Effect of body 1 mass and melanism on heat balance in 2 Liolaemus lizards of the goetschi clade.

MORENO AZÓCAR D.L; BONINO MF; PEROTTI MG; SCHULTE JA; ABDALA CS; CRUZ FB

JOURNAL OF EXPERIMENTAL BIOLOGY

COMPANY OF BIOLOGISTS LTD

Lugar: Cambridge; Año: 2016 vol. 219 p. 1162 - 1171

0022-0949

Body temperature of ectotherms depends on the environmental temperatures and19 behavioral adjustments, but morphology may also affect it. For example, in colder20 environments animals tend to be larger and show higher thermal inertia, as proposed by21 Bergmann?s rule and the heat balance hypothesis (HBH). Additionally, dark coloration22 increases solar radiation absorption and should accelerate heat gain (Thermal melanism23 hypothesis, TMH).24 We tested Bergmann´s rule, HBH and TMH within the Liolaemus goetschi lizards clade25 that show variability in body size and melanic coloration. We measured heating and26 cooling rates of live and euthanized animals, and tested how morphology and color27 affect these rates. Live organisms show less variable and faster heating rates, compared28 to cooling rates, suggesting behavioral and/ or physiological adjustments.29 Our results support Bergmann?s rule and the HBH, as larger species show slower30 heating and cooling rates. However, we did not find a clear pattern to support TMH. The31 influence of dorsal melanism on heating by radiation was masked by body size effect in32 live animals, while results from euthanized individuals show no clear effects of33 melanism on heating rates either. However, when compared three groups of live34 individuals with different degree of melanism we found that that darker euthanized35 animals actually heat faster than lighter ones, favoring TMH. Although unresolved36 aspects remain, body size and coloration influenced heat exchange suggesting complex37 thermoregulatory strategies in these lizards, probably regulated through physiology and38 behavior, what may allow these small lizards to inhabit harsh weather environments.