Hochstetter's frog (Leiopelma hochstetteri) egg,mobile larvae and froglet development

Egg strings and larvae of Hochstetter's frog (Leiopelma hochstetteri) were located at three widely separated North Island sites: in seeps at Brynderwyns in December 2004, in an open pool at Wharerino in March 2009, and in an underground pool near the Kaipawa Track, Coromandel, in late May 2009. Ten egg strings were also laid by captive frogs in water courses at Hamilton Zoo in April 2009. All egg strings held from 11 to 13 eggs. The egg strings laid in the Brynderwyns were regularly observed until metamorphosis was completed in March 2005. Twenty-four swimming larvae emerged from 25 capsules at c. 40 days after discovery, and at least 14 froglets were produced at c. 90 days. All of them developed in darkness, in a 120 ml pool <30 mm deep. The emerged froglets ranged from 9.8 to 10.8 mm snout-vent length. The detection of eggs, larvae and <11 mm froglets indicates that the egg laying period is at least from late September to May.     

The evolution of hypervariable sex and supernumerary (B) chromosomes in the relict New Zealand frog,Leiopelma hochstetteri

Chromosomes exhibiting elevated levels of differentiation are termed hypervariable but no proposed mechanisms are sufficient to account for such enhanced evolutionary divergence. Both hypervariable sex and supernumerary (B) chromosomes were investigated in the endemic New Zealand frog, Leiopelma hochstetteri, which is chromosomally polymorphic both within and between populations and has sufficiently elevated variation that different populations can be identified solely by their C-banded karyotypes. This frog is further distinguished by the univalent, female-specific W-chromosome (0W/00 sex determination) uniquely possessed by North Island populations. This sex chromosome exhibited variation in morphology, size, and heterochromatin distribution, sufficient to resolve 11 different types, including isochromosomes. Five of the 12 populations examined also had supernumerary chromosomes that varied in number (up to 15 per individual) and morphology. Specific variations seen among the hypervariable chromosomes could have resulted from heterochromatinisation, chromosome fusions, loss-of-function mutations, deletions, and/or duplications. Frogs of the same species from Great Barrier Island, however, had neither supernumeraries nor the female-specific chromosome. The 0W/00 sex chromosome system must have been derived after the isolation of Great Barrier Island from North Island populations by raised sea levels between 14 000 and 8000 years ago. Furthermore, biochemical divergence between populations is minor and therefore the chromosomal variation seen is comparatively recent in origin. The one characteristic common to all known hypervariable chromosomes is curtailment or lack of recombination. Their accelerated evolution therefore is possible via the mechanism of Muller's ratchet, either alone or in concert with other factors.     

Integrated control of apple pests in New Zealand 6. Incidence of European red mite,Panonychus ulmi (Koch), and its predators

Mite relationships were investigated in an orchard near Nelson from 1962 to 1974 in conjunction with a long‐term experiment into integrated control of apple pests. From 42% to 57% of the total winter eggs of Panonychus ulmi hatched over a period of 48–53 days from the last week of September until mid November. The main hatch—from 10% to 90%—took 19–20 days. Five generations occurred in each season, from October to March, although some females laid winter eggs from mid January if leaf condition became poor. Insect predators found were Stethorus bifidus, Sejanus albisignata, Arthrocnodax sp., and Xylapothrips sp. The mite Typhlodromus pyri (Phytoseiidae), the most important predator, had up to 5 generations from October to March; some females ceased to feed or oviposit from mid February onwards, and took on the characteristics of the overwintering diapause phase. With the integrated programme based on ryania, a favourable balance of P. ulmi and T. pyri was established after an initial outbreak of P. ulmi in the 1st or 2nd season, and was maintained until 1970–71, when P. ulmi outbreaks occurred on several cultivars in a season marked by hot, dry conditions in November and December. Natural control was restored the next year except on cy. Delicious, where P. ulmi remained in greater numbers for several years. With a complete commercial spray programme from 1962 to 1967 P. ulmi became resistant to all acaricides used; with the regular azinphos‐methyl programme and no acaricides in 1967–68 a population of T. pyri resistant to this insecticide emerged. The approximately × 10 resistance level did not increase appreciably, so the azinphos‐methyl dosage was reduced from 0.05% to 0.025% to allow greater survival. Several hot, dry summers followed, and commercial control of P. ulmi by T. pyri did not occur until 1973–74. A programme of low‐dosage carbaryl allowed T. pyri and S. albisignata to establish in fair numbers, but control of P. ulmi was not achieved. Experiments with mineral oils and cyhexatin have shown them to have some potential for inclusion against P. ulmi in future integrated programmes.     

