Digestive ability of the freshwater crayfish Paranephrops zealandicus (White) (Parastacidae) and the role of microbial enzymes

SUMMARY. 1 Ingestion rate, assimilation efficiency and digestive enzyme activity were investigated in the New Zealand freshwater crayfish, Paranephrops zealandicus (White). Rates of ingestion of fresh and decaying Elodea canadensis Michx. were highly variable at 15°C and assimilation efficiency averaged 21%.
2.Hepatopancreas extracts showed enzyme activity towards each of nine substrates tested; microcrystalline cellulose (MCC), carboxymethyl cellulose (CMC), cellobiose, amylose, pectin, mannan, laminarin, chitin and'Azocoll' (a dye-collagen complex).
3. Three genera of Enterobacteriacae were isolated from digestive juices and hepatopancreas samples and microbial activity was implicated in the breakdown of MCC, laminarin and protein. Host-specific activity was not detected in the assays with MCC suggesting a solely microbial source for this enzyme.
4. Although cellulose cannot be broken down without some degree of prior conditioning, the polytrophic feeding strategy of P. zealandicus is indicated by the presence of host-specific enzymes that hydrolyse storage and structural sugars of algae, fungi and higher plants as well as animal protein.     

陕西渭南一早更新世哺乳动物群及其层位

在陕西渭南游河下游产有泥河湾动物群的三门组之下和上新世蓝田组之上的灰绿色堆积中,发现了许多哺乳类化石。其中的一些主要类别明显地具有其上新世种和更新世种之间的过渡特点。使整个动物群表现出与上下动物群都不相同的特有性质,因而把它称为“游河动物群”;其所在的一套地层称为“游河组”。时代为早更新世早期。     

The Early Pliocene re-colonisation of the deep Mediterranean Sea by benthic foraminifera and their pulsed Late Pliocene–Middle Pleistocene decline

Ninety-five species and 19 genera of cosmopolitan, deep-sea benthic foraminifera belonging to the families Pleurostomellidae, Stilostomellidae and Nodosariidae, became extinct during the Late Pliocene–Middle Pleistocene. Only 50% of these (44 species) were present in the Pliocene or Pleistocene of the deep Mediterranean Sea (ODP Sites 654, 966, 967, 975, 976), being those which had successfully migrated in via the Strait of Gibraltar from the deep Atlantic following the annihilation of the Mediterranean deep-sea fauna during the Late Miocene Messinian Crisis. Most colonisation occurred within the first 0.8 myrs (5.3–4.5 Ma) after re-establishment of the Mediterranean–Atlantic link, with possibly a second lesser period of immigration in the Late Pliocene (3.4–3.0 Ma). We infer that colonisations may have been fortuitous and few in number, as some common members of the group in the Atlantic never succeeded in establishing in the Mediterranean Sea. There is no evidence of any new immigration events during the Pleistocene, implying that the present anti-estuarine circulation may have been in place throughout this period. Our studies suggest that these deep-water, low-oxygen-tolerant foraminifera survived the many periods of deep-water sapropel formation in the Pliocene–Early Pleistocene, possibly in somewhat shallower (~ 500 m) refuges with dysoxic, rather than anoxic conditions.The Pliocene–Pleistocene stratigraphic record of this group of elongate, cylindrical benthic foraminifera with constricted and specialised apertures is similar in the west and east Mediterranean basins. The group declined in abundance (flux) and diversity in two pulses, during the Late Pliocene (3.1–2.7 Ma) and the late Early Pleistocene (1.3–1.0 Ma) in concert with global, southern-sourced, deep-water sites (AABW, CPDW) and earlier than the single decline (1.0–0.6 Ma) in global, intermediate water sites (uNADW, AAIW). All species, with one possible exception, disappeared earlier in the Mediterranean than globally. The highest occurrence of any species of this group in Mediterranean sites was 0.8–0.43 Ma, comparable with 0.7–0.2 Ma outside with the youngest survivors being in abyssal, deep-water.Thus, despite the unusual oceanographic conditions and isolation, the deep Mediterranean Sea was in this case neither the centre for the evolution of new species nor a refuge where species survived after they had disappeared elsewhere.     

