MATERNAL EFFECTS ON OFFSPRING MASS AND STAGE OF DEVELOPMENT AT BIRTH IN THE HARBOR SEAL,<i>PHOCA VITULINA</i>

Ellis, Sara L.; Bowen, W. D.; Boness, Daryl J.; Iverson, Sara J.

doi:10.1644/1545-1542(2000)081<1143:meooma>2.0.co;2

Cited by 41 publications

(57 citation statements)

References 42 publications

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“…Results show a highly synchronized pupping season where individual females were generally consistent in their annual timing of pupping, indicating that the interannual variation in pupping phenology that we recorded was the result of individuals responding in a consistent manner, as observed in other colonial breeders [40]. This supports previous work that demonstrated individual consistency in the timing of pupping both in captivity [41], and in the only other individual-based study of breeding phenology in wild harbour seals on Sable Island, Canada [26]. The negative relationship between pupping dates and lactation durations suggests that variation in breeding phenology is condition dependent, as observed in other mammals and birds where the timing of breeding was delayed during years of low food availability [14][15][16]18,42].…”

Section: Discussionsupporting

confidence: 89%

“…If phenological data can offer an indication of changes in their prey base, this could provide an important tool for exploring the causes underlying unexplained pinniped population declines in other regions [23][24][25]. However, these investigations must be underpinned by direct individual-based estimates of pupping dates, which for harbour seals are currently available from only two populations worldwide; Sable Island, Canada [26] and the Moray Firth, Scotland [27]. At other sites, information on the presence of harbour seal pups is available only from broader scale surveys, typically from aircraft, which are used to monitor abundance trends [22,28].…”

Section: Introductionmentioning

confidence: 99%

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Variation in breeding phenology provides insights into drivers of long-term population change in harbour seals

Cordes

Thompson

2013

Proc. R. Soc. B.

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Phenological trends provide important indicators of environmental change and population dynamics. However, the use of untested population-level measures can lead to incorrect conclusions about phenological trends, particularly when changes in population structure or density are ignored. We used individual-based estimates of birth date and lactation duration of harbour seals (Phoca vitulina) to investigate energetic consequences of changes in pupping phenology. Using generalized linear mixed models, we first demonstrate annual variation in pupping phenology. Second, we show a negative relationship between lactation duration and the timing of pupping, indicating that females who pup early nurse their pups longer, thereby highlighting lactation duration as a useful proxy of female condition and resource availability. Third, individual-based data were used to derive a population-level proxy that demonstrated an advance in pupping date over the last 25 years, co-incident with a reduction in population abundance that resulted from fisheries-related shootings. These findings demonstrate that phenological studies examining the impacts of climate change on mammal populations must carefully control for changes in population density and highlight how joint investigations of phenological and demographic change provide insights into the drivers of population declines.

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Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Variation in breeding phenology provides insights into drivers of long-term population change in harbour seals

Cordes

Thompson

2013

Proc. R. Soc. B.

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“…For instance, water depth was found to predict female reproductive success in our study population, possibly because females found in shallow water may benefit from higher prey density (31). In addition, other parameters, such as age and previous breeding experience, were also found to affect female reproductive success in other marine mammals (32)(33)(34).…”

Section: Discussionmentioning

confidence: 68%

Social and genetic interactions drive fitness variation in a free-living dolphin population

Frère

Krützen

Mann

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

206

161

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The evolutionary forces that drive fitness variation in species are of considerable interest. Despite this, the relative importance and interactions of genetic and social factors involved in the evolution of fitness traits in wild mammalian populations are largely unknown. To date, a few studies have demonstrated that fitness might be influenced by either social factors or genes in natural populations, but none have explored how the combined effect of social and genetic parameters might interact to influence fitness. Drawing from a long-term study of wild bottlenose dolphins in the eastern gulf of Shark Bay, Western Australia, we present a unique approach to understanding these interactions. Our study shows that female calving success depends on both genetic inheritance and social bonds. Moreover, we demonstrate that interactions between social and genetic factors also influence female fitness. Therefore, our study represents a major methodological advance, and provides critical insights into the interplay of genetic and social parameters of fitness.animal model | gene-culture coevolution | social learning | reproductive success | relatedness

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“…Most mothers of newborns were also captured and weighed once during the season. Body mass of pups and females taken within 24 h of birth were defined as birth mass and MPPM, respectively (Ellis et al, 2000). Rate of mass gain (mass gained during lactation divided by the number of days between birth and weaning) and weaning mass were also measured on a subset of pups (Bowen, Boness, Iverson et al, 2001).…”

Section: Methodsmentioning

confidence: 99%

Maternal and newborn life‐history traits during periods of contrasting population trends: implications for explaining the decline of harbour seals (Phoca vitulina), on Sable Island

et al. 2003

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Annual censuses of the number of harbour seal Phoca vitulina pups born on Sable Island Canada showed an increasing trend during the 1980s, but a rapid decline through the 1990s from 625 pups in 1989 to only 32 by 1997. Weekly surveys of the North Beach of the island during the 1991-98 breeding seasons showed that the number of adults and juveniles also declined during the 1990s. Despite the dramatic demographic changes, maternal postpartum mass, pup birth mass, relative birth mass, lactation duration, pup weaning mass and relative weaning mass showed no significant trends during 1987-96. However, two traits did change. The age structure of parturient females increased significantly, indicating reduced recruitment to the breeding population. Mean birth date increased by 7 days during the early 1990s, suggesting nutritional stress of females and later implantation dates. This nutritional stress may in turn have been caused by increased competition from the rapidly increasing grey seal population on Sable Island. Although minimum estimates of shark-inflicted mortality can account for much of the decline, evidence suggests that food shortage arising from interspecific competition may have also played a role in causing the decline of the population through effects on fecundity and juvenile survival.

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MATERNAL EFFECTS ON OFFSPRING MASS AND STAGE OF DEVELOPMENT AT BIRTH IN THE HARBOR SEAL,PHOCA VITULINA

Cited by 41 publications

References 42 publications

Variation in breeding phenology provides insights into drivers of long-term population change in harbour seals

Variation in breeding phenology provides insights into drivers of long-term population change in harbour seals

Social and genetic interactions drive fitness variation in a free-living dolphin population

Maternal and newborn life‐history traits during periods of contrasting population trends: implications for explaining the decline of harbour seals (Phoca vitulina), on Sable Island

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