Genetic differentiation among populations of the shortfinned eel Anguilla australis from East Australia and New Zealand

Variability at seven microsatellite loci was used to survey the genetic population structure of the shortfinned eel Anguilla australis . Samples were collected from six estuaries along the east coast of Australia and from three estuaries around New Zealand. Hierarchical analysis of molecular variance of the five loci with good fit to Hardy–Weinberg genotypic proportions detected highly significant differences among samples ( F _ST= 0·016, P < 0·001). The fixation index between countries ( F _CT= 0·012, P < 0·001) was more than double the index among samples within countries ( F _SC= 0·005, P < 0·05). An unweighted pair-group method with arithmetic mean (UPGMA) tree also supported the separation of Australian and New Zealand populations, as did assignment tests, which correctly assigned 80 and 84% of the individuals to Australia and New Zealand, respectively. Isolation-by-distance appeared among samples overall ( r = 0·807, P < 0·001), but not among samples within countries ( r = 0·027, P > 0·05 in Australia; r = 0·762, P > 0·05 in New Zealand). These findings indicate that populations of A. australis in East Australia and in New Zealand may be reproductively isolated from one another. Genetic differentiation among populations of A. australis was two- to 10-fold higher than that among populations of other temperate eels in the North Atlantic Ocean, suggesting that two group of A. australis may reflect sub-species. Anguilla australis in the two countries have different genetic structures and thus require separate management. Genetic isolation between Australian and New Zealand populations indicates that juveniles recruit independently into these two regions from geographically or temporally isolated spawning areas.     

Asymmetric dispersal of southern bull‐kelp (Durvillaea antarctica) adults in coastal New Zealand: testing an oceanographic hypothesis

Coastal populations are often connected by unidirectional current systems, but the biological effects of such asymmetric oceanographic connectivity remain relatively unstudied. We used mtDNA analysis to determine the phylogeographic origins of beach‐cast bull‐kelp (Durvillaea antarctica) adults in the Canterbury Bight, a 180 km coastal region devoid of rocky‐reef habitat in southern New Zealand. A multi‐year, quantitative analysis supports the oceanographically derived hypothesis of asymmetric dispersal mediated by the north‐flowing Southland Current. Specifically, 92% of beach‐cast specimens examined had originated south of the Bight, many drifting north for hundreds of kilometres, and some traversing at least 500 km of ocean from subantarctic sources. In contrast, only 8% of specimens had dispersed south against the prevailing current, and these counter‐current dispersers likely travelled relatively small distances (tens of kilometres). These data show that oceanographic connectivity models can provide robust estimates of passive biological dispersal, even for highly buoyant taxa. The results also indicate that there are no oceanographic barriers to kelp dispersal across the Canterbury Bight, indicating that other ecological factors explain the phylogeographic disjunction across this kelp‐free zone. The large number of long‐distance dispersal events detected suggests drifting macroalgae have potential to facilitate ongoing connectivity between otherwise isolated benthic populations.     

New Zealand Lepidoptera: Basic biogeography

Abstract

The composition of the New Zealand Lepidoptera fauna is briefly described, and affinities within Tortricidae analysed. Sixty-five genera are used to indicate four possible sets of relationships, but shortcomings of taxonomic interpretations are outlined. Except for species with a wide dispersal range (some 6% of the fauna) most show affinities consonant with terrane biogeography. The panbiogeographic methodology is a potent tool in systematics, giving direction to the research effort.     

A gharial from the Oligocene of Puerto Rico: transoceanic dispersal in the history of a non-marine reptile

The Indian gharial (Gavialis gangeticus) is not found in saltwater, but the geographical distribution of fossil relatives suggests a derivation from ancestors that lived in, or were at least able to withstand, saline conditions. Here, we describe a new Oligocene gharial, Aktiogavialis puertoricensis, from deltaic-coastal deposits of northern Puerto Rico. It is related to a clade of Neogene gharials otherwise restricted to South America. Its geological and geographical settings, along with its phylogenetic relationships, are consistent with two scenarios: (i) that a single trans-Atlantic dispersal event during the Tertiary explains the South American Neogene gharial assemblage and (ii) that stem gharials were coastal animals and their current restriction to freshwater settings is a comparatively recent environmental shift for the group. This discovery highlights the importance of including fossil information in a phylogenetic context when assessing the ecological history of modern organisms.     