Neogene stratigraphy,foraminifera, diatoms,and depositional history of Maria Madre Island,Mexico: Evidence of early Neogene marine conditions in the southern Gulf of California

Foraminifera and diatoms have been analyzed from an upper Miocene through Pleistocene(?) sequence of marine sediments exposed on Maria Madre Island, largest of the Trés Marias Islands off the Pacific coast of Mexico. The Neogene stratigraphic sequence exposed on Maria Madre Island includes a mid-Miocene(?) non-marine and/or shallow marine sandstone unconformably overlain by a lower upper Miocene to uppermost Miocene upper to middle bathyal laminated and massive diatomite, mudstone, and siltstone unit. This unit is unconformably overlain by lower Pliocene middle to lower bathyal sandstones and siltstones which, in turn, are unconformably overlain by upper Pliocene through Pleistocene(?) upper bathyal to upper middle bathyal foraminiferal limestones and siltstones. These beds are unconformably capped by Pleistocene terrace deposits. Basement rocks on the island include Cretaceous granite and granodiorite, and Tertiary(?) andesites and rhyolites. The upper Miocene diatomaceous unit contains a low diversity foraminiferal fauna dominated by species of Bolivina indicating low oxygen conditions in the proto-Gulf Maria Madre basin. The diatomaceous unit grades into a mudstone that contains a latest Miocene upper to middle bathyal biofacies characterized by Baggina californica and Uvigerina hootsi along with displaced neritic taxa. An angular unconformity separates the upper Miocene middle bathyal sediments from overlying lower Pliocene siltstones and mudstones that contain a middle to lower bathyal biofacies and abundant planktonic species including Neogloboquadrina acostaensis and Pulleniatina primalis indicating an early Pliocene age. Significantly, this Pliocene unit contains common occurrences of benthic species restricted to Miocene sediments in California including Bulimina uvigerinaformis. Pliocene to Pleistocene(?) foraminiferal limestones and siltstones characterize submarine bank accumulations formed during uplift of the Trés Marias Island area, and include abundant planktonic foraminifera such as Pulleniatina obliquiloculata and Neogloboquadrina duterteri. Common benthic foraminifera in this unit are indicative of upper bathyal water depths. The Neogene depositional history recorded on Maria Madre Island involves an early late Miocene subsidence event marking formation of the Trés Marias Basin with relatively undiluted diatomaceous sediment deposited in a low oxygen setting. Subsidence and deepening of the basin continued into the early Pliocene along with rapid deposition of terrigenous clastics. Uplift of the basinal sequence began in late Pliocene time accompanied by deposition of upper Pliocene-Pleistocene foraminiferal limestones on a rising submarine bank. Continued episodic uplift of the Neogene deposits brought the island above sea level by late Pleistocene time.     

Out of Africa: the slow train to australasia

We used mitochondrial DNA (mtDNA) sequences to test biogeographic hypotheses for Patiriella exigua (Asterinidae), one of the world's most widespread coastal sea stars. This small intertidal species has an entirely benthic life history and yet occurs in southern temperate waters of the Atlantic, Indian, and Pacific oceans. Despite its abundance around southern Africa, southeastern Australia, and several oceanic islands, P. exigua is absent from the shores of Western Australia, New Zealand, and South America. Phylogenetic analysis of mtDNA sequences (cytochrome oxidase I, control region) indicates that South Africa houses an assemblage of P. exigua that is not monophyletic (P = 0.04), whereas Australian and Lord Howe Island specimens form an interior monophyletic group. The placement of the root in Africa and small genetic divergences between eastern African and Australian haplotypes strongly suggest Pleistocene dispersal eastward across the Indian Ocean. Dispersal was probably achieved by rafting on wood or macroalgae, which was facilitated by the West Wind Drift. Genetic data also support Pleistocene colonization of oceanic islands (Lord Howe Island, Amsterdam Island, St. Helena). Although many biogeographers have speculated about the role of long-distance rafting, this study is one of the first to provide convincing evidence. The marked phylogeographic structure evident across small geographic scales in Australia and South Africa indicates that gene flow among populations may be generally insufficient to prevent the local evolution of monophyly. We suggest that P. exigua may rely on passive mechanisms of dispersal.     

