Mate choice explains high genetic diversity in a small founding population of the New Zealand sea lion (Phocarctos hookeri)

2018 ◽  
Vol 66 (6) ◽  
pp. 343
Author(s):  
Imogen Foote ◽  
Stephanie S. Godfrey ◽  
Bruce C. Robertson
Keyword(s):  
Genetic Diversity ◽  
New Zealand ◽  
Mate Choice ◽  
Genetic Lineage ◽  
Source Population ◽  
Founder Population ◽  
Sea Lion ◽  
High Genetic Diversity ◽  
Founding Population ◽  
Phocarctos Hookeri

Founder populations are susceptible to reduced genetic diversity, which can hinder successful population establishment. A new genetic lineage of the New Zealand sea lion (Phocarctos hookeri) has recently colonised the historical range of the New Zealand mainland (Otago Peninsula). Despite a small founding population, previous research indicated that nuclear genetic diversity in the Otago Peninsula population is similar to that of the larger source population (Sandy Bay, Auckland Islands). Our research aimed to identify whether mechanisms of female mate choice could help to explain the unexpectedly high level of genetic diversity in the founder population. We used genetic data at 12 microsatellite loci for mother–pup pairs from both populations, and the software COLONY to identify putative paternal genotypes inferred from allele sharing between known mother–pup pairs. We found that mating pairs were, on average, more related at the Otago Peninsula location. However, Sandy Bay females were mating with males more related to themselves than expected by chance, while the Otago Peninsula females were not. These findings suggest that female choice in this otariid species appears important, although may be constrained in some situations. Our findings also help to explain how the recently founded population is able to maintain a viable, growing population.

Foraging energetics and diving behavior of lactating New Zealand sea lions, Phocarctos hookeri

2000 ◽  
Vol 203 (23) ◽  
pp. 3655-3665 ◽  
Author(s):  
D.P. Costa ◽  
N.J. Gales
Keyword(s):  
New Zealand ◽  
Metabolic Rate ◽  
Dive Depth ◽  
Diving Behavior ◽  
Metabolic Rates ◽  
Sea Lion ◽  
Water Turnover ◽  
Sea Lions ◽  
The Mean ◽  
Phocarctos Hookeri

The New Zealand sea lion, Phocarctos hookeri, is the deepest- and longest-diving sea lion. We were interested in whether the diving ability of this animal was related to changes in its at-sea and diving metabolic rates. We measured the metabolic rate, water turnover and diving behavior of 12 lactating New Zealand sea lions at Sandy Bay, Enderby Island, Auckland Islands Group, New Zealand (50 degrees 30′S, 166 degrees 17′E), during January and February 1997 when their pups were between 1 and 2 months old. Metabolic rate (rate of CO(2) production) and water turnover were measured using the (18)O doubly-labeled water technique, and diving behavior was measured with time/depth recorders (TDRs). Mean total body water was 66.0+/−1.1 % (mean +/− s.d.) and mean rate of CO(2) production was 0. 835+/−0.114 ml g(−)(1)h(−)(1), which provides an estimated mass-specific field metabolic rate (FMR) of 5.47+/−0.75 W kg(−)(1). After correction for time on shore, the at-sea FMR was estimated to be 6.65+/−1.09 W kg(−)(1), a value 5.8 times the predicted standard metabolic rate of a terrestrial animal of equal size. The mean maximum dive depth was 353+/−164 m, with a mean diving depth of 124+/−36 m. The mean maximum dive duration was 8.3+/−1.7 min, with an average duration of 3.4+/−0.6 min. The deepest, 550 m, and longest, 11.5 min, dives were made by the largest animal (155 kg). Our results indicate that the deep and long-duration diving ability of New Zealand sea lions is not due to a decreased diving metabolic rate. Individual sea lions that performed deeper dives had lower FMRs, which may result from the use of energetically efficient burst-and-glide locomotion. There are differences in the foraging patterns of deep and shallow divers that may reflect differences in surface swimming, time spent on the surface and/or diet. Our data indicate that, although New Zealand sea lions have increased their O(2) storage capacity, they do not, or cannot, significantly reduce their at-sea metabolic rates and are therefore likely to be operating near their physiological maximum.

