Download or read book Recruitment Probabilities and Reproductive Costs for Weddell Seals in Erebus Bay Antarctica written by Gillian Louise Hadley and published by . This book was released on 2006 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of life history traits such as age at first reproduction and the evaluation of recruitment probabilities and reproductive costs allow insight regarding the diverse factors and mechanisms shaping reproductive strategies. We investigated these mechanisms using a 26-year mark-resight dataset for Weddell seals (Leptonychotes weddellii) in Erebus Bay, Antarctica. Mean age at first reproduction was 7.62 years of age (SD=1.71), but varied from four to 14 suggesting the presence of important heterogeneity in quality among females. Survival rate was maximized for offspring of age-14 mothers (=0.70 [=0.08]), whereas recruitment probability was highest for pups born to youngest-breeding mothers. For example, probability of recruitment at age 7 was an average of 43% lower for seals born to age-14 mothers than for seals born to age-6 mothers. These results suggest the influence of countervailing selection (where favored genotypes for reproductive success are generally those that are selected against as juveniles). Sea-ice extent affected annual recruitment rates, likely due to cascading effects of oceanographic conditions on marine primary productivity and fluctuations in food availability for female Weddell seals. Results from the reproductive cost analysis strongly supported the presence of reproductive costs to survival (£p. SE£p. was 0.91 for breeders versus 0.94 for nonbreeders). Costs to fecundity were present for first-time breeders (mean probability of breeding the next year was 0.20 lower for first-time breeders than for experienced breeders). Females that delayed breeding until later in life experienced highest reproductive costs to fecundity, possibly due to their inferiority relative to other individuals in the population, again suggesting the influence of heterogeneity in individual quality. From these analyses we have gained insight into 1) the extent of within-population variation in important life-history characteristics for a long-lived species, and 2) the sources of this variation and potential linkages with environmental variables. Keys to future research will be 1) explaining variation in individual quality with random effects models or by using mass as an indicator variable, and 2) more detailed exploration of appropriate climate and sea-ice indices to elucidate linkages between this top trophic level predator and variation in the Antarctic marine environment.
Download or read book Variation in Temporary Emigration and Survival Rates and Implications for Recruitment for Female Weddell Seals written by Glenn Elton Stauffer and published by . This book was released on 2012 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: The life-history of many colonial-breeding species includes a period of absence from the natal colony followed by a period of attendance as prebreeders prior to first reproduction. During this prebreeder period, survival rates, and the probability of temporary emigration is variable, and patterns of attendance can have implications for future reproduction. We used 26 - 28 years of encounter data of female Weddell seals (Leptonychotes weddellii) in Erebus Bay, Antarctica to estimate variability in survival and temporary emigration rates and to evaluate implications for recruitment rates. Temporary emigration rates were nearly 1 at age 1, decreased until age 8, and increased slightly thereafter. Annual variation in temporary emigration rates was substantial, and rates were positively related to the distance from the fast-ice edge to Erebus Bay and to the population of adult females in the previous year. Recruitment rates varied annually, and were typically, but not always, positively related to the number of years (0, 1, 2+) that a prebreeder had previously attended reproductive colonies in Erebus Bay. Survival rates varied by birth-cohort and were positively related to the extent of current-year winter sea-ice in the Ross Sea. The influence of birth-cohort on survival rates was persistent for several years but did not last indefinitely. Survivorship from birth to age 6 was related to the specific sequence of sea-ice conditions experienced by each cohort, and cohort-specific rates varied from 0.13 (SE = 0.04) to 0.42 (SE = 0.06), and averaged 0.25 (SE = 0.02). Our results suggest that (1) the influences on survival of conditions experienced in early life, along with later influences, act as a filter that determines what proportion of a cohort of female Weddell seals reaches reproductive maturity, and (2) there are benefits and potential costs to prebreeders that are associated with attending reproductive colonies, and the decision to attend or not likely depends on the balance of consequent tradeoffs. Useful avenues for additional research include (1) inter-annual movements within and outside Erebus Bay, especially in relation to previous-year conditions, and (2) implications of prebreeder attendance patterns and age at first reproduction for reproductive success after recruitment.
