Author: Kaitlyn Murphy Page 1 of 2

While nesting is ubiquitous across taxa, Dr. Jenna Pruett is interested (like many of us on this site) in non-avian reptiles. Dr. Pruett is currently and NSF Postdoctoral Fellow at University of Colorado – Boulder under Dr. Ambika Kamath and completed her Ph.D. with Dr. Daniel Warner at Auburn University in 2021. For her doctoral work, Dr. Pruett studied nesting behavior in the Cuban brown anole (Anolis sagrei). She found that A. sagrei females tend to nest on the ground, under cover objects (e.g., under rocks), and in areas with high soil moisture and lower temperatures than compared to ambient surroundings. Interestingly, she found that these nest sites were correlated with positive effects on offspring survival.

At SICB 2022, Dr. Pruett discussed a chapter of dissertation research where she was interested in other environmental variables that might influence nesting behavior, such as the presence of predators. The northern curly-tailed lizard (Leiocephalus carinatus) has a shared evolutionary history (i.e., native to Bahamas, invasive in Florida) with A. sagrei. Additionally, A. sagrei is considered a trunk-ground species and L. carinatus is mostly ground-dwelling. Other research suggests that when L. carinatus is present, individual A. sagrei tend to perch higher in the canopy and an increase in mortality is observed (particularly for females).

To address whether predation risk influences A. sagrei nesting behavior, Dr. Pruett designed walk-in cages that were visually separated from each other and contained two nesting options for females: (1) a nest pot above the ground and (2) a nest pot on the ground in a cage with L. carinatus. Some of these cages contained a predator, while some did not. She predicted that females would prefer to nest in above-ground areas when predators were present.

Dr. Pruett found that overall, females tended to prefer laying eggs on the ground prior to predator presence. After predators were added to cages, there was a distinct difference in nesting behavior in cages with and without a predator (i.e., over 50% of eggs laid were above ground when a predator was present). Lastly, when predators were removed, there was a continued upward trend of laying eggs above ground in both treatments. Dr. Pruett suggests that this might result because above-ground pots are a relatively pristine environment to nest, and that if given that option under natural conditions, females might tend to nest above ground as well. Additionally, the above-ground pot may have also gotten more sunlight and more/less moisture that might account for female preference. Dr. Pruett also adds that lizards in cages that were without a predator may have sensed that L. carinatus were in the area (i.e., through mechanisms other than visual) that led them to nest higher.

Dr. Pruett concluded her SICB talk with three remarks: 1) there is an effect of predator presence on A. sagrei nesting behavior, 2) there is an increased preference for above-ground nests in both treatment groups that could be due to other environmental factors, and 3) there need to be more studies on anole nesting, which is a critical component of reproduction, but is understudied in many species. Dr. Pruett is one of the world’s leading researchers in anole nesting behavior and I would highly encourage you to reach out to her with any questions!

“SICB has provided invaluable networking opportunities for me! I met my PhD advisor there, and each year it’s an opportunity to see current research and exchange exciting ideas,” Dr. Pruett says of SICB.

Check out Dr. Pruett’s talk here! Check out Dr. Pruett’s twitter page here!

It’s no surprise that reproductive traits are important for the survival and fitness of species- particularly in the face of changing environments. What I learned from Mr. Wayne Wang’s talk at SICB 2022, though, was that male fertility is often more heat-sensitive than female fertility and even adult thermal tolerance! Wayne is a 3^rd year Ph.D. student at Tulane University under Dr. Alex Gunderson and at SICB this year, he discussed his preliminary results on Cuban brown anole (Anolis sagrei) sperm thermal tolerance and mobility.

In some species, the temperature associated with infertility in males is often a better determinant of population distribution than adult thermal tolerance. Additionally, sperm are under strong selection because only few make the journey to fertilize an egg (which means that they are also one of the most highly diverse cell types). Mr. Wang noticed that in the literature, there is a large focus on sperm morphology, rather than physiological traits like mobility or speed. In his talk, he sought to 1) test thermal tolerance of sperm, 2) test repeatability of thermal tolerance, and 3) identify any correlations between sperm and adult thermal tolerance in A. sagrei. He began by rounding up some lizards and copulating them until they ejaculated sperm, which he states is a lot easier process than one might imagine. Sperm were diluted and incubated at various temperatures until videos were recorded to measure sperm motility.

Mr. Wang found that A. sagrei sperm motility did not differ much between 33°C and 41°C; however, at approximately 43°C, there is a steady decline where approaching 48-50°C, none survive. In fact, 50% of sperm stop moving at about 43°C. This experiment was repeated with the same group of lizards during a second week following a seven-day acclimation period. Similar patterns were observed and during week 2, more individuals had a higher percentage of sperm motility. Lastly, no correlations between sperm and adult thermal tolerance were identified–Mr. Wang speculates that this might be because these traits are not linked or his sample size did not allow for enough resolution.

Be sure to check out Wayne Wang’s awesome talk here!

The Society for Integrative and Comparative Biology (SICB) conference is a national gem for highlighting research from biologists across the country. This year, over a thousand researchers shared their work in Phoenix, AZ and on online platforms for the 2022 SICB conference. Fourth-year Ph.D. Candidate, Annelise Blanchette, from Tulane University in New Orleans, LA under Drs. Alex Gunderson and Jordan Karubian was one of these presenters. Like Phoenix, New Orleans is a bustling city with everything from high-rise skyscrapers soaking in the Louisiana sun to paved neighborhoods polluted with anthropogenic waste (e.g., Mardi Gras beads). Ms. Blanchette discussed this idea of pollution, particularly the contaminant lead, at SICB 2022 and wanted to know more about the influence of lead on physiological performance of her study species, the Cuban brown anole (Anolis sagrei).

