Evolution and biogeography of New Zealand's longjaw galaxiids (Osmeriformes: Galaxiidae): the genetic effects of glaciation and mountain building

1. The biological impact of glaciation in Southern Hemisphere freshwaters is poorly understood. Several large rivers of eastern South Island, New Zealand, represent a mosaic of glaciated and non-glaciated regions, and are thus well-suited for studies of post-glacial recolonization.
2. We conducted mtDNA analyses of South Island's endemic non-migratory longjaw galaxiids Galaxias prognathus and G. cobitinis (Osmeriformes: Galaxiidae) to test hypotheses of post-glacial recolonization, and to assess the vicariant effects of Pleistocene mountain building.
3. We analysed the phylogeography of longjaw cytochrome b sequences from 38 sites in central South Island ( n  = 83). On the basis of our sampling it seems that G. prognathus and G. cobitinis have a parapatric distribution in the Waitaki River system, their disjunction broadly coinciding with three large post-glacial lakes. Waitaki clades of both species are deeply divergent relative to conspecific taxa in drainages to the north and south.
4. Tests for recent population growth – predicted under post-glacial expansion of G. prognathus – do not refute recent recolonization of streams above glaciated lakes in the Waitaki River drainage. The apparent absence of potential 'source' populations from non-glaciated regions suggests a post-glacial population decline for G. prognathus below the Waitaki lakes.
5. Molecular clock calibrations based on several freshwater vicariant events elsewhere in New Zealand supported the geologically-derived hypothesis of Waitaki–Canterbury drainage isolation approximately 300 ka.     

Molecular evidence for long-distance dispersal in the New Zealand pteridophyte flora

Aim To examine the relative importance of long‐distance dispersal in shaping the New Zealand pteridophyte (ferns and lycophytes) flora and its relationships with other floras, with the null hypothesis that the extant New Zealand pteridophyte flora has been isolated since New Zealand’s separation from Gondwana. Location New Zealand. Methods rbcL DNA sequences were assembled for 31 New Zealand pteridophyte genera, with each genus represented by one New Zealand species and the most closely related non‐New Zealand species for which data were available. Maximum‐likelihood, maximum‐parsimony, and Bayesian analysis phylograms were constructed and used as input for r 8s molecular dating, along with 23 fossil calibrations. Divergence estimates less than conservatively recent ages for New Zealand’s geological isolation, namely H_o > 30 Ma for pairs involving New Caledonian and Norfolk Island species and H_o > 55 Ma for all others, were taken as rejection of the null hypothesis. Results The null hypothesis was rejected for all pairs except, under some parameter conditions, for those involving the New Zealand species Cardiomanes reniforme, Lindsaea trichomanoides, Loxsoma cunninghamii, Lygodium articulatum, Marattia salicina, and Pteris comans. However, the Lindsaea and Pteris results probably reflect the absence in the analyses of closely related non‐New Zealand samples, while the Marattia divergence was highly contingent on which fossil calibrations were used. Main conclusions Rejection of the null hypothesis for the majority of pairs implies that the extant New Zealand lineage has undergone long‐distance dispersal either into or out of New Zealand. The notion of a long isolation since geological separation can, therefore, be dismissed for much of New Zealand’s pteridophyte flora. The analyses do not identify the direction of the long‐distance dispersal, and these New Zealand lineages could have had vicariant origins with subsequent long‐distance emigration. However, the alternative that many extant New Zealand pteridophyte lineages only arrived by long‐distance immigration after geological isolation seems likely.     

Process and pattern in the biogeography of New Zealand – a global microcosm?

