Kiore (Rattus exulans) distribution and relative abundance on a small highly modified island

ABSTRACT

Kiore (Pacific rat; Rattus exulans) is both a target for eradication and a taonga or highly valued species in New Zealand, and its abundance and distribution vary considerably throughout the country. We investigated reports of an abundant kiore population on Slipper Island (Whakahau), off the east coast of New Zealand’s North Island, in March 2017. We trapped kiore to examine their distribution across a range of habitats with varying degrees of human activity. Kiore were captured in all habitats, with particularly high abundance at a campground with a fruiting fig tree (50 kiore per 100 trap nights corrected for sprung traps). We found no evidence of other rat species; Slipper Island appears to remain one of few New Zealand islands with kiore but without ship rats (Rattus rattus) and Norway rats (R. norvegicus), the two other rat species present in New Zealand. Slipper Island potentially provides opportunities to research kiore behaviour and population dynamics in a New Zealand commensal environment, and genetics of an isolated island population.     

Distribution of Aeromonas hydrophila hybridization groups and their virulence properties in Australasian clinical and environmental strains

A total of 182 Aeromonas hydrophila strains isolated from environmental (food and water) and clinical (stool and other sources) samples taken in mainland Australia, Tasmania and New Zealand were assigned to one of three DNA/DNA hybridization groups (HGs) on the basis of biochemical characteristics, and tested with regard to their ability to produce virulence factors. Strains from HG2 were rarely isolated; strains from HG1 were most commonly isolated from clinical sources; and strains from HG3 formed the majority of environmental strains. There was no correlation of HG to geographic source. Strains from HG2 infrequently produced virulence factors. Strains from HG1 were more likely to produce virulence factors if they came from a clinical source. Overall, strains from mainland Australia produced virulence factors more frequently than those from Tasmania or New Zealand. Strains from HG1 may be of more clinical significance than strains from the other two HGs.     

Chloroplast DNA diversity of Hieracium Pilosella (Asteraceae) introduced to New Zealand: reticulation, hybridization, and invasion

The European hawkweed Hieracium pilosella is a successful invader and a troublesome weed in New Zealand. The systematics of the genus Hieracium is extremely complex and contentious, probably due to recent speciation, hybridization, polyploidy, and diverse reproductive strategies. In the first chloroplast DNA survey of the group, we sequenced 285 plants (including H. pilosella and 12 other species of subgenus Pilosella) from New Zealand and Europe for 900 bp of trnL-trnF. Eleven haplotypes were identified with much sharing among species. Three haplotypes (A, D, G) were found in seven, three, and four species, respectively, but two species (H. lactucella and H. auricula) had single, private haplotypes. Our cpDNA data for subgenus Pilosella are consistent with the group's having incomplete lineage sorting and/or recent reticulate evolution. Six haplotypes were identified in H. pilosella, four of these unique to this taxon in our sample. In New Zealand, haplotype A was common and occurred in plants of different ploidy (i.e., 4×, 5×, 6×), whereas haplotypes C, B, and M were restricted to 4×, 5×, and 6× plants, respectively. The distribution of haplotype variation suggests that some or all of the H. pilosella seeds accidentally introduced into New Zealand probably came from east Europe rather than the United Kingdom and that a minimum of four lineages were introduced. Within New Zealand, hybridization of H. pilosella with a related taxon (probably H. praealtum) has occurred at least three times, involving both obligate sexual tetraploids and facultative apomictic pentaploids of H. pilosella.     

The parasites of the Polynesian rat: biogeography and origins of the New Zealand parasite fauna.

Unique aspects of the prehistory and current distribution of the Polynesian rat (Rattus exulans Peale) have been applied to the problem of determining the biogeographical origin of its parasites as found on 'exulans only' islands of New Zealand. The database consists of collated records of both endo- and ectoparasites reported from throughout this rat's geographical range. The analytical method is based on the concepts of Sprent (1969. Immunity to Parasitic Animals, pp. 14-17) and includes the formulation and testing of two hypotheses. A total of six 'heirloom' species is identified, and a further seven are classified as 'old souvenirs'. Contrary to prediction, 11 species are considered to be 'new souvenirs', acquired from other rodent species now present in New Zealand.     

