Dear colleagues, On behalf of my co-authors, I am pleased to announce the publication of the following papers on subantarctic fur seal fasting capabilities and their ecological implications. If you are interested in PDF copies, please email me at: ddlafouine@free.fr Best wishes, Delphine PAPER #1: Verrier, D., Groscolas, R., Guinet, C. and Arnould, J. P. Y. , Development of fasting abilities in subantarctic fur seal pups: balancing the demands of growth under extreme nutritional restrictions. Functional Ecology, no. doi: 10.1111/j.1365-2435.2010.01823.x Summary: 1. Surviving prolonged food deprivation requires various metabolic adaptations such as energy and protein sparing, which can be highly conflicting with energy-demanding stages of an animal’s life history such as growth. 2.Due to the maternal attendance pattern, subantarctic fur seal (Arctocephalus tropicalis Gray) pups must repeatedly endure exceptionally long fasts of increasing duration throughout the 10-month lactation period. Little is known of (i) how these infants adapt to such extreme energetic constraints while sustaining growth and development; and (ii) the ecological implications of repeated prolonged fasting in early life in terms of offspring survival, maternal care and growth strategy in this species, as well as the evolutionary consequences of such life history trait. 3. Physiological responses to prolonged fasting and how they change with development throughout the pre-weaning period were investigated. Results show that beginning with their first fast, subantarctic fur seal pups are able to mobilize lipid reserves preferentially while conserving protein stores in response to nutritional deprivation. As pup age, profound changes in energy expenditure allow the implementation of an efficient strategy of fat storage and lean body mass preservation, which proves highly adaptive in the face of the low maternal provisioning rates experienced. 4. Despite increasing fasting durations, pup mortality decreased markedly throughout the maternal dependence period. Consistent with predictions, field measurements indicate that fasting endurance, although limited in early life, increases up to durations of nearly 3 months with age. Results suggest that the maternal provisioning strategy could be constrained by these ontogenetic changes in pup fasting abilities. 5. Furthermore, extreme energetic constraints and local density-dependent effects appear to exert a strong selective pressure upon the adoption of a convergent growth strategy between the sexes aiming to maximize fat storage and pre-weaning survival. 6. The issues of resulting trade-offs between pre- and post-weaning survival and the evolutionary consequences of extreme fasting abilities are also addressed. PAPER #2: Verrier, D., Guinet, C., Authier, M., Tremblay, Y., Schaffer, S., Costa, D. P., Groscolas, R. and Arnould, J. P. , The ontogeny of diving abilities in subantarctic fur seal pups: developmental trade-off in response to extreme fasting?. Functional Ecology, no.doi: 10.1111/j.1365-2435.2011.01846.x Summary: 1. A major hypothesis of life-history theory is that conditions of early development affect future survival and reproductive success. Responses to detrimental environments during early ontogeny may involve trade-offs between current and future fitness. Yet, the functional mechanisms involved in such evolutionary trade-offs remain poorly documented. 2. The physiological and behavioural ontogeny of diving abilities was examined in subantarctic fur seal (Arctocephalus tropicalis Gray) pups to assess whether the repeated extreme fasts they naturally endure throughout the period of maternal dependence impacts on their development. 3. The ontogeny of pup body oxygen storage capacity was slow, in particular for the muscle compartment, which shows limited increase in myoglobin content (0·23–0·85 g 100 g wet muscle−1). As a consequence, by the time of weaning, mass-specific oxygen stores had only reached 76%, 24% and 61% of adult female capacity for blood, muscle and total, respectively. Concomitantly, in marked contrast to other pinniped infants, they spent decreasing amounts of time in water (16–7%) with age and exhibited very little diving experience and skills. 4. Overall, in addition to experiencing the longest fasting durations throughout the maternal dependence period, subantarctic fur seal pups demonstrate the lowest levels of mass-specific total oxygen stores and maximum dive duration of any otariid near the age of weaning reported to date. 5. Furthermore, dives that exceeded the calculated aerobic dive limit occurred with a very low frequency (0·04%), suggesting that behavioural limitations linked to the necessity to conserve energy to survive repeated fasting, rather than restricted oxygen storage capacity, constrained pup diving behaviour. 6. Hence, these animals appear to trade-off the early development of both their physiological and behavioural diving abilities in favour of body fat accumulation to survive the prolonged fasts they must endure and, potentially, provide a nutritional buffer while they locate appropriate food patches after weaning. While promoting pre-weaning survival, this strategy renders pups more vulnerable to unpredictable changes in environmental conditions and food availability at the transition to independent foraging and, thus, could have negative impact on post-weaning survival. ********************************************************************************* Dr Delphine Verrier DVM, PhD Head of Primate Centre Projet leader for the "Primatology and Health" programme (URES) International Centre for Medical Research of Franceville (CIRMF) B.P. 769, Franceville, Gabon Phone : +241 67 70 62 / Mobile: +241 07 98 56 69 Email: <mailto:ddlafouine@free.fr> ddlafouine@free.fr Skype: ddlafouine1 ********************************************************************************* cid:34994B7F-E15C-441B-8A1E-AFDCC209897F
