Elephant Seals

2021 ◽  
Author(s):  
Bernard J. Le Boeuf
Keyword(s):  
Graduate Students ◽  
Elephant Seal ◽  
Colony Development ◽  
Lifetime Reproductive Success ◽  
Population Changes ◽  
Elephant Seals ◽  
Fundamental Information ◽  
Reproductive Life ◽  
Changes Over Time ◽  
Feeding Migration

How did the elephant seal survive being driven to the brink of extinction in the nineteenth century? What variables determine the lifetime reproductive success of individual seals? How have elephant seals adapted to tolerate remarkable physiological extremes of nutrition, temperature, asphyxia, and pressure? Answering these questions and many more, this book is the result of the author's 50-year study of elephant seals. The chapters cover a broad range of topics including diving, feeding, migration and reproductive behavior, yielding fundamental information on general biological principles, the operation of natural selection, the evolution of social behavior, the formation of vocal dialects, colony development, and population changes over time. The book will be a valuable resource for graduate students and researchers of marine mammal behavior and reproductive life history as well as for amateur naturalists interested in these fascinating animals.

scholarly journals The Role of the Immune System from an Evolutionary Perspective

2019 ◽  
pp. 198-209
Author(s):  
Carsten Schradin ◽  
Rainer H. Straub
Keyword(s):  
Evolutionary Medicine ◽  
Future Generations ◽  
Lifetime Reproductive Success ◽  
Life History Stage ◽  
Evolutionary Perspective ◽  
Lifetime Fitness ◽  
Fitness Consequences ◽  
Reproductive Life ◽  
Fitness Benefits

“Nothing in Biology makes sense, except in the light of evolution.” This famous citation of Theodosius Dobzhansky also underlies the integrative field of evolutionary medicine, which faces the challenge to combine (patho-)physiological mechanisms with evolutionary function. Here we introduce a concept from the study of animal behavior, which are the four questions of Tinbergen that consider: 1. the ontogeny of an individual describing its development, 2. its physiological machinery, which 3. has fitness consequences influencing 4. the evolutionary history (phylogeny) of future generations. It is shown how this concept can be applied to infectious disease and to chronic inflammatory systemic diseases. Evolutionary medicine takes lifetime reproductive success into account. The hypothesis to be tested is that mechanisms underlying a disease in old age might have higher fitness benefits in the pre-reproductive and/or reproductive life history stage, leading to an overall increased lifetime fitness.

scholarly journals Breeding Colony Dynamics of Southern Elephant Seals at Patelnia Point, King George Island, Antarctica

2020 ◽  
Vol 12 (18) ◽  
pp. 2964
Author(s):  
Katarzyna Fudala ◽  
Robert Józef Bialik
Keyword(s):  
Statistical Tests ◽  
Ground Level ◽  
Elephant Seal ◽  
South Shetland Islands ◽  
Southern Elephant Seal ◽  
King George Island ◽  
Elephant Seals ◽  
Southern Elephant Seals ◽  
Physical Barriers ◽  
Population Counts

During the 2019 breeding season (October-December), a battery-powered DIJ Inspire 2 drone was used to investigate a breeding southern elephant seal colony located at Patelnia Point (ASPA 128, King George Island, South Shetland Islands, maritime Antarctica). Twelve unmanned aerial vehicle (UAV) missions conducted 50–70 m above ground level (AGL) were completed to monitor the breeding ground with a maximum of 0.348 km2. The missions were planned in Pix4D Capture software. A drone, with the support of ground cameras and observations, was used to derive population counts, map harems, and track the phenology of the southern elephant seals. Based on data obtained from the UAV missions, orthophotomaps were created in PIX4D Mapper and then analyzed in QGIS. Calculated values of body size parameters such as body length and orthogonal body surface area were used to determine the age and sex of individuals. Analysis of the ranges of the harems on particular days, supported by an analysis of land conditions that generate physical barriers to the movement of animals, allowed zones in which the transformations of groups of harems took place to be determined. The hypothesized hermeticity of the designated zones was supported by statistical tests. The use of drones allows for comprehensive population analyses of the breeding colonies of elephant seals such as censuses of pups and adult individuals, determination of the sex ratio, and spatial analysis of the distribution of breeding formations. In addition, it allows for a more accurate result than ground counting.

