Maternal body size and condition determine calf growth rates in southern right whales

Southern right whales (Eubalaena australis) have been studied on their nursery ground at Península Valdés, Argentina, every year since 1970. Since 1990, 1,208 individuals have been identified from photographs taken during annual aerial surveys; 618 whales were seen in two or more years. Patterns of habitat use have changed during the study in ways which suggest that right whales may be capable of substantial behavioral and ecological flexibility. One male and three females from Península Valdés have been sighted on other nursery grounds (Tristan da Cunha and southern Brazil). Three individuals from Península Valdés were sighted on feeding grounds off Shag Rocks and South Georgia. Some right whales from Península Valdés showed carbon and nitrogen isotope ratios very similar to those seen in right whales off South Africa, while others showed distinctive isotope ratios indicating that they fed in a different area. Whales of all ages and both sexes moved frequently between three major regions of concentration on the Península Valdés nursery ground. Subadults and adult females with calves were resighted at higher rates than adult males and females in non-calf years. Changes in the geographic distribution of whales at the Península include: (1) abandonment of a major region of concentration; (2) establishment of a nursery area adjacent to thecentre of a growing whalewatching industry; and (3) small-scale shifts in distribution, possibly in response to natural and human disturbances.

Download Full-text

Variation in growth and instar number in field and laboratory Manduca sexta

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2006.0036 ◽

2007 ◽

Vol 274 (1612) ◽

pp. 977-981 ◽

Cited By ~ 48

Author(s):

Joel G Kingsolver

Keyword(s):

North Carolina ◽

Body Size ◽

Manduca Sexta ◽

Growth Rates ◽

Developmental Plasticity ◽

Larval Growth ◽

Physiological Control ◽

Larval Instars ◽

Laboratory Colony ◽

Early Larval Development

The tobacco hornworm Manduca sexta has been an important model system for understanding physiological control of growth, development and metamorphosis of insects for more than half a century. Like all Manduca , M. sexta typically has five larval instars, with developmental commitment to metamorphosis occurring early in the 5th (final) instar. Here we show that M. sexta from a field population in North Carolina (USA) shows substantial intraspecific variation in the number of larval instars when feeding on a modified artificial diet. Individuals with six instars consistently exhibited slower growth rates during early larval development than individuals with five instars. The frequency of individuals with six instars decreased with increased rearing temperature. In contrast, M. sexta from a laboratory colony consistently had five instars, and had more rapid larval growth rates than M. sexta from the field. We identify a threshold body size at the start of the 5th instar that predicts whether an individual will have five (greater than 600 mg) or six instars (less than 600 mg). Variation in field populations in Manduca provides an important resource for understanding physiological control, developmental plasticity and evolution of growth rate, body size and instar number.

Download Full-text

Conservation Advances for the Southern Right Whales in Brazil

Advances in Marine Vertebrate Research in Latin America - Coastal Research Library ◽

10.1007/978-3-319-56985-7_16 ◽

2017 ◽

pp. 441-475 ◽

Cited By ~ 4

Author(s):

Karina Groch

Keyword(s):

Right Whales ◽

Southern Right Whales

Download Full-text