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Tevs DR, Mukhalian JA, Simpson E, Cox CL, Schrey AW, McBrayer LD. DNA Methylation and Counterdirectional Pigmentation Change following Immune Challenge in a Small Ectotherm. Physiol Biochem Zool 2023; 96:418-429. [PMID: 38237192 DOI: 10.1086/727692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
AbstractBy allowing for increased absorption or reflectance of solar radiation, changes in pigmentation may assist ectotherms in responding to immune challenges by enabling a more precise regulation of behavioral fever or hypothermia. Variation in epigenetic characteristics may also assist in regulating immune-induced pigmentation changes and managing the body's energetic reserves following infection. Here, we explore how dorsal pigmentation, metabolic rate, and DNA methylation in the Florida scrub lizard (Sceloporus woodi) respond to two levels of immune challenge across two habitat types. We found changes in pigmentation that are suggestive of efforts to assist in behavioral fever and hypothermia depending on the intensity of immune challenge. We also found correlations between DNA methylation in liver tissue and pigmentation change along the dorsum, indicating that color transitions may be part of a multifaceted immune response across tissue types. The relationship between immune response and metabolic rate supports the idea that energetic reserves may be conserved for the costs associated with behavioral fever when immune challenge is low and the immune functions when immune challenge is high. While immune response appeared to be unaffected by habitat type, we found differences in metabolic activity between habitats, suggesting differences in the energetic costs associated with each. To our knowledge, these results present the first potential evidence of pigmentation change in ectotherms in association with immune response. The relationship between immune response, DNA methylation, and pigmentation change also highlights the importance of epigenetic mechanisms in organism physiology.
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Trait Covariances in Eastern Box Turtles Do Not Support Pleiotropic Effects of the Melanocortin System on Color, Behavior, and Stress Physiology. J HERPETOL 2022. [DOI: 10.1670/22-010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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González-Morales JC, Rivera-Rea J, Moreno-Rueda G, Bastiaans E, Castro-López M, Fajardo V. Fast and dark: The case of Mezquite lizards at extreme altitude. J Therm Biol 2021; 102:103115. [PMID: 34863479 DOI: 10.1016/j.jtherbio.2021.103115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 09/17/2021] [Accepted: 10/19/2021] [Indexed: 10/19/2022]
Abstract
Sprint speed is a major performance trait in animal fitness involved in escaping from predators, obtaining food, and defending territory. Biotic and abiotic factors may influence sprint speed in lizards. Temperature decreases at higher altitude. Therefore, lizards at high elevations may require longer basking times to reach optimal body temperatures, increasing their vulnerability to predation and decreasing their time for other activities such as foraging or reproduction. Here, we tested whether the maximum sprint speed of a lizard that shows conservative thermal ecology varied along an altitudinal gradient comprising low (2500 m), middle (3400 m) and high-altitude (4300 m) populations. We also tested whether sprint speed was related to dorsal reflectance at different ecologically relevant temperatures. Given that the lizard Sceloporus grammicus shows conservative thermal ecology with altitude, we expected that overall average sprint speed would not vary with altitude. However, given that darker lizards heat up quicker, we expected that darker lizards would be faster than lighter lizards. Our results suggest that S. grammicus at high altitude are faster and darker at 30 °C, while lizards from low and middle altitude are faster and lighter in color at 20 °C than high altitude lizards. Also, our results suggest a positive relationship between sprint speed and dorsal skin reflectance at 10 and 20 °C. Sprint speed was also affected by snout-vent length, leg length, and leg thickness at 10 °C. These results suggest that, even though predation pressure is lower at extreme altitudes, other factors such as vegetation cover or foraging mode have influenced sprint speed.