Comparative phylogeography reveals pre‐decline population structure of New Zealand Cyclodina (Reptilia: Scincidae) species

We examined the comparative phylogeography of all species within the endemic New Zealand skink genus Cyclodina to gain insight into the influence of historical processes on the biogeography of the North Island fauna. Until 1–2 kya, six Cyclodina species occurred sympatrically across the North Island of New Zealand. However, most species have undergone dramatic distributional declines subsequent to the introduction of mammals and the arrival of humans. We compare the phylogeographic patterns evident in Cyclodina species in three biogeographic categories: widespread species (Cyclodina aenea, Cyclodina ornata), North Island disjunct relics (Cyclodina macgregori, Cyclodina whitakeri), and northeastern island relics (Cyclodina alani, Cyclodina oliveri, Cyclodina townsi). Mitochondrial DNA (ND2) sequence data was obtained from across the entire range of each Cyclodina species. We used Neighbour‐joining, maximum likelihood and Bayesian methods to examine the phylogeographic patterns present in each species. Phylogeographic patterns varied among species in different biogeographic categories. Substantial phylogeographic structure was evident in the two widespread species (C. aenea, C. ornata), with Pliocene and Pleistocene divergences between clades evident. Divergences among island groups in the three northeastern island relic species (C. alani, C. oliveri, C. townsi) occurred during the late Pliocene–Pleistocene. By contrast, relatively shallow structure, indicative of late Pleistocene divergences, was present in the two North Island disjunct species (C. macgregori, C. whitakeri). The results strongly suggest that the Poor Knights Islands population of C. ornata represents a new species. We suggest that the contrasting phylogeographic patterns exhibited by Cyclodina species in different biogeographic categories might be related to body size, ecology, and habitat preferences. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 388–408.     

Adaptive radiation within New Zealand endemic species of the cockroach genus Celatoblatta Johns (Blattidae): a response to Plio-Pleistocene mountain building and climate change

The South Island of New Zealand offers unique opportunities to study insect evolution due to long-term physical isolation, recent alpine habitats and high levels of biotic endemism. Using DNA sequence data from cytochrome oxidase subunit 1, we investigated the phylogeographical pattern among 10 endemic cockroach species within the genus Celatoblatta Johns (Blattidae). We tested the hypothesis that an ancestral cockroach species underwent rapid speciation in response to major climatic differentiation induced by mountain building. Results suggest that speciation was a twofold process, with an interspecific radiation of Pliocene/Pleistocene age followed by intraspecific diversification during the mid Pleistocene. Average genetic distance (maximum likelihood GTR + I + Gamma) was 9.17%, with a maximum of 14.5%. Data revealed eight deep well-supported branches, each with terminal clades. Six clades were differentiated according to morphological species, while the seventh was composed of three sympatric species. We consider the latter to be a phylogenetic species, possibly as a result of hybridization within a defined geographical area. This finding seriously challenges species distinctions for these three cockroach species. Correlation between genetic distances and a Climate Similarity Index (CSI) was negative, suggesting that species found in similar habitats are also genetically closely related. A Mantel test on within-clade genetic distances vs. linear geographical distance was positive, suggesting allopatric isolation for those haplotypes. We present a model of speciation for South Island Celatoblatta.     

Movement of exotic plants into coastal native forests from gardens in northern New Zealand

The anti-predator behaviours of a New Zealand freshwater crayfish (Paranephrops zealandicus) to the native long-finned eel (Anguilla dieffenbachii) and the introduced brown trout (Salmo trutta) were investigated. Crayfish modified their behaviour in the presence of both trout and eels. However, a significantly greater number of defensive chela displays and swimming responses were made to eels than trout. Crayfish were able to use chemical cues from skin mucus to detect eels but not trout. Paranephrops zealandicus is able to make some appropriate defensive behavioural responses to the introduced brown trout as well as to its native predator, the long-finned eel. However, crayfish may be at greater risk from the introduced predator because of their apparent inability to detect trout using non-contact chemical cues. This may be a reflection of the different co-evolutionary histories crayfish have had with trout and eels.     

