Author: Nick Herrmann Page 2 of 4

New literature alert!

Evidence for fasting induced extra-adrenal steroidogenesis in the male brown anole, Anolis sagrei

In Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology
Himmelstein, Spahija, and Fokidis

Abstract

Glucocorticoids (GCs) and dehydroepiandrosterone (DHEA) are steroids secreted by the adrenal glands into circulation to effect distant target tissues and coordinate physiological processes. This classic systemic view of steroids has been challenged by evidence that other tissues can independently synthesize their own steroids. Little is known however regarding circumstances that can promote this extra-adrenal steroidogenesis. Here we tested if fasting can induce tissues to increase GC and DHEA synthesis in the brown anole lizard Anolis sagrei. Lizards fasted for eight days lost body mass and increased fatty acid oxidation. Fasting also increased plasma concentrations of DHEA and corticosterone, but not cortisol. Corticosterone concentration within the adrenals, heart, intestines, lungs and liver exceeded that in plasma, with the latter two increasing with fasting. Levels of DHEA in the adrenals and heart were higher than in plasma, but no significant effect of fasting was observed, expect for a noticeable increase in intestinal DHEA. Two steroidogenic genes, the steroidogenic acute regulatory (Star) protein and Cyp17a1, a cytochrome P450 enzyme, were expressed in several tissues including the liver, lungs and intestines, which were increased with fasting. Continued research should aim to test for expression of additional enzymes further along the steroidogenic pathway. Nonetheless these data document potential extra-adrenal steroidogenesis as a possible mechanism for coping with energy shortages, although much work remains to be done to determine the specific roles of locally synthesized steroids in each tissue.

Read the full paper here!

Photograph was taken in Hahashima, Ogasawara Islands, by Hideaki Mori.

New literature alert!

Testing the Ability of Dogs to Detect Different Odor Concentrations of the Carolina Anole (Anolis carolinensis) in Japan

In frontiers in Veterinary Science
Fukuzawa and Shibata

Abstract

The Carolina anole (Anolis carolinensis) is regarded as a problem in the Ogasawara Islands. The decision to use eradication measures depends on the limit of detection at low densities. We tested the ability of two dogs to discriminate the odor of anole to assess the possibility of using dogs to detect anoles at low densities. The two dogs were trained to discriminate the basic target odor concentration (512 anoles/ha) on 10-g coconut peat sachets. When they reached 100% accuracy, they were tested at different odor concentrations (densities of 385, 256, 128, 26, and 3 anoles/ha). During training, both dogs achieved 100% accuracy after 2 daily sessions in only 2 days. They were able to select the positive odor concentration sachet, and their accuracy was from 75 to 100%. We believe that testing using soil from sites of high anole high density and at the limit of detection in the Ogasawara Islands will be useful.

Read the full paper here!

New literature alert!

Identification of a reptile lyssavirus in Anolis allogus provided novel insights into lyssavirus evolution

In Virus Genes
Horie, Akashi, Kawata, and Tomonaga

Abstract

Lyssaviruses (genus Lyssavirus) are negative-strand RNA viruses belonging to the family Rhabdoviridae. Although a lyssa-like virus (frog lyssa-like virus 1 [FLLV-1]), which is distantly related to lyssaviruses, was recently identified in frogs, a large phylogenetic gap exists between those viruses, and thus the evolution of lyssaviruses is unclear. In this study, we detected a lyssa-like virus from publicly available RNA-seq data obtained using the brain and skin of Anolis allogus (Spanish flag anole), which was designated anole lyssa-like virus 1 (ALLV-1), and determined its complete coding sequence. Via mapping analysis, we demonstrated that ALLV-1 was actively replicating in the original brain and skin samples. Phylogenetic analyses revealed that ALLV-1 is more closely related to lyssaviruses than FLLV-1. Overall, the topology of the tree is compatible with that of hosts, suggesting the long-term co-divergence of lyssa-like and lyssaviruses and vertebrates. The ψ region, which is a long 3′ untranslated region of unknown origin present in the G mRNA of lyssaviruses (approximately 400–700 nucleotides), is also present in the genome of ALLV-1, but it is much shorter (approximately 180 nucleotides) than those of lyssaviruses. Interestingly, FLLV-1 lacks the ψ region, suggesting that the ψ region was acquired after the divergence of the FLLV-1 and ALLV-1/lyssavirus lineages. To the best of our knowledge, this is the first report to identify a lyssa-like virus in reptiles, and thus, our findings provide novel insights into the evolution of lyssaviruses.

