Mitochondrial DNA structure and colony expansion dynamics of New Zealand fur seals (Arctocephalus forsteri) around Banks Peninsula

New Zealand fur seals are one of many pinniped species that survived the commercial sealing of the eighteenth and nineteenth centuries in dangerously low numbers. After the enforcement of a series of protection measures in the early twentieth century, New Zealand fur seals began to recover from the brink of extinction. We examined the New Zealand fur seal populations of Banks Peninsula, South Island, New Zealand using the mitochondrial DNA control region. We identified a panmictic population structure around Banks Peninsula. The most abundant haplotype in the area showed a slight significant aggregated structure. The Horseshoe Bay colony showed the least number of shared haplotypes with other colonies, suggesting a different origin of re-colonisation of this specific colony. The effective population size of the New Zealand fur seal population at Banks Peninsula was estimated at approximately 2500 individuals. The exponential population growth rate parameter for the area was 35, which corresponds to an expanding population. In general, samples from adjacent colonies shared 4.4 haplotypes while samples collected from colonies separated by between five and eight bays shared 1.9 haplotypes. The genetic data support the spill-over dynamics of colony expansion already suggested for this species. Approximate Bayesian computations analysis suggests re-colonisation of the area from two main clades identified across New Zealand with a most likely admixture coefficient of 0.41 to form the Banks Peninsula population. Approximate Bayesian computations analysis estimated a founder population size of approximately 372 breeding individuals for the area, which then rapidly increased in size with successive waves of external recruitment. The population of fur seals in the area is probably in the late phase of maturity in the colony expansion dynamic.     

Interannual variation in pup production and the timing of breeding in benthic foraging Australian fur seals

Large interannual variations in reproductive success caused by fluctuations in oceanography and prey availability are common to many species of air breathing epipelagic predators. In contrast, little is known about variation in benthic foragers such as Australian fur seals ( Arctocephalus pusillus doriferus ). Between 1997 and 2007, pup production was assessed in 9 yr, while the timing of breeding and adult female condition was assessed in 5 yr at Kanowna Island in Bass Strait, southeastern Australia. Pup production was variable (     = 1,726 ± 42, range = 1,386–2,301), but without temporal trend, as was median birth date (     = 23 November ± 1, range = 21–25 November) and pupping synchrony (period of 90% births:     = 28 ± 2 d, range = 23–31 d). Pup production was negatively correlated with median birth date and positively correlated with female condition, winter sea-surface temperature (SST) and zonal wind strength within Bass Strait. Pup production was also negatively correlated with SST in the previous summer within Bass Strait and in the eastern Great Australian Bight upwelling region. The results suggest that the reproductive success of Australian fur seals is influenced by oceanography but less so than in otariids foraging epipelagically in major upwellings. Despite spanning several El Niño events, no correlation between pup production and the Southern Oscillation Index was observed.     

Morphological and genetic evidence for two evolutionarily significant units (ESUs) in the South American fur seal, <Emphasis Type="Italic">Arctocephalus gazella</Emphasis>

The South American fur seal (Arctocephalus australis) is widely distributed, occurring along both the Atlantic and the Pacific coasts of South America. Previous work suggests there may be more than one subspecies, highlighting the need for further study. Here, we combine traditional and geometric morphometric analysis of skull shape and size with genetic data to compare two populations of South American fur seals, one from Uruguay and one from Peru. As a control group we used material from the closely related species Arctocephalus gazella. Both techniques of morphometric analysis reveal pronounced geographic variation in size and shape of the skull, with Peruvian specimens (n = 102) being larger than Uruguayan skulls (n = 133) and significant shape differences concentrated in the rostral region. Similarly, seven highly polymorphic microsatellite loci reveal highly significant differences in allele frequency. Moreover, Bayesian analysis implemented using the program structure reveals two separate clusters corresponding perfectly to the two populations, with an assignment test correctly placing over 98% of specimens in their population of origin. This degree of differentiation for both genetic and morphological traits suggests complete and possibly prolonged isolation to the extent that we believe these populations should be considered distinct evolutionarily significant units.     

The biology of the stoat (Mustela erminea) in the National Parks of New Zealand III. Morphometric variation in relation to growth,geographical distribution,and colonisation

Abstract

A total of 1599 stoats were collected from 14 study areas (including all 10 National Parks) from 1972 to 1976. Samples were larger in summer, and contained more females. Young stoats are born in September-October, and females reach adult weight by the following March, though males not until after August. There was significant geographic variation in the body size of adult stoats sampled: males from lowland podocarp/broadleaved forests averaged 3% smaller than males from upland beech forests in skull length, and 4% smaller in head-and-body length. This pattern was repeated, less clearly, in females and in young (approximately 2–5 months old). In contrast with stoats in Britain, assumed to be still the same size as the colonising stock introduced into New Zealand in 1884 and subsequently, males from lowland podocarp forests were unchanged or possibly smaller, and males from upland beech forests were larger; females were larger in all habitats. In males, the extent of geographic variation is almost as great in New Zealand as in the whole of continental Europe. Possible explanations of this pattern are discussed.     

Modeling the effects of El Niño, density-dependence, and disturbance on harbor seal (Phoca vitulina) counts in Drakes Estero, California: 1997–2007

Harbor seal ( Phoca vitulina ) haul-out site use may be affected by natural or anthropogenic factors. Here, we use an 11-yr (1997–2007) study of a seal colony located near a mariculture operation in Drakes Estero, California, to test for natural (El Niño-Southern Oscillation (ENSO), density-dependence, long-term trends) and anthropogenic (disturbance or displacement related to oyster production activities) factors that may influence the use of haul-out subsites. Annual mariculture related seal disturbance rates increased significantly with increases in oyster harvest ( r _s= 0.55). Using generalized linear models (GLMs) ranked by best fit and Akaike's Information Criteria, ENSO and oyster production (as a proxy for disturbance/displacement) best explained the patterns of seal use at all three subsites near the mariculture operations, with effects being stronger at the two subsites closest to operations. Conversely, density-dependence and linear trend effects poorly explained the counts at these subsites. We conclude that a combination of ENSO and mariculture activities best explain the patterns of seal haul-out use during the breeding/pupping season at the seal haul-out sites closest to oyster activities.     

The taxonomy, distribution and origins of two species of Phaulacridium (Orthoptera: Acrididae) in the South Island of New Zealand

Extensive collecting of grasshoppers of the genus Phaulacridium in New Zealand has indicated the presence of a new species, P. otagoense Ritchie & Westerman, distributed parapatrically with respect to the common and widespread species, P. marginale (Walker) in the Mackenzie Plains and Central Otago regions of South Island. Phaulacridium otagoense occurs on exposed hillsides with bare patches caused by rabbit grazing while P. marginale is found in adjoining areas with lusher vegetation and less severe erosion. A key to the two species and a differential diagnosis are provided. Statistically significant differences in morphology and in nuclear DNA content and chiasma frequency confirm the separate species status of the two taxa. The present-day distribution and probable allopatric origin of P. otagoense from P. marginale is discussed in the light of past and present vegetational and climatic factors and their recent disruption by human agencies. The holotype and some paratypes of P. otagoense are deposited in the Canterbury Museum, Christchurch, New Zealand and further paratypes are deposited in the Australian National Insect Collection, Canberra and the British Museum (Natural History), London