar groups of lizards possess the remarkable evolutionary accessory of sticky pads on their fingers and toes.

Sticky toepads have independently evolved in geckos, skinks, and Anolis lizards—producing tree acrobats specially adapted to life in the forest canopy. Scientists have long considered sticky toepads an “evolutionary key innovation” that allow arboreal lizards to interact with the environment in ways that many padless lizards cannot.

Yet, some lizards without toepads have adopted the canopy lifestyle, an observation that has puzzled scientists for decades. Biologists Aryeh Miller and James Stroud at Washington University in St. Louis set out to find if lizards with toepads had an evolutionary advantage for life in the trees relative to their padless counterparts.

“Lizards with toepads have a greater ecological advantage in the arboreal environment,” says Miller, a graduate student in the evolution, ecology, and population biology program at Washington University in St. Louis and lead author of the study. “Toepads are essentially a biological superpower for lizards to access new resources that lizards without toepads cannot.”

“We found that lizards with sticky feet dominate the arboreal environment. Once adapted to life in the trees, they rarely leave,” says Stroud, a postdoctoral research associate and the senior author of the paper. “Conversely, lizards without sticky toepads frequently transition away from living in trees to living on the ground.”

The study appears in Systematic Biology.

ANATOMICAL EVOLUTION

“Scientists have long wondered about the role that the origin of key innovation plays in subsequent evolutionary diversification. Lizards are an excellent type of organism for such studies due to their exceptional species richness and the incredible extent of anatomical variation and habitat use,” says Jonathan Losos, professor of biology and director of the university’s Living Earth Collaborative.

Using a recently published database of habitat use for nearly every lizard species across the globe, the researchers were able to perform a comprehensive analysis of toepad evolution in the context of lizard habitat use—for the first time, the evolutionary relationships between which lizards live in trees and which do not became clear.

“Miller and Stroud have developed an elegant new approach to understand this diversity and the role that anatomical evolution plays in shaping the great diversity of lizard kind. This work will be a model for researchers working on many types of plants, animals, and microbes,” Losos adds.

TOEPADS LET LIZARDS STICK AROUND

Miller, who led the analysis, is the first to find that species have evolved for specialized life in trees at least 100 times in thousands of lizards. In other words, it is evolutionarily easy for a lizard to become a tree lizard.

What’s difficult is sticking around (pun intended!). Toepads don’t evolve until after lizards get into the trees, not before. And padless lizards will leave trees at a high frequency—much higher than padbearing lizards.

“There are hundreds of lizards living in the trees, but over evolutionary time many of those species end up leaving for life on the ground because, presumably, they interact with these padded lizards that have a greater advantage,” Stroud says.

The next step in this research is to find out exactly what padbearing lizards can do that their padless relatives can’t. Scientists can learn about this by watching the animals in their natural habitat.

“Analyzing evolutionary relationships can tell us a lot, but next we need to go out into nature—to see what parts of the environment the lizards use and why these evolutionary relationships exist,” Miller says.

Source: Washington University in St. Louis

Insectivorous Bird Eats Anole!

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On August 6, 2021

In All Posts, New Lit Abstracts, New Research

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.

Read the full article here, available as First Cite.

Tear-feeding by Cockroaches: Reptile Tears to Increase Reproductive Output?

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On July 30, 2021

In All Posts, New Lit Abstracts

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.

Read the full paper here!

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