Phylogeography of two New Zealand lizards: McCann's skink (Oligosoma maccanni) and the brown skink (O. zelandicum)

The New Zealand skink fauna has proven to be an ideal taxonomic group in which to examine the impact of climatic and geological processes on the evolution of the New Zealand biota since the Pliocene. Here we examine the phylogeography of McCann's skink (Oligosoma maccanni) in order to gain insight into the relative contribution of Pliocene and Pleistocene processes on patterns of genetic structure in the South Island biota, and investigate the phylogeography of the brown skink (O. zelandicum) to examine whether Cook Strait landbridges facilitated geneflow between the North and South Islands in the late-Pleistocene. We obtained mitochondrial DNA sequence data (ND2 and ND4; 1282bp) from across the range of both species. We examined the phylogeographic patterns evident in each species using Neighbour-Joining, Maximum Likelihood and Bayesian methods. We found substantial phylogeographic structure within O. maccanni, with seven distinct clades identified. Divergences among clades are estimated to have occurred during the Pliocene. Populations in the Otago/Southland region (south of the Waitaki River valley) formed a well-supported lineage within O. maccanni. A substantial genetic break was evident between populations in east and west Otago, either side of the Nevis-Cardrona fault system, while north-south genetic breaks were evident within the Canterbury region. Within-clade divergences in O. maccanni appear to have occurred during the mid- to late-Pleistocene. Shimodaira-Hasegawa topology tests indicated that the 'Garston' skink is not genetically distinct from O. maccanni. There was only relatively minor phylogeographic structure within O. zelandicum, with divergences among populations occurring during the mid- to late-Pleistocene. Our genetic data supports a single colonisation of the North Island by O. zelandicum from the South Island, with the estimated timing of this event (0.46mya) consistent with the initial formation of Cook Strait.     

Diversification in the northern neotropics: mitochondrial and nuclear DNA phylogeography of the iguana Ctenosaura pectinata and related species

While Quaternary climatic changes are considered by some to have been a major factor promoting speciation within the neotropics, others suggest that much of the neotropical species diversity originated before the Pleistocene. Using mitochondrial and nuclear sequence data, we evaluate the relative importance of Pleistocene and pre-Pleistocene events within the evolutionary history of the Mexican iguana Ctenosaura pectinata , and related species. Results support the existence of cryptic lineages with strong mitochondrial divergence (> 4%) among them. Some of these lineages form zones of secondary contact, with one of them hybridizing with C. hemilopha . Evolutionary network analyses reveal the oldest populations of C. pectinata to be those of the northern and southern Mexican coastal regions. Inland and mid-latitudinal coastal populations are younger in age as a consequence of a history of local extinction within these regions followed by re-colonization. Estimated divergence times suggest that C. pectinata originated during the Pliocene, whereas geographically distinct mitochondrial DNA lineages first started to diverge during the Pliocene, with subsequent divergence continuing through the Pleistocene. Our results highlight the influence of both Pliocene and Pleistocene events in shaping the geographical distribution of genetic variation within neotropical lowland organisms. Areas of high genetic diversity in southern Mexico were detected, this finding plus the high levels of genetic diversity within C. pectinata , have implications for the conservation of this threatened species.     

Phylogeographic structure and historical demography of the western diamondback rattlesnake (Crotalus atrox): A perspective on North American desert biogeography

The western diamondback rattlesnake (Crotalus atrox) is a prominent member of North American desert and semi-arid ecosystems, and its importance extends from its impact on the region's ecology and imagery, to its medical relevance as a large deadly venomous snake. We used mtDNA sequences to identify population genetic structure and historical demographic patterns across the range of this species, and relate these to broader patterns of historical biogeography of desert and semi-arid regions of the southwestern USA and adjacent Mexico. We inferred a Late Pliocene divergence between peninsular and continental lineages of Crotalus, followed by an Early Mid Pleistocene divergence across the continental divide within C. atrox. Within desert regions (Sonoran and Chihuahuan Deserts, Southern Plains, and Tamaulipan Plain) we observed population structure indicating isolation of populations in multiple Pleistocene refugia on either side of the continental divide, which we attempt to identify. Evidence of post-glacial population growth and range expansion was inferred, particularly in populations east of the continental divide. We observed clear evidence of (probably recent) gene flow across the continental divide and secondary contact of haplotype lineages. This recent gene flow appears to be particularly strong in the West-to-East direction. Our results also suggest that Crotalus tortugensis (Tortuga Island rattlesnake) and a population of 'C. atrox' inhabiting Santa Cruz Island (in the Gulf of California) previously suggested to be an unnamed species, are in fact deeply phylogenetically nested within continental lineages of C. atrox. Accordingly, we suggest C. tortugensis and 'C. atrox' from Santa Cruz Island be placed in the synonymy of C. atrox.     