Rapid recovery of a population of the cryptic and evolutionarily distinct Hochstetter's Frog,Leiopelma hochstetteri,in a pest‐free environment

New Zealand's native frogs (genus Leiopelma) display a very high degree of endemism and belong to a distinctive and ancient evolutionary lineage. All four extant species are considered to be threatened or endangered, but the mechanisms behind their decline are poorly understood. Many of the potential factors causing population declines are confounded for the two species living on the mainland; in particular, habitat degradation and the presence of introduced mammalian pests have been difficult to disentangle in the past. Here we present data on a population of Hochstetter's Frog (Leiopelma hochstetteri) living in a pest‐free mainland sanctuary, the 3363‐ha Maungatautari Ecological Island. Survey data from this population shows a fourfold increase in numbers between 2009 and 2012 from a very low initial density. Our results suggest that for Hochstetter's Frog at least, and possibly the other mainland species of Leiopelma, introduced mammals are a major driving factor in population declines. Given that the frog population at Maungatautari was discovered by serendipity when planning for the pest‐free sanctuary was already well underway, this also highlights the conservation value of large pest‐free areas and ecosystem‐level management.     

An electrophoretic study of genetic variation in the New Zealand frog genus Leiopelma

Abstract

Genetic variation at 33 loci in three species of Leiopelma was examined by cellulose acetate electrophoresis of liver enzymes. Heterozygosity is apparently comparable to levels detected in other amphibians. Genetic differentiation between species is extensive. L. hochstetteri is greatly divergent from both L. archeyi and L. hamiltoni, but these two are relatively similar genetically, in agreement with morphological, ecological, and developmental patterns. We tentatively estimate that the divergence of hochstetteri from the other two species occurred during the Miocene, whereas that of archeyi and hamiltoni occurred during the Pliocene. Implications of the genetic data for conservation of these rare species are discussed.     

Supernumerary chromosome variation and heterochromatin distribution in the endemic New Zealand frog Leiopelma hochstetteri

Specimens of the endemic New Zealand frog Leiopelma hochstetteri from Tapu on North Island were found to have six, nine or ten supernumerary chromosomes in their karyotypes. In comparison with previously published data, these results further indicate probable geographic variation in supernumerary chromosome number between populations. Increased numbers of supernumeraries in these frogs is correlated with apparent decrease of centromeric heterochromatin in the five large metacentric chromosomes of the karyotype, as detected by C-banding. Meiosis was abnormal in a male with a high number of supernumeraries. In lampbrush preparations from a single female with one supernumerary univalent, the supernumerary often had a denser, beaded appearance in comparison with the regular bivalents. Evidence is consistent with the notion that these supernumerary chromosomes may have arisen from centromeric fragments.     

Phylogenetic relationships within the New Zealand frog genus Leiopelma — immunological evidence

Abstract

Albumin evolution is examined within the anuran genus Leiopelma using the quantitative immunological technique of micro-complement fixation (MC'F). The albumins of L. archeyi and L. hamiltoni are relatively similar to each other, yet both differ greatly from the albumin of L. hochstetteri. Using albumin as a molecular clock, we estimate that L. hochstetteri diverged from the lineage leading to L. archeyi and L. hamiltoni during the Miocene, about 15 million years ago. The divergence of L. archeyi and L. hamiltoni appears to have been a Pliocene event (about 3 million years ago).     

Conservation status of New Zealand frogs, 2009

Abstract

A reappraisal of the conservation status of the New Zealand frog fauna is presented using the 2008 version of the New Zealand Threat Classification System. Of New Zealand's four extant endemic species, three are judged to be ‘Threatened’ (Leiopelma hamiltoni being ‘Nationally Critical’, and L. pakeka and L. archeyi being ‘Nationally Vulnerable’) and one ‘At Risk’ (L. hochstetteri ‘Declining’). Three Leiopelma species are listed as extinct—they are known from bone deposits in caves throughout the country until some time in the last 1000 years. Three introduced and naturalised Litoria species are abundant in New Zealand although two (L. aurea and L. raniformis) are threatened in their country of origin (Australia). An additional unidentified frog taxon from northern Great Barrier Island is listed as ‘Data Deficient’.     

