Drosophilidae (Diptera) associated to fungi: differential use of resources in anthropic and Atlantic Rain Forest areas

This study investigates the Drosophilidae species associated to fruiting bodies of fungi in forested and anthropized environments of the Atlantic Rain Forest Biome, in south and southeastern Brazil. We collected samples of imagoes flying over and emerging from fruiting bodies of species of five fungi families, in six collection sites. We obtained 18 samples, from which emerged 910 drosophilids of 31 species from the genera Drosophila Fallen, 1823, Hirtodrosophila Duda, 1923, Leucophenga Mik, 1886, Mycodrosophila Oldenberg, 1914, Scaptomyza Hardy, 1849, Zaprionus Coquillett, 1901 and Zygothrica Wiedemann, 1830. The Drosophila species collected on fungi, as well as Zaprionus indianus Gupta, 1970, had previously been recorded colonizing fruits, demonstrating their versatility in resource use. Most of these species belong to the immigrans-tripunctata radiation of Drosophila. Our records expands the mycophagous habit (feeding or breeding on fungi) to almost all species groups of this radiation in the Neotropical region, even those supposed to be exclusively frugivorous. Assemblages associated to fungi of forested areas were more heterogeneous in terms of species composition, while those associated to fungi of anthropized areas were more homogeneous. The drosophilids from anthropized areas were also more versatile in resource use.

Fish assemblages in two sandy beaches in lower Purus river, Amazonas, Brazil

Fish assemblages from two sandy beaches in the lower Purus river (Amazonas, Brazil) were compared. Four sampling groups were represented by: day and night samples in sandy beach inside the Reserva Biológica de Abufari (biological reserve) and day and night samples in the Reserva de Desenvolvimento Sustentável Piagaçu-Purus (sustainable development reserve). Samples were collected during low water levels (November) in 2007. The fish were sampled by means of seines with mesh size of 5 mm between opposing knots, 11 m long and 6 m wide. A total of 112 fish species belonging to nine orders and 27 families was captured. The vast majority of the dominant forms consisted of small fishes (< 100 mm SL) or juveniles. Samples collected in Abufari at night presented more specimens (3,540), higher richness (84 spp.), larger total biomass (76,614 g) and higher diversity (H'= 2.57) than the other groups. The composition of fish assemblages was significantly different among all analyzed groups (ANOSIM, p < 0.0001, R= 0.71). NMDS analysis also clustered all species in four distinct groups according to species composition per period and site. SIMPER analyses showed that 80% of variation of species composition among the groups examined was due to 12 species. However, fish composition did not show any correlation with the abiotic factors examined. Different levels of use in both reserves may explain differences in fish composition.

Composition and structure of a Miridae (Hemiptera, Heteroptera) assemblage from a relict of deciduous rainforest in southern Brazil

A two-year study was carried out to evaluate the composition, abundance and species richness of Miridae from Parque Estadual do Turvo, municipality of Derrubadas, state of Rio Grande do Sul, Brazil. Samplings were made in the springs of 2003 and 2004 (October), and autumns of 2004 and 2005 (May), using a beating tray method, along two trails of the park. Sampling effort (hours x collectors) in the quantitative collections totaled 153 hours. Two-hundred mirid specimens of 50 species were collected. The most abundant mirid was Prepops setosipes (Reuter, 1910), representing 23% of the collected individuals, followed by Collaria capixaba Carvalho & Fontes, 1981 (10.5%) and Tropidosteptes cribratus (Stål, 1860) (7%), the latter recorded in all sampling periods. The highest abundance was observed in the springs of 2003 and 2004, with 53 and 78 individuals, respectively. Rarefaction method showed that estimated species richness was higher in autumn/2004 than in the other sampling periods, and higher along Yucumã than in Garcia trail. Besides a higher species richeness, Yucumã had more exclusive species than Garcia trail. The percent of species represented by one or two specimens in quantitative samplings (singletons and doubletons) was 60%. Additional samplings including hand collection, random beating tray and light trap collections added 20 species not recorded in the quantitative samplings.