Phylogeny and diversification of the cloud forest Morpho sulkowskyi group (Lepidoptera,Nymphalidae) in the evolving Andes

The monophyletic Morpho sulkowskyi butterfly group, endemic of Andean cloud forests, was studied to test the respective contributions of Mio‐Pliocene intense uplift period and Pleistocene glacial cycles on Andean biodiversity. We sampled nine taxa covering the whole geographical range of the group. Two mitochondrial and two nuclear genes were analysed using a Bayesian method. We established a dated phylogeny of the group using a relaxed clock method and a wide‐outgroup approach. To discriminate between two hypotheses, we used a biogeographical probabilistic method. Results suggest that the ancestor of the M. sulkowskyi group originated during the Middle–Late Miocene uplift of the Eastern Cordillera in northern Peru. Biogeographical inference suggests that the M. sulkowskyi and Morpho lympharis clades diverged in the northern Peruvian Andes. The subsequent divergences, from the Late Miocene to the Late Pliocene, should have resulted from a dispersal towards the Northern Andes (M. sulkowskyi clade), after the closure of the West Andean Portal separating the Central and Northern Andes, and a southwards dispersal along the Peruvian and Bolivian Eastern Cordilleras (M. lympharis clade). Only a few divergences occurred at the very end of the Pliocene or during the Pleistocene, a period when the more recent uplifts interfered with Pleistocene glacial cycles.     

Identifying glacial refugia in a geographic parthenogen using palaeoclimate modelling and phylogeography: the New Zealand stick insect Argosarchus horridus (White)

We have used phylogeographic analysis of mitochondrial DNA (COI and COII genes) and ecological niche modelling (ENM) to reconstruct the population history of Argosarchus horridus (White), a widespread species of New Zealand stick insect. These data were used to address outstanding questions on the role of glacial refugia in determining the distribution and genetic structure of New Zealand species. Phylogeographic analysis shows a general pattern of high diversity in upper North Island and reduced diversity in lower North Island and South Island. The ENM indicates that during the last glacial maximum, A. horridus was largely restricted to refugia around coastal areas of North Island. The ENM also suggests refugia on the northeast coast of South Island and southeast coast of North Island and this prediction is verified by phylogeographic analysis, which shows a clade restricted to this region. Argosarchus horridus is also most likely a geographic parthenogen where males are much rarer at higher latitudes. The higher levels of genetic variation in northern, bisexual populations suggest southern and largely unisexual populations originated from southwardly expanding parthenogenetic lineages. Bayesian skyline analysis also provides support for a recent population size increase consistent with a large increase in geographic distribution in the late Pleistocene. These results exemplify the utility of integrating ENM and phylogeographic analysis in testing hypotheses on the origin of geographic parthenogenesis and effects of Pleistocene environmental change on biodiversity.     

Defining evolutionary boundaries across parapatric ecomorphs of Black Salamanders (Aneides flavipunctatus) with conservation implications

The accurate delimitation of evolutionary population units represents an important component in phylogeographic and conservation genetic studies. Here, we used a combined population assignment and historical demographic approach to study a complex of ecomorphologically distinctive populations of Black Salamanders (Aneides flavipunctatus) that are parapatrically distributed and meet at a three‐way contact zone in north‐western California. We used mitochondrial tree‐based and multilocus clustering methods to evaluate a priori two‐ (Northern and Southern) and three (Northern, Coast and Inland) population hypotheses derived from previous studies. Mitochondrial results were consistent with the two‐ and three‐population hypotheses, while the nDNA clustering results supported only the two‐population hypothesis. Historical demographic analyses and mtDNA gene divergence estimates revealed that the Northern and Southern populations split during the Pliocene (2–5 Ma). Subdivision of the Southern population into Coast and Inland populations was estimated to be late Pleistocene (0.24 Ma), although our mtDNA results suggested a Pliocene divergence. Effective gene flow estimates (2N_em) suggest that either the two‐ or three‐population hypotheses remain valid. However, our results unexpectedly revealed that the Northern population might instead represent two parapatric populations that separated nearly 4 Ma. These results are surprising because the Pliocene divergence between these ecomorphologically conservative forms is similar or older than for the ecomorphologically divergent Coast and Inland sister populations. We conclude that Black Salamanders in north‐western California belong to at least three or four populations or species, and these all meet criteria for being Evolutionary Significant Units or ‘ESUs’ and therefore warrant conservation consideration.     