Philopatry and site fidelity of New Zealand sea lions (Phocarctos hookeri)

2008 ◽  
Vol 35 (5) ◽  
pp. 463 ◽  
Author(s):  
B. Louise Chilvers ◽  
Ian S. Wilkinson
Keyword(s):  
New Zealand ◽  
Site Fidelity ◽  
Breeding Area ◽  
Quantitative Investigation ◽  
Sea Lion ◽  
Breeding Sites ◽  
Auckland Island ◽  
Sea Lions ◽  
Breeding Habitats ◽  
Phocarctos Hookeri

The New Zealand sea lion (NZ sea lion), Phocarctos hookeri, is New Zealand’s only endemic pinniped, and one of the worlds rarest otariids. It is classified as ‘Threatened’ based primarily on the low number of breeding sites and restricted distribution. In New Zealand, a species listed as ‘threatened’ is required to be managed to allow its recovery and removal from the list within 20 years. For NZ sea lions this is dependant on the establishment of new breeding areas. However, understanding the recolonisation processes for pinnipeds is still in its infancy with factors such as philopatry needing more research to understand individual dispersal and the recolonisation process. This paper presents the first quantitative investigation into the level of site fidelity and philopatry to breeding beaches in NZ sea lions. Data from resights of NZ sea lions marked as pups from the northern Auckland Island breeding area suggest that both site fidelity and philopatry are important characteristics of this species. Our results show that overall: (1) females have a higher resighting rate than males, particularly at natal sites; (2) female non-natal resightings are predominantly restricted to locations within the northern Auckland Island breeding area (an area of ~10 km2), whereas male resightings are more widely dispersed (up to 700 km to NZ mainland); and (3) philopatry occurs for both sexes, but is more predominant in females than males, with males displaying delay related to sexual and social maturity. The colonisation of new breeding habitats rarely occurs when philopatry is strong and population density is low, stable or declining such as seen for NZ sea lions. Therefore, this research indicates that management of NZ sea lions needs to minimise anthropogenic mortality and encourage population growth to maximise density at breeding sites and encourage females to disperse to establish new breeding areas.

Conservation needs for the endangered New Zealand sea lion,Phocarctos hookeri

2017 ◽  
Vol 27 (4) ◽  
pp. 846-855 ◽  
Author(s):  
B. Louise Chilvers ◽  
Stefan Meyer
Keyword(s):  
New Zealand ◽  
Sea Lion ◽  
Phocarctos Hookeri

scholarly journals Extensive variation at MHC DRB in the New Zealand sea lion (Phocarctos hookeri) provides evidence for balancing selection

Heredity ◽  
2013 ◽  
Vol 111 (1) ◽  
pp. 44-56 ◽  
Author(s):  
A J Osborne ◽  
M Zavodna ◽  
B L Chilvers ◽  
B C Robertson ◽  
S S Negro ◽  
...  
Keyword(s):  
New Zealand ◽  
Balancing Selection ◽  
Sea Lion ◽  
Extensive Variation ◽  
Phocarctos Hookeri

New Zealand sea lion (Phocarctos hookeri) epidemic 2002

2003 ◽  
Vol 51 (1) ◽  
pp. 45-46 ◽  
Author(s):  
PJ Duignan ◽  
I Wilkinson ◽  
MR Alley
Keyword(s):  
New Zealand ◽  
Sea Lion ◽  
Phocarctos Hookeri

scholarly journals Historical population size of the threatened New Zealand sea lion Phocarctos hookeri

