Comparisons of species richness among assemblages using different sample sizes may produce erroneous conclusions due to the strong positive relationship between richness and sample size. A current way of handling the problem is to standardize sample sizes to the size of the smallest sample in the study. A major criticism about this approach is the loss of information contained in the larger samples. A potential way of solving the problem is to apply extrapolation techniques to smaller samples, and produce an estimated species richness expected to occur if sample size were increased to the same size of the largest sample. We evaluated the reliability of 11 potential extrapolation methods over a range of different data sets and magnitudes of extrapolation. The basic approach adopted in the evaluation process was a comparison between the observed richness in a sample and the estimated richness produced by estimators using a sub‐sample of the same sample. The Log‐Series estimator was the most robust for the range of data sets and sub‐sample sizes used, followed closely by Negative Binomial, SO‐J1, Logarithmic, Stout and Vandermeer, and Weibull estimators. When applied to a set of independently replicated samples from a species‐rich assemblage, 95% confidence intervals of estimates produced by the six best evaluated methods were comparable to those of observed richness in the samples. Performance of estimators tended to be better for species‐rich data sets rather than for those which contained few species. Good estimates were found when extrapolating up to 1.8‐2.0 times the size of the sample. We suggest that the use of the best evaluated methods within the range of indicated conditions provides a safe solution to the problem of losing information when standardizing different sample sizes to the size of the smallest sample.
We suggest a new phylogenetic hypothesis for the tripunctata radiation based on sequences of mitochondrial genes. Phylogenetic trees were reconstructed by parsimony, maximum likelihood and Bayesian methods. We performed tests for hypotheses of monophyly for taxonomic groups and other specific hypotheses. Results reject the monophyly for the tripunctata group whereas monophyly is not rejected for the tripunctata radiation and other specific groups within the radiation. Although most of the basal nodes were unresolved we were able to identify four clusters within the tripunctata radiation. These results suggest the collection of additional data before a proper taxonomic revision could be proposed.
ABSTRACT. It was sampled the litter frogs at altitudinal sites of a semideciduous mesophytic forest located at SeITa do Japi (Jundiaí, São Paulo, 23°I7'S, 47°00'W, 800-1300m altitude, 1500mm rain/year). Forty two plots of 8x8m were sampled in the dly/cold season of 1995: 21 at a Higher Site (HS) (lOOOm) and 21 at a Lower Site (LS) (850m). The plots were evenly located near, mid-distance, and far from lhe stream-bed. lt was found a total of tive species, three aI each sile. Eleulherodaclylus guenlheri comprised 83% of lhe individuaIs aI HS and E. juipoca 67% aI LS. The density of individuaIs was higher aI HS and near lhe slream. The grealer density aI HS may be due to grealer humidity there, provided by mist. The frogs may aggregate in wetter places (stream edges) in lhe dry/cold season. The studied sites represent harsh and early successional environments and bolh these factors may be acting together to produce the low observed diversity. KEY WORDS. Brachycephalus, Eleutherodactylus, Hyla, litter frogs, diversity, Southeastern Brazil Species composition and abundance of litter frogs are influenced by local environmental conditions such litter depth and humidity (SCOTT 1976; TOFT 1980) in addition to historical factors such as human disturbance (LIEBERMAN 1986; HErNEN 1992). The Serra do Japi is a group of low mountains in the Mantiqueira range in Southeastern Brazil mostly covered by a seasonally dry semideciduous mesophytic forest (LEITÃO-FILHO & MORELLATO 1997). On its west face, in a 300m altitudinal range (850-1 170m), different vegetational types are found (RODRIGUES & SHEPHERD 1992). lt was sampled the litter frogs at two altitudinal sites on this west face, in the altitudinal extremes where an accessible forest stream is found. Specifically it was asked: I) Do lhe litter frog diversity and abundance differ between the sites?; and 2) Do the abundance vary with distance from the stream? Revta bras. Zool. 14 (2): 341 -346 ,1 997