Speciation in North American black basses,Micropterus (Actinopterygii: Centrarchidae)

Abstract.— The Pleistocene Epoch has been frequently cited as a period of intense speciation for a significant portion of temperate continental biotas. To critically assess the role of Pleistocene glaciations on the evolution of the freshwater fish clade Micropterus , we use a phylogenetic analysis of complete gene sequences from two mitochondrial genes (cytochrome b and ND2), and a fossil calibration of the molecular clock to estimate ages of speciation events and rates of diversification. The absence of substantial morphological and ecological divergence together with endemism of five of the eight species in North American tributaries of the Gulf of Mexico may be interpreted as the result of a recent Pleistocene origin for these species. Speciation dates in Micropterus range from 1.01 ± 0.32 to 11.17 ± 1.02 million years ago. Only one speciation event is dated to the Pleistocene, and rates of diversification are not significantly variable in Micropterus. The premise that the Pleistocene was an exceptional period of speciation in Micropterus is not supported. Instead, a Gulf Coast allopatric speciation model is proposed, and predicts periods of dynamic speciation driven by sea level fluctuations in the Late Miocene and Pliocene. The Pleistocene, however, was a period of significant intraspecific mitochondrial lineage diversification. The application of the Gulf Coast allopatric speciation model to the remaining aquatic fauna of the Gulf of Mexico coast in North America will rely on robust phylogenetic hypotheses and accurate age estimations of speciation events.     

Phylogeography and systematics of the Peromyscus eremicus species group and the historical biogeography of North American warm regional deserts

Phylogeographic relationships among 26 populations from throughout the geographic range of the Peromyscus eremicus species group are described based on sequence data for a 699-bp fragment of the mitochondrial DNA COIII gene. Distance, maximum-likelihood, and maximum-parsimony analyses of phylogenetic trees generated under four separate character-weighting strategies and representing five alternative biogeographic hypotheses revealed the existence of a cryptic species (Peromyscus fraterculus, previously included under P. eremicus) on the Baja California Peninsula and adjacent southwestern California and two distinct forms of P. eremicus, one from the Mojave, Sonoran, and northwestern Chihuahuan regional deserts (West) and one from the remainder of the Chihuahuan Desert (East). Distinctiveness of P. fraterculus is supported by previous morphometric and allozyme analyses, including comparisons with neighboring P. eremicus and parapatric P. eva, with which P. fraterculus shares a sister taxon relationship. Divergence of the eva + fraterculus, West + East eremicus, and P. merriami haplotype lineages likely occurred in the late Neogene (3 Ma), in response to northern extension of the Sea of Cortéz and elevation of the Sierra Madre Occidental; divergence of eva from fraterculus is concordant with the existence of a trans-Peninsular seaway during the Pleistocene (1 Ma); and divergence of West from East eremicus occurred during the Pleistocene pluvial-interpluvial cycles, but well before the Wisconsinan glacial interval. The sequence of divergence within the eremicus species group and causal association of geological events of the Neogene and Holocene provide a working hypothesis against which phylogeographic patterns among other arid-adapted species of the warm regional deserts of North America may be compared.     

Evolution and phylogeography of Halimeda section Halimeda (Bryopsidales, Chlorophyta)

Nuclear ribosomal and plastid DNA sequences of specimens belonging to section Halimeda of the pantropical green seaweed genus Halimeda show that the group under scrutiny contains many more genetically delineable species than those recognized by classical taxonomy. Discordances between phylograms inferred from nuclear and plastid DNA sequences suggest that reticulate evolution has been involved in speciation within the clade. Nonetheless, our data do not allow ruling out certain alternative explanations for the discordances. Several pseudo-cryptic species are restricted to the margins of the generic distribution range. In a clade of H. cuneata sibling species from widely separated subtropical localities in the Indian Ocean, the South African sibling branches off first, leaving the Arabian and West Australian species as closest relatives. We hypothesize that geographic isolation of the siblings may have taken place following Pleistocene or Pliocene periods of climatic cooling during which subtropical species occupied larger distribution ranges. A more basal separation of Atlantic, Indo-Pacific, and Mediterranean species indicates vicariance. The alternative events that could have caused this vicariance are discussed.     