Modelling the distribution and interaction of introduced rodents on New Zealand offshore islands

Aim To establish the factors that correlate with the distribution of the four most commonly introduced rodent species on New Zealand offshore islands — ship rat (Rattus rattus), Norway rat (R. norvegicus), Pacific rat or kiore (R. exulans) and house mouse (Mus musculus) — and examine if these distributions are interactive at the archipelago scale. Location The 297 offshore islands of the New Zealand archipelago (latitude: 34° S to 47° S; longitude: 166° E to 179° E). Methods Data on the distribution of all four introduced rodent species and the characteristics of New Zealand offshore islands were collated from published surveys and maps. The distribution of individual rodent species was regressed on island characteristics using a logistic generalized linear model. Interactions were examined by including the distributions of other rodent species as predictors in models. Results All four rodent species appear to be limited by a variety of factors, which differ between species in both number and type. The distribution of ship rats is limited by the most factors, reflecting the extent of its distribution across the archipelago. The distribution of mice is the least explicative. Only the three rat species interacted in their distribution. The distribution of kiore on offshore islands is significantly negatively related to that of ship rats and to a lesser extent Norway rats. The distribution of mice did not appear affected in any way by the number of other rodent species on an island. Main conclusions Differences in competitive ability and dispersal allow all four species to inhabit the New Zealand archipelago. Kiore distribution appears to be most limited by ship rat (and to a lesser extent Norway rat) distribution. The distribution of kiore was not found to interact with the distribution of mice on offshore islands, as has been suggested by others. The distribution of mice on offshore islands was difficult to model, which highlights the difficulties in managing this species. Overall the results offer valuable insights for management methods to assist preventing the invasion of offshore islands.     

Glycogen synthase phosphatase of rat liver. Its separation from phosphorylase phosphatase on DE-52 columns.

Glycogen synthase D was prepared from rat liver by chromatographing the glycogen pellet on DE-52 columns. It was free of glycogen and phosphorylase and converted readily into synthase I upon incubation with glycogen synthase phosphatase. With this synthase D as substrate, the identity of rat liver glycogen synthase phosphatase was studied by means of DE-52 column chromatography. Under the conditions developed, synthase phosphatase emerged from the columns as a sharp, single peak, and phosphorylase phosphatase came off later. The two phosphatases were also different from each other in stability, synthase phosphatase being less stable than phosphorylase phosphatase.     

Beetles in the diet of six species of deep‐sea fish

Abstract

Four scarab beetles (Acrossidius tasmaniae) and two unidentified weevils were recovered from the guts of a single individual of six deep‐sea fishes trawled from depths of 326–418 m, c. 30–40 km off the Wairarapa coast, North Island, New Zealand. These constitute the first records of terrestrial arthropods in the diet of deep‐sea fishes from the New Zealand region. Possible reasons describing how these terrestrial beetles came to be eaten by these fishes are discussed.     

Hoarding behavior by ship rats (Rattus rattus) in captivity and its relevance to the effectiveness of pest control operations

Hoarding of food items is well known among muroid rodents, but evidence for hoarding behavior among ship rats (Rattus rattus) is scant. Here, we characterize hoarding behavior in ship rats maintained in captivity after capture from the wild. After acclimatization to captivity, 40 ship rats (21 females, 19 males) were presented with baits in experiments designed to emulate a typical poison control operation for vertebrate pests in New Zealand: this involved first offering rats nontoxic cereal baits (of 2- or 6-g size) as a prefeed for three nights consecutively, followed by 6- or 12-g cereal baits laden with 0.15% 1080 on the fourth night. Seventy-eight percent of rats (31/40) hoarded food in distinct cache sites when presented with nontoxic baits although there was no significant effect of bait size or type on hoarding behavior and nor did hoarding behavior vary according to rat gender. When rats were presented with 1080-laden baits, the incidence of hoarding was reduced to 40%, due to the onset of toxicosis. This study indicates that R. rattus will show hoarding behavior analogous to other rat species when presented with an excess of cereal-based baits, at least under conditions of captivity and free from competition. This finding may have practical relevance: since 1080 is the principal toxin used against the major vertebrate pest species in New Zealand (the brushtail possum, Trichosurus vulpecula), ship rats have the potential to deplete supplies of prefeed and/or toxic baits intended for possum control. However, based on typical rat densities recorded in New Zealand native forest (c. 5 rats/ha), the degree of removal and manipulation of toxic baits observed by ship rats here is unlikely to impact adversely on the efficacy of possum control operations.     