The taxonomic identity of a population of terrestrial Leiopelma (Anura: Leiopelmatidae) recently discovered in the northern king country,New Zealand

Abstract

A terrestrial endemic frog resembling Leiopelma archeyi was discovered in the Whareorino Forest, northern King Country, New Zealand, in 1991, where it is broadly sympatric with L. hochstetteri. To clarify its taxonomic status, allozyme electrophoresis of toe tissue was used to compare it genetically with four other populations of terrestrial Leiopelma (L. archeyi from Tapu and Tokatea, Coromandel; L. hamiltoni from Stephens Island; L. pakeka from Maud Island). Thirteen presumed genetic (allozyme) loci could be consistently scored for the five populations. At 11 loci, no genetic differences were found between the Whareorino frog and the two Coromandel L. archeyi populations. Allelic frequencies differed slightly at two loci. We therefore conclude that the terrestrial Whareorino frog represents a western population of L. archeyi. L. hamiltoni from Stephens Island is genetically closer to L. archeyi than is L. pakeka from Maud Island. The Whareorino L. archeyi population is morphologically similar to Coromandel L. archeyi populations, although multivariate analysis suggests subtle morphological differences, including the relative position of the nostril. Size comparisons between Whareorino and three Coromandel sites (Moehau, Tapu, Tokatea) show there were more larger frogs (35–38 mm snout‐vent length) at Whareorino and Tokatea compared with Moehau and Tapu, where maximum snout‐vent lengths were 34 and 36 mm, respectively.     

Cytogenetic studies in six species of Scinax (Anura,Hylidae) clade Scinax ruber from northern and northeastern Brazil

Scinax species are still underrepresented in cytogenetic studies, mainly with respect to populations from northeastern and northern Brazil. In this study, we provide new chromosomal information on Scinax boesemani, S. camposseabrai, S. garbei, S. pachycrus, S. trilineatus and S. x-signatus, all belonging to clade S. ruber. They were collected at two locations in the Caatinga biome (northeastern Brazil) and at one in the Amazon (northern Brazil) biomes. Chromosomes were analyzed by conventional staining, C-banding, Ag-NOR staining, and fluorochrome staining. All species shared a modal diploid value of 2n = 24 and fundamental arm number (FN) of 48. Moreover, both chromosomal size and morphology were similar to other species in this Scinaxclade. C-banding revealed centromeric heterochromatin in all species, along with terminal species-specific C-bands in some species. Active nucleolar organizer regions (Ag-NORs) were identified at 11q in most species, except for S. boesemani and S. garbei (Ag-NORs at interstitial region of 8q). Differing from most anurans, GC-rich regions were not restricted to NORs, but also coincident with some centromeric and terminal C-bands. These data contribute to the cytotaxonomy of Scinax by providing chromosomal markers and demonstrating the occurrence of microstructural rearrangements and inversions on chromosomal evolution of Scinax.     

Habitat distribution and predation on a western population of terrestrial Leiopelma (Anura: Leiopelmatidae) in the northern King Country,New Zealand

Abstract

A new population of terrestrial Leiopel‐matid frog was discovered in the Whareorino Forest, northern King Country, New Zealand, in 1991. Searches were carried out from June 1991 to December 1993 to determine the species present and to document variation in external morphology, habitat, and local distribution. These confirmed that a terrestrial frog resembling L. archeyi is present in the area, as well as Hochstetter's frog Leiopelma hochstetteri and the introduced Australian hylid frog Litoria aurea.

In Whareorino Forest, the terrestrial Leiopelma was mostly above 500 m altitude and L. hochstetteri above 350 m. The terrestrial Leiopelma occupies sites under rocks and logs in forest. It also occurs in vegetation, such as crown fern Blechnum discolor, tree fern Cyathea smithii, hook grass Uncinia uncinata, and rice grass Microlaena avenacea. Egg clusters of this frog were found in crown fern and tree fern, as well as under stones.

The terrestrial Leiopelma is susceptible to predation by Litoria aurea and rats. This is the first documented evidence of predation on Leiopelma on the New Zealand mainland. The future of this small remnant Leiopelma population is uncertain, and further investigation of the impact of anuran and mammalian predators is needed.     

