Pollinator foraging behavior and pollen collection on the floral morphs of tristylous Pontederia cordata L.

Summary The foraging behavior of the pollinators of tristylous Pontederia cordata was studied to determine if differences in floral morphology would lead to preferential visitation of the floral morphs. Although nectar production is not different in the three floral morphs, differences in the production and size of pollen grains produced by the three anther levels results in the morphs offering variable amounts of resources to pollen-collecting insects. Bumblebees (Bombus spp.) and the solitary bee Melissodes apicata used P. cordata primarily as a nectar source and therefore did not seem to exhibit any morph preference. In contrast, honeybees visited flowers mainly for pollen and preferred to forage on long-level anthers of the short-and mid-styled morphs. An analysis of the composition of corbicular pollen loads indicated that, relative to the frequency of production in the population: 1) honeybees collected an excess of pollen from long-level anthers; 2) bumblebees collected the three types of pollen without any apparent preference; and 3) M. apicata preferentially collected pollen from the short-level anthers — presumably because their proboscides are modified by the presence of tiny hairs. The results suggest that P. cordata in Ontario is serviced by a diverse, unspecialized pollinator fauna which is not co-adapted to the tristylous floral polymorphism.     

Renewed hope for the threatened avian endemics of northeastern Brazil

The forests north of the São Francisco River, in northeastern Brazil, conform a centre of endemism for plants and animals. Currently only 5% of its original forest cover is left, following 500 years of human colonisation. Avian endemism is high, and during the 1980s four birds were described from these forests, Alagoas Foliage-gleaner Philydor novaesi, Orange-bellied Antwren Terenura sicki, Alagoas Antwren Myrmotherula snowi and Alagoas Tyrannulet Phylloscartes ceciliae. Their type locality, Murici Ecological Station, in the coastal mountains of Alagoas state, was the only site where the four species were known to occur together, and became the focus of much attention from conservation organisations. We here report on recent surveys at Reserva Privada do Patrimônio Natural Frei Caneca, in the mountains of Pernambuco state, which found these 4 species and 27 other threatened and endemic birds, and a yet undescribed taxon. We propose that more thorough surveys are needed in the reserve and its vicinity, to locate fragments of suitable forest for these species. These should be regarded within a management plan for the reserve (including research and monitoring), and such work should be expanded to a regional level. An educational programme focusing on the values of these forests and the negative impacts of human activities is needed very much.     

Multiple origins of self-fertilization in tristylous Eichhornia paniculata (Pontederiaceae): Inferences from style morph and isozyme variation

Populations of Eichhornia paniculata (Pontederiaceae) exhibit a wide range of mating systems, from predominant outcrossing to high levels of self-fertilization. The origin of self-fertilization in this tristylous species is associated with the loss of style-length morphs from populations and the spread of self-pollinating, floral variants. We examined geographic variation in style morph and allozyme frequencies to determine whether the loss of style morphs and transition to selfing could have multiple origins in E. paniculata. Surveys of floral variation in 167 populations from six states in northeastern Brazil revealed that at least one style morph was absent from 29.3%. Non-trimorphic populations occurred in all states and ranged in frequency from 9% in Ceará to 68% in Alagoas. Selfing variants occurred in 8.5% and 55% of trimorphic and non-trimorphic populations, respectively, and were distributed among five of six states with primary concentrations in Alagoas and Pernambuco. A comparison of electrophoretic variation at 24 isozyme loci in 28 trimorphic, 13 dimorphic and 3 monomorphic populations indicated that non-trimorphic populations contained 84% of the allelic variation present in trimorphic populations and were markedly differentiated from one another. Analyses of genetic distance and the distribution of rare alleles indicated that non-trimorphic populations were often more similar to neighbouring trimorphic populations than to one another. Populations with selfing variants occurred at low frequency in three genetically distinct parts of the range. These results, in combination with genetic and morphological evidence suggest that style morphs are lost repeatedly from populations of E. paniculata and that selfing variants may have originated on at least three separate occasions in northeastern Brazil.     

The effects of floral display on pollinator visitation vary among populations ofPhacelia linearis (Hydrophyllaceae)