Factors affecting the activity of two species of eel (Anguilla spp.) in a small New Zealand lake

Fyke net captures of both the shortfinned eel, Anguilla ausrralis Richardson, and the longfinned eel. A. dieffenbachü Gray, were recorded over a 4-year period in Lake Pounui. New Zealand. Eel activity measured as catch per unit effort (CPUE) was correlated to 36 indices of water temperature water level, barometric pressure, amount of light at night and lunar period using multiple regression analysis. For longfinned eels, water temperature was the only individual parameter significantly related (P<0.001) to CPUE. The multiple regression model was improved (R²= 0.29. P <0.01) by the addition of lunar phase and change in barometric pressure. Water level was the most important parameter in the model for shortfinned eels, although water temperature and change in barometric pressure were significant influences in the predictability of the model (R²= 0.51. P<0.001.     

Salinity-linked growth in anguillid eels and the paradox of temperate-zone catadromy

Temperate-zone anguillid eels use both saline (marine or brackish) and fresh waters during their continental phase, but use of fresh waters is paradoxical because on average these fishes grow more rapidly in saline than in fresh waters. Based on data from anguillid eels whose habitat-residency histories had been determined by Sr:Ca otolithometry, superiority of growth rates in saline water is much greater in American eels Anguilla rostrata in north-eastern North America (mean saline:fresh growth rate ratio 2·07) than in European Anguilla anguilla , Japanese Anguilla japonica and shortfinned Anguilla australis eels (range of mean ratios 1·12–1·14). Data from A. rostrata in the Hudson Estuary, U.S.A., and Prince Edward Island, Canada, were used to test adaptive explanations of catadromous migrations. The hypothesis that lower mortality in fresh water offsets faster growth in saline water was not supported because loss (mortality + emigration ) rates did not vary between saline and fresh zones of the Hudson Estuary. Hypotheses that anguillid eels move to fresh water to escape from larger anguillid eels in saline water or to evaluate habitat quality were not supported by size and age distributions. Catadromy in temperate-zone anguillid eels increases the diversity of occupied habitats and therefore lowers fitness variance caused by environmental fluctuations. Catadromy in temperate-zone anguillid eels could be due to natural selection for maximum geometric mean fitness which is sensitive to fitness variance. Temperate-zone catadromy might also be maladaptive, at least in local areas, due to shifts over time in selective pressures or to inability of panmictic genetic systems to adapt to local conditions.     

Sympatric cryptic species in New Zealand Onychophora

Allozyme electrophoresis was used to examine genetic diversity within live-bearing Peripatopsid Onychophora from the North Island of New Zealand. Specimens of two previously described morpho-species that differ in leg number (Peripatoides suteri and P. novaezealandiae) were found to be genetically diverse. P. suteri showed little intraspecific genetic variation but were very distinct from specimens assignable to P. novaezealandiae. Within P. novaezealandiae five genetically differentiated species were identified although none showed any consistent morphological differentiation, thus P. novaezealandiae (Hutton) is a species complex. All of these species occur in sympatry or parapatry (in one instance) with other cryptic species of the P. novaezealandiae group or with P. suteri. Four new species are described on the basis of this genetic evidence, they are P. morgani, P. aurorbis, P. kawekaensis and P. sympatrica. Other genotypes encountered indicate further cryptic species remain unrecognized. Among the North Island species, P. suteri and P. aurorbis sp. nov. are both more closely related to undescribed species from the South Island than to others examined from the North Island. P. sympatrica sp. nov. exists in sympatry with at least three other species in different parts of its range. The complexity of relationships and distributions probably arose through the interaction of low vagility in peripatus and the active geophysical history of the region. How these cryptic species persist in sympatry is not known but may be linked to differences in ecology not evident in their morphology, and/or may indicate recent dispersal from allopatry.     

Calanoid copepod biogeography in New Zealand

The distribution of four calanoid copepod species of Boeckella in New Zealand are mapped and described. An explanation of their distribution patterns based on panbiogeographic methods is compared to an explanation based on dispersalist concepts. The panbiogeographic explanation is simpler, and is consistent with explanation of distribution patterns among other genera of plants, invertebrates, amphibians and birds. This revised version was published online in July 2006 with corrections to the Cover Date.     

