An estimate of the of tropical tree

The high richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual of tropical tree . Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 , we use a fitted value of Fisher's alpha and an approximate pantropical stem total to estimate the minimum of tropical forest tree to fall between similar to 40,000 and similar to 53,000, i.e., at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as -rich as the Neotropics, with both regions having a minimum of similar to 19,000-25,000 tree . Continental Africa is relatively depauperate with a minimum of similar to 4,500-6,000 tree . Very few are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating richness in trees that may help refine richness estimates of tree-dependent taxa.

Avian comparative genomics: reciprocal chromosome painting between domestic chicken (Gallus gallus) and the stone curlew (Burhinus oedicnemus, Charadriiformes) - An atypical with low diploid

The chicken is the most extensively studied in birds and thus constitutes an ideal reference for comparative genomics in birds. Comparative cytogenetic studies indicate that the chicken has retained many chromosome characters of the ancestral avia

Biodiversity loss and ecosystem functioning: Distinguishing between and identity of

Given currently high rates of extinction, it is critical to be able to predict how ecosystems will respond to loss of and consequent changes in community structure. Much previous research in this area has been based on terrestrial systems, using synthetically assembled communities. There has beer! much less research on inter-trophic effects in different systems, using in situ removal experiments. Problems with the design of early experiments have made it difficult to determine whether reductions in ecosystem functioning in low diversity treatments were due to the of present or merely to the reduced likelihood of including particular (

A technique for mapping three-dimensional densities of in laser produced plumes

The potential of a diagnostic technique to provide quantitative three-dimensional (3D) density distributions of in a low temperature laser-produced plume is shown. An expanded, short pulse, tunable dye laser is used to probe the plume at a set time during the expansion. Simultaneous recording of two-dimensional in-line absorbance maps and orthogonal recording of laser induced fluorescence permits the 3D density mapping by scanning the dye laser frequency. Preliminary data, supported by a simple model, is presented for the case of Ba II ions in a YBCO plume heated by a KrF laser. (C) 1996 American Institute of Physics.

Is the of on earth increasing or decreasing? Time, chaos and the origin of

Darwin's On the Origin of has led to a theory of evolution with a mass of empirical detail on population genetics below level, together with heated debate on the details of macroevolutionary patterns above level. Most of the main principles are clear and generally accepted, notably that life originated once and has evolved over time by descent with modification. Here, I review the fossil and molecular phylogenetic records of the response of life on Earth to Quaternary climatic changes. I suggest that the record can be best understood in terms of the nonlinear dynamics of the relationship between genotype and phenotype, and between climate and environments. 'The origin of ' is essentially unpredictable, but is nevertheless an inevitable consequence of the way that organisms reproduce through time. The process is 'chaotic', but not 'random'. I suggest that biodiversity is best considered as continuously branching systems of lineages, where '' are the branch tips. The Earth's biodiversity should thus (1) be in a state of continuous increase and (2) show continuous discrepancies between genetic and morphological data in time and space. © The Palaeontological Association.

The Tnt1 family member Retrosol copy and structure disclose retrotransposon diversification in different Solanum

Eukaryotic genome expansion/retraction caused by LTR-retrotransposon activity is dependent on the expression of full length copies to trigger efficient transposition and recombination-driven events. The Tnt1 family of retrotransposons has served as a model to evaluate the diversity among closely related elements within Solanaceae and found that members of the family vary mainly in their U3 region of the long terminal repeats (LTRs). Recovery of a full length genomic copy of Retrosol was performed through a PCR-based approach from wild potato, Solanum oplocense. Further characterization focusing on both LTR sequences of the amplified copy allowed estimating an approximate insertion time at 2 million years ago thus supporting the occurrence of transposition cycles after genus divergence. Copy of Tnt1-like elements in Solanum were determined through genomic quantitative PCR whereby results sustain that Retrosol in Solanum is a low copy retrotransposon (1-4 copies) while Retrolyc1 has an intermediate copy (38 copies) in S. peruvianum. Comparative analysis of retrotransposon content revealed no correlation between genome size or ploidy level and Retrosol copy . The tetraploid cultivated potato with a cellular genome size of 1,715 Mbp harbours similar copy per monoploid genome than other diploid Solanum (613-884 Mbp). Conversely, S. peruvianum genome (1,125 Mbp) has a higher copy . These results point towards a lineage specific dynamic flux regarding the history of amplification/activity of Tnt1-like elements in the genome of Solanum .