Summary Individual plants in gynodioecious populations ofPhacelia linearis (Hydrophyllaceae) vary in flower gender, flower size, and flower number. This paper reports the effects of variation in floral display on the visitation behaviour of this species' pollinators (mainly pollen-collecting solitary bees) in several natural and three experimental plant populations, and discusses the results in terms of the consequences for plant fitness. The working hypotheses were: (1) that because female plants do not produce pollen, pollen-collecting insects would visit hermaphrodite plants at a higher rate than female plants and would visit more flowers per hermaphrodite than per female; and (2) that pollinator arrival rate would increase with flower size and flower number, the two main components of visual display. These hypotheses were generally supported, but the effects of floral display on pollinator visitation varied substantially among plant populations. Hermaphrodites received significantly higher rates of pollinator arrivals and significantly higher rates of visits to flowers than did females in all experimental populations. Flower size affected arrival rate and flower visit rate positively in natural populations and in two of the three experimental populations. The flower size effect was significant only among female plants in one experimental population, and only among hermaphrodites in another. The effect of flower number on arrival rate was positive and highly significant in natural populations and in all experimental populations. In two out of three experimental populations, insects visited significantly more flowers per hermaphrodite than per female and visited more flowers on many-flowered plants than on few-flowered plants, but neither effect was detected in the third experimental population. Because seed production is not pollen-limited in this species, variation in pollinator visitation behaviour should mainly affect the male reproductive success of hermaphrodite plants. These findings suggest that pollinator-mediated natural selection for floral display inP. linearis varies in space and time.     

Dispersal of Artemia franciscana Kellogg (Crustacea; Anostraca) populations in the coastal saltworks of Rio Grande do Norte, northeastern Brazil

In spite of the presence of Artemia franciscana Kellogg in several saltworks in the State of Rio Grande do Norte (RN) (northeastern Brazil) that were colonized from inoculations made in Macau (RN) in April 1977 with cysts from a San Francisco Bay (California, U.S.A.) stock, there is no recent data on the degree of regional dispersal of this anostracan. For 12 months (July 1996 – June 1997), 55 saltworks located in the municipalities of Areia Branca, Grossos, Galinhos, Guamaré and Macau in RN were visited and sampled for the presence of Artemia franciscana and the occurrence of its cysts. Populations of Artemia franciscana were found in all 55 saltworks, although significant amounts of cysts were only found in six sites. The presence of Artemia franciscana in all visited sites brings further evidence to the ample dispersal of this anostracan throughout the saltwork region of RN. However, the relatively low incidence of cysts suggests that most of these populations are reproducing ovoviviparously.     

A new species of Solanum subgenus Leptostemonum (Solanaceae) from northeastern Brazil

Solanum jabrense is apparently rare, and is only known from few collections in the Pico do Jabre of the state of Paraíba, Brazil. It is illustrated and its affinities with the informalErythrotrichum group are discussed.     

A new species of Sinningia (Gesneriaceae) from northeastern Brazil

Sinningia nordestina is described and illustrated. Morphological and molecular characters are discussed. It is a new species endemic to northeastern Brazil and is distinguished from other members of the genus by its vestigial tubers, ascending pedicels with pendent flowers, small corollas, and deviating flowering period.     

Fertility differences among floral morphs following selfing in tristylous Eichhornia paniculata (Pontederiaceae): inbreeding depression or partial incompatibility?

Reduction in seed set following self- vs. cross-pollination in flowering plants can result from abortion of selfed offspring owing to inbreeding depression and/or partial self-incompatibility. Previous studies on tristylous Eichhornia paniculata (Pontederiaceae) indicate that reduced seed set following self-pollination generally occurs in the short- (S), but not the long-(L) or mid-styled (M) morphs. To determine whether this pattern results from morph-specific differences in inbreeding depression owing to the sheltering of deleterious alleles at the S locus and/or partial self-incompatibility, we conducted controlled hand-pollinations of the floral morphs and measured seed set and levels of seed abortion. There were no significant differences in fertilization success and seed set following self-, illegitimate, and legitimate pollinations in the L and M morphs. In contrast, in the S morph self-, intramorph and intermorph illegitimate pollinations resulted in significant reduction in seed set in comparison with legitimate pollination. This indicates that the reduced seed set observed in self-pollination is the result of partial incompatibility rather than inbreeding depression. Significantly reduced fertilization success and low levels of ovule abortion in illegitimate pollinations of S plants also supported this conclusion. Reduced fertility in the S morph may have implications for the observed loss of this morph from natural populations and the evolutionary breakdown of tristyly.     

Phenology of woody species in tropical coastal vegetation, northeastern Brazil

The study was carried out in the Private Nature Reservation Nossa Senhora do Outeiro de Maracaípe, located along the southern coast of Pernambuco state, in the Nossa Senhora do Ó District (08°31′48″S and 35°01′05″W), Ipojuca municipality, northeastern Brazil. The reserve has 76.20 ha of tropical coastal vegetation (Restinga forest). The aims were to determine the existence of seasonal phenological pattern of woody species as a function of rainfall. During the study period, the rainfall was 26.8 mm in the driest month (November 2003) and 538.9 in the wettest (June 2004). Observations on flowering, fruiting, leaf fall, and leaf flushing were recorded monthly, during 16 months (April 2003 to July 2004). All species with a ground level perimeter >10 cm and represented by at least three individuals, were selected and tagged. A total of 51 species represented by 156 individuals were recorded. Leaf flushing and leaf fall did not have seasonal variation and the species continued to gain and loose leaves during the dry (August to February) and rainy (March to July) seasons. Flowering, when evaluated by the Fournier's percentage, varied between 1.9% and 20.2%, with maximum intensity in December 2003 (16.4%) and January 2004 (20.2%). Likewise, fruiting varied between 3.8% and 21.4% with the highest percentages in February (17.2%) and March (21.4%) 2004. The analysis comparing reproductive phenological patterns with monthly rainfall did not show a significant correlation, which may suggest investigations concerning other factors, including biotic ones, as pollination and/or dispersal modes, which can be influencing reproductive events of plants in the studied Restinga forest.     

