Ophthalmology of Canidae: Foxes, Wolves, and Relatives

Mowat, Freya M.; Peichl, Leo

doi:10.1007/978-3-030-81273-7_11

Cited by 3 publications

(1 citation statement)

References 120 publications

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“…Using the same software, these multispectral images were then converted to the cone‐catch models, that is, predicted photoreceptor responses (Troscianko & Stevens, 2015), of different species: domestic dog ( Canis familiaris ), human ( Homo sapiens ), peafowl ( Pavo cristatus ), and blue tit ( Cyanistes caeruleus ). The domestic dog visual model was chosen to represent the visual system of the coyote ( Canis latrans ) since visual pigments are conserved across all canids species (Jacobs, 1993; Jacobs et al., 1993; Mowat & Peichl, 2022). The human visual system was added as a reference to our own visual system.…”

Section: Methodsmentioning

confidence: 99%

You can't see me: Background matching is independent of body temperature in the Western diamond‐backed rattlesnake

Da Cunha,

Fournier,

Horne

et al. 2024

Journal of Zoology

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Coloration is crucial for ambush mesopredators' survival as they depend on it for camouflage to hunt and avoid predation. Furthermore, coloration is especially important in ectotherms as it is linked to two essential functions for survival: thermoregulation and crypsis. In a context of trade‐offs between thermoregulation and crypsis, the comprehension of how ectotherms employ color to address conflicting demands of thermoregulation and crypsis is limited. This study investigated background matching and thermoregulation in western diamond‐backed rattlesnakes (Crotalus atrox). Rattlesnakes were predicted to better match selected microhabitats in terms of color, luminance, and pattern than random microhabitats within their home range, and body temperature was predicted to influence their body coloration with higher temperatures favoring lighter colors. Pictures of 14 radiotracked western diamond‐backed rattlesnakes were taken in situ with a full spectrum camera (UV/VIS) and body temperature was recovered from internal temperature‐datalogging radiotransmitters. Crotalus atrox matched the color, luminance, and pattern of the background better than a randomly selected background, thus enhancing background matching. Additionally, rattlesnake coloration varied independently of temperature indicating that rattlesnakes are behaviorally modifying crypsis regardless of thermoregulation.

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Section: Methodsmentioning

confidence: 99%

You can't see me: Background matching is independent of body temperature in the Western diamond‐backed rattlesnake

Da Cunha,

Fournier,

Horne

et al. 2024

Journal of Zoology

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Eye features and retinal photoreceptors of the nocturnal aardvark (Orycteropus afer, Tubulidentata)

Peichl,

Meimann,

Solovei

et al. 2024

Preprint

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The nocturnal aardvark Orycteropus afer is the only extant species in the mammalian order Tubulidentata. Previous studies have claimed that it has an all-rod retina. In the retina of one aardvark, we found rod densities ranging from 124,000/mm² in peripheral retina to 214,000/mm² in central retina; the retina of another aardvark had 182,000 – 245,000 rods/mm². This is moderate in comparison to other nocturnal mammals. With opsin immunolabelling we found that the aardvark also has a small population of cone photoreceptors. Cone densities ranged from 300 to 1,300/mm² in one animal, and from 1,100 to 1,600/mm² in the other animal, with large local variations and no large central-peripheral density gradient. Overall, cones comprised 0.25-0.9% of the photoreceptors. Both typical mammalian cone opsins, longwave-sensitive (L) and shortwave-sensitive (S), were present. However, there was colocalization of the two opsins in many cones across the retina (35 – 96% dual pigment cones). Pure L cones and S cones formed smaller populations. This probably results in poor colour discrimination. Thyroid hormones, important regulators of cone opsin expression, showed normal blood serum levels. The relatively low rod density and hence a relatively thin retina may be related to the fact that the aardvark retina is avascular and its oxygen and nutrient supply have to come from the choriocapillaris by diffusion. In contrast to some previous studies, we found that the aardvark eye has a reflective tapetum lucidum with features of a choroidal tapetum fibrosum, in front of which the retinal pigment epithelium is unpigmented. The discussion considers these findings from a comparative perspective.

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You can’t see me: Background matching in the Western diamond-backed rattlesnake (Crotalus atrox)

Cunha,

Fournier,

Horne

et al. 2023

Preprint

View full text Add to dashboard Cite

Coloration is crucial for ambush mesopredators’ survival as they depend on it for camouflage to hunt and avoid predation. Furthermore, coloration is especially important in ectotherms as it is linked to two essential functions for survival: thermoregulation and crypsis. In a context of trade-offs between thermoregulation and crypsis, the comprehension of how ectotherms employ color to address conflicting demands of thermoregulation and crypsis is limited. This study investigated background matching and thermoregulation in western-diamond-backed rattlesnakes (Crotalus atrox). Rattlesnakes were predicted to better match selected microhabitats in terms of color, luminance, and pattern than random microhabitats within their home range, and temperature was predicted to influence their body coloration. Pictures of fourteen radiotracked western diamond-backed rattlesnakes were taken in situ with a full spectrum camera (UV/VIS) and body temperature was recovered from internal temperature-datalogging radio-transmitters. Crotalus atrox matched the color, luminance, and pattern of the background better than a randomly selected background, thus enhancing crypsis. Additionally, rattlesnake coloration varied independently of temperature indicating that rattlesnakes are behaviorally modifying crypsis regardless of thermoregulation.

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Ophthalmology of Canidae: Foxes, Wolves, and Relatives

Cited by 3 publications

References 120 publications

You can't see me: Background matching is independent of body temperature in the Western diamond‐backed rattlesnake

You can't see me: Background matching is independent of body temperature in the Western diamond‐backed rattlesnake

Eye features and retinal photoreceptors of the nocturnal aardvark (Orycteropus afer, Tubulidentata)

You can’t see me: Background matching in the Western diamond-backed rattlesnake (Crotalus atrox)

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