Read the full paper here!

Orange-legged wandering spider (Cupiennius coccineus) consuming house gecko (Hemidactylus frenatus) at Sirena Biological Station, Corcovado, Costa Rica

New literature alert!

Lizard predation by spiders: A review from the Neotropical and Andean regions

In Ecology and Evolution
Reyes-Olivares, Guajardo‐Santibáñez, Segura, Zañartu, Penna, and Labra

Abstract

Vertebrate predation by invertebrates has been classically underexplored and thus underestimated, despite the fact that many arthropods consume vertebrates. To shed some light on the relevance that spider predation may have upon lizards in the Neotropical and Andean regions, we compiled the available information in the literature on this trophic interaction. We found 50 reports of spiders consuming lizards in these regions, and the 88% of these were from the Neotropical region. Spiders belong to eight families, but Ctenidae and Theraphosidae were the most frequently reported predators. Lizards belong to 12 families, and the most commonly consumed species corresponded to the families Dactyloidae (all Anolis lizards), Gymnophthalmidae, and Sphaerodactylidae. Data suggest trophic spider–lizard associations between Ctenidae and Dactyloidae, followed by Theraphosidae and Liolaemidae. The body sizes of the spiders and lizards showed a positive relationship, and spiders were smaller than their prey. We conclude that various spider taxa can be considered lizard predators and they may be ecologically important in the Neotropical and Andean regions. However, spiders of prime predation relevance seem to be those of the Ctenidae and Theraphosidae families.

Read the full paper here!

Anolis sagrei and A. carolinensis. Photo by Dave Welling.

New literature alert!

Competing native and invasive Anolis lizards exhibit thermal preference plasticity in opposite directions

In The Journal of Experimental Zoology Part A
Ryan and Gunderson

Abstract

Invasive species have emerged as a significant problem in the age of anthropogenic change. Behavior can be key to invasive species success and is strongly affected by temperature. Therefore, knowledge of the temperature dependence of behavior is likely critical to understand invasive species dynamics and their interactions with native species. In this study, we tested for differences in thermal preference plasticity and temperature‐dependent activity levels in a pair of congeneric lizards found in the United States: the invasive Anolis sagrei and the native A. carolinensis. We predicted that A. sagrei would demonstrate greater thermal preference plasticity and would utilize a higher and/or wider range of activity temperatures than A. carolinensis. Both would point to plasticity allowing A. sagrei to behaviorally exploiting thermal conditions that A. carolinensis cannot. We found that both species exhibited plasticity in thermal preference, but in opposite directions: preferred temperatures of A. carolinensis increased with acclimation temperature, while those of A. sagrei decreased. As a result, which species had a higher thermal preference changed with acclimation conditions. We saw no difference in overall field activity rates between the species, but that A. sagrei did tend to be active over a broader range of body temperatures. In sum, we found little evidence that differences in thermal preference plasticity between the species allow A. sagrei to remain active at a higher or broader temperature range than A. carolinensis. Nonetheless, the thermal preference data suggest complementary thermal preferences between the species that could promote microclimatic partitioning, though more work is required to test this idea.

Read the full paper here!

New literature alert!

Disentangling the determinants of transposable elements dynamics in vertebrate genomes using empirical evidences and simulations

In PLOS Genetics
Bourgeois, Ruggiero, Hariyani, and Boissinot

Author Summary

Transposable elements (TEs) are mobile DNA sequences that can replicate and insert in genomes. By doing so, they can disrupt gene function and meiotic process, but also generate evolutionary novelties. It is however unclear how different processes such as varying rates of transposition, selection on TEs, linked selection and genome properties interact with each other. Here, we use the green anole (Anolis carolinensis) as a model, since it harbors one of the highest diversities of TEs found in a vertebrate (including non-LTR retrotransposons, LTR-Retrotransposons, DNA transposons and SINEs). By studying the population genomics of these different categories of TEs within the same species, we are able to disentangle processes that are specific to TE clades from general processes related to drift and selection. To do so, we use simulations of TEs in their genomic context to provide an interpretation of associations between recombination rate and statistics summarizing TE diversity and abundance. Our results highlight clear differences in TE dynamics across clades, with a clear dichotomy between SINEs/DNA-transposons and LTR-Retrotransposons/long LINEs. These differences can be mostly explained by changes in the relative impact of selection against TEs, linked selection, and insertional preferences.