Invasion success of the bumblebee, Bombus terrestris, despite a drastic genetic bottleneck

In early 1992, the European bumblebee, Bombus terrestris, was first seen in Tasmania and currently has spread to most of the island. Here, we report on the genetic structure, using micro-satellites, of the invading population from samples collected in the years 1998-2000, a few years after the first sighting of the species in its new area. The data show that the Tasmanian population has a very low genetic diversity, with less than half of the allelic richness (Richness=2.89 alleles; H(exp)=0.591) and lower levels of heterozygosity as compared to populations in New Zealand (4.24 alleles; H(exp)=0.729) and Europe (5.08 alleles; H(exp)=0.826). In addition, the genetic data suggest that the invasion must have happened once, probably around late 1991, and was the result of very few, perhaps only two, individuals arriving in Tasmania. Furthermore, these founders came from the New Zealand population. Today, the population in the south of Tasmania seems to act as a source population from which individuals migrate into other parts of the state. A similar source-sink structure seems also the case for New Zealand. The data show that B. terrestris is a highly invasive species capable of establishing itself even after a dramatic genetic bottleneck. B. terrestris may be an invasive species due to the haplo-diploid sex determination system, which exposes recessive, deleterious mutations to selection. Offspring of such purged lines may then be able to tolerate high levels of inbreeding.     

Change in Diet of Stoats Following Poisoning of Rats in a New- Zealand Forest

The abundance and diet of stoats (Mustela erminea) were compared before and after an aerial 1080-poison operation for possums (Trichosurus vulpecula) in a New Zealand podocarp- hardwood forest. Poisoning dramatically reduced ship rat (Rattus rattus) abundance. Although rats were the main prey item of stoats before the poisoning, stoat abundance was unaffected by the operation and there was a change in stoats' diet from rats to birds. The conservation benefits and risks of undertaking such operations are not clear. It is not known whether the predation risk for any particular species of bird (or other animal) will be higher or lower with fewer rats but the same density of stoats. As large-scale poison operations are now common in New Zealand forests, a better understanding of predator-prey relationships in these areas is required as soon as possible.     

Welcome back New Zealand: regional biogeography and Gondwanan origin of three endemic genera of mite harvestmen (Arachnida, Opiliones, Cyphophthalmi)

Aim Biogeographers have long been intrigued by New Zealand’s biota due to its unique combination of typical ‘continental’ and ‘island’ characteristics. The New Zealand plateau rifted from the former supercontinent Gondwana c. 80 Ma, and has been isolated from other land masses ever since. Therefore, the flora and fauna of New Zealand include lineages that are Gondwanan in origin, but also include a very large number of endemics. In this study, we analyse the evolutionary relationships of three genera of mite harvestmen (Arachnida, Opiliones, Cyphophthalmi) endemic to New Zealand, both to each other and to their temperate Gondwanan relatives found in Australia, Chile, Sri Lanka and South Africa. Location New Zealand (North Island, South Island and Stewart Island). Methods A total of 94 specimens of the family Pettalidae in the suborder Cyphophthalmi were studied, representing 31 species and subspecies belonging to three endemic genera from New Zealand (Aoraki, Neopurcellia and Rakaia) plus six other members of the family from Chile, South Africa, Sri Lanka and Australia. The phylogeny of these taxa was constructed using morphological and molecular data from five nuclear and mitochondrial genes (18S rRNA, 28S rRNA, 16S rRNA, cytochrome c oxidase subunit I and histone H3, totalling c. 5 kb), which were analysed using dynamic as well as static homology under a variety of optimality criteria. Results The results showed that each of the three New Zealand cyphophthalmid genera is monophyletic, and occupies a distinct geographical region within the archipelago, grossly corresponding to palaeogeographical regions. All three genera of New Zealand mite harvestmen fall within the family Pettalidae with a classic temperate Gondwanan distribution, but they do not render any other genera paraphyletic. Main conclusions Our study shows that New Zealand’s three genera of mite harvestmen are unequivocally related to other members of the temperate Gondwanan family Pettalidae. Monophyly of each genus contradicts the idea of recent dispersal to New Zealand. Within New Zealand, striking biogeographical patterns are apparent in this group of short‐range endemics, particularly in the South Island. These patterns are interpreted in the light of New Zealand’s turbulent geological history and present‐day patterns of forest cover.     

Dense material associated with apparent presynaptic elements in cell cultures of the CNS

Summary In cell cultures of the rat cerebellum, electron-dense material has been found occasionally between adjacent cells. More often than not, presynaptic elements on one side of the dense material faced either neuronal or nonneuronal cells on the other side. The 20 nm thick material was stained either with the osmium-uranyl-lead (OsUL) procedure or with the ethanolic phosphotungstic acid (E-PTA) procedure. To determine the source of the dense material, various compounds were added to cultures at 7 days in vitro. Only a crude nuclear fraction was able to duplicate the appearance of the dense material associated with the apparent presynaptic elements. It was concluded that apparent presynaptic elements were associated with the polybasic dense material and that this type of association may duplicate an interaction in the normal development of synaptic contacts.Support for this research came from the National Institutes of Health Grant No. NS 09641 from the NINCDS to Dr. Robert S. Lasher and USPH Grant No. NS 12590 to Dr. John G. Wood. Additional support came from the USPHS grant through NINCDS, NS 15894 (RWB)The author is deeply indebted to Drs. Robert S. Lasher and John G. Wood in whose laboratories parts of this work were carried out     