Download or read book Antarctica written by Gabrielle Walker and published by A&C Black. This book was released on 2012-03-01 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: There have been many books about Antarctica in the past, but all have focused on only one aspect of the continent - its science, its wildlife, the heroic age of exploration, personal experiences or the sheer awesome beauty of the landscape, for example - but none has managed to capture whole story, till now. Gabrielle Walker, author, consultant to New Scientist and regular broadcaster with the BBC has written a book unlike any that has ever been written about the continent. Antarctica weaves all the significant threads into an intricate tapestry, made up of science, natural history, poetry, epic history, what it feels like to be there and why it draws so many different kinds of people back there again and again. It is only when all the parts come together that the underlying truths of the continent emerge. Antarctica is the most alien place on Earth, the only part of our planet where humans could never survive unaided. It is truly like walking on another planet. And yet, in its silence, its agelessness and its mysteries lie the secrets of our past, and of our future.
Download or read book Ethology and Behavioral Ecology of Phocids written by Daniel P. Costa and published by Springer Nature. This book was released on 2022-03-17 with total page 651 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phocid (or earless or true) seals are ecologically diverse, occupying habitats from the tropics to the poles in marine and freshwater and feeding on anything from tiny zooplankton to other marine mammals. There are 18 species of phocid seals, the smallest species (ringed seal) is more than 20 times smaller than the largest (southern elephant seal), with marked sexual dimorphism present in some species. This book examines the behavior, ecology, and physiology that allow phocid seals to inhabit such a wide range of habitats. The book is composed of 16 chapters written by 37 authors from 8 countries. The book first describes the general patterns of phocid behavior, followed by descriptions of what is known about well-studied species. We have taken a holistic approach, focusing not only on the behaviors themselves but also on the factors that constrain the expression of behavior and the proximate mechanisms driving behavior. In many cases, the chapters represent collaborations between well-established researchers and early-mid career individuals who bring new perspectives to help carry the field of phocid behavioral ecology well into the future.
Download or read book Modeling Demographic Processes in Marked Populations written by David L. Thomson and published by Springer Science & Business Media. This book was released on 2008-12-11 with total page 1110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Here, biologists and statisticians come together in an interdisciplinary synthesis with the aim of developing new methods to overcome the most significant challenges and constraints faced by quantitative biologists seeking to model demographic rates.
Download or read book Mass Dynamics of Weddell Seals in Erebus Bay Antarctica written by Kelly Michelle Proffitt and published by . This book was released on 2008 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: An individual's body mass is an important life history trait that may vary with environmental conditions and be related to reproductive performance. In this dissertation, we used a 35-year dataset to investigate variations in body mass of Weddell seals (Leptonychotes weddellii) in Erebus Bay, Antarctica with goals of linking environmental conditions, body mass, and reproductive performance. We predicted that variations in environmental conditions and maternal traits would correlate with variations in maternal body mass at parturition, and that variations in maternal body mass may be linked with offspring's body mass and survival probability. We found maternal body mass at parturition showed substantial age- and environmental-related variations. Maternal body mass increased with age through the young and middle ages, and evidence of senescent declines in body mass was found amongst the oldest ages. Additionally, body mass at parturition was strongly influenced by environmental variations during the pregnancy period, specifically body mass was negatively correlated with sea-ice extent and positively correlated with the Southern Oscillation. Annually, pup weaning mass was highly variable. Pup weaning mass was negatively correlated with summer sea-ice extent and positively correlated with summer Southern Oscillation, and these two variables explained 86% of the annual variation in the population average weaning mass. Weaning mass was positively correlated with juvenile survival probability, particularly for males, and we estimated the odds of a male surviving from weaning to age 3 increased 7.3% for every 10 additional kilograms of body mass accrued by weaning. Together, these results suggest large-scale atmospheric-oceanographic variations may affect Weddell seal maternal foraging success and ultimately reproductive performance. Finally, we investigated statistical methodologies accounting for measurement error in photogrammetrically estimated body mass with goals of developing techniques to employ estimated body mass as a covariate in simple linear regression models. We demonstrated that error associated with estimating body mass induces bias in regression statistics and decreases model explanatory power and we described simple statistical techniques accounting for measurement error in covariates. These statistical developments may allow future studies to employ photogrammetric mass estimation techniques and utilize estimated body mass as a covariate in ecological modeling exercises.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2006 with total page 854 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Male Reproductive Success Relatedness and the Mating System of Weddell Seals in Mcmurdo Sound Antarctica written by Thomas Scott Gelatt and published by . This book was released on 2001 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamics of a Weddell Seal Leptonychotes Weddellii Population in McMurdo Sound Antarctica written by Michael Foley Cameron and published by . This book was released on 2001 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Weddell Seals written by Jeremy Schmidt and published by Weddell Seal Science. This book was released on 2023-10-06 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: For more than 50 years, the Weddell Seal Science project has been studying the world’s southernmost breeding mammal in its farthest-south location, McMurdo Sound, on the ice-bound edge of Antarctica. This book explores the life history of Weddell seals — surprisingly approachable big-eyed, smiling-faced creatures — and details the science of studying them: the techniques, the motivations, the objectives, and the results. Although science is at the heart of the book, this is also an adventure story about scientists living in a remote field camp, far out on the sea ice, surrounded by glaciers, where you can feel the ocean pulsing beneath your feet. Seals are all around, penguins walk through camp, the weather can be exquisitely beautiful or too severe to step outside. Simply being there would be a wonderful experience on its own but in this case the objective is science — a deeper understanding of our endlessly fascinating planet.
