Abstract:
Documenting variation in thermoregulatory patterns across
phylogenetically and geographically diverse taxa is key to understanding
the evolution of endothermy and heterothermy in
birds and mammals. We recorded body temperature (Tb) in
free-ranging desert hedgehogs (Paraechinus aethiopicus) across
three seasons in the deserts of Saudi Arabia. Modal Tb’s (357–
36.57C) were slightly below normal formammals but still warmer
than those of other hedgehogs. The single maximum Tb recorded
was 39.27C, which is cooler than maximum Tb’s recorded in
most desert mammals. Desert hedgehogs commonly used torpor
duringwinter and spring but never during summer. Torpor
bouts occurred frequently but irregularly, and most lasted less
than 24 h. Unlike daily heterotherms, desert hedgehogs did
occasionally remain torpid for more than 24 h, including one
bout of 101 h. Body temperatures during torpor were often
within 27–37C of ambient temperature; however, we never recorded
repeated bouts of long, predictable torpor punctuated by
brief arousal periods similar to those common among seasonal
hibernators. Thus, desert hedgehogs can be included on the
ever-growing list of species that display torpor patterns intermediate
to traditionally defined hibernators and daily heterotherms.
Extant hedgehogs are a recent radiation within an ancient
family, and the intermediate thermoregulatory pattern
displayed by desert hedgehogs is unlike the deeper and more
regular torpor seen in other hedgehogs, suggesting that this may
be a derived—as opposed to ancestral—trait in this subfamily.
We suggest that this family (Erinaceidae) and order (Eulipotyphla)
may be important for understanding the evolution of
thermoregulatory patterns among Laurasiatheria and mammals
in general.