Historical trends in frog populations in New Zealand based on public perceptions

Surveys were distributed to New Zealand land users in 1998 and 2008 to acquire information about New Zealand frogs with the aim of compiling and mapping their distribution and inferred population trends without costly and time-consuming field surveys. The overall frog population trend was reported as declining, with possible causes reported as an increase in agriculture, an increase in the distribution of predatory fish and disease. The resultant maps could be used for four main purposes: 1) to identify regions where Litoria populations are known to occur, which can be eliminated when considering suitable regions for translocation of Leiopelma; 2) to identify growing or stable populations of Litoria species, which may assist future disease surveys, population monitoring and to identify sources of genetic material that may serve as an Ark for declining Australian populations; 3) to highlight populations that are in decline to enable effective targeting of detailed disease studies; and 4) to approximate the stability of amphibian populations in the absence of more accurate, but costly, scientific monitoring.     

Karyotypes,heterochromatin distribution and rDNA patterns in South American Grindelia (Asteraceae)

Grindelia is a genus with a complex evolutionary history with reticulate evolution. We studied the karyotype, fluorescent banding, and fluorescence in situ hybridization (FISH) using 18–5.8–26 S and 5 S ribosomal DNA probes to survey karyotypic diversity of South American Grindelia species. Chromosome basic numbers were x = 6 (with several ploidy levels: 2x, 4x, and 6x). All the Grindelia studied conserved the patterns of CG-rich heterochromatin and 18-5.8-26 S rDNA. The third m sat-chromosome pair was homeologous in Grindelia. Chromosome variation, although not always large, accompanied the evolutionary divergence of the taxa studied. The Grindelia studied formed two species groups: (1) G. globularifolia and G. pulchella var. pulchella, (2) G. buphthalmoides, G. cabrerae var. alatocarpa and var. cabrerae, G. chiloensis, G. orientalis, and G. prostrata. These groups do not show any morphological affinities and their phylogenetic relationships are not clearly resolved, suggesting that these groups have recently diverged.     

Chromosome diversity and evolution in Allium (Allioideae,Amaryllidaceae)

Despite extensive literature on the diversity of karyotypes in Allium is available, no attempt to analyse these data together, within a robust phylogenetic framework, has been carried out so far. Thus, we examined patterns and trends in chromosome evolution across the genus. Based on literature survey, karyo-morphometric features for 207 species belonging to 12 subgenera of Allium were obtained. Included in the data-set were basic chromosome number (x), somatic chromosome number (2n), total haploid (monoploid) chromosome length (THL) and three different measures defining karyotype structure: CV_CI, measuring how heterogeneous are centromeres positions in a karyotype, CV_CL and M_CA, quantifying interchromosomal and intrachromosomal karyotype asymmetry, respectively. Trends in karyotype evolution were analysed by phylogenetic regressions and independent contrasts. Mean karyotypes highlighted differences and similarities in karyotype structure between the 12 subgenera. Further differences were noted when the two parameters for analysing karyotype asymmetry were assessed. In addition, by examining the effects of increasing karyotype dimensions (a proxy for genome size) on karyotype structure and asymmetry, it was shown that in Allium species, the DNA was added proportionally to their arm lengths. Overall, p = 8 and somehow intermediate karyotype asymmetry levels seem to represent plesiomorphic character-states in Allium.     

Karyological studies in Tripleurospermum (Asteraceae, Anthemideae) from north-east Anatolia

Chromosome number and morphology in 14 taxa belonging to 19 populations of Tripleurospermum Sch. Bip. were studied using karyological and numerical taxonomical techniques. Data on chromosome measurements were analysed using cluster analysis. Chromosome numbers of these taxa are 2 n  = 2 x  = 18, 4 x  = 36 and 5 x  = 42–48. Seven records are new, two are not consistent with previous counts, and the remainder confirm the very limited previous data (one to three records). A new ploidy level (pentaploidy) is reported for the first time for the genus. Some correlations between ploidy levels and morphological characters are noted and several systematic and evolutionary aspects of the genus are discussed in the light of karyological data.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 146 , 427–438.     