Diet and functional feeding groups of Chironomidae (Diptera) in the Middle Paraná River floodplain (Argentina)

The gut contents of nine genera of benthic Chironominae and Tanypodinae from the Middle Paraná River floodplain habitats (a lake and a secondary channel) were analyzed to determine their feeding patterns and functional feeding groups. Amorphous detritus, animal and vegetal tissues, and mineral materials (predominantly sand) were observed in the larval guts. Amorphous detritus were the main food item found for Polypedilum (Tripodura) sp., Chironomus gr. decorus sp., Endotribelos sp., Phaenopsectra sp., Cladopelma sp., and Pelomus sp. (Chironominae), while animal tissues (mainly oligochaetes) were the most important food item found for Ablabesmyia (Karelia) sp., Coelotanypus sp., and Procladius sp. (Tanypodinae). Dietary overlap was calculated for all pairs of genera. Within predators, the highest overlap was obtained between Coelotanypus sp. and Ablabesmyia (Karelia) sp., while within detritivores the highest niche overlap was obtained between Endotribelos sp. and Phaenopsectra sp.

Establishment of a new genus for Parastenocaris itica (Copepoda, Harpacticoida) from El Salvador, Central America, with discussion of the Parastenocaris fontinalis and P. proserpina groups

A new genus of Parastenocarididae is described from the Neotropical region. Iticocaris gen. nov. is established to include Parastenocaris itica Noodt, 1962. Iticocaris gen. nov. is defined by the following characters: 1) male leg 3 with 2-segmented exopod; 2) first exopodal segment short and rectangular; 3) thumb hypertrophic, longer than the second exopodal segment and inserted on the distal edge of exopod segment 1, occupying the whole distal margin; 4) exopod 2 or apophysis strongly sclerotized, articulated with the exopod segment 1 on its inner margin and curved against the thumb, forming a strong forceps; 5) leg 4 endopod without dimorphism in shape and size vs. minor dimorphism in ornamentation; 6) leg 5 with three setae and 7) lack of the anterolateral furcal seta II. The new genus is monotypic, represented by Iticocaris itica (Noodt, 1962) comb. nov., from El Salvador, Central America. A close relationship is hypothesized between I. itica and the genus Brasilibathynellocaris Jakobi, 1972, the males of which both share the forceps-like elongated apophysis.

Shifts in composition of avian communities related to temperate-grassland afforestation in southeastern South America

Afforestation of temperate grasslands with fast-growing trees for industrial pulpwood production is spreading in South America. Despite high afforestation rates resulting from governmental policies that stimulate pulpwood production in grasslands of southern Brazil and Uruguay, the impact of this activity on biodiversity remains to be properly assessed. We used an Impact-Reference study design to evaluate how grassland afforestation affects the composition of grassland bird assemblages. We sampled eucalyptus plantations and neighboring natural grasslands in southern Brazil from 2006-2009, and relied on nested sampling and analysis to separate the effects of afforestation from the natural variability of grasslands. We recorded a significant difference in composition between assemblages from grasslands and tree plantations. Species adapted to open, treeless areas tended to be negatively affected in relation to edge or forest birds in eucalyptus plantations. Afforestation is systematically replacing the bird assemblage of hilltop grasslands by a collection of common edge and forest species that occur in nearby riverine and hillside forests. Although most grassland birds negatively affected by tree plantations are common and widespread, observed and predicted afforestation rates in southeastern South America may result in regional population reductions in the near future.

Bird-habitat associations in coastal rangelands of southern Brazil

Nearly all remnants of temperate grasslands in southeastern South America are used for livestock ranching and are subject to habitat degradation resulting from this activity. Exploring how habitat features affect the composition of grassland avifaunal communities is a first step to understand how current cattle-ranching management practices impact avian diversity. We used canonical ordination to test for relationships between five habitat variables and the composition of the bird community in coastal grasslands in southern Brazil. We sampled pastures with different heights, from overgrazed short-grass to tall herbaceous vegetation. We recorded 1,535 individuals and 27 species of birds. The first ordination axis indicated a strong contribution of mean vegetation height on the composition of the bird community, whereas the second axis revealed the influence of herbaceous vegetation patchiness and woody vegetation cover. Three groups of species were revealed by the ordination: one more diffuse associated with intermediate and tall herbaceous vegetation, another with short grass, and a third with vegetation patchiness and woody vegetation. Species restricted to tall herbaceous vegetation are negatively impacted from habitat degradation resulting from overgrazing and trampling by livestock, and mowing and burning of tall plants. Occurrence of these species in our study area is related with the presence of swales immediately behind the dune system and where remnants of tall vegetation persist. Birds of pastures with ample cover of short herbaceous plants, including one globally threatened species and six other restricted to short-grass habitat, apparently benefit from local livestock management practices. Woody vegetation possibly functions as a keystone structure, enabling the occurrence in grasslands of avian species that rely on shrubby habitat. Although livestock ranching promotes the diversity of habitats by creating distinct patches of vegetation height in grasslands, current management practices directed to the maintenance of short grass pastures may eliminate an entire subset of species, including regionally threatened taxa, and reduce avian diversity. The maintenance of large patches of tall herbaceous plants is needed to ensure the survival of species reliant on this type of grassland structure in our study area.

