Vision in dim light and the evolution of color pattern in a crepuscular/nocturnal frog

Robertson, Jeanne M.; Bell, Rayna C.; Loew, Ellis R.

doi:10.1007/s10682-022-10173-w

Cited by 11 publications

(8 citation statements)

References 48 publications

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“…To account for nocturnal light conditions in the visual models, we used starlight and full moonlight irradiance data for all models (Johnsen et al., 2006). Spectral data from 300 to 349 nm for the full moon spectrum were lacking and were interpolated using the as.rspec function from ‘pavo’ (Maia et al., 2019; Robertson et al., 2022). We set Weber fractions to 0.05 for all species (Siddiqi et al., 2004; Stuart‐Fox et al., 2008).…”

Section: Methodsmentioning

confidence: 99%

“…Such variability is present not only in diurnal but also in nocturnal amphibians (e.g. Roberts et al., 2022; Robertson et al., 2022). However, only a handful of studies have investigated the visual thresholds in dim light and the role that coloration may play in nocturnal amphibians (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…However, only a handful of studies have investigated the visual thresholds in dim light and the role that coloration may play in nocturnal amphibians (e.g. Kelber et al., 2017; Robertson et al., 2022; Yovanovich et al., 2017). Available evidence suggests that the amphibian retina enables vision at very low light thresholds (Aho et al., 1993; Yovanovich et al., 2017).…”

Section: Introductionmentioning

confidence: 99%

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Color morphs of the fire salamander are discriminated at night by conspecifics and predators

Aguilar,

Pérez i de Lanuza,

Martínez‐Gil

et al. 2023

Journal of Zoology

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The coexistence of multiple discrete color phenotypes (i.e. color polymorphism) has been studied in many diurnal species where environmental light allows most visual systems to chromatically discriminate color morphs. However, there is a large gap in our understanding of the discrimination thresholds and the function color polymorphisms play at night. We collected spectral data from the throats of red‐ and yellow‐morph males in a polymorphic population of the nocturnal amphibian Salamandra salamandra gallaica. We estimated the discriminability between morphs and their conspicuousness at night by fitting visual models of conspecifics and predators. We also collected morphological, behavioral and physiological data and assessed the abundance and activity patterns of each morph to explore their potential function. Visual models indicated that both conspecifics and predators can visually discriminate salamander color morphs under night‐light conditions. Assuming the potential role of yellow and red color patches as visual signals, putatively related to social signaling, we could suspect that these colors represent different adaptive optima. Red‐morph individuals had shorter bodies and lower body condition, but both morphs showed similar space use. In addition, both color morphs exhibited similar metabolic physiology, suggesting that the observed similarity in these traits may be better explained by the shared environmental conditions, rather than color. Finally, differences in the conspicuousness of red and yellow morphs could result in differential predation pressure.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Color morphs of the fire salamander are discriminated at night by conspecifics and predators

Aguilar,

Pérez i de Lanuza,

Martínez‐Gil

et al. 2023

Journal of Zoology

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“…Thus, ear loss may only be puzzling when viewed through a lens that is focused on anuran acoustic communication. As research into other, less studied anuran sensory systems (e.g., vision - [58][59][60][61]; olfaction - [62,63]; vibration - [64][65][66]) and communication styles [67] increases, tympanic middle ear loss might not seem so odd from a frog's sensory standpoint.…”

Section: Sensory and Communication Constraints Associated With Smalle...mentioning

confidence: 99%

Convergent Anuran Middle Ear Loss Lacks a Universal, Adaptive Explanation

Womack,

Hoke

2023

Brain Behav Evol

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Shared selection pressures often explain convergent trait loss, yet anurans (frogs and toads) have lost their middle ears at least 38 times with no obvious shared selection pressures unifying ‘earless’ taxa. Anuran tympanic middle ear loss is especially perplexing because acoustic communication is dominant within Anura and tympanic middle ears enhance airborne hearing in most tetrapods. Here we examine whether particular geographic ranges, microhabitats, activity patterns, or aspects of acoustic communication are associated with anuran tympanic middle ear loss. Although we find modest differences between the geographic ranges of eared and earless species and increased diurnality in earless species, we find no universal adaptive explanation for the many instances of anuran tympanic middle ear loss. The puzzling lack of shared selection pressures motivates discussion of alternative hypotheses, including genetic or developmental constraints, and the possibility that tympanic middle ear loss is maladaptive.

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“…In general, frogs have up to two types of rods (maximally green and blue sensitive) and up to six types of cones including maximally red, green, blue, and violet-sensitive single and double cones (for reviews, see Donner and Yovanovich 2020 ; Schott et al 2022b ). The green-sensitive rods (homologous with other vertebrate rods) express the rod opsin RH1 and absorb maximally (λ max ) in the range of 491 to 503 nm ( Liebman and Entine 1968 ; Siddiqi et al 2004 ; Robertson et al 2022 ). The blue-sensitive rods (unique to amphibians) express a cone visual pigment (SWS2) and have λ max in the range of 430 to 440 nm ( Liebman and Entine 1968 ; Hisatomi et al 1999 ; Ma et al 2001 ; Darden et al 2003 ; Govardovskii and Reuter 2014 ; Robertson et al 2022 ).…”

Section: Introductionmentioning

confidence: 99%

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

Schott,

Fujita,

Streicher

et al. 2024

Molecular Biology and Evolution

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

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Vision in dim light and the evolution of color pattern in a crepuscular/nocturnal frog

Cited by 11 publications

References 48 publications

Color morphs of the fire salamander are discriminated at night by conspecifics and predators

Color morphs of the fire salamander are discriminated at night by conspecifics and predators

Convergent Anuran Middle Ear Loss Lacks a Universal, Adaptive Explanation

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

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