A hidden cost of reproduction: the trade‐off between clutch size and escape take‐off speed in female zebra finches

Abstract

1. The concept of reproductive costs is a central tenet of life-history theory, but the proximate mechanisms whereby such costs are mediated remain poorly understood. In this paper we demonstrate a link between clutch size and escape take-off speed in small birds, mediated through changes in flight muscle volume during laying. 2. In a series of experiments the same adult female zebra finches ( Taeniopygia guttata ) were made to lay both large and small clutches. When producing the larger clutches, females lost more flight muscle condition and became significantly slower to take off during escape flights. 3. This reduction in take-off speed with increased egg production was evident after the last egg was laid, and was independent of changes in body mass, so was not simply due to the presence of the eggs inside the female. 4. This indicates that there is a trade-off between fecundity and the maintenance of somatic musculature critical to an animal's escape response. As changes in take-off speed can have disproportionate effects on the chances of ground-feeding birds surviving a predatory attack, the degree of reduction in flight muscle condition during laying could be a constraint on clutch sizes in such birds.

Pregnancy is a drag: hydrodynamics, kinematics and performance in pre- and post-parturition bottlenose dolphins (Tursiops truncatus)

“…The diminished locomotor performance of pregnant dolphins observed in this study is in accordance with those for other gravid and pregnant animals across aquatic, terrestrial and aerial environments (Shine, 1980;Winfield and Townsend, 1983;Berglund and Rosenquist, 1986;Seigel et al, 1987;Cooper et al, 1990;Lee et al, 1996;Shaffer and Formanowicz, 1996;Isaacs and Byrne, 1998;Seibel et al, 2005;Gu and Danthanarayana, 2000;McLean and Speakman, 2000;Veasey et al, 2001;Plaut, 2002;Guillemette and Ouellet, 2005;Svendsen et al, 2009) and has profound implications for animals that rely on speed for hunting and predator avoidance. Both speed and maneuverability (ability to turn in a confined space) (Norberg and Rayner, 1987) play key roles in predator-prey interactions (Howland, 1974;Maresh et al, 2004).…”

“…It was hypothesized that the decreased maternal locomotor ability was due to carrying an extra load associated with gravidity or pregnancy for crustaceans (Winfield and Townsend, 1983;Berglund and Rosenquist, 1986), fish (Plaut, 2002;Svendsen et al, 2009), scorpions (Shaffer and Formanowicz, 1996), insects (Isaacs and Byrne, 1998;Gu and Danthanarayana, 2000), reptiles (Shine, 1980;Seigel et al, 1987;Cooper et al, 1990), birds (Lee et al, 1996;Veasey et al, 2001) and mammals (McLean and Speakman, 2000). Prelaying common eiders (Somateria mollissima) are even rendered flightless (Guillemette and Ouellet, 2005).…”

The urinary bladder as a physiological reservoir that moderates dehydration in a large desert lizard, the Gila monsterHeloderma suspectum

“…Storing a large volume of water in the coelomic cavity may also have negative consequences. For example, similar coelomic cavity space is needed to accommodate the increased mass and volume associated with reproduction or consumption of a large meal, both of which can have deleterious effects on locomotor performance (Seigel et al, 1987;Shine, 2003) or predator avoidance (Shine, 1980;Lee et al, 1996;Veasey et al, 2001). It is unknown whether a fluid-filled bladder has similar deleterious effects on locomotion or anti-predator behavior, which could be critical in widely foraging predators like the Gila monster.…”

Hematological changes associated with egg production: estrogen dependence and repeatability

“…Most studies to date have focused on relatively simple models of resource-based allocation trade-offs (e.g. Gustafsson et al, 1994;Houston et al, 1995;Oppliger et al, 1997;Veasey et al, 2001;Kullberg et al, 2002;Martin et al, 2003), in which energy and/or nutrients are reallocated to egg production and away from other physiological functions with negative consequences. More recently, it has been suggested that costs of reproduction might also be caused by the reproductive process itself or the regulatory (hormonal) mechanisms underlying reproduction (e.g.…”