scholarly journals A Test of the Thermal Melanism Hypothesis in the Wingless GrasshopperPhaulacridium vittatum

2013 ◽  
Vol 13 (51) ◽  
pp. 1-18 ◽  
Author(s):  
Rebecca M. Harris ◽  
Peter McQuillan ◽  
Lesley Hughes
Keyword(s):  
Thermal Melanism

scholarly journals Thermal melanism explains macroevolutionary variation of dorsal pigmentation in Eurasian vipers

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Fernando Martínez-Freiría ◽  
Ken S. Toyama ◽  
Inês Freitas ◽  
Antigoni Kaliontzopoulou
Keyword(s):  
Solar Radiation ◽  
Environmental Variables ◽  
Large Scale ◽  
Monophyletic Group ◽  
Comparative Approach ◽  
Cold Environments ◽  
Zigzag Pattern ◽  
High Predation ◽  
Dorsal Pattern ◽  
Thermal Melanism

Abstract Colouration may endorse thermoregulatory and antipredatory functions in snakes. The thermal melanism hypothesis predicts that dark-coloured individuals are ecologically favoured in cool climates. However, the loss of aposematic and cryptic colourations may imply high predation for melanistic snakes. Here, we used the monophyletic group of Eurasian vipers (subfamily Viperinae) to test whether an increase in the extent of dark area inside the characteristic zigzag dorsal pattern is associated to colder environments. We measured two colouration traits in zigzag-patterned individuals (number of dorsal marks and weighted pigmentation index) and used a phylogenetic comparative approach to explore macroevolutionary patterns of dorsal pigmentation and test whether its extent is associated to ecogeographic characteristics of lineages’ ranges. Phylogenetically-naïve and phylogenetically-informed analyses yielded a significant association between the degree of pigmentation of the zigzag pattern and environmental variables such as solar radiation, elevation and latitude. The degree of pigmentation of the zigzag pattern is highlighted as an adaptive trait that matches range attributes mirroring cold environments irrespective of the phylogeny. These results constitute the first large-scale evidence supporting the thermal melanism hypothesis in snakes, opening new avenues of inquiry for the mechanisms that shape the evolution of colour phenotypes.

scholarly journals To be small and dark is advantageous for gaining heat in mezquite lizards, Sceloporus grammicus (Squamata: Phrynosomatidae)

2020 ◽  
Vol 132 (1) ◽  
pp. 93-103
Author(s):  
Juan Carlos González-Morales ◽  
Jimena Rivera-Rea ◽  
Gregorio Moreno-Rueda ◽  
Elizabeth Bastiaans ◽  
Héctor Díaz-Albiter ◽  
...  
Keyword(s):  
Body Size ◽  
High Altitude ◽  
Heating Rate ◽  
Small Body ◽  
Individual Performance ◽  
Lizard Species ◽  
Heat Gain ◽  
Thermal Environments ◽  
Sceloporus Grammicus ◽  
Thermal Melanism

Abstract Body temperature is important in determining individual performance in ectotherms such as lizards. Environmental temperature decreases with increasing altitude, but nevertheless many lizards inhabit high-altitude environments. The ‘thermal melanism hypothesis’ proposes that a dark dorsal coloration enables darker individuals to heat up faster because they absorb more solar radiation and thus being darker may be advantageous in cold habitats. The aim of the present study is to evaluate how heating rate, cooling rate and net heat gain vary with body size and dorsal skin coloration in Sceloporus grammicus lizards along an altitudinal gradient. We measured these traits multiple times in the same individuals with a radiation heat source and spectrophotometry under laboratory conditions. Our results showed that S. grammicus lizards are smaller and darker at high elevations than at low elevations. In addition, the smallest and darkest lizards showed the greatest heating rate and net heat gain. Therefore, in S. grammicus, we suggest that small body size and dark dorsal coloration provide thermoregulatory benefits in high-altitude environments. Hence, this study supports the thermal melanism hypothesis in a lizard species under varied thermal environments.

scholarly journals Thermal melanism in ectotherms

2007 ◽  
Vol 32 (5) ◽  
pp. 235-245 ◽  
Author(s):  
Susana Clusella Trullas ◽  
Johannes H. van Wyk ◽  
James R. Spotila
Keyword(s):  
Thermal Melanism

scholarly journals Testing the thermal melanism hypothesis: a macrophysiological approach

2008 ◽  
Vol 22 (2) ◽  
pp. 232-238 ◽  
Author(s):  
S. Clusella-Trullas ◽  
J. S. Terblanche ◽  
T. M. Blackburn ◽  
S. L. Chown
Keyword(s):  
Thermal Melanism
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