Read the full paper here!

Photograph was taken in Hahashima, Ogasawara Islands, by Hideaki Mori.

New literature alert!

Prevalence and antimicrobial-resistance profiles of Salmonella spp. isolated from green anoles (Anolis carolinensis) collected on the Haha-jima of the Ogasawara archipelago, Japan

In Journal of Veterinary Medical Science
Sumiyama, Hayashida, Kanazawa, Anzai, and Murata

Abstract

We investigated the prevalence of Salmonella enterica and its antimicrobial resistance from 79 green anoles, the invasive alien species inhabits Haha-jima of the Ogasawara archipelago. Samples were collected during the period between 2009 and 2010. The resistance of S. enterica of these samples against 12 common antimicrobial agents was also determined. Salmonella strains, including serovar Oranienburg and Aberdeen, were detected from the large intestines of 30.4% of 79 green anole samples. And 37.5% of which were resistant to Oxytetracycline. This study suggests that green anoles may play an important role of the infection of S. enterica on this island. Attention is needed from the aspect of public and ecological health.

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New literature alert!

Endurance and sprint training affect immune function differently in green anole lizards (Anolis carolinensis)

In Journal of Experimental Biology
Wang and Husak

Abstract

Limited resources must be partitioned among traits that enhance fitness. Although survival-related traits often trade off with reproduction, survival-related traits themselves may trade off with each other under energy limitation. Whole-organism performance and the immune system both enhance survival, yet are costly, but it is unclear how the two might trade off with each other under energy-limited conditions. Resources may be allocated to very different types of performance (e.g., aerobic endurance versus anaerobic sprinting) just as they may be allocated to different components of the immune system (e.g., innate versus acquired) to maximize survival. We forced allocation to different performance traits in green anole lizards (Anolis carolinensis), using specialized exercise training, to determine how different components of the immune system would be impacted by shifts in energy use. We measured immunocompetence in endurance trained, sprint trained, and untrained control lizards with the swelling response to phytohemagglutinin (cell-mediated), antibody response to sheep red blood cells (acquired humoral), and wound healing (integrated). Endurance-trained lizards had reduced cell-mediated immunity, whereas sprint-trained lizards had reduced rates of wound healing. The acquired immune response was not affected by either type of training. Because each immune measure responded differently to the different types of training, our results do not support the hypothesis that simple energy limitation determines overall investment in immunity. Instead, different components of the immune system appear to be affected in ways specific to how energy is invested in performance.

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New literature alert!

Plasticity and evolutionary convergence in the locomotor skeleton of Greater Antillean Anolis lizards

In eLife
Feiner, Jackson, Munch, Radersma, and Uller

Abstract

Plasticity can put evolution on repeat if development causes species to generate similar morphologies in similar environments. Anolis lizards offer the opportunity to put this role of developmental plasticity to the test. Following colonization of the four Greater Antillean islands, Anolis lizards independently and repeatedly evolved six ecomorphs adapted to manoeuvring different microhabitats. By quantifying the morphology of the locomotor skeleton of 95 species, we demonstrate that ecomorphs on different islands have diverged along similar trajectories. However, microhabitat-induced morphological plasticity differed between species and did not consistently improve individual locomotor performance. Consistent with this decoupling between morphological plasticity and locomotor performance, highly plastic features did not show greater evolvability, and plastic responses to microhabitat were poorly aligned with evolutionary divergence between ecomorphs. The locomotor skeleton of Anolis may have evolved within a subset of possible morphologies that are highly accessible through genetic change, enabling adaptive convergence independently of plasticity.

Read the full paper here!

You can also read a brief summary of the paper by the authors here.