Seed dispersal systems in the New Zealand flora

Knowledge of the dispersal mechanisms used by plants is important in phylogenetic, ecological, biogeographical, and conservation studies. Here we attempt to assign dispersal mechanisms to the entire flora-2595 plant species of the New Zealand Botanical Region. Anemochory is the most frequent dispersal mechanism, utilised by 79% of species. The next most frequent mechanisms are endozoochory (33%), hydrochory (28%), epizoochory (26%), and ballistic (8%). Polychory is common, particularly in monocotyledonous and dicotyledonous families and hydrochorous, epizoochorous, and ballistically dispersed species. Epizoochory is more common in New Zealand than in other regions, and species using this dispersal mechanism are over-represented among threatened species. Frugivory is less common than previously reported, and is under-represented among threatened species. Some mechanisms are poorly known, and entanglement and capsulivory are dispersal mechanisms apparently unique to New Zealand. Dispersal mechanisms reflective of New Zealand's distinctive assemblages of large flightless birds and reptiles are not apparent. A pattern of reduction in dispersal-related structures is evident in some genera. The mechanisms utilised by some species are ambiguous. Thus there remains a need for further investigation of the dispersal mechanisms utilised by plants in New Zealand.     

Inadvertent biological control: an Australian thrips killing an invasive New Zealand tree in California

Transport hubs of international trade and tourism are sites of unprecedented long-distance dispersal of species and novel ecological interactions. In cases of invasive plants released from their specialist natural enemies, novel interactions with both resident enemies and new arrivals can accumulate and potentially reduce weed competitiveness. I present here one dramatic example of this, where an invasive woody weed in southern California is being rapidly controlled by an accidentally introduced genus-specialist herbivorous insect. The New Zealand native shrub/small tree, Myoporum laetum, is a long-time popular ornamental plant in California and has become an invasive woody weed. In 2005, a Myoporum-specific thrips, Klambothrips myopori, was discovered (and described) in California feeding on M. laetum leaves. Several searches have failed to find K. myopori in New Zealand and a population has recently been discovered in Tasmania, Australia, feeding on Myoporum insulare. In 5 years, K. myopori has killed off about half of southern Californian M. laetum with almost all surviving individuals being gradually defoliated. Inadequate border biosecurity has resulted in inadvertent biological control, in a rapid timeframe, caused by a novel enemy. Unfortunately, K. myopori has subsequently been accidentally transported from California to Hawaii where it is now killing off Hawaiian native Myoporum sandwicense. Transport hubs can both connect weeds with natural enemies and disperse those enemies more widely.     

Panbiogeography and conservation science in New Zealand

Abstract

New Zealand’s official conservation science framework, the Protected Natural Areas Programme (PNA), is evaluated in relation to current biogeographic/systematic methods and principles with reference to philosophy, taxonomy, information content, and historical geological/biological relations. The PNA Programme and its parent International Union for Conservation of Nature and Natural Resources (IUCN) framework is based on a phenetic system of classification that does not reflect process (phylogenetic) characters of ecological systems. The PNA philosophy of conservation science is shown to be essentialist, rooted in traditional medieval Western metaphysics, and out of step with current developments in biogeography, systematics, and ecology. Panbiogeography is an appropriate global perspective for developing a conservation science because it meets the requirements of homology, monophyly, increased information content, and empirical testability whereas the PNA programme does not. Establishment of a Panbiogeographic Track Atlas is proposed as a suitable conservation framework for historical ecology and biogeography. The atlas could provide an empirical natural resource inventory to identify priority areas for conservation at an economically acceptable cost compared to the PNA Programme. Application of cladistic techniques to ecological and biogeographic patterns in relation to the Atlas can provide aphylogenetically sound hierarchical classification for conservation science. The potential benefits of the panbiogeographic approach for conservation education and tourism are discussed.     