Chromosome homologies of the highly rearranged karyotypes of four Akodon (Rodentia, Cricetidae) resolved by reciprocal chromosome painting: the evolution of the lowest diploid in rodents

Traditionally comparative cytogenetic studies are based mainly on banding patterns. Nevertheless, when dealing with with highly rearranged genomes, as in Akodon , or with other highly divergent , cytogenetic comparisons of banding patterns prove inadequate. Hence, comparative chromosome painting has become the method of choice for genome comparisons at the cytogenetic level since it allows complete chromosome probes of a to be hybridized in situ onto chromosomes of other , detecting homologous genomic regions between them. In the present study, we have explored the highly rearranged complements of the Akodon using reciprocal chromosome painting through -specific chromosome probes obtained by chromosome sorting. The results revealed complete homology among the complements of Akodon sp. n. (ASP), 2n = 10; Akodon cursor (ACU), 2n = 15; Akodon montensis (AMO), 2n = 24; and Akodon paranaensis (APA), 2n = 44, and extensive chromosome rearrangements have been detected within the with high precision. Robertsonian and tandem rearrangements, pericentric inversions and/or centromere repositioning, paracentric inversion, translocations, insertions, and breakpoints, where chromosomal rearrangements, seen to be favorable, were observed. Chromosome painting using the APA set of 21 autosomes plus X and Y revealed eight syntenic segments that are shared with A. montensis, A. cursor, and ASP, and one syntenic segment shared by A. montensis and A. cursor plus five exclusive chromosome associations for A. cursor and six for ASP chromosome X, except for the heterochromatin region of ASP X, and even chromosome Y shared complete homology among the . These data indicate that all those closely related have experienced a recent extensive process of autosomal rearrangement in which, except for ASP, there is still complete conservation of sex chromosomes homologies.

Cytogenetic characterization of Eurysternus caribaeus (Coleoptera: Scarabaeidae): evidence of sex-autosome fusion and diploid reduction prior to dispersion

Mitotic and meiotic chromosomes of several populations of Eurysternus caribaeus (Coleoptera: Scarabaeidae) were analysed through conventional staining, C-banding, base-specific fluorochromes, silver nitrate staining and fluorescent in situ hybridization (FISH). All specimens showed 2n = 8 in their karyotypes, with a neo-XY sex system (Y is a submetacentric and X a metacentric) and three pairs of submetacentric autosomes. The analysis of constitutive heterochromatin (CH) revealed small blocks located in the centromeric region of all chromosomes which do not present positive staining under the fluorochromes CMA3 and DAPI. Silver nitrate staining revealed that the nucleolar organizer region (NORs) is associated with the sex chromosomes. The FISH technique revealed that rDNA sites in the X and Y are different in size. Data from different populations indicate that the diploid reduction (2n = 8) observed in E. caribaeus is established and presumably has preceded the dispersion of this . Moreover, this reduction occasioned the translocation of rDNA sites to the sex chromosomes, X and Y, an uncommon pattern in Scarabaeidae that was observed for the first time by the FISH in this work.

Extreme degree of chromosome variability in of the spider genus Scytodes (Araneae, Haplogynae, Scytodidae)

Genus Scytodes includes most of the spider family Scytodidae. Until now, 187 of the genus have been described. In spite of this great diversity, only three Scytodes were karyotyped so far. The present paper provides for the first time karyotype analysis of two synanthropic , Scytodes fusca and Scytodes itapevi. Furthermore, new data on karyotype of Scytodes globula are also provided using conventional and differential cytogenetical procedures. The diploid in the genus Scytodes varied considerably, namely from 2n = 13 to 2n = 31. The diploid found in S. globula (2n male = 13) is the lowest in haplogyne spiders with monocentric chromosomes. Except S. globula, this has been found only in one haplogyne spider with monocentric chromosomes, namely Ochyrocera sp. (Ochyroceratidae). on the contrary, the diploid of S. fusca (2n male = 31) is one of the highest diploid s recorded in haplogyne spiders. The degree of intrageneric variation found in the genus Scytodes is the highest recorded in araneomorph spiders with monocentric chromosomes so far. Some karyotype characteristics (diploid , chromosome morphology, total chromosome length, and distribution of constitutive heterochromatin) allowed us to postulate a close relationship between S. globula and S. itapevi. According to the karyotype data, S. fusca is not closely related to these two . This conclusion corroborates a recent taxonomic work that grouped S. globula, S. itapevi, and other four Scytodes in the 'globula group'.