This paper describes the composition and abundance of Drosophila species found in three forest remnants in the State of São Paulo. A well-standardized sampling procedure applied on four collecting trips to the same sites on four areas resulted on 944 samples. All males collected were identified by analyses of the genitalia, this being the only data set used. One hundred and twenty five species were detected amongst the 29,289 males analyzed. From them 57,6% could be identified as described species. Thirteen of the species found were absent from the previous species list for the state of São Paulo State, thus represent an increase of 13% on the number known. We argue that the majority of the 53 unidentified species are in fact undescribed. The sites studied did not differ significantly in the proportion of identified species. On average identified species were almost seven times more abundant than unidentified ones, and this difference was significant. Rarefaction curve analysis confirmed that the proportion of unidentified species increase with sample size, and did not reach a plateau with our data set. These results illustrate the large richness of Drosophila species in forest remnants of São Paulo State. It also indicates that about half of the species in this region remain to be described. This conclusion is particularly important when one considers that this is a well studied genus of Diptera, on the best sampled region of Brazil.Key words: composition; diversity; richness; inventory; atlantic forest; neotropical region. ResumoEste trabalho descreve a composição e a abundância de espécies de Drosophila encontradas em três remanescentes florestais do estado de São Paulo. Um procedimento de coletas bem padronizado aplicado em quatro coletas nos mesmos sítios em três áreas resultou em 944 amostras. Todos os machos coletados foram identificados pela análise da genitália, e apenas os dados destes foram analisados. Cento e vinte e cinco espécies foram detectadas entre os 29.289 machos analisados. Destas 57,6% puderam ser identificadas como espécies já descritas. Treze das espécies encontradas estavam ausentes da lista prévia de espécies do estado de São Paulo, resultado em um aumento de 13% nesta lista. A maioria das 53 espécies não identificadas são, provavelmente, não descritas. Os sítios estudados não diferem significativamente na proporção de espécies identificadas. Em média as espécies identificadas foram quase sete vezes mais abundantes do que as não identificadas, e esta diferença foi significativa. Uma análise de curvas de rarefação confirmou que a proporção de espécies não identificadas aumenta com o tamanho amostral, e não atinge um platô em nosso conjunto de dados. Estes resultados ilustram a grande riqueza de espécies de Drosophila nos remanescentes florestais do estado de São Paulo. Eles também indicam que cerca de metade das espécies desta região ainda não foram descritas. Esta conclusão mostra-se particularmente importante considerando que este é um gênero de Diptera bem estudado, na região ...
The idea of a general independence between the phenotypic plasticity and the mean value of a trait is, presently, a consensus.Here, we use the reaction norm of abdominal pigmentation (number of dark spots) of Drosophila mediopunctata in response to temperature, to test this idea. We raised eight strains, bearing two different chromosomal inversions and with varying mean phenotypic values, under 11 temperatures in a thermal gradient to test for predictions concerning mean phenotypic values, chromosomal inversions, and reaction norms. Our results revealed a strong effect of different phenotypic groups and no effect of different karyotypes on reaction norms. Moreover, we found a significant negative correlation between mean phenotypic value and the curvature of the reaction norms, revealing a high dependency of the reaction norm shape on mean phenotypic value. These results clearly reject the idea of genetic independence between mean value and phenotypic plasticity, and may indicate a pattern of correlation, which may include results from other traits and species, with an importance that has not been fully appreciated.
ABSTRACT. Here is described the diet of Proceratophrys boiei (Wied, 1825), a leaf litter frog of the Atlantic Forest, and test for relationships between frog size and prey size and type. The diet was determined by stomach content analysis. In 38 frogs, was found 76 prey items belonging to 23 taxa. Insects predominate in the diet and the most frequent categories were coleopterans (39.4 % of total volume) and orthopterans (25.0 %). There was a positive correlation between frog size and volume of prey taken. The most imp0l1ant ontogenetic shift in prey type was an increase in the consume of coleopterans and insect larvae with increasing frog size.
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