Ms. Blanchette’s previous work showed that anoles from areas in New Orleans with high soil lead levels had over 10X the toxicity threshold of lead (in comparison to birds and mammals) in their bloodstreams. She wanted to know how these lizards were influenced physiologically by lead exposure and how that translates to physiological performance by measuring sprint speeds and balancing ability of anoles from these regions. She predicted that there would be an overall negative effect of high bloodstream lead levels and that lizards from these high exposure areas would 1) not be as fast as their counterparts in terms of sprint speed, and 2) have decreased balance, measured by counting the number of times they slipped on a wooden beam.

From her results, she found that there is no correlation between lead exposure and sprint speeds; however, there is a negative effect of lead on balance that may be sex-dependent. In fact, male anoles exposed to low levels of lead had fewer slips (i.e., better balance) than males exposed to high levels of lead. She states “It’s surprising given the incredibly high levels of lead in their bloodstream that the brown anole is coping with the exposure so well.” This work is particularly fascinating because it begins to uncover ways urbanization can influence wildlife in nearby regions though pollution of heavy metals. “… if we don’t find an obvious or devastating affect behaviorally or cognitively in the brown anole, perhaps we’ll find that they have adapted and are less resistant to lead’s detrimental effects – which would be so cool!” Ms. Blanchette says. She hopes that next year, like many other virtual SICB members, she will be able to present her work in person!

You can check out Annelise’s talk from SICB 2022 here! Follow her on Twitter @basicbiologist!

In August 2019, while feeding a captive colony of brown anoles (Anolis sagrei) in Dr. Daniel Warner’s lab at Auburn University, I noticed a female anole crouching on the side of her nesting pot. Upon closer inspection, I realized she had dug a hole in the soil and was perched above it- apparently preparing to lay an egg. Gently prying up the lid of the cage, I snapped a few photos of this (somewhat still mysterious) event.

During the subsequent observations of this female in the lab, she laid an egg on the topsoil; however, jumping from the nesting pot, she knocked the freshly oviposited egg into the hole she created. She then returned to the nesting pot and looked to be positioning the egg within the hole (see video attached). This behavior has been previously documented in Anolis species (Propper et al. 1991; Stamps 1976) and suggests that females may provide additional influence on offspring survival and phenotype through egg-positioning. 

Nest sites are critically important for embryonic development and resulting offspring phenotype (Tiatragul et al. 2019; Reedy, Zaragoza, and Warner 2013). The sequence of nesting events (i.e., oviposition, “egg-rolling” [Tokarz and Jones 1979]) may also assist females in choosing a nest-site that will maximize the survival of her offspring. While female nesting behavior has long been documented in scientific literature, it was interesting to see such (what I think of as) cryptic anole behavior! Thanks for letting me spy in on you little one!

References

Propper, Catherine R., Richard E. Jones, Matthew S. Rand, and Harriet Austin. 1991. “Nesting behavior of the lizard Anolis carolinensis.” Journal of Herpetology 25 (4): 484. https://doi.org/10.2307/1564774.

Reedy, Aaron M., David Zaragoza, and Daniel A. Warner. 2013. “Maternally chosen nest sites positively affect multiple components of offspring fitness in a lizard.” Behavioral Ecology 24 (1): 39–46. https://doi.org/10.1093/beheco/ars133.

Stamps, Judy A. 1976. “Egg retention, rainfall and egg laying in a tropical lizard Anolis Aeneus.” Copeia 1976 (4): 759–64. https://doi.org/10.2307/1443460.

Tiatragul, Sarin, Joshua M. Hall, Nathaniel G. Pavlik, and Daniel A. Warner. 2019. “Lizard nest environments differ between suburban and forest habitats.” Biological Journal of the Linnean Society 126 (3): 392–403. https://doi.org/10.1093/biolinnean/bly204.

Tokarz, Richard R., and Richard E. Jones. 1979. “A study of egg-related maternal behavior in Anolis Carolinensis (Reptilia, Lacertilia, Iguanidae).” Journal of Herpetology 13 (3): 283–88. https://doi.org/10.2307/1563320.

Cellular processes, including metabolism and longevity, are regulated by the insulin and insulin-like signaling network. This cascade of internal systems is regulated by two similar but unique hormones, IGF1 and IGF2. Expression of these hormones not only differs among species, but also varies throughout the lifespan of individuals. For example, in humans IGF1 and IGF2 expression remains on into adulthood. However, in rodents IGF2 expression is switched off shortly after birth; thus, IGF2 post-natal effects have largely been ignored because of the lack of expression in mice. 

Ph.D. Candidate, Abby Beatty, of Dr. Tonia Schwartz’s lab at Auburn University, sought to address this imbalance by using the Cuban brown anole (Anolis sagrei) which, like humans, expresses IGF2 into adulthood. To do this, Abby first quantified gene expression of IGF1 and IGF2 hormones by using quantitative PCR on embryonic, juvenile, and adult A. sagrei liver cDNA. She compared this expression across a variety of taxa including, but not limited to, mice, zebra finches, and eastern fence lizards. Secondly, Abby mined adult liver transcriptomes for all amniotes in NCBI and quantified the expression of IGF1 and IGF2. 

She found that, in contrast to the mice used for many biomedical models, IGF2 is expressed in adult birds and reptiles and in many mammals. Abby speculates that our understanding of IGF expression is biased, with laboratory mice serving as a default for many human-mediated models, and warrants the use of other species to study the function of IGF2.