Aim  To describe New Zealand's historical terrestrial biogeography and place this history in a wider Southern Hemisphere context.
Location  New Zealand.
Methods  The analysis is based primarily on literature on the distributions and relationships of New Zealand's terrestrial flora and fauna.
Results  New Zealand is shown to have a biota that has broad relationships, primarily around the cool Southern Hemisphere, as well as with New Caledonia to the north. There are hints of ancient Gondwanan taxa, although the long-argued predominance of taxa derived by vicariant processes, driven by plate tectonics and the fragmentation of Gondwana, is no longer accepted as a principal explanation of the biota's origins and relationships.
Main conclusions  Most of the terrestrial New Zealand flora and fauna has clearly arrived in New Zealand much more recently than the postulated separation of New Zealand from Gondwana, dated at c. 80 Ma. There is a view that New Zealand may have disappeared completely beneath the sea in the early Cenozoic, and acceptance of this would mean derivation of the entire biota by transoceanic dispersal. However, there are elements in the biota that seem to have broad distributions that date back to Gondwanan times, and also some that are thought unlikely to have been able to disperse to New Zealand across ocean gaps, especially freshwater organisms. Very strong connections to the biota of Australia, rather than to South America, are inconsistent with the timing of New Zealand's ancient and early separation from Gondwana and seem likely to have resulted from dispersal.     

New Zealand phylogeography: evolution on a small continent

New Zealand has long been a conundrum to biogeographers, possessing as it does geophysical and biotic features characteristic of both an island and a continent. This schism is reflected in provocative debate among dispersalist, vicariance biogeographic and panbiogeographic schools. A strong history in biogeography has spawned many hypotheses, which have begun to be addressed by a flood of molecular analyses. The time is now ripe to synthesize these findings on a background of geological and ecological knowledge. It has become increasingly apparent that most of the biota of New Zealand has links with other southern lands (particularly Australia) that are much more recent than the breakup of Gondwana. A compilation of molecular phylogenetic analyses of ca 100 plant and animal groups reveals that only 10% of these are even plausibly of archaic origin dating to the vicariant splitting of Zealandia from Gondwana. Effects of lineage extinction and lack of good calibrations in many cases strongly suggest that the actual proportion is even lower, in keeping with extensive Oligocene inundation of Zealandia. A wide compilation of papers covering phylogeographic structuring of terrestrial, freshwater and marine species shows some patterns emerging. These include: east–west splits across the Southern Alps, east–west splits across North Island, north–south splits across South Island, star phylogenies of southern mountain isolates, spread from northern, central and southern areas of high endemism, and recent recolonization (postvolcanic and anthropogenic). Excepting the last of these, most of these patterns seem to date to late Pliocene, coinciding with the rapid uplift of the Southern Alps. The diversity of New Zealand geological processes (sinking, uplift, tilting, sea level change, erosion, volcanism, glaciation) has produced numerous patterns, making generalizations difficult. Many species maintain pre‐Pleistocene lineages, with phylogeographic structuring more similar to the Mediterranean region than northern Europe. This structure reflects the fact that glaciation was far from ubiquitous, despite the topography. Intriguingly, then, origins of the flora and fauna are island‐like, whereas phylogeographic structure often reflects continental geological processes.     

Biogeographic area relationships in southern New Zealand: a cladistic analysis of Lepidoptera distributions

ABSTRACT. Recently, attention has been directed toward the application of cladistic techniques to reconstruct the history of areas from species distribution data. In this study, hypotheses of area relationships for southern New Zealand are generated from lepidopteran distribution data analysed at two taxonomic levels. Data are shown to possess cladistic structure and area relationships presented here are consistent with the geological history of the southern region of New Zealand. Our results suggest a recolonization of inland lowland regions from the south following a period of extinction during the early Pliocene. Analysis of selected data including only flightless or locally endemic species resulted in little resolution of area relationships but topologies were significantly congruent with a total species dataset. Hypotheses generated from this study are open to testing with congruence analysis using independent species phylogenies.     