Fleshy-fruitedness in the New Zealand flora

Aim It has been claimed that the New Zealand flora has an unusually high frequency of fleshy-fruitedness. This paper tests whether fleshy-fruitedness is indeed more common in New Zealand than in other temperate floras, then examines the distribution of fleshy-fruitedness among taxa and floristic elements to determine whether the flora conforms to predictions for a continental island with a relictual floristic element. Lastly, I test the extent to which fleshy-fruitedness has influenced colonization success and subsequent speciation within New Zealand. Methods Information on fruit characteristics for all indigenous seed plants was extracted from the Flora of New Zealand series and analysed with χ² tests. Results Contrary to previous claims fleshy-fruitedness was not unusually common in the New Zealand flora as a whole, when compared with other temperate floras. It is only more common in alpine communities and among trees. I also found no evidence for selective immigration; fleshy-fruited New Zealand genera were not more likely, than dry-fruited genera, to also occur in Australia. Furthermore there is no evidence that the New Zealand environment has favoured fleshy-fruited taxa; there has been no autochthonous evolution of fleshy-fruitedness in New Zealand, fleshy-fruitedness has had no significant effect on speciation within New Zealand, and endemic genera are no more likely to be fleshy-fruited than nonendemic genera. Fleshy-fruitedness in New Zealand is, however, strongly related to floristic elements of the flora. New Zealand is a continental island and therefore, theoretically, those elements of the flora dating from a time when the landmass was less isolated, should show a more balanced representation of dispersal modes. Contrary to this, fleshy-fruitedness is more common among species in Gondwanan taxa or in taxa with pollen records dating to before the Miocene. Main conclusions Fleshy-fruitedness in New Zealand conforms to neither the expectations for an isolated landmasses, namely a disharmonic range of dispersal modes, nor expectations for a continental island. I suggest that this pattern may be a product of selective survival of highly vagile taxa in the low-lying archipelago that was New Zealand during the late Cretaceous to mid-Cenozoic, followed by an invasion by taxa with a broader range of dispersal modes facilitated by the establishment of the circumpolar current.     

Mortality from asthma: a new epidemic in New Zealand

Trends in mortality attributed to asthma in the 5-34-year age group were examined in New Zealand, Australia, England and Wales, the United States, Canada, and West Germany for the years 1959-79. An epidemic of deaths from asthma occurred in the mid-1960s in New Zealand, Australia, and England and Wales but not in the other countries. In Australia and England and Wales the death rate quickly returned to pre-epidemic levels, but in New Zealand the decline in mortality was slow, and by 1974 the death rate was still almost double the pre-epidemic level. Of great concern was an abrupt increase in reported deaths from asthma in New Zealand after 1976 with the mortality rate during 1977-9 being greater than during the previous epidemic. In contrast, asthma mortality had remained relatively stable in the other populations.The new epidemic in New Zealand was investigated and appeared to be real. It could not be explained by changes in the classification of deaths from asthma, inaccuracies in death certification, or changes in diagnostic fashions. The most likely explanation appeared to be related to the management of asthma in New Zealand, and this is being investigated.     

The relationships and origins of the New Zealand wattlebirds (Passeriformes, Callaeatidae) from DNA sequence analyses

The monophyly of the endemic New Zealand wattlebirds (Callaeatidae) was examined through the sequencing of nuclear RAG-1 and c-mos genes and comparison to other passerine sequences. The New Zealand wattlebirds were strongly supported to be monophyletic and were nested within Corvida. An estimate for the time of divergence of the New Zealand wattlebirds indicated that the ancestors of this family arrived via transoceanic dispersal after the separation of New Zealand from Gondwana. Long branches separated the three New Zealand wattlebird genera from one another and relationships among them were unresolved, even in analyses including a further 1.5 kb of mitochondrial DNA sequences. However, most of the analyses supported either a basally diverging huia or kokako.     