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Affiliation(s)
- Juan Carlos González-Morales
- Posgrado en Ciencias Biológicas, Centro Tlaxcala de Biología de la Conducta, Universidad Autónoma de Tlaxcala, Km 1.5 Carretera Tlaxcala-Puebla S/N, AP 262, Tlaxcala, Mexico; Instituto para la Conservación de la Cordillera Neovolcánica ante al Cambio Climático, Lago Atitlán No. 502B, Colonia Nueva Oxtotitlán, Toluca, Estado de México, C.P. 50100, México
| | - Jimena Rivera-Rea
- Instituto para la Conservación de la Cordillera Neovolcánica ante al Cambio Climático, Lago Atitlán No. 502B, Colonia Nueva Oxtotitlán, Toluca, Estado de México, C.P. 50100, México; Posgrado en Ciencias Agropecuarias y Recursos Naturales, Universidad Autónoma del Estado de México, México, Instituto Literario No. 100, Colonia Centro, Toluca, Estado de México, C.P. 50000, Mexico
| | - Gregorio Moreno-Rueda
- Departamento de Zoología, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva S/N, E-18071, Granada, Spain
| | - Elizabeth Bastiaans
- Biology Department, State University of New York College at Oneonta, 108 Ravine Parkway, Oneonta, NY, 13820, USA
| | - Meily Castro-López
- Universidad del Istmo, Campus Juchitán, Carretera Transísmica Juchitán-La ventosa Km. 14, La ventosa, Oaxaca, AP 70102, México
| | - Víctor Fajardo
- Instituto para la Conservación de la Cordillera Neovolcánica ante al Cambio Climático, Lago Atitlán No. 502B, Colonia Nueva Oxtotitlán, Toluca, Estado de México, C.P. 50100, México.
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Megía-Palma R, Barrientos R, Gallardo M, Martínez J, Merino S. Brighter is darker: the Hamilton–Zuk hypothesis revisited in lizards. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Abstract
Several studies of lizards have made an erroneous interpretation of negative relationships between spectral brightness and parasite load, and thus provided misleading support for the Hamilton–Zuk hypothesis (HZH). The HZH predicts that infected hosts will produce poorer sexual ornamentation than uninfected individuals as a result of energetic trade-offs between immune and signalling functions. To test whether there is a negative relationship between spectral brightness and pigment content in the skin of lizards, we used spectrophotometry to quantify the changes in spectral brightness of colour patches of two species after chemically manipulating the contents of orange, yellow and black pigments in skin samples. Carotenoids were identified using high-performance liquid chromatography. In addition, we compared the spectral brightness in the colour patches of live individuals with differential expression of nuptial coloration. Overall, the analyses demonstrated that the more pigmented the colour patch, the darker the spectrum. We provide a comprehensive interpretation of how variation in pigment content affects the spectral brightness of the colour patches of lizards. Furthermore, we review 18 studies of lizards presenting 24 intraspecific tests of the HZH and show that 14 (58%) of the tests do not support the hypothesis.
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Affiliation(s)
- Rodrigo Megía-Palma
- Universidad de Alcalá (UAH), Área de Parasitología, Departamento de Biomedicina y Biotecnología, Facultad de Farmacia, Alcalá de Henares, Spain
- CIBIO, InBIO – Research Network in Biodiversity and Evolutionary Biology, Universidade do Porto, Campus de Vairão, Rua Padre Armando Quintas, Vairão, Porto, Portugal
| | - Rafael Barrientos
- Road Ecology Laboratory, Departamento de Biodiversidad, Ecología y Evolución, Facultad de Ciencias Biológicas, Universidad Complutense de Madrid, José Antonio Novais, Madrid, Spain
| | - Manuela Gallardo
- Laboratorio de Histología, Museo Nacional de Ciencias Naturales-CSIC, c/ José Gutiérrez Abascal, Madrid, Spain
| | - Javier Martínez
- Universidad de Alcalá (UAH), Área de Parasitología, Departamento de Biomedicina y Biotecnología, Facultad de Farmacia, Alcalá de Henares, Spain
| | - Santiago Merino
- Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales-CSIC, c/ José Gutiérrez Abascal, Madrid, Spain
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