Cytogenetic analyses of eight in the genus Leptodactylus Fitzinger, 1843 (Amphibia, Anura, Leptodactylidae), including a new diploid and a karyotype with multiple translocations

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Chromosome banding in three of Hypsiboas (Hylidae, Hylinae), with special reference to a new case of B-chromosome in anuran frogs and to the reduction of the diploid of 2n=24 to 2n=22 in the genus

The chromosomes of hylids Hypsiboas albopunctatus, H. raniceps, and H. crepitans from Brazil were analyzed with standard and differential staining techniques. The former presented 2n = 22 and 2n = 23 karyotypes, the odd diploid is due to the presence of an extra element interpreted as B chromosome. Although morphologically very similar to the small-sized chromosomes of the A complement, the B was promptly recognized, even under standard staining, on the basis of some characteristics that are usually attributed to this particular class of chromosomes. The two other have 2n = 24, which is the chromosome usually found in the of Hypsiboas karyotyped so far. This means that 2n = 22 is a deviant diploid , resulted from a structural rearrangement, altering the chromosome of 2n = 24 to 2n = 22. Based on new chromosome data, some possibilities were evaluated for the origin of B chromosome in Hypsiboas albopunctatus, as well as the karyotypic evolution in the genus, leading to the reduction in the diploid of 2n = 24 to 2n = 22.

A new of Urostreptus (Diplopoda, Spirostreptidae): description and chromossome

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Description and chromosome of a of Pseudonannolene Silvestri (Arthropoda, Diplopoda, Pseudonannolenidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cytogenetics of three Brazilian Goniosoma : A new record for diploid in Laniatores (Opiliones, Gonyleptidae, Goniosomatinae)

Currently, 60 of harvestmen have been karyotyped and all of these are from the Nearctic and Palearctic regions. This work is the first cytogenetic report of three gonyleptid of the suborder Laniatores: Goniosoina aff. badiuln, G. proxiinuni and G. spelaeum of the Neotropical region, from the southeastern region of Brazil. Conventional Giemsa stain chromosome preparations were obtained from embryonic cells and adult male testes. Embryo mitotic plates of G. aff. badium and G. proximum indicated 88 chromosomes, and mitotic spermatogonial plates of G. spelaeum males revealed intra- and interindividual variation of chromosome , ranging from 92-109 chromosomes. In the three analyzed , the mitotic chromosomes were meta- or subinetacentric with no obvious sex chromosomes being identified during mitosis. Prophase I spermatocytes of G. spelaeum also revealed intra- and interindividual bivalent variation and furthermore indicated the presence of multivalence. The karyotypes of these three Goniosoina exhibited the largest chromosome pair with a negative heteropycnosis in the distal region of the shortest arrn chromosomes of G. spelaeum submitted to silver impregnation evidenced this negative heteropycnotic region as nucleolus organizer region (NOR). These results, when compared with cytogenetic data of other Laniatores from the Palearctic region, indicated that a new record for diploid chromosome probably characterize the genus Goniosoma in the Neotropical region.

Climatic variables and altitude as predictors of anuran richness and of reproductive modes in Brazil

Because anuran are highly dependent on environmental variables, we hypothesized that anuran richness and the of reproductive modes from different Brazilian localities vary according to climatic and altitudinal variables. Published data were compiled from 36 Brazilian localities and climatic and altitudinal data were extracted from an available database. A partial redundancy analysis (pRDA) showed that 23.5% of the data set's variation was explained by climatic and altitudinal data, while the remaining 76.5% remained unexplained. This analysis suggests that other factors not analysed herein may also be important for predicting anuran richness and the of reproductive modes in Brazil. Altitude and total annual rainfall were positively correlated with anuran richness and the of reproductive modes, and total annual rainfall was strongly associated with these two biotic variables in the triplot of pRDA. The positive association of total annual rainfall and the negative association of the concentration of annual rainfall were already expected based on physiological and reproductive requirements of anurans. On the other hand, temperature was not associated with richness or the of reproductive modes. Copyright © 2010 Cambridge University Press.