Karyotype variation, evolution and phylogeny in Borago (Boraginaceae), with emphasis on subgenus Buglossites in the Corso-Sardinian system

BACKGROUND AND AIMS: Karyological variation in the Mediterranean genus Borago and cytogeography of subgenus Buglossites in Corsica, Sardinia and the Tuscan Archipelago were investigated in combination with a molecular phylogenetic analysis aimed at elucidating relationships between subgenera and taxa with different chromosome features. METHODS: Karyotype analysis was performed on population samples of B. pygmaea, B. morisiana, B. trabutii and B. officinalis. Phylogenetic analyses were based on ITS1 nrDNA and matK cpDNA sequences. KEY RESULTS: Four base numbers were found, x = 6, 8, 9 and 15, and three ploidy levels based on x = 8. In subgenus Buglossites the Sardinian endemic B. morisiana is diploid with 2n = 18, while B. pygmaea includes three allopatric cytotypes with 2n = 30 (Sardinia), 2n = 32 (southern Corsica) and 2n = 48 (central northern Corsica and Capraia). In subgenus Borago, the Moroccan endemic B. trabutii and the widespread B. officinalis have 2n = 12 and 2n = 16, respectively. Molecular data support the monophyly of Borago, while relationships in subgenus Borago remain unclear. Borago trabutii appears as the earliest divergent lineage and is sister to a clade with B. officinalis, B. morisiana and B. pygmaea. Subgenus Buglossites is also monophyletic, but no correspondence between ITS1 phylogeny and B. pygmaea cytotypes occurs. CONCLUSIONS: Chromosome variation in Borago is wider than previously known. Two base numbers may represent the ancestral condition in this small genus, x = 6 or x = 8. An increase in chromosome number and karyotype asymmetry, a decrease in chromosome size and heterochromatin content, and the appearance of polyploidy are the most significant karyological changes associated with the divergence of the Buglossites clade. High ITS1 variation in the tetra- and hypotetraploid races of B. pygmaea suggests a multiple origin, while the lower polymorphism of the hexaploid race and its allopatric distribution in the northernmost part of the range is better explained with a single origin via union of unreduced and reduced gametes.     

Intraspecific karyotype variation is not concordant with allozyme variation in the Auckland tree weta of New Zealand, Hemideina thoracica (Orthoptera: Stenopelmatidae)

Nine karyotypes are described within a single species of common New Zealand tree weta. Their diploid numbers range from 11 to 25. The distribution of the karyotypes suggests that each had a single origin except the 17-karyotype which was the most common karyotype and had a disjunct distribution. The overall level of allozyme diversity observed is similar to that seen within many widespread taxa. The distribution of allozyme alleles did not coincide with the distribution of karyotypes within this species and the Neighbour-Joining tree was not concordant with the chromosome based sub-divisions of the species. Thus, no evidence was found to suggest that chromosomal differentiation has been acting as a barrier to the flow of alleles within H. thoracica. The lack of concordance of genetic markers is thought to result from rapid chromosome radiation and reticulate evolution. Northland peninsula of North Island, New Zealand is a region of high chromosomal and allozymic diversity in H. thoracica. This may have resulted from geographic isolation during the Pliocene when Northland formed an archipelago of many small low-lying islands.     

Chromosomes of caryophyllidean cestodes: Diploidy, triploidy, and parthenogenesis in Glaridacris catostomi

Mitotic and meiotic chromosomes were studied in Giemsa post-stained Feulgen squashes of testicular, ovarian, and vitelline cells. G. catostomi is 2n = 20 with eight pairs of metacentrics and two pairs of submetacentrics in its karyotype. The fundamental number of chromosome arms is FN = 40. At mitotic metaphase the mean total chromosome length (TCL) of the complement was 111·4 μm; the largest chromosomes were 8 μm (7% TCL) and the smallest 3 μm (3% TCL). Karyotype variation was not found among five diploid populations from New York State and Canada. Meiotic activity was abundant in spermatogenesis which proceeds as usual with sperm developing after two meiotic divisions. Chiasma frequency at diakinesis was 37/cell; as many as five chiasmata were observed in a single bivalent. A triploid ‘race’ (3n = 30) of G. catostomi was discovered in Bozenkill Creek near Albany, New York. Karyotype analysis confirms the triploid nature of these variants. Spermatogenesis in triploids is abnormal to the point of complete failure. The presence of an extra set of chromosomes has resulted in a breakdown of meiosis with subsequent sterility of the male system. Eggs remain unfertilized and parthenogenetic reproduction is presumed to occur. The possible origins of this unusual condition and its evolutionary implications are discussed. Seventeen figures, two tables of measurements, and a system of chromosome nomenclature supplement the paper.