Relationships between plasma ketones and fasting duration in neonatal elephant seals

1990 ◽  
Vol 259 (5) ◽  
pp. R1086-R1089 ◽  
Author(s):  
M. A. Castellini ◽  
D. P. Costa
Keyword(s):  
Ketone Bodies ◽  
Elephant Seal ◽  
Northern Elephant Seal ◽  
Elephant Seals ◽  
Long Duration ◽  
Fat Stores ◽  
Low Levels ◽  
Beta Hydroxybutyrate ◽  
Fasting Duration ◽  
Circulating Levels

Long-duration fasting in mammals can ultimately lead to stage three terminal starvation, which is characterized by depleted fat stores, a metabolic shift away from fat metabolism toward lean tissue catabolism, and a sharp decline in circulating levels of plasma fatty acids and ketone bodies. However, this biochemical shift has never been observed outside of the laboratory in a naturally fasting, nonhibernating mammal. In the current study, plasma levels of the ketone body D-beta-hydroxybutyrate (beta-HBA) were assayed in 10 Northern elephant seal pups during suckling and the postweaning fast and in 12 fasting adult seals. Plasma beta-HBA concentration in the pups was minimal during suckling (0.09 +/- 0.06 mM; n = 10) and began to increase immediately after weaning. The concentration rose until about 55 days into the fast (1.34 +/- 0.36 mM; n = 10) and then declined sharply. Within 10 days of this deflection point, the seal pups left for sea. By contrast, adult elephant seals showed consistently low levels of beta-HBA after several months of fasting (0.06 +/- 0.07 mM; n = 12). The data suggest that the duration of fasting in elephant seal pups may be determined, in part, by biochemical shifts that occur near the end of the fast and that the regulation of ketone concentration is different in fasting neonatal and adult elephant seals.

The skin and hair of the southern elephant seal, Mirounga leonina (Linn.) I. The facial vibrissae

1966 ◽  
Vol 14 (5) ◽  
pp. 855 ◽  
Author(s):  
JK Ling
Keyword(s):  
Elephant Seal ◽  
Sensory Function ◽  
Southern Elephant Seal ◽  
Sweat Glands ◽  
Mirounga Leonina ◽  
Sebaceous Glands ◽  
Elephant Seals

The arrangement, number, and anatomy of the facial vibrissa follicles of the southern elephant seal, Mirounga leonina (Linn.), are described. There are three groups of vibrissae: mystacial, supraorbital, and rhinal, containing approximately 38, 7, and 1 follicles, respectively. These specialized hairs appear to be retained for at least 2 yr and are not shed with the pelage hairs at each annual moult. The histology of the vibrissa follicles and associated organs is described and discussed in relation to their sensory function. Vibrissa follicles of elephant seals are different in anatomy from those described in the mouse and rat: the ringwulst is relatively smaller and, in addition to the sebaceous glands, there are tubular glands of unidentified function but resembling apocrine sweat glands.

scholarly journals Summer and Winter Cycles in Plasma Melatonin Levels in the Elephant Seal (Mirounga Leonina)

1979 ◽  
Vol 32 (6) ◽  
pp. 581 ◽  
Author(s):  
D Griffiths ◽  
RF Seamark ◽  
MM Bryden
Keyword(s):  
Elephant Seal ◽  
Day Length ◽  
Polar Regions ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
Melatonin Concentration ◽  
Plasma Melatonin ◽  
Long Day ◽  
Ambient Lighting ◽  
Nocturnal Rise

Plasma melatonin concentration of immature male elephant seals was determined by radioimmunoassay. Comparison of concentrations during two 24-h periods, one in midsummer and one in midwinter, showed that there was a marked circadian cycle in winter which was greatly modified during the long day length of summer. It is suggested that in summer there was sufficient ambient lighting during the night hours to depress the nocturnal rise in plasma melatonin. The complexity of pineal cycles in the natural environment is stressed, and in this regard the polar regions are of particular interest due to the extreme seasonal changes in day length there.