Extensive genetic differentiation in Gobiomorphus breviceps from New Zealand

Partial mitochondrial DNA sequences for parts of the cytochrome b gene and control region were obtained for 89 upland bullies Gobiomorphus breviceps from 19 catchments in New Zealand. There were two highly distinctive mtDNA clades: a northern clade corresponding to the North Island, northern South Island and west coast South Island, and a south‐east clade, in the southern and eastern South Island. Within these major clades there were further distinct clades that correlated with geographic sub‐regions and catchments. The marked genetic differentiation has occurred in the absence of obvious morphological divergence. Based on cytochrome b sequence divergences and the molecular clock hypothesis, the northern and southeastern clades correspond with the uplift of the Southern Alps during the Pliocene, while populations in the North Island and northern South Island were estimated to have diverged during the Pleistocene. The widescale geographic divergences were similar to those observed in the galaxiids, Galaxias vulgaris and Galaxias divergens , but biogeographic management boundaries may not be the same, reflecting different evolutionary histories for non‐diadromous species occupying the same areas.     

INCREASED SAMPLING FOR INFERRING PHYLOGEOGRAPHIC PATTERNS IN BOSTRYCHIA RADICANS/B. MORITZIANA (RHODOMELACEAE,RHODOPHYTA) IN THE EASTERN USA1

Zuccarello and West (2003) reported on the phylogenetic diversity of algae identified as Bostrychia radicans (Montagne) Montagne and B. moritziana (Sonder ex Kützing) J. Agardh from around the world. They showed that the species complex consisted of seven distinct lineages, of which two lineages were common on the East Coast of the USA and eastern Gulf of Mexico. The distribution of haplotypes within these lineages on the East Coast of the USA showed a general north–south distribution. One haplotype of lineage 5 (B) was mostly collected in northern areas, while the other common haplotype (C) was more southerly in distribution. Samples in lineage 6 (haplotype D) were not found north of Sapelo Island, Georgia. Increased sampling from the eastern USA over 5 years later has revealed an altered pattern. Haplotype D is distributed in North Carolina and is common in some populations. Haplotype C is rare or absent in many sampled populations. Haplotype B is only observed in the northern sampled sites on both sides of the Florida peninsula. This disjunct distribution agrees with geological scenarios for a strait between the western Gulf of Mexico and southern Georgia in the Miocene/Pliocene, which closed in the late Pliocene. This paper highlights the importance of increased sampling to determine phylogeographic patterns and hypotheses of dispersal scenarios in algae.     

Speciation of Iberian diving beetles in Pleistocene refugia (Coleoptera, Dytiscidae)

The Mediterranean basin is an area of high diversity and endemicity, but the age and origin of its fauna are still largely unknown. Here we use species-level phylogenies based on approximately 1300 base pairs of the genes 16S rRNA and cytochrome oxidase I to establish the relationships of 27 of the 34 endemic Iberian species of diving beetles in the family Dytiscidae, and to investigate their level of divergence. Using a molecular clock approach, 18-19 of these species were estimated to be of Pleistocene origin, with four to six of them from the Late Pleistocene ( approximately 100 000 years). A second, lower speciation frequency peak was assigned to Late Miocene or Early Pliocene. Analysis of the distributional ranges showed that endemic species placed in the tip nodes of the trees are significantly more likely to be allopatric with their sisters than endemic species at lower node levels. Allopatric sister species are also significantly younger than sympatric clades, in agreement with an allopatric mode of speciation and limited subsequent range movement. These results strongly suggest that for some taxa Iberian populations were isolated during the Pleistocene long enough to speciate, and apparently did not expand their ranges to recolonize areas north of the Pyrenees. This is in contradiction to observations from fossil beetles in areas further north, which document large range movements associated with the Pleistocene glacial cycles hypothesized to suppress population isolation and allopatric speciation.