Download or read book To Pup Or Not to Pup Using Physiology and Dive Behavior to Answer the Weddell Seal s Overwinter Question written by Michelle R. Shero and published by . This book was released on 2015 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: Female Weddell seals (Leptonychotes weddellii) haul-out on the fast-ice surrounding the Antarctic continent in October and November each year to give birth to and nurse their pups. Breeding follows directly after weaning (December) and the annual molt begins in January-February. Animals reduce foraging efforts during the lactation and molting periods, but very little is known regarding the influence of this reduced activity on physiological condition. After a period of embryonic diapause, the annual molt coincides with embryo attachment and the start of active gestation. Consequently, female physiological condition at this time may influence reproductive success the following year. Overall female health and the ability to forage successfully throughout the gestation period (austral winter) may impact the likelihood that a pregnancy is brought to term. Therefore, this study tested whether overwinter changes in Weddell seal physiology and foraging efforts are reflected in reproductive outcomes the following year (i.e., to answer the over winter question of "to pup or not to pup?"). From 2010-2012, 100 (January-February: n = 53; October-November: n = 47) adult female Weddell seals were captured in Erebus Bay, Antarctica to assess overwinter changes in physiological condition and/or dive behavior that may be associated with reproductive success. Morphometric measurements and isotopic dilution procedures revealed that female Weddell seals gain ~10-15% of their body mass across the winter period, primarily in the form of blubber and lipid mass. The proportion of mass and lipid gain was similar regardless of whether females returned the following year and successfully gave birth, or did not produce a pup. Further, the amount of mass and energy acquired across gestation in the Weddell seal was markedly less than previously reported for other phocid species. Despite changes in activity patterns and body composition, Weddell seals maintained blood hemoglobin and muscle myoglobin concentrations across the winter. Therefore, Weddell seal total body oxygen stores and calculated aerobic dive limit (cADL) were conserved. This ensures that females have the physiological capabilities to effectively forage directly following the annual molt when they are at their leanest and must regain body mass and lipid stores. Although aerobic capacities did not change, dive effort varied considerably throughout the austral winter. Proxies of dive effort (duration, depth, %dives > cADL) were highest just after the molt (January-February) and just prior to the subsequent pupping season (August-September). Additionally, the proportion of each day spent diving increased mid-winter. Females that were observed the following year with a pup significantly increased all indices of foraging effort during the austral winter as compared to females that returned without a pup. This study is the first to identify and measure differences in dive efforts due to reproductive status, and indicates that successful reproduction is associated with greater foraging effort.
Download or read book Assessing Weddell Seal Maternal Investment in Offspring written by Jennifer Michelle Mannas and published by . This book was released on 2011 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reproduction is costly and involves a number of sequential physiological processes that require different levels of energetic investment. In mammalian species gestation and lactation require the most energy and the amount of energy invested in reproduction is reflected in litter size at birth and by offspring growth through weaning. The object of this study was to describe variation in Weddell seal (Leptonychotes weddellii) pup mass at birth and during several ages of the lactation/nursing period, and to evaluate the ability of several maternal traits to explain this variation. Mass measurements were collected from 887 pups at parturition and throughout lactation in Erebus Bay, Antarctica during the 2004 through 2010 field seasons and maternal traits were taken from a long term database. Analysis demonstrated high individual variation in pup mass within a season and modest variation among seasons which suggests that pup mass may be correlated with individual animal attributes rather than annual variation in environmental conditions. Maternal age, a female's reproductive status the previous season and their interaction were found to be the most influential maternal traits. Pup body mass at parturition and during lactation showed maternal age-related variation with evidence of senescence during pre-partum investment and terminal investment during post-partum investment. A female's reproductive status in one season affected her reproductive investment during lactation in consecutive seasons but that effect was correlated with age. Younger females who pupped in consecutive seasons weaned larger pups than those females who were of the same age and did not give birth in consecutive seasons. The opposite was found to be true for older females. The variation in the affect of maternal traits on maternal investment may be due to the increased energy requirement of lactation, age specific changes in reproductive costs, and a senescent decline in physiological function.