Physiological implications of continuous, prolonged, and deep dives of the southern elephant seal (Mirounga leonina)

1992 ◽  
Vol 70 (2) ◽  
pp. 370-379 ◽  
Author(s):  
Mark A. Hindell ◽  
David J. Slip ◽  
Harry R. Burton ◽  
Michael M. Bryden
Keyword(s):  
Resting Metabolic Rate ◽  
Elephant Seal ◽  
Southern Elephant Seal ◽  
Adult Males ◽  
Mirounga Leonina ◽  
Physiological Mechanisms ◽  
Elephant Seals ◽  
Aerobic Dive Limit ◽  
Southern Elephant Seals ◽  
Extended Surface

The diving behaviour of 14 adult southern elephant seals was investigated using time depth recorders. Each of the seals performed some dives that were longer than its theoretical aerobic dive limit. Forty-four percent of all dives made by post-moult females exceeded the calculated limit compared with 7% of those made by postbreeding females and less than 1% of those made by adult males. The extended dives displayed characteristics that suggested that they were predominantly foraging dives, although some were apparently rest dives. Dives longer than the calculated aerobic limits often occurred in bouts; the longest consisted of 63 consecutive dives and lasted 2 days. Postmoult females performed longer bouts of extended dives than postbreeding females. Extended surface periods (longer than 30 min) were not related to the occurrence of extended dives or bouts of extended dives. The possible physiological mechanisms that permit such prolonged continuous dives are discussed. Southern elephant seals may increase the aerobic capacity of dives by lowering their metabolism to approximately 40% of the resting metabolic rate on long dives. There is substantial interseal variability in the methods used to cope with long dives. Some animals appear to use physiological strategies that allow them to prolong the time available to them at the bottom of a dive, while others use alternative strategies that may limit the time available at the bottom of their dives.

Branding Elephant Seals for life-history studies

Polar Record ◽  
1967 ◽  
Vol 13 (85) ◽  
pp. 447-449 ◽  
Author(s):  
Susan E. Ingham
Keyword(s):  
Ecological Study ◽  
Individual Recognition ◽  
Elephant Seal ◽  
Southern Elephant Seal ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
Macquarie Island ◽  
Heard Island ◽  
Antarctic Research

In 1949 the Australian National Antarctic Research Expeditions (ANARE) began a long-term ecological study of the Southern Elephant Seal (Mirounga leonina) at HeardIsland. The biologists devised a method of branding seals for individual recognition (Chittleborough and Ealey, 1953) which has been modified only in detail since then (Carrick and Ingham, 1962a). At Heard Island, pups were branded every year until 1953, but the study here came to an end with the closing of the ANARE station in 1955. At Macquarie Island, pups have been branded every year from 1951 to 1965, giving a sample of individuals of known age and known history.

scholarly journals Birth timing after the long feeding migration in elephant seals

2020 ◽  
Author(s):  
Richard Condit ◽  
Roxanne S. Beltran ◽  
Patrick W. Robinson ◽  
Daniel E. Crocker ◽  
Daniel P. Costa
Keyword(s):  
Body Condition ◽  
Birth Interval ◽  
High Speed ◽  
Birth Timing ◽  
Elephant Seals ◽  
Female Age ◽  
Northern Elephant Seals ◽  
Parturition Date ◽  
Feeding Migration ◽  
Feeding Grounds

