Diversity and Evolution of Frog Visual Opsins: Spectral Tuning and Adaptation to Distinct Light Environments

Molecular Biology and Evolution, Journal Year: 2024, Volume and Issue: 41(4)

Published: April 1, 2024

Abstract Visual systems adapt to different light environments through several avenues including optical changes the eye and neurological in how signals are processed interpreted. Spectral sensitivity can evolve via visual pigments housed retinal photoreceptors gene duplication loss, differential coexpression, sequence evolution. Frogs provide an excellent, yet understudied, system for evolution research due their diversity of ecologies (including biphasic aquatic-terrestrial life cycles) that we hypothesize imposed selective pressures leading adaptive system, notably opsins encode protein component responsible first step perception. Here, analyze opsin genes from 93 new transcriptomes plus published data a combined dataset spanning 122 frog species 34 families. We find most express four previously identified frogs but show evidence loss two lineages. Further, present positive selection three shifts associated with differences habitat history, not activity pattern. identify substantial novel variation and, using microspectrophotometry, highly variable spectral sensitivities, expanding known ranges all pigments. Mutations at spectral-tuning sites only partially account this variation, suggesting have used tuning pathways unique among vertebrates. These results support hypothesis photoreceptor physiology across tree response varying environmental ecological factors further our growing understanding vertebrate

Language: Английский

---

Caecilians maintain a functional long-wavelength-sensitive cone opsin gene despite signatures of relaxed selection and more than 200 million years of fossoriality

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 8, 2025

ABSTRACT Visual systems are tuned to animals’ ecologies, evolving in response specific light environments and visual needs. Ecological transitions fossorial lifestyles impose strong selective pressures favoring morphological adaptations for underground life, such as increased skull ossification reduced eye protrusion. Fossoriality may simultaneously relax constraints on other aspects of vision leading diminished capabilities. Caecilians (Gymnophiona)— specialized, amphibians—possess eyes covered by skin or bone. For years, these traits, along with the presence a single photoreceptor expressing one functional opsin gene, have been interpreted evidence limited capabilities, including an inability focus perceive color. Our results challenge assumptions: we identified long-wavelength-sensitive ( LWS ) gene 11 species caecilians spanning 8 10 recognized families. Molecular indicates that is intact transcribed at least Caecilia orientalis ). Anatomical observations from five caecilian families indicate highly organized retinae even vestigial eyes. While cone cells our study remains uncertain, putatively suggests capabilities role perception their ecology be underestimated.

Language: Английский

---

Passive accumulation of alkaloids in inconspicuously colored frogs refines the evolutionary paradigm of acquired chemical defenses

eLife, Journal Year: 2024, Volume and Issue: 13

Published: Aug. 2, 2024

Understanding the origins of novel, complex phenotypes is a major goal in evolutionary biology. Poison frogs family Dendrobatidae have evolved novel ability to acquire alkaloids from their diet for chemical defense at least three times. However, taxon sampling has been biased towards colorful species, without similar attention paid inconspicuous ones that are often assumed be undefended. As result, our understanding how this group incomplete. Here, we provide new data showing that, contrast previous studies, species each undefended poison frog clade measurable yet low amounts alkaloids. We confirm dendrobatids regularly consume mites and ants, which known sources Thus, suggest insufficient explain defended phenotype. Our support existence phenotypic intermediate between toxin consumption sequestration — passive accumulation differs it involves no derived forms transport storage mechanisms results levels accumulation. discuss concept its potential role origin defenses other toxin-sequestering organisms. In light ideas pharmacokinetics, incorporate old into an model could help acquired animals insight molecular processes govern fate ingested toxins.

Language: Английский

---

The genomic evolution of visual opsin genes in amphibians

Vision Research, Journal Year: 2024, Volume and Issue: 222, P. 108447 - 108447

Published: June 20, 2024

Language: Английский

---

Expression patterns of melanin‐related genes are linked to crypsis and conspicuousness in a pumpkin toadlet

Molecular Ecology, Journal Year: 2024, Volume and Issue: unknown

Published: July 6, 2024

Abstract Colour signals play pivotal roles in different communication systems, and the evolution of these characters has been associated with behavioural ecology, integumentary production processes perceptual mechanisms species involved. Here, we present first insight into molecular histological basis skin colour polymorphism within a miniaturized pumpkin toadlet, potentially representing lowest size threshold for polytypism tetrapods. Brachycephalus actaeus exhibits coloration ranging from cryptic green to conspicuous orange skin, our findings suggest that morphs differ their capability be detected by potential predators. We also found distribution abundance chromatophores are variable morphs. The expression pattern related genes was predominantly melanin synthesis (including dct , edn1 mlana oca2 pmel slc24a5 tyrp1 wnt9a ). Up‐regulation grey, brown higher melanophore than where xanthophores predominate. Our provide significant foundation comparing understanding diverse pathways contribute pigment amphibians.