Mitracarpus longicalyx (Rubiaceae, Spermacoceae), a new species from northeastern Brazil

Mitracarpus longicalyx is here described and illustrated from sandy areas of the caatingas of northeastern Brazil. The new species is similar toM. hirtus andM. megapotamicus.     

Fragmentation causes rarity in common marmosets in the Atlantic forest of northeastern Brazil

The purpose of this study was to investigate the population status of the common marmosets, Callithrix jacchus, in one of their main habitats, the northeastern Atlantic forest of Brazil, where only 2% of its original area remains as small and isolated forest fragments, to determine long-term viable populations. The study was carried out in 15 forest fragments, measuring from 3,478.3 ha (the largest) to 6 ha, which were invariably subjected to high human impact. Line transect surveys were carried out between January 2002 and December 2004, along transects measuring from 350 to 4,000 m, between 0500 h and 0900 h. Common marmosets were registered in 73% (n = 11) of the forest fragments, were not recorded in the largest one, the Coimbra Forest, and group sizes varied from 1 to 4 individuals. A negative significant relationship was detected between the size of the fragment and the number of sightings of common marmosets. It is shown that the number of groups of common marmosets dwelling in this highly impacted landscape is nowadays lower than necessary for long-term survival. Additionally, smaller fragments having more groups suggests that they live in total association with humans, which assure their subsistence through the supply of introduced and exotic foods.     

UDP-Glucuronosyltransferase activity is correlated to saponin production in Gypsophila paniculata root in vitro cultures

UDP-Glucuronosyltransferase (UGT, EC 2.4.1.17) activity was detected in excised root cultures of Gypsophila paniculata. The UGT activity (up to 0.8 nkat mg^–1 protein) correlated to the total saponin content (2 mg g^–1 dw) during the exponential phase of the batch culture. This gives rise to the hypothesis of a direct relationship in the biosynthetic pathway regulation between the enzyme activity and the saponin biosynthesis.     

Florivores decrease pollinator visitation in a self-incompatible plant

Different biotic interactions may influence one another to produce complex patterns of direct and indirect effects, which together influence plant reproductive success. However, so far most studies on plant-animal interactions have focused on single interactions in isolation. In this study, we studied the effect of florivory by the weevil Cionus nigritarsis on pollinator visitation rate in the self-incompatible perennial herb Verbascum nigrum by combining observations of florivory and pollination in natural populations with records of pollinator visitation to plants with different levels of experimentally inflicted damage.Increasing levels of damage through either natural or simulated florivory resulted in fewer pollinator visits per plant and per flower. As expected, the magnitude of the indirect effect of florivory on pollinator visitation was proportional to the intensity of florivory. Our results indicate that biotic non-pollinating agents, such as florivores, may induce substantial changes in pollinator availability. Therefore, studies addressing different plant-animal interactions in parallel are necessary to better comprehend the factors influencing the reproductive performance and demography of flowering plants.     

Diversity of reproductive modes in anurans communities in the Caatinga (dryland) of northeastern Brazil

Anuran reproductive activities in xeric environments are strongly influenced by local rainfall and temperatures. Anuran species that inhabit the Caatinga biome in northeastern Brazil demonstrate numerous behavioral and reproductive strategies that avoid or minimize the negative effects of elevated temperatures and scarce water resources on egg development. Among the various anuran species found in the Caatinga region, members of the family Leptodactylidae demonstrate the greatest number of reproductive modes adapted to a terrestrial life style while most of the Hylidae species are more susceptible to variations in water availability. Laying eggs in foam nests is a common strategy among species that inhabit environments with open vegetation forms and water resources that are restricted to only short periods during the year. Data concerning anuran communities in the localities examined here indicated a greater diversity of reproductive modes in ponds with more diverse vegetation structures and longer periods of water availability indicating that the deeper the temporary ponds (permitting a longer hydroperiod) the more diverse will be the aquatic and bordering vegetation, and the richer will be the diversity of anuran species observed and the number of reproductive modes encountered there.     

Cissus xerophila (Vitaceae), a new species from the xerophytic vegetation of northeastern Minas Gerais, Brazil

A new species of Vitaceae is described and illustrated:Cissus xerophila, a simple-leaved species similar toC. verticillata