AbstractNorthern elephant seals migrate long distances from feeding grounds to raise pups during a brief period on breeding beaches. Since gestation sets a parturition date months in advance, timing of the arrival must be precise. We used satellite-tracked animals to examine this timing, establishing arrival and birth dates in 106 migrating females and estimating how far they traveled in the days just before birth. Females arrived a mean of 5.5 days prior to birth (range 1-11, sd=1.6), and females arriving later in the breeding season cut that pre-birth interval by 1.8 days relative to early arrivers. There was no correlation between female body condition, nor female age, and the pre-birth interval. The last 15 days prior to birth, animals traveled as far as 1465 km. Those furthest from the colony traveled > 100 km per day, three times faster than animals near the colony at the same time. Despite migrations covering several thousand kilometers while pregnant, female elephant seals were able to time their arrival within 6 days, swimming steadily at high speed if needed. This allows them to maintain a precise annual cycle for many years consecutively.

scholarly journals Elephant seal muscle cells adapt to sustained glucocorticoid exposure by shifting their metabolic phenotype

2021 ◽  
Author(s):  
Julia Maria Torres-Velarde ◽  
Sree Rohit Raj Kolora ◽  
Jane I. Khudyakov ◽  
Daniel E. Crocker ◽  
Peter H. Sudmant ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Survival ◽  
Food Deprivation ◽  
Mitochondrial Fission ◽  
Elephant Seal ◽  
Metabolic Phenotype ◽  
Cellular Respiration ◽  
Mitochondrial Morphology ◽  
Cellular Mechanisms ◽  
Elephant Seals

AbstractElephant seals experience natural periods of prolonged food deprivation while breeding, molting, and undergoing postnatal development. Prolonged food deprivation in elephant seals increases circulating glucocorticoids without inducing muscle atrophy, but the cellular mechanisms that allow elephant seals to cope with such conditions remain elusive. We generated a cellular model and conducted transcriptomic, metabolic, and morphological analyses to study how seal cells adapt to sustained glucocorticoid exposure. Seal muscle progenitor cells differentiate into contractile myotubes with a distinctive morphology, gene expression profile, and metabolic phenotype. Exposure to dexamethasone at three ascending concentrations for 48h modulated the expression of 6 clusters of genes related to structural constituents of muscle and pathways associated with energy metabolism and cell survival. Knockdown of the glucocorticoid receptor (GR) and downstream expression analyses corroborated that GR mediates the observed effects. Dexamethasone also decreased cellular respiration, shifted the metabolic phenotype towards glycolysis, and induced mitochondrial fission and dissociation of mitochondria-ER interactions without decreasing cell viability. Knockdown of DDIT4, a GR target involved in the dissociation of mitochondria-ER membranes, recovered respiration and modulated antioxidant gene expression. These results show that adaptation to sustained glucocorticoid exposure in elephant seal myotubes involves a metabolic shift toward glycolysis, which is supported by alterations in mitochondrial morphology and a reduction in mitochondria-ER interactions, resulting in decreased respiration without compromising cell survival.

Aggression in the Female Northern Elephant Seal, Mirounga Angustirostris

Behaviour ◽  
1978 ◽  
Vol 64 (1-2) ◽  
pp. 158-171 ◽  
Author(s):  
T.E. Christenson ◽  
B.J. Le Boeuf
Keyword(s):  
Reproductive Success ◽  
Aggressive Behavior ◽  
Elephant Seal ◽  
Mirounga Angustirostris ◽  
Northern Elephant Seal ◽  
Elephant Seals ◽  
Advantages And Disadvantages ◽  
Northern Elephant Seals ◽  
Pup Survival ◽  
Male Activity

AbstractMaternal aggressive behavior of northern elephant seals enhances reproductive success by increasing the likelihood of pup survival. Detailed observations of marked mother-pup pairs revealed that female aggressiveness increased dramatically after giving birth. Maternal aggressiveness also correlated negatively with the number of times the pup was bitten by alien females. Mothers of these pups were less aggressive than the 17 whose pups survived. Pup behavior was not directly related to mortality. Frequencies of interfemale aggressive encounters were compared for different beach areas. Aggression was most frequent on the smallest area, where interfemale distance was the shortest, and tidal action extreme. Aggression was least frequent on the sparcely populated beach, affected little by tide or male activity. Interfemale distance was greatest here. Reproductive advantages and disadvantages of pupping on each area are noted.

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