Evidence for the recent dispersal of Sophora (Leguminosae) around the Southern Oceans: molecular data

Aim The aim is to use DNA sequence data to test between vicariance and long range dispersal (by floating seed-pods) explanations for the origin and range of the Edwardsia species of Sophora (Sophoreae: Papilionoideae: Leguminosae). Location This group is widely distributed around the South Pacific and into the South Atlantic on both continental fragments and oceanic islands. Methods DNA sequences from an intergene region (atpB-rbcL) of the chloroplast were determined for twelve taxa (including outgroups) and used to test these hypotheses. Sophora fossils were used to calibrate the evolutionary tree. Results The Edwardsia group of Sophora appears monophyletic and is well differentiated from other Sophora. However, the genetic difference between species within the South Pacific and to the South Atlantic is very low. Main conclusionsThe results eliminate vicariance explanations for this section of Sophora and strongly support an origin from other (non-Edwardsia) Sophora in the north-west Pacific. Dispersal appears initially to be to Tuvalu, Lord Howe Island, New Zealand, and subsequently across the South Pacific, probably within the last 2–5 million years. Dispersal of buoyant Sophora seeds to oceanic islands is the most likely explanation of its distributions. Fossil pollen dates in New Zealand are consistent with the conclusion.     

Diversification of Chionochloa (Poaceae) and biogeography of the New Zealand Southern Alps

Aim We test hypotheses regarding the origin of diversity and patterns of species richness in and around the New Zealand Southern Alps with 25 species of Chionochloa (Poaceae, Danthonioideae). Location New Zealand. Methods We inferred a well‐resolved and mostly robustly supported chloroplast phylogeny based on multiple DNA sequence markers (trnT–L–F, rpl16, trnD–psbM, atpB–rbcL, matK and ndhF), sampling 92% of the recognized species and 82% of the subspecific taxa. Nuclear ribosomal internal transcribed spacer sequences were also sampled, but proved uninformative. Biogeographic reconstruction and character optimization were done using both parsimony and likelihood approaches, and molecular dating used relaxed clock approaches. Results Most of the species diversity in Chionochloa stemmed from a common ancestor in the southern South Island with subsequent dispersal between areas. One clade of apparently cryptic taxa diversified within the central South Island ‘endemism gap’, persisting there throughout at least the latter half of the Pleistocene. Exclusively alpine and other habitat specialist species originated independently, the former relatively recently (between 7.6 Ma and the present). Main conclusions The phylogeny of Chionochloa and other published phylogenies of New Zealand plant groups demonstrate that the higher degree of endemism in the north and south of the New Zealand South Island relative to a central endemism gap cannot be explained by Alpine Fault displacement. Furthermore, our results suggest that if extinctions resulting from glaciations played a role in the origin of the central endemism gap, their impact was less than might be presumed on the basis of the distribution of taxa as they are currently defined. The diversification of Chionochloa and a number of New Zealand plant groups, such as Ranunculus, was contemporaneous with the initiation of the uplift of the Southern Alps. In contrast to patterns of diversifications within the alpine regions typical of the hyperdiverse Andes, exclusively alpine species in New Zealand arose independently from ancestors distributed in more lowland areas. Similarly, habitat specialists in Chionochloa arose independently from more generalist ancestors. Thus, although diversification in these groups may have been stimulated by mountain building and Pleistocene climatic oscillations, cladogenesis did not occur within the high alpine habitat itself.     

Biogeographical affinities of the New Caledonian biota: a puzzle with 24 pieces

Aim The distributions of many New Caledonian taxa were reviewed in order to ascertain the main biogeographical connections with other areas. Location Global. Methods Panbiogeographical analysis. Results Twenty‐four areas of endemism (tracks) involving New Caledonia and different areas of Gondwana, Tethys and the central Pacific were retrieved. Most are supported by taxa of lower and higher plants, and lower and higher animals. Main conclusions Although parts of New Caledonia were attached to Gondwana for some time in the mid‐Cretaceous, most of the New Caledonian terranes formed as oceanic island arcs and sections of sea floor bearing seamounts. The flora and fauna have evolved and survived for tens of millions of years as metapopulations on ephemeral islands. Later, the biotas were juxtaposed and fused during terrane accretion. This process, together with the rifting of Gondwana, explains the biogeographical affinities of New Caledonia with parts of Gondwana, Tethys and the Pacific.     