Endocrine control of Anguilla anguilla glass eel dispersal: effect of thyroid hormones on locomotor activity and rheotactic behavior

Dispersal, one of the most important processes in population ecology, is an issue linking physiological and behavioral features. However, the endocrine control of animal dispersal remains poorly understood. Here, we tested whether and how thyroid hormones may influence dispersal in glass eels of Anguilla anguilla, by testing their influence on locomotor activity and rheotactic behavior. Glass eels were caught during their estuarine migration and treated by immersion in either a l-thyroxine (T(4)) or a thiourea (TU) solution. As measured by radioimmunoassay, T(4) and TU treatments induced, respectively, increased and decreased whole-body thyroid hormone levels relative to untreated controls. We tested a total of 960 glass eels distributed into control, and T(4) and TU treatment groups, on their swimming behavior in experimental flume tanks equipped with upstream and downstream traps that allowed us to concurrently measure both the locomotor activity and the rheotactic behavior. Compared to controls, locomotor activity significantly increased among the hyperthyroid, T(4)-treated eels, but significantly decreased among the hypothyroid, TU-treated eels. The results on rheotactic behavior suggested a more complex regulatory mechanism, since TU but not T(4) treatment significantly affected rheotactic behavior. The influence of thyroid hormones on locomotor activity suggests a central role for these hormones in the regulation of mechanisms leading to the colonization of continental habitats by glass eels. Thyroid hormones are also implicated in the control of locomotor activity in mammals and migratory behavior in birds, suggesting that these hormones represent conserved, proximate mediators of dispersal in vertebrates.     

Water temperature and upstream migration of glass eels in New Zealand: implications of climate change

Glass eels migrating upstream in a New Zealand river showed a clear preference for water temperatures between 12 and 20°C, with an optimum of 16.5°C. Water temperatures <12°C and >22°C almost completely inhibited migration, which implies that warmer temperatures associated with global climate change might have a detrimental impact on glass eel recruitment in their current ranges. We established this by trapping glass eels of shortfin, Anguilla australis, and longfin, A. dieffenbachii, eels nightly from September to November. Eels caught in 2001 (50,287) outnumbered those caught in 2002 (19,954); shortfin glass eels dominated catches in both years, comprising 91–93% of the catch. Longfins were larger than shortfins, and size and pigmentation in both species increased as the seasons progressed. Temperatures within the migratory season in 2001 showed ∼14-day intervals between maxima that appeared to be associated with the new and full moons.     

Functional antifreeze glycoprotein genes in temperate-water New Zealand nototheniid fish infer an Antarctic evolutionary origin

The fish fauna of the Antarctic Ocean is dominated by five endemic families of the Perciform suborder Notothenioidei, thought to have arisen in situ within the Antarctic through adaptive radiation of an ancestral stock that evolved antifreeze glycoproteins (AFGPs) enabling survival as the ocean chilled to subzero temperatures. The endemism results from geographic confinement imposed by a massive oceanographic barrier, the Antarctic Circumpolar Current, which also thermally isolated Antarctica over geologic time, leading to its current frigid condition. Despite this voluminous barrier to fish dispersal, a number of species from the Antarctic family Nototheniidae now inhabit the nonfreezing cool temperate coasts of the southern continents. The origin of these temperate-water nototheniids is not completely understood. Since the AFGP gene apparently evolved only once, before the Antarctic notothenioid radiation, the presence of AFGP genes in extant temperate-water nototheniids can be used to infer an Antarctic evolutionary origin. Genomic Southern analysis, PCR amplification of AFGP genes, and sequencing showed that Notothenia angustata and Notothenia microlepidota endemic to southern New Zealand have two to three AFGP genes, structurally the same as those of the Antarctic nototheniids. At least one of these genes is still functional, as AFGP cDNAs were obtained and low levels of mature AFGPs were detected in the blood. A phylogenetic tree based on complete ND2 coding sequences showed monophyly of these two New Zealand nototheniids and their inclusion in the monophyletic Nototheniidae consisted of mostly AFGP-bearing taxa. These analyses support an Antarctic ancestry for the New Zealand nototheniids. A divergence time of approximately 11 Myr was estimated for the two New Zealand nototheniids, approximating the upper Miocene northern advance of the Antarctic Convergence over New Zealand, which might have served as the vicariant event that lead to the northward dispersal of their most recent common ancestor. Similar secondary northward dispersal likely applies to the South American nototheniid Paranotothenia magellanica, which has four AFGP genes in its DNA, but not to the sympatric nototheniid Patagonotothen tessellata, which does not appear to have any AFGP sequences in its genome at all.     