The end of an 80-million year experiment: a review of evidence describing the impact of introduced rodents on New Zealand’s ‘mammal-free’ invertebrate fauna

Since separating from its super-continental origin 80 million years ago, New Zealand has effectively been isolated from the impacts of terrestrial mammals. The arrival of Polynesians in 13th C heralded the end of this era, with the introduction of kiore, (Rattus exulans, or Pacific rat), which had far-reaching effects on plant regeneration, survival of small ground vertebrates, larger invertebrates, and seabird breeding colonies. This paper reviews the evidence available from raptor nest sites and Quaternary beetle fossils to summarise extinctions thought to be caused by kiore in New Zealand. It also utilises invertebrate comparisons between islands with and without rats, or where rats have been eradicated, in order to document the impacts of rats (R. exulans, R. norvegicus) on invertebrate abundance, body mass, and the behavioural responses of some large New Zealand insects to the presence of rats. The role of a ‘mammal-free’ evolutionary history is discussed.     

Using testis size to predict the mating systems of New Zealand geckos

Abstract

The mating system is unknown for the majority of New Zealand geckos (Family Gekkonidae). I investigated interspecific variation in relative testis volume across 19 New Zealand gecko taxa and 63 additional species of squamate reptiles from other countries to make predictions about the social mating system of the New Zealand geckos. Relative testis size varied greatly between species of New Zealand gecko, with testes ranging from 119% larger than expected to 75% smaller than expected. This variation was even greater across other squamates, with testes ranging from 55 to 152% of expected size. This variation could not be explained by seasonality of breeding, clutch size or the sex ratio of populations. As species subject to more intense sperm competition sport relatively larger testes in other vertebrate groups, it is likely that similar variation in gecko testis size is due to differences in mating systems between species. Based on testis volume, it is predicted that at least half of the New Zealand gecko taxa studied are likely to have polygynandrous mating systems.     

Biogeography and phylogeny of the New Zealand cicada genera (Hemiptera: Cicadidae) based on nuclear and mitochondrial DNA data

Aim Determine the geographical and temporal origins of New Zealand cicadas. Location New Zealand, eastern Australia and New Caledonia. Methods DNA sequences from 14 species of cicadas from New Zealand, Australia, and New Caledonia were examined. A total of 4628 bp were analysed from whole genome extraction of four mitochondrial genes (cytochrome oxidase subunits I and II, and ribosomal 12S and 16S subunits) and one nuclear gene (elongation factor‐1 alpha). These DNA sequences were aligned and analysed using standard phylogenetic methods based primarily on the maximum likelihood optimality criterion. Dates of divergences between clades were determined using several molecular clock methods. Results New Zealand cicadas form two well‐defined clades. One clade groups with Australian taxa, the other with New Caledonian taxa. The molecular clock analyses indicate that New Zealand genera diverged from the Australian and New Caledonian genera within the last 11.6 Myr. Main conclusions New Zealand was likely colonized by two or more invasions. One NZ lineage has its closest relatives in Australia and the other in New Caledonia. These invasions occurred well after New Zealand became isolated from other land masses, therefore cicadas must have crossed large bodies of water to reach New Zealand.     

Phylogeny of the Bangia flora of New Zealand suggests a southern origin for Porphyra and Bangia (Bangiales, Rhodophyta)

Analysis of nuclear small subunit ribosomal RNA gene (18S rDNA) sequence data from 123 samples of the red algal genus Bangia from mainland New Zealand has revealed diversity exceeding that reported for the genus from any other region in the world. Our study resolves two New Zealand Bangia taxa basal to the order Bangiales, and five clades of Bangia, four of which include New Zealand members. The basal taxa are separated from each other by 139 bp and differ from all other Bangia taxa in the New Zealand region by 103-163 bp over approximately 1750 bp 18S rDNA sequence data. Our results reveal a Bangia flora of previously unsuspected richness, and show that the simple morphology of these organisms obscures significant levels of genetic diversity. The presence of high diversity and retention of basal taxa in New Zealand Bangia raises the prospect that the southern hemisphere, and particularly eastern Gondwana, is not only a centre of diversity, but a centre of origin for the modern Bangiales.     

Cephaloziella tahora Bever. & Glenny,a new species of Cephaloziella (Jungermanniopsida,Cephaloziellaceae) from eastern Taranaki,New Zealand

Cephaloziella tahora, a new species of Cephaloziella is described and illustrated from a lowland forest habitat in eastern Taranaki in the North Island of New Zealand. It has similarities to six other New Zealand species of Cephaloziella, and appears closest in New Zealand to Cephaloziella aenigmatica R.M.Schust. It is defined by a unique combination of features and distinguished from C. aenigmatica and other New Zealand species by having entire, distant leaves that reach the dorsal stem mid-line, and have large conspicuous hemispherical and hemi-ellipsoidal papillae, underleaves on gemmiparous and gynoecial shoots, and by its dioecy. The addition brings the number of New Zealand species of Cephaloziella to 18, 12 of which are endemic to New Zealand.