Thyroid hormone fluctuations indicate a thermoregulatory function in both a tropical (Alouatta palliata) and seasonally cold-habitat (Macaca fuscata) primate.
Abstract
Thyroid hormones boost animals' basal metabolic rate and represent an important thermoregulatory
pathway for mammals that face cold temperatures. Whereas the cold thermal pressures
experienced by primates in seasonal habitats at high latitudes and elevations are
often apparent, tropical habitats also display distinct wet and dry seasons with modest
changes in thermal environment. We assessed seasonal and temperature-related changes
in thyroid hormone levels for two primate species in disparate thermal environments,
tropical mantled howlers (Alouatta palliata), and seasonally cold-habitat Japanese
macaques (Macaca fuscata). We collected urine and feces from animals and used ELISA
to quantify levels of the thyroid hormone triiodothyronine (fT3). For both species,
fT3levels were significantly higher during the cooler season (wet/winter), consistent
with a thermoregulatory role. Likewise, both species displayed greater temperature
deficits (i.e., the degree to which animals warm their body temperature relative to
ambient) during the cooler season, indicating greater thermoregulatory pressures during
this time. Independently of season, Japanese macaques displayed increasing fT3levels
with decreasing recently experienced maximum temperatures, but no relationship between
fT3and recently experienced minimum temperatures. Howlers increased fT3levels as recently
experienced minimum temperatures decreased, although demonstrated the opposite relationship
with maximum temperatures. This may reflect natural thermal variation in howlers'
habitat: wet seasons had cooler minimum and mean temperatures than the dry season,
but similar maximum temperatures. Overall, our findings support the hypothesis that
both tropical howlers and seasonally cold-habitat Japanese macaques utilize thyroid
hormones as a mechanism to boost metabolism in response to thermoregulatory pressures.
This implies that cool thermal pressures faced by tropical primates are sufficient
to invoke an energetically costly and relatively longer-term thermoregulatory pathway.
The well-established relationship between thyroid hormones and energetics suggests
that the seasonal hormonal changes we observed could influence many commonly studied
behaviors including food choice, range use, and activity patterns.
Type
Journal articleSubject
energeticstemperature
thermal environment
thermoregulation
thyroid hormone
Alouatta
Animals
Basal Metabolism
Body Temperature Regulation
Macaca
Seasons
Species Specificity
Temperature
Thyroid Hormones
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https://hdl.handle.net/10161/16138Published Version (Please cite this version)
10.1002/ajp.22714Publication Info
Thompson, Cynthia L; Powell, Brianna L; Williams, Susan H; Hanya, Goro; Glander, Kenneth
E; & Vinyard, Christopher J (2017). Thyroid hormone fluctuations indicate a thermoregulatory function in both a tropical
(Alouatta palliata) and seasonally cold-habitat (Macaca fuscata) primate. Am J Primatol, 79(11). 10.1002/ajp.22714. Retrieved from https://hdl.handle.net/10161/16138.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Kenneth Earl Glander
Professor Emeritus of Evolutionary Anthropology
Primate ecology and social organization: the interaction between feeding patterns
and social structure; evolutionary development of optimal group size and composition;
factors affecting short and long-term demographic changes in stable groups; primate
use of regenerating forests.

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