First record of an Australian fruit bat (Megachiroptera: Pteropodidae) reaching New Zealand

A red fruit bat (Pteropus scapulatus Peters, 1862) was picked up freshly dead after hitting power lines in a storm in Hamilton East, North Island, between 1927 and 1929 and kept, stuffed, on a Waikato farm. Unusually large southerly migrations of the red fruit bat into New South Wales and Victoria occurred for a few years after the severe drought in Queensland in 1926–27. This specimen may have been on migration, and blown across the Tasman by a storm. This is the first confirmed record of an Australian bat reaching New Zealand alive in European times.     

Application of parsimony analysis of endemicity in Amazonian biogeography: an example with primates

The distributions of 51 non-human primate species are used for Parsimony Analysis of Endemicity (PAE) to determine the relationships among 14 interfluvial regions in the Amazon basin, South America. Two most parsimonious cladograms were found. The strict consensus tree of these cladograms suggests an early separation between Lower Amazonia (eastern) and Upper Amazonia (western). The major clusters of interfluvial regions identified in the PAE cladogram are congruent with the areas of endemism delimited for birds. When interfluvial regions are converted into avian areas of endemism, the PAE cladogram is congruent with one of the two general areas cladograms suggested for Amazonia based on phylogenies of several clades of forest birds. Our analysis suggests that PAE can be used as a tool to objectively identify areas of endemism at an intra-continental scale as well as to make historical inferences. However, the value of a PAE cladogram in this latter application should be always evaluated by congruence with area cladograms built upon cladistic biogeography procedures.     

Phylogeography of Ptychadena mascareniensis suggests transoceanic dispersal in a widespread African-Malagasy frog lineage

Aim The Mascarene ridged frog, Ptychadena mascareniensis, is the only African amphibian species thought to occur on Madagascar and on the Seychelles and also Mascarene islands. We explored its phylogenetic relationships and intraspecific genetic differentiation to contribute to the understanding of transoceanic dispersal in amphibians. Methods Fragments of the mitochondrial 16S rRNA gene were sequenced from specimens collected over most of the distribution area of P. mascareniensis, including populations from Madagascar, Mascarenes and Seychelles. Results We identified five deeply divergent clades having pairwise divergences >5%, which probably all represent cryptic species in a P. mascareniensis complex. One of these seems to be restricted to Madagascar, the Mascarenes and the Seychelles. Sequences obtained from topotypic material (Réunion) were identical to the most widespread haplotype from Madagascar. The single Mauritian/Seychellean haplotype differed by only one mutation from a Malagasy haplotype. Main conclusions It is likely that the Mascarene and Seychellean populations were introduced from Madagascar by humans. In contrast, the absence of the Malagasy haplotypes from Africa and the distinct divergences among Malagasy populations (16 mutations in one divergent hapolotype from northern Madagascar) suggest that Madagascar was populated by Ptychadena before the arrival of humans c. 2000 years ago. Because Madagascar has been separated from Africa since the Jurassic, this colonization must have taken place by overseas rafting, which may be a more widespread dispersal mode in amphibians than commonly thought.     

A High-Resolution Chronology of Rapid Forest Transitions following Polynesian Arrival in New Zealand

Human-caused forest transitions are documented worldwide, especially during periods when land use by dense agriculturally-based populations intensified. However, the rate at which prehistoric human activities led to permanent deforestation is poorly resolved. In the South Island, New Zealand, the arrival of Polynesians c. 750 years ago resulted in dramatic forest loss and conversion of nearly half of native forests to open vegetation. This transformation, termed the Initial Burning Period, is documented in pollen and charcoal records, but its speed has been poorly constrained. High-resolution chronologies developed with a series of AMS radiocarbon dates from two lake sediment cores suggest the shift from forest to shrubland occurred within decades rather than centuries at drier sites. We examine two sites representing extreme examples of the magnitude of human impacts: a drier site that was inherently more vulnerable to human-set fires and a wetter, less burnable site. The astonishing rate of deforestation at the hands of small transient populations resulted from the intrinsic vulnerability of the native flora to fire and from positive feedbacks in post-fire vegetation recovery that increased landscape flammability. Spatially targeting burning in highly-flammable seral vegetation in forests rarely experiencing fire was sufficient to create an alternate fire-prone stable state. The New Zealand example illustrates how seemingly stable forest ecosystems can experience rapid and permanent conversions. Forest loss in New Zealand is among the fastest ecological transitions documented in the Holocene; yet equally rapid transitions can be expected in present-day regions wherever positive feedbacks support alternate fire-inhibiting, fire-prone stable states.