Pregnancy limits lung function during exercise and depresses metabolic rate in the skink Tiliqua nigrolutea

Abstract

High gestational loads have been associated with a range of ecological costs, such as decreased locomotor ability; however, the physiological mechanisms that underpin these changes are poorly understood. In this study, breathing patterns, metabolic rates, lung volume and lung diffusing capacity were measured at rest and during exercise in the pregnant skink Tiliqua nigrolutea. Breathing patterns were largely unaffected by gestation; however, decreases in metabolic rate (rate of oxygen consumption) in the late stages of pregnancy induced a relative hyperventilation. The reductions in metabolic rate during late pregnancy prevent the calculation of the maintenance cost of pregnancy based on post-partum and neonatal metabolic rates. Despite the high relative litter mass of 38.9±5.3%, lung diffusing capacity was maintained during all stages of pregnancy, suggesting that alterations in diffusion at the alveolar capillary membrane were not responsible for the relative hyperventilation. Lung volume was increased during pregnancy compared with non-pregnant females, but lung volume was significantly lower during pregnancy compared with post-partum lung volume. Pregnant females were unable to produce the same metabolic and ventilatory changes induced by exercise in nonpregnant females. This lack of ability to respond to increased respiratory drive during exercise may underpin the locomotor impairment measured during gestation in previous studies.

Ontogeny of sex differences in the energetics and kinematics of terrestrial locomotion in leghorn chickens (Gallus gallus domesticus)

“…Although there is evidence amongst vertebrate species for reductions in locomotor performance with pregnancy/gravidity 35 36 37 38 39 40 , U max was actually greater in M ♀ than in J ♀ . This is despite the two age cohorts of female sharing similar absolute limb lengths and muscle mass, whilst only M ♀ were gravid and were also 1.36-fold heavier than J ♀ .…”

Sex‐ and state‐dependent covariation of risk‐averse and escape behavior in a widespread lizard

“…Life stage is a typically state‐dependent characteristic that has long been recognized to have an overwhelming effect on behavior. For example, most adult females, especially in live‐bearing species, experience an increased physical burden, which induces changes in locomotor performance, hormone levels, metabolic rates, and thermoregulation patterns (Bonnet et al., 2001 ; Braña, 1993 ; Hare & Cree, 2010 ; Le Galliard et al., 2003 ; Miles et al., 2000 ; Munns et al., 2015 ; Olsson et al., 2000 ). In turn, these changes can make gravid females more vulnerable to predators, and can have cascading effects on interconnected behavioral traits (Miles et al., 2007 ), and affect behavioral syndromes.…”