Diversity, composition and phenology of araneid orb-weavers (Araneae, Araneidae) associated with riparian forests in southern Brazil

The Araneidae is a speciose family including web-spinning spiders that are very abundant in various terrestrial ecosystems. Several studies demonstrate that changes in vegetation surrounding rivers, streams and brooks affect the associated araneofauna. The aim of this research was to compare differences found in diversity (abundance and richness), composition and phenology of Araneidae spiders sampled in different habitats in four riparian forest catchments in southern Brazil. Samples were taken from riparian forests in four rivers of Rio Grande do Sul State: Piratini, Camaquã, Sinos and Maquiné rivers, each in a different hydrographic basin. Samples were taken twice seasonally on each basin during two years, sampling the araneofauna of the tree-shrub strata with beating tray. Six transects were employed on each basin, two per habitat: edge with grassland, forest interior and river edge. Araneids totalled 20 genera and 65 species. Comparing riparian forests significant differences are found. Spider abundance differed among riparian forests as well as species richness. Overall, Piratini river riparian forest had the higher abundance and richness for Araneidae; the lower values were in Sinos river forest. The stronger degradation and fragmentation of the riparian forests of Sinos river probably influenced the results, with human disturbance gradients associated negatively to web building. We present data on the diversity of these spiders, which were very abundant in the riparian forest interior and very rich in species in the grassland/riparian forest edge. Species composition also differs among the studied habitats (the above plus river/riparian forest edge). For the most abundant species the phenological pattern across the seasons was also analysed.

Composition and ecological patterns of snake assemblages in an Amazon-Cerrado Transition Zone in Brazil

ABSTRACT The present study encompasses the species composition and ecological characteristics of the snake community in a Cerrado-Amazon transition zone in Midwest of Brazil (state of Mato Grosso). The data were collected during six excursions to the "Tanguro" (study area) by visual encounter survey, pitfall traps with drift fences and non-systematic sampling. We collected 194 specimens, distributed in 34 species, 26 genera, and eight families. The most abundant species were Crotalus durissus Linnaeus, 1758 (n = 50), Philodryas olfersii (Lichtenstein, 1823) (n = 15), Philodryas nattereri Steindachner, 1870 (n = 13), Xenodon rabdocephalus (Wied, 1824) (n = 12), Lachesis muta (Linnaeus, 1766) (n = 10) and Erythrolamprus almadensis (Wagler, 1824) (n = 10). The composition of species found here represents a combination of Cerrado and Amazonian savanna fauna.

A vegetação no município de Ilhéus Estado da Bahia: IV - Caracaterísticas analíticas e periodicidade sociológica