Microsatellite DNA analyses of a highly disjunct New Zealand tree reveal strong differentiation and imply a formerly more continuous distribution

Although New Zealand is a biodiversity hotspot, there has been little genetic investigation of why so many of its threatened and uncommon plants have naturally disjunct distributions. We investigated the small tree Pseudopanax ferox (Araliaceae), which has a widespread but highly disjunct lowland distribution within New Zealand. Genotyping of nuclear microsatellites and a chloroplast locus revealed pronounced genetic differentiation and four principal genetic clusters. Our results indicate that the disjunct distribution is a product of vicariance rather than long‐distance dispersal. This highlights the need to preserve multiple populations when disjunct distributions are the result of vicariance, rather than focusing conservation efforts on a core area, in order to retain as much as possible of a species’ evolutionary legacy and potential. Additionally, based on our genetic findings and the ecology of P. ferox, we hypothesize that it was more continuously distributed during the drier (but not maximally colder) interstadials of glacial periods and/or on the fertile soils available immediately postglacial. We further hypothesize that P. ferox belongs to a suite of species of drought‐prone and/or fertile habitats whose distributions are actually restricted during warmer and wetter interglacial periods, despite being principally of the lowlands. Our genetic data for P. ferox are also the first consistent with the survival during the Last Glacial Maxima of a lowland tree at high latitudes in the south‐eastern South Island.     

Evolution of New Zealand's terrestrial fauna: a review of molecular evidence

New Zealand biogeography has been dominated by the knowledge that its geophysical history is continental in nature. The continental crust (Zealandia) from which New Zealand is formed broke from Gondwanaland ca 80 Ma, and there has existed a pervading view that the native biota is primarily a product of this long isolation. However, molecular studies of terrestrial animals and plants in New Zealand indicate that many taxa arrived since isolation of the land, and that diversification in most groups is relatively recent. This is consistent with evidence for species turnover from the fossil record, taxonomic affinity, tectonic evidence and observations of biological composition and interactions. Extinction, colonization and speciation have yielded a biota in New Zealand which is, in most respects, more like that of an oceanic archipelago than a continent.     

Population density and geographical range size in the introduced and native passerine faunas of New Zealand

The current avifauna of New Zealand comprises species with two distinct origins: those that evolved in New Zealand or colonized naturally from neighbouring landmasses, and those that were deliberately introduced to the islands by European settlers. Elsewhere, it has been shown that for species introduced to New Zealand from Britain there is a positive interspecific correlation between the geographical range sizes attained in both countries. Since positive relationships between abundance, measured either as population size or density, and geographical range size are a near ubiquitous feature of assemblages of closely related animal species, this suggests that species’ abundances may also be so correlated between the two countries. Here, data for 12 passerine bird species introduced to New Zealand from Britain are used to compare population densities and density–range size relationships in their native and alien ranges. In addition, the density–range size relationship for 12 passerine bird species that can be considered native to New Zealand is compared to that for the introduced species. The geographical range size and the mean and maximum densities of introduced species in New Zealand were significantly positively correlated with those values for the same species in Britain. However, in no case was the relationship between mean density and range size significant. While not statistically significant, density–range size relationships for introduced species are similar in New Zealand and Britain, but those for introduced and native species in New Zealand are quite different. Implications of these patterns are discussed.     

A history of the introduction,establishment, dispersal and management of Haemaphysalis longicornis Neumann, 1901 (Ixodida: Ixodidae) in New Zealand

ABSTRACT

The earliest concerns New Zealand farmers had about ticks are chronicled here, together with the eventual invasion and establishment of Haemaphysalis longicornis, which, still today, remains the only livestock tick parasite in this country. Early attempts, legislative and practical, to restrict the spread of the tick, and later attempts to manage a permanent problem are presented and discussed. Brief biographies of many of the main persons mentioned in this history are presented in an Appendix, as is a reconsideration of how the tick may have arrived.     