2015 ◽  
Vol 97 (2) ◽  
pp. 436-443 ◽  
Author(s):  
Catherine J. Collins ◽  
B. Louise Chilvers ◽  
Matthew Taylor ◽  
Bruce C. Robertson
Keyword(s):  
New Zealand ◽  
Population Size ◽  
Effective Population Size ◽  
Carrying Capacity ◽  
Effective Population ◽  
Sea Lion ◽  
Sea Lions ◽  
Target Values ◽  
Phocarctos Hookeri

Abstract Marine mammal species were exploited worldwide during periods of commercial sealing in the 18th and 19th centuries. For many of these species, an estimate of the pre-exploitation abundance of the species is lacking, as historical catch records are generally scarce and inaccurate. Genetic estimates of long-term effective population size provide a means to estimate the pre-exploitation abundance. Here, we apply genetic methods to estimate the long-term effective population size of the subantarctic lineage of the New Zealand sea lion (NZ sea lion), Phocarctos hookeri . This species is predominantly restricted to the subantarctic islands, south of mainland New Zealand, following commercial sealing in the 19th century. Today, the population consists of ~9,880 animals and population growth is slow. Auckland Island breeding colonies of NZ sea lion are currently impacted by commercial trawl fisheries via regular sea lion deaths as bycatch. In order to estimate sustainable levels of bycatch, an estimate of the population’s carrying capacity ( K ) is required. We apply the genetically estimated long-term effective population size of NZ sea lions as a proxy for the estimated historical carrying capacity of the subantarctic population. The historical abundance of subantarctic NZ sea lions was significantly higher than the target values of K employed by the contemporary management. The current management strategy may allow unsustainable bycatch levels, thereby limiting the recovery of the NZ sea lion population toward historical carrying capacity.

scholarly journals Commensal Rodents in 19th Century Australasia: Diversity, Invasion Routes and the China Connection

2021 ◽  
Author(s):  
Andrew James Veale ◽  
Carolyn King ◽  
Wayne Johnson ◽  
Lara Shepherd
Keyword(s):  
Genetic Diversity ◽  
New Zealand ◽  
Dna Sequences ◽  
Archaeological Site ◽  
House Mice ◽  
Mus Musculus Domesticus ◽  
The South ◽  
The North ◽  
Founding Population ◽  
Norway Rats

Abstract The present genetic diversity of commensal rodent populations is often used to inform the invasion histories of these species, and as a proxy for historical events relating to the movement of people and goods. These studies assume that modern genetic diversity generally reflects early colonising events. We investigate this idea by sequencing the mitochondrial DNA of rodent bones found in a 19th-century archaeological site in The Rocks area of Sydney, Australia, the location of the first historical European port. We identified 19th-century bones from two species, Rattus norvegicus and Mus musculus domesticus. We found six genetic haplotypes in the 39 Norway rats, showing either multiple early introductions or a diverse initial founding population. One of them was identical with Norhap01 common in the North Island of New Zealand, but none was like the haplotype Norhap02 found throughout the South Island. We found three haplotypes in seven house mice, all belonging to the dominant subspecies established in Australia, M.m. domesticus. There was no evidence for M. m. castaneus or M. m. musculus having established there. We had few modern R. norvegicus and M. musculus DNA sequences from Sydney, but those we had did tentatively support the hypotheses that (1) modern samples can represent at least a preliminary estimate of historical diversities and origins, and (2) Asian haplotypes of both Norway rats and of house mice reached the South Island of New Zealand early in colonial times direct from China rather than through Port Jackson.

Variability in the diet of New Zealand sea lion (Phocarctos hookeri) at the Auckland Islands, New Zealand

2009 ◽  
Vol 25 (2) ◽  
pp. 302-326 ◽  
Author(s):  
Laureline Meynier ◽  
Duncan D. S. Mackenzie ◽  
Pádraig J. Duignan ◽  
B. Louise Chilvers ◽  
Patrick C. H. Morel
Keyword(s):  
New Zealand ◽  
Sea Lion ◽  
Phocarctos Hookeri
Sign in / Sign up

Export Citation Format

Share Document