Download or read book The Evolution of Senescence in the Tree of Life written by Richard P. Shefferson and published by Cambridge University Press. This book was released on 2017-02-23 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: The existing theories on the evolution of senescence assume that senescence is inevitable in all organisms. However, recent studies have shown that this is not necessarily true. A better understanding of senescence and its underlying mechanisms could have far-reaching consequences for conservation and eco-evolutionary research. This book is the first to offer interdisciplinary perspectives on the evolution of senescence in many species, setting the stage for further developments. It brings together new insights from a wide range of scientific fields and cutting-edge research done on a multitude of different animals (including humans), plants and microbes, giving the reader a complete overview of recent developments and of the controversies currently surrounding the topic. Written by specialists from a variety of disciplines, this book is a valuable source of information for students and researchers interested in ageing and life history traits and populations.
Download or read book Antarctic Nutrient Cycles and Food Webs written by W.R. Siegfried and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 715 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is a pleasure and a distinct honour for me to greet the participants, guests and ob servers of this Fourth International Symposium on Antarctic Biology which has adopted nutrient cycles and food webs as its central theme. On behalf of the Scientific Committee on Antarctic Research (SCAR) and other bodies of the International Council of Scientific Unions (ICSU), I bid you welcome. SCAR is pleased to acknowledge the role of the co-sponsors for this Symposium which include the Scientific Committee on Oceanic Research (SCOR), the Interna tional Association of Biological Oceanography (IABO), and the International Union of Biological Sciences (IUBS). In addition, SCAR and its co-sponsors wish to acknowledge the financial support of the Council for Scientific and Industrial Re search (CSIR) and the Department of Transport (DOT) of the South African govern ment. Nor should we forget to acknowledge also the role of the South African Scientific Committee on Antarctic Research (SASCAR) and one of its leaders and Vice President of SCAR, Mr. Jan de Wit, in arranging this charming venue for this Symposium.
Download or read book Antarctic Peninsula Compendium written by Ron Naveen and published by . This book was released on 2011-03 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: First published in 1997, the Compendium is an important reference tool for everyone who works in or visits the Antarctic Peninsula - setting forth updated site-descriptive information, census data, species presence/absence data, and regional maps compiled by the Antarctic Site Inventory project since 1994. The Inventory is operated by the US non-profit science and educational organization Oceanites, Inc., the only non-profit, publicly supported, science project working in Antarctica, and the only project monitoring and analysing environmental changes throughout the vastly warming Antarctic Peninsula ecosystem, where it's warming faster - or as fast - as any other location on Earth. The new, 3rd edition covers the 142 sites visited and censused by Antarctic Site Inventory researchers in 17 field seasons through February 2011.
Download or read book Antarcticness written by Ilan Kelman and published by UCL Press. This book was released on 2022-02-08 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Antarcticness joins disciplines, communication approaches and ideas to explore meanings and depictions of Antarctica. Personal and professional words in poetry and prose, plus images, present and represent Antarctica, as presumed and as imagined, alongside what is experienced around the continent and by those watching from afar. These understandings explain how the Antarctic is viewed and managed while identifying aspects which should be more prominent in policy and practice. The authors and artists place Antarctica, and the perceptions and knowledge through Antarcticness, within inspirations and imaginations, without losing sight of the multiple interests pushing the continent’s governance as it goes through rapid political and environmental changes. Given the diversity and disparity of the influences and changes, the book’s contributions connect to provide a more coherent and encompassing perspective of how society views Antarctica, scientifically and artistically, and what the continent provides and could provide politically, culturally and environmentally. Offering original research, art and interpretations of different experiences and explorations of Antarctica, explanations meld with narratives while academic analyses overlap with first-hand experiences of what Antarctica does and does not – could and could not – bring to the world.
Download or read book Antarctic Climate Change and the Environment written by John Turner and published by . This book was released on 2009 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt:
