Survival Rates of the California Sea Lion,<i>Zalophus californianus</i>, in Mexico

Hernández‐Camacho, Claudia J.; Aurioles‐Gamboa, David; Laake, Jeffrey L.; Gerber, Leah R.

doi:10.1644/07-mamm-a-404.1

Cited by 48 publications

(62 citation statements)

References 45 publications

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“…The genetic parameters are MHC-DRB divergence (MHC div and its square, MHC div number of functionally important loci or genome-wide levels of heterozygosity. Surveys on marine mammals in general, and pinnipeds in particular, indicate that pathogens (especially nematodes and viruses) are one of the major causes for mortality in these species [22,40], with mortality being especially high during early life [38,41]. The immunologically important MHC genes therefore provide a clear candidate locus for fitness.…”

Section: Discussionmentioning

confidence: 99%

Divergent allele advantage at MHC-DRB through direct and maternal genotypic effects and its consequences for allele pool composition and mating

et al. 2013

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It is still debated whether main individual fitness differences in natural populations can be attributed to genome-wide effects or to particular loci of outstanding functional importance such as the major histocompatibility complex (MHC). In a long-term monitoring project on Galápagos sea lions (Zalophus wollebaeki), we collected comprehensive fitness and mating data for a total of 506 individuals. Controlling for genome-wide inbreeding, we find strong associations between the MHC locus and nearly all fitness traits. The effect was mainly attributable to MHC sequence divergence and could be decomposed into contributions of own and maternal genotypes. In consequence, the population seems to have evolved a pool of highly divergent alleles conveying near-optimal MHC divergence even by random mating. Our results demonstrate that a single locus can significantly contribute to fitness in the wild and provide conclusive evidence for the 'divergent allele advantage' hypothesis, a special form of balancing selection with interesting evolutionary implications.

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Section: Discussionmentioning

confidence: 99%

Divergent allele advantage at MHC-DRB through direct and maternal genotypic effects and its consequences for allele pool composition and mating

et al. 2013

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“…For example, in both Californian and Steller sea lions, adult females have higher survival rates than adult males (Pendleton et al. 2006, Hernandez‐Camacho et al. 2008).…”

Section: Possible Reasons For the Nz Sea Lion Declinementioning

confidence: 99%

The population decline of the New Zealand sea lion Phocarctos hookeri: a review of possible causes

Robertson¹,

Chilvers²

2011

Mammal Review

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1. The New Zealand (NZ) sea lion Phocarctos hookeri is NZ's only endemic pinniped and is listed as 'nationally critical'. The species breeds in the NZ sub-Antarctic: 71% of the population at the Auckland Islands (2010 pup production: 1814 Ϯ 39) and the remaining 29% on Campbell Island (726 pups in 2010). 2.Pup production at the Auckland Islands has declined by 40% since 1998 (1998: 3021 pups produced): only 1501 pups were born in 2009. This decline is directly linked to philopatric females not returning to breeding areas. While the Auckland Island population has declined, the Campbell Island population appears to be increasing slowly. 3. Potential reasons for the decline in the Auckland Island population, but not in the Campbell Island population, include non-anthropogenic factors: (i) disease epizootics, (ii) predation, (iii) permanent dispersal or migration, (iv) environmental change; and anthropogenic impacts: (v) population 'overshoot', (vi) genetic effects, (vii) effects of contaminants, (viii) indirect effects of fisheries (i.e. resource competition) and (ix) direct effects of fisheries (i.e. by-catch deaths). Of the nine potential reasons examined here, six can be discounted (ii-vii). Bacterial epizootics (i) occur in the NZ sea lion population, but their impact has predominantly increased pup mortality, which is unlikely to cause the severe decline observed, as pup mortality throughout the species is naturally high and variable. 4. The most plausible hypotheses, based on available evidence, are that the observed decline, in particular, the decreasing number of breeding females in the Auckland Island population, is caused by (viii) fisheries-induced resource competition and (ix) fisheries-related by-catch. By-catch is the main known anthropogenic cause of mortality in the species. Competition with fisheries resulting in resource competition, nutrient stress and decreased reproductive ability in NZ sea lions should be a priority area for future research.

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“…, Hernández‐Camacho et al . ). Consequently, population analysis has often been based on trends in indices such as annual counts of pups or adults, but the causal factors producing the trends are often unknown (Lowry et al .…”

mentioning

confidence: 97%

Age‐ and sex‐specific survival of California sea lions (Zalophus californianus) at San Miguel Island, California

DeLong

Melin

Laake

et al. 2017

Marine Mammal Science

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We conducted a mark‐recapture study of California sea lions (Zalophus californianus) using pups branded on San Miguel Island, California, from 1987 to 2014, and annual resightings from 1990 to 2015. We used the Burnham model (Burnham 1993), an extension of the Cormack‐Jolly‐Seber mark‐recapture model, which includes recoveries of dead animals, to analyze age, sex, and annual patterns in survival. Generally, females had higher survival than males. For female pups, the average annual survival was 0.600 and for male pups it was 0.574. Yearling survival was 0.758 and 0.757 for females and males, respectively. Peak annual survival was at age 5 and was 0.952 for females and 0.931 for males. Pups with larger mass at branding had higher survival as pups and yearlings, but the effect was relative within each cohort because of large between‐cohort variability in survival. Annual variability in sea surface temperature (SST) affected survival. For each 1°C increase in SST, the odds of survival decreased by nearly 50% for pups and yearlings; negative SST anomalies yielded higher survival. Annual variation in male survival was partly explained by leptospirosis outbreaks. Our study provides a unique view of one demographic parameter that contributed to the successful recovery of the California sea lion population.

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Survival Rates of the California Sea Lion,Zalophus californianus, in Mexico

Cited by 48 publications

References 45 publications

Divergent allele advantage at MHC-DRB through direct and maternal genotypic effects and its consequences for allele pool composition and mating

Divergent allele advantage at MHC-DRB through direct and maternal genotypic effects and its consequences for allele pool composition and mating

The population decline of the New Zealand sea lion Phocarctos hookeri: a review of possible causes

Age‐ and sex‐specific survival of California sea lions (Zalophus californianus) at San Miguel Island, California

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