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 Sea Ice written by David N. Thomas and published by John Wiley & Sons. This book was released on 2008-04-15 with total page 419 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sea ice, which covers up to 7% of the planet’s surface, is a major component of the world’s oceans, partly driving ocean circulation and global climate patterns. It provides a habitat for a rich diversity of marine organisms, and is an extremely valuable source of information in studies of global climate change and the evolution of present day life forms. Increasingly sea ice is being used as a proxy for extraterrestrial ice covered systems. Sea Ice provides a comprehensive review of our current available knowledge of polar pack ice, the study of which is severely constrained by the logistic difficulties of working in such harsh and remote regions of the earth. The book’s editors, Drs Thomas and Dieckmann have drawn together an impressive group of international contributing authors, providing a well-edited and integrated volume, which will stand for many years as the standard work on the subject. Contents of the book include details of the growth, microstructure and properties of sea ice, large-scale variations in thickness and characteristics, its primary production, micro-and macrobiology, sea ice as a habitat for birds and mammals, sea ice biogeochemistry, particulate flux, and the distribution and significance of palaeo sea ice. Sea Ice is an essential purchase for oceanographers and marine scientists, environmental scientists, biologists, geochemists and geologists. All those involved in the study of global climate change will find this book to contain a wealth of important information. All libraries in universities and research establishments where these subjects are studied and taught will need multiple copies on their shelves. David Thomas is at the School of Ocean Sciences, University of Wales, Bangor, UK. Gerhard Dieckmann is at the Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
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 Dissertation Abstracts International written by and published by . This book was released on 2001 with total page 850 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reproductive Ecology of Weddell Seals Leptonychotes Wedelli in McMurdo Sound Antarctica written by Susanne Elaine Braun Hill and published by . This book was released on 1985 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evolution From Molecules to Men written by D. S. Bendall and published by CUP Archive. This book was released on 1983 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: Giving a broad view of biological evolution the topics discussed here range from the history of the development of evolutionary thought, through current problems in molecular evolution and the evolution of whole organisms, to evolution of behaviour, sociobiology and man's place in evolution.
Download or read book Canadian Journal of Zoology written by and published by . This book was released on 2004 with total page 742 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Exploring the relationship between parental relatedness and male reproductive success in the Antarctic fur seal Arctocephalus gazella written by J.I. HOFFMAN and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book American Doctoral Dissertations written by and published by . This book was released on 2000 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Antarctic Ecosystems written by William Davison and published by . This book was released on 2000 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Population Genetics and Mating System of Antarctic Fur Seals Arctocephalus Gazella at Livingston Island Antarctica written by Carolina Aimoré Bonin and published by . This book was released on 2012 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: Antarctic fur seals, Arctocephalus gazella, were hunted to near-extinction in the early 1800's, but have recovered during the past 70 years to re-colonize most of their historical range. The large South Georgia (SG) fur seal population has been considered the main source of immigrants that re-colonized other areas, including Livingston Island (LI). Despite being one of the most exploited marine mammal species, clear evidence for a genetic bottleneck is lacking and instead, exceptionally high genetic diversity has been detected. Nevertheless, little is known about population-level patterns of genetic structure, or how this species' polygynous mating system may influence such patterns. This thesis fills some of this knowledge gap via extensive efforts in the field and in the laboratory, where over 1,000 individual samples were processed to obtain data on 17 highly polymorphic microsatellite markers; of these, 365 were also sequenced for mtDNA hypervariable region 1. The results of this work uncovered : (i) unexpected genetic differentiation between SG and LI indicating that LI was re-colonized by immigrants from one or more sources in addition to SG, (ii) remarkably high male reproductive success at a low-density LI colony during four breeding seasons, suggesting reduced competition among males at LI relative to the high-density colony of Bird Island (SG) (iii) a low percentage of rematings among individuals over the course of a decade, which was surprising considering the high level of breeding site fidelity and male reproductive skew found in this species, and (iv) one case of multiple-paternity in Antarctic fur seals among twins, showing that females may often escape control of territorial males within a breeding period. Not only do these findings provide unique insights into the remarkable re-colonization of Antarctic fur seals, but they also emphasize the importance of satellite populations for harboring genetic diversity through a period of profound anthropogenic disturbance. Additionally, by revealing complexities within male and female breeding behavior, this work advances our overall understanding of polygyny, providing insight into how it might function under different population densities and how individuals may interact over the course of their lives within this mating system.
Download or read book Reproduction in Mammals written by Virginia Hayssen and published by JHU Press. This book was released on 2017-10-27 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Newborn mammals can weigh as little as a dime or as much as a motorcycle. Some receive milk for only a few days, whereas others nurse for years. Humans typically have only one baby at a time following nine months of pregnancy, but other mammals have 20 or more young after only a few weeks in utero. What causes this incredible reproductive diversity? Reproduction in Mammals is a fascinating examination of the diverse reproductive strategies of a broad spectrum of mammals and the ways in which natural selection has influenced that diversity. While accounts of reproduction in individual taxa abound, this unique book's comprehensive coverage gathers stories from many taxa into a single, cohesive perspective that centers on the reproductive lives of females. The authors shed light on intriguing questions such as: Do bigger moms have bigger babies? Do primates have longer pregnancies than other groups? Do aquatic animals have particular patterns? Do carnivores like lions often produce larger litters than prey species? The book opens with the authors' definition of what constitutes a female perspective and an examination of the evolution of reproduction in mammals. It then outlines the individual female: her genetics, anatomy, and physiology. From this nuanced basis, the text progresses to mirror the female reproductive cycle and includes her interactions with males and offspring. The final section contextualizes the reproductive cycle within the rest of the world--both abiotic and biotic environments. To close, the authors include dedicated chapters on human concerns: conservation and women as mammals. Readers will come away from this thought-provoking book with an understanding not only of how reproduction fits into the lives of female mammals but also of how biology has affected the enormously diverse reproductive patterns of the phenotypes we observe today."-- Provided by publisher.
Download or read book Mating Strategies and Reproductive Success of the Male Pacific Harbor Seal phoca Vitulina Richardsi written by Sean Arthur Hayes and published by . This book was released on 2002 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Low reproductive success in territorial male Antarctic fur seals Arctocephalus gazella suggests the existence of alternative mating strategies written by N.J. GEMMELL and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