It is well-known that diverse groups of vegetation with an analogous but not identical floristic composition show an ecological similarity which leads to a determined type of vegetation. Starting from this fact it becomes evident that the scope of phytosociological work is the establishing of the significance of the species within the association and the discovery of the rules which govern associations. The floristic surveys made in the field have to be analysed statistically so as to obtain satisfactory results. The usefulness of this method depends largely on the possibilities of comparing the results with previous studies of the same kind, in the same country, or elsewhere. The method used in this paper is that of measuring circumferences and counting individuals in the different associations studied because it permits the presentation of the results in tables which show the phytosociological complexity of the Brazilian rain-forests. The classical method of characteristics is valuable because the more evolved an association is the less sociable are the species it contains, so that such groups do not show clear differences between species but rather between sinusia or strata of individuals. Five tables are presented in which several of the qualitative and quantitative characteristics are studied with a view to discussing their value in relation to groups and species. They are: I - Abundance (number of individuals). II - Density (distance in meters between the individuals belonging to each stratum). III - Basal coverture (circles measured in square meters of the mean projection of the individuals on the surface). IV - Basal area (mean circle in square meters occupied by individuals on the surface). V - Frequency, abundance and sociability in relation to occurrence. TABLE I. This table indicates first the number of individuals in relation to the sinusia studied: next, the sum total of the individuals belanging to the strata are given for each association, thus providing the numeric value of the sinusia: finally, the relation between the total number of individuals in the association and the total for the sinusium thus fursnishing the abundance per sinusium, in the classic sence, that is the percentage, or rather the relative number, of the elements which compose the group. CONCLUSIONS. The general character of abundance of the regional vegetation of Ilheos may be summed up in the following way: as an association evolves towards permanent equilibirum the number of individuals the inferior strata diminishes in relation to those of the superior strata which increase. For the shrub sinusium, two important facts were observed: a) in a given association the number of elements of the inferior strata diminishes as the diameter of the individuals increases; b) the percentage of individuals belonging to the shrub sinusium in the sere diminishes as the association evolve. In the subarboreal sinusium it is seen that: in the sere the number of subarboreal individuals does not vary much; whereas in the climax or the prisere there is a fall owing to the equilibrum of the biologic forms. In the arboreal sinusium the following conclusion can be deduced from analogous facts: the number of individuals of the lower strata diminishes as circumference increases. Also, in the sere there is a progressive sequence for the individuals belonging to the superior strata. TABLE II. The relation between the mean distances of individuals belonging to the same stratum and the area of an association is equal to the density. The table shows that the mean density of the association and the distance between the individuals belonging to the strata of the same sinusium in relation to the total number of individuals belonging to the association. CONCLUSIONS. As rule, the density of individuals in the associations studied follows a very general character or at least a regional one: the distance between the individuals in the diverse strata varies according to their abundance and sociability. Two other facts of some sociological importance are: a) in identical strata of the same sere the density of individuals oscillates in an analogous manner in teh subclimaces and varies in the stages which have reached equilibrium. b) the density of individuals varias in accordance with the sinusium and the distances between individuals of the same sinusium varg in accordance with the strata. TABLE III. This table presents the mean basal individual coverture, that is the mean projection of the frond of the various individuals belonging to the same stratum. The means were obtained by measurement in the field, of 100 individuals belonging to each stratum and their projection on the surface. In the latoratory these measurements were converted into mean circles (in square meters) and the result was multiplied by the individuals belonging to the strata corresponding to the sinusium of each association. The result obtained is named basal coverture. CONCLUSIONS. As a rule, the basal coverture of the vegetation of the county of Ilhéus indicates that: in the evolution of the vegetation the basal coverture of the arbustive sinusium diminishes progressively whereas that of the arboreal one increases. The special norms obtained are: 1) in the shrub sinusium the basal coverture seems to follow a uniform norm, that is, in stages of evolution of the subclimax the basal coverture oscillates with a certain uniformity. 2) in the subarboreal sinusium this fact is related to the vitality and age of the species, as in the subclimax the number of young trees is large and the vitality of the species very variable. This permits the conclusion that: in the sere the basal coverture increases with the evolution of the vegetation and diminishes when an equilibrium is reached. 3) in the tree sinusium the climax association of the prisere and subsere seem to obey a binomial rule, as the coverture (density-abundance) increases until a determined stratum is reached and...

Polynomial-time complexity for instances of the endomorphism problem in free groups

We say the endomorphism problem is solvable for an element W in a free group F if it can be decided effectively whether, given U in F, there is an endomorphism Φ of F sending W to U. This work analyzes an approach due to C. Edmunds and improved by C. Sims. Here we prove that the approach provides an efficient algorithm for solving the endomorphism problem when W is a two- generator word. We show that when W is a two-generator word this algorithm solves the problem in time polynomial in the length of U. This result gives a polynomial-time algorithm for solving, in free groups, two-variable equations in which all the variables occur on one side of the equality and all the constants on the other side.

Distortion of surface groups in Cat (0) free-by-cyclic groups

Given a non-positively curved 2-complex with a circle-valued Morse function satisfying some extra combinatorial conditions, we describe how to locally isometrically embed this in a larger non- positively curved 2-complex with free-by-cyclic fundamental group. This embedding procedure is used to produce examples of CAT(0) free-by-cyclic groups that contain closed hyperbolic surface subgroups with polynomial distortion of arbitrary degree. We also produce examples of CAT(0) hyperbolic free-by-cyclic groups that contain closed hyperbolic surface subgroups that are exponentially distorted.

An illustrated flora of the northern United States, Canada and the British possessions, from Newfoundland to the parallel of the southern boundary of Virginia, and from the Atlantic Ocean westward to the 102d meridian, by Nathaniel Lord Britton and Addison Brown. The descriptive text chiefly prepared by Britton, with the assistance of specialists in several groups; the figures also drawn under his supervision.

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