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The small heart of the Ornate Tinamou is compatible with endothermy and flight but compromises aerobic metabolism and thermoregulation during recovery from exhaustive activity
Author(s) -
Altimiras Jordi,
Deck Lina Maria Giraldo,
GaritanoZavala Álvaro
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1149.18
Subject(s) - biology , heart rate , anaerobic exercise , thermoregulation , medicine , vo2 max , ecology , zoology , endocrinology , physiology , blood pressure
Tinamous are an ancient family of neotropical flying birds. Scant data from a few species show that they have a small heart so our aim was to characterize relative heart size of two species of the genus Nothoprocta and assess the physiological limitations associated with a small heart size. Relative heart size (0.24% for the Ornate Tinamou OT, a highland species and 0.28% for the Chilean Tinamou CT, a lowland species) was significantly smaller than high and lowland chickens (0.54% and 0.42% respectively), without evidence of right ventricular hypertrophy. Resting aerobic metabolism was 31% lower in OT than in highland chickens. When subjected to exhaustive activity, OT had elevated glucose and lactate levels suggesting a severe oxygen debt when exhausted. This was further shown as a significant drop in body temperature after an exhaustive bout. Finally heart rate while running on a treadmill at 3 km h −1 was 5% lower in OT, indicating that tinamous cannot compensate for the reduction in heart size with a faster heart rate. Altogether, we provide evidence that heart size is a phylogenetically conserved trait among tinamous and that the Ornate Tinamou cannot compensate aerobically for its small heart. Instead, it relies on anaerobic metabolism incurring in a large oxygen debt while exhausted. Supported by FORMAS Centre of Excellence in Animal Welfare Science and career grant from Linköpings universitet to JA.