Evolution and phylogeny of the New Zealand cicada genus Kikihia Dugdale (Homoptera: Auchenorrhyncha: Cicadidae) with special reference to the origin of the Kermadec and Norfolk Islands' species

Aim Determine the phylogeny and dispersal patterns of the cicada genus Kikihia in New Zealand and the origin of the Norfolk, Kermadec, and Chatham Island cicadas. Location New Zealand, Norfolk Island, Kermadec Islands and Chatham Island. Methods DNA sequences from 16 species and four soon to be described species of cicadas from New Zealand and Norfolk Island (Australia) were examined. A total of 1401 base pairs were analysed from whole genome extraction of three mitochondrial genes (cytochrome oxidase subunit II, ATPase6 and ATPase8). These DNA sequences were aligned and analysed using standard likelihood approaches to phylogenetic analysis. Dates of divergences between clades were determined using a molecular clock based on Bayesian statistics. Results Most species in the genus Kikihia diverged between 3 and 5 million years ago (Ma) coincident with a period of rapid mountain building in New Zealand. Cicada species on the Kermadec and Norfolk Islands invaded recently from New Zealand and are closely related to the New Zealand North Island species Kikihia cutora. Main conclusions Speciation in the genus Kikihia was likely due in large part to the appearance of new habitats associated with the rise of the Southern Alps, starting c. 5 Ma. Dispersal of Kikihia species within mainland New Zealand probably occurred gradually rather than through long‐distance jumps. However, invasion of Norfolk, the Kermadecs and Chatham Islands had to have occurred through long‐distance dispersal.     

Geological subsidence, river capture, and cladogenesis of galaxiid fish lineages in central New Zealand

We used mtDNA and isozyme analysis of a freshwater fish, Galaxias divergens (Osmeriformes: Galaxiidae), to test a hypothesis of drainage evolution in South Island, New Zealand. Geological evidence indicates that the presently north-flowing Kaituna River branch of the Pelorus River system once flowed south into the Wairau River system. The subsequent flow-reversal is thought to have resulted from Pleistocene subsidence in central New Zealand. mtDNA sequence data corroborated this geological hypothesis: rivers draining into Pelorus Sound were found to retain a genetic lineage of G. divergens that is otherwise restricted to the Wairau River system and adjacent coastal drainages (based on current sampling). Other sampled drainages in northern South Island and southern North Island were found to house lineages that were highly divergent from the Wairau–Pelorus clade. Isozyme data yielded groupings based on fixed differences that were largely congruent with mtDNA clades. Standard molecular calibrations suggest that vicariant isolation of Pelorus and Wairau systems (drainage reversal) occurred in the mid-Pleistocene rather than the late Pleistocene as suggested by geology. Future multidisciplinary analyses will aim to improve our understanding of geological and molecular evolutionary rates.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88 , 367–376.     

The expanding range of Undaria pinnatifida in southern New Zealand: distribution, dispersal mechanisms and the invasion of wave-exposed environments

Very few studies have addressed how the invasive kelp Undaria pinnatifida (Harvey) Suringar spreads beyond initial founding populations in harbours. Surveys of the harbours and accessible areas of open coast throughout southern New Zealand were conducted to determine how far U. pinnatifida populations had extended since initial incursions. Our findings clearly demonstrate that U. pinnatifida is capable of invading native communities and can establish reproductive populations in locations subjected to significant and consistent wave action. The extent of spread from source populations differs between harbours in which it has established. Dispersal is greatest in harbours with long established populations, those where populations have not been strategically managed, harbours with high water exchange with surrounding coastal waters, and where prevailing currents allow establishment of U. pinnatifida on suitable substrata close to harbour entrances. Dispersal along the open coast is primarily achieved by drifting adult sporophytes that are washed up in the rocky intertidal zone. Founding populations are most often found in the intertidal zone, primarily within rockpools. Subtidal transects and observations indicate that U. pinnatifida is well adapted to invade exposed coastlines and can establish within a broad range of niches in wave-exposed areas including rockpools, the low intertidal, shallow subtidal, Macrocystis pyrifera kelp forests, and in low light areas beyond the vertical extent of large native macroalgae. The current range of U. pinnatifida is much greater than expected and appears to be expanding. Due to its ability to grow in a broad range of environments and to form dense monospecific stands, U. pinnatifida has the potential to strongly modify almost all rocky subtidal and intertidal communities in temperate locations.