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Titolo:
ONTOGENY OF DIFFERENTIAL MIGRATION AND SEXUAL SEGREGATION IN NORTHERNELEPHANT SEALS
Autore:
STEWART BS;
Indirizzi:
HUBBS SEA WORLD RES INST,2595 INGRAHAM ST SAN DIEGO CA 92109 UNIV CALIF BERKELEY,BOALT HALL SCH LAW BERKELEY CA 94720
Titolo Testata:
Journal of mammalogy
fascicolo: 4, volume: 78, anno: 1997,
pagine: 1101 - 1116
SICI:
0022-2372(1997)78:4<1101:OODMAS>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
BLACK-TAILED DEER; DIVING BEHAVIOR; SATELLITE TELEMETRY; FORAGING BEHAVIOR; ECOLOGICAL CAUSES; HABITAT USE; MULE DEER; BODY-SIZE; DIMORPHISM; SELECTION;
Keywords:
MIROUNGA ANGUSTIROSTRIS; NORTHERN ELEPHANT SEAL; DIFFERENTIAL MIGRATION; SEXUAL DIMORPHISM; SATELLITE TELEMETRY; SEXUAL SELECTION;
Tipo documento:
Review
Natura:
Periodico
Citazioni:
102
Recensione:
Indirizzi per estratti:
Citazione:
B.S. Stewart, "ONTOGENY OF DIFFERENTIAL MIGRATION AND SEXUAL SEGREGATION IN NORTHERNELEPHANT SEALS", Journal of mammalogy, 78(4), 1997, pp. 1101-1116

Abstract

Adult northern elephant seals (Mirounga angustirostris) are substantially sexually dimorphic in size and in migratory behavior. Both sexes migrate over vast areas of the North Pacific Ocean during biannual migrations between rookeries in California waters and northern foraging grounds, but adult males segregate from adult females during each of these double migrations. I used satellite-linked radiotelemetry to document the ontogeny of differential migration and sexual segregation as ameans to better define the ultimate causal mechanisms of these patterns and to evaluate the potential influence of this sexually dimorphic trait on the magnitude of size dimorphism between sexes in the northern elephant seal. The initial direction of migration (northwesterly from rookeries) was established during the 1st year of life in both malesand females. Differential migration and sexual segregation appears todevelop during puberty, when growth rates of males are substantially greater than those of females, and those patterns are well establishedby the time males are 4.5-5 years old. This outcome suggests that thedevelopment and proximate cause of sexual segregation of northern elephant seals is more precisely related to differential metabolic needs of males during the period of sexual maturation and accelerated growthrather than to sexual differences in gross energy requirements of adults. Segregation appears to confer to pubescent males survival benefits, which more than compensate for the higher mortality that generally is associated with rapid growth during puberty in other taxa with male-biased, sexual dimorphism. The most parsimonious explanation for the evolution of sexual dimorphism in size in northern elephant seals still appears to be sexual selection (intrasexual competition) acting through differential mating success of males. Moreover, differential, rapid growth during puberty and deferred maturity of males versus females are proximate mechanisms promoting larger size of males as adults. I suggest, however, that natural selection has led to sexually dimorphic migratory patterns and segregation of foraging elephant seals and thatthe segregation may partially maintain and, indeed, enhance sexual dimorphism in size.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 19/09/20 alle ore 18:07:42