Language: Английский

---

Evidence for ecological tuning of anuran biofluorescent signals

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: Oct. 15, 2024

Although biologists have described biofluorescence in a diversity of taxa, there been few systematic efforts to document the extent within taxonomic group or investigate its general significance. Through field survey across South America, we discover and patterns tropical amphibians. We more than triple number anuran species that tested for this trait. find evidence ecological tuning (i.e., specific adaptation signal environment which it is received) biofluorescent signals. For 56.58% tested, fluorescence excitation peak matches wavelengths most abundant at twilight, light frogs are active. Additionally, emission spans both low availability twilight sensitivity green-sensitive rods eye, likely increasing contrast conspecific receiver. propose an expanded key testing significance future studies, providing potential explanations other half fluorescent signals not originally meeting formerly proposed criteria. With ecology sensory systems frogs, our results suggest frog functioning communication.

Language: Английский

---

Insights into the evolution of photoreceptor oil droplets in frogs and toads

Proceedings of the Royal Society B Biological Sciences, Journal Year: 2024, Volume and Issue: 291(2027)

Published: July 1, 2024

Photoreceptor oil droplets (ODs) are spherical organelles placed most commonly within the inner segment of cone photoreceptors. Comprising neutral lipids, ODs can be either non-pigmented or pigmented and have been considered optically functional in various studies. Among living amphibians, were only reported to occur frogs toads (Anura), while they absent salamanders caecilians. Nonetheless, limited understanding their taxonomic distribution anurans impedes a comprehensive assessment evolution relationship with visual ecology. We studied retinae 134 anuran species, extending knowledge 46 58 currently recognized families, providing new perspective on this group that complements available information from other vertebrates. The occurrence shows strong phylogenetic signal, our findings revealed evolved at least six times during evolutionary history group, independently Although no evident correlation was found between OD occurrence, adult habits diel activity, it is inferred each independent origin involves distinct scenarios concerning photic habits. Furthermore, results significant differences size nocturnal arrhythmic relative length cones’ outer segment.

Language: Английский

---

Passive accumulation of alkaloids in non-toxic frogs challenges paradigms of the origins of acquired chemical defenses

Published: Aug. 2, 2024

Understanding the origins of novel, complex phenotypes is a major goal in evolutionary biology. Poison frogs family Dendrobatidae have evolved novel ability to acquire alkaloids from their diet for chemical defense at least three times. However, taxon sampling has been biased towards colorful species, without similar attention paid inconspicuous ones that are often assumed be undefended. As result, our understanding how this group incomplete. Here we provide new data showing that, contrast previous studies, species each undefended poison frog clade measurable yet low amounts alkaloids. We confirm dendrobatids regularly consume mites and ants, which known sources Further, presence two putatively non-toxic other families. Our suggest existence phenotypic intermediate between toxin consumption sequestration—passive accumulation—that differs active sequestration it involves no derived forms transport storage mechanisms results levels accumulation. discuss concept passive accumulation its potential role origin defenses toxin-sequestering organisms.

Language: Английский

---

The relationship between spectral signals and retinal sensitivity in dendrobatid frogs

PLoS ONE, Journal Year: 2024, Volume and Issue: 19(11), P. e0312578 - e0312578

Published: Nov. 14, 2024

Research on visually driven behavior in anurans has often focused Dendrobatoidea, a clade with extensive variation skin reflectance, which is perceived to range from cryptic conspicuous coloration. Because these patterns are important intraspecific and interspecific communication, we hypothesized that the visual spectral sensitivity of dendrobatids should vary conspecific spectrum. We predicted physiological response frog retinas would be tuned portions visible light spectrum match their body reflectance. Using wavelength-specific electroretinograms (ERGs; 350-650 nm), spectrometer measurements, color-calibrated photography skin, compared retinal reflectance two species ( Allobates talamancae Silverstoneia flotator ), intermediate Colostethus panamansis Phyllobates lugubris aposematic Dendrobates tinctorius Oophaga pumilio ). Consistent matched filter hypothesis, retinae were sensitive across spectrum, without evidence tuning specific wavelengths, yielding low-threshold broadband sensitivity. In contrast, was found different between morphologically distinct populations O . , where frogs exhibited better matching morph’s This sensory specialization particularly interesting given rapid phenotypic divergence by this behavioral preference for sympatric reflectances. Overall, study suggests coevolving reflective strategy dendrobatids.

Language: Английский

---

What makes lionfish successful invaders? : Exploring lionfish behavior and cognition

Published: Jan. 1, 2024

Invasive species are globally on the rise due to human-induced environmental change and often a source of harm their new ecosystems.Tracking spread invaders is crucial better manage invasive species, citizen science used collect sighting data.However, this can be unreliable general public's limited expertise for accurate identification lack clear absence data.Here, we introduce refined method by tracking lionfish (Pterois miles) in Mediterranean Sea using dive centers' local marine wildlife.We contacted 1131 centers coast via email received 216 responses reporting whether or not were present area and, if present, year they first sighted.Currently, sightings observed eastern half Mediterranean, though front continuing move west with furthest as far Corfu, Greece (19.939423°E, 39.428017°N).In 2020, also expanded range north Turkish Aegean Karaburun (26.520657°E, 38.637033°N),showing that invasion ongoing.We found now exceeding previous models, highlighting need additional research biology inform management efforts.Continuous monitoring fronts based center reports understanding what makes so creating effective strategies mitigating negative impact native ecosystems.to use coordinates locations since coastal typically sites close center. ResultsAfter contacting centers, responses.Of these responses, 75 reported 141 no (Figure 2.1).We had been sighted at least once Israel, Lebanon, Cyprus, Turkey, Greece, Spain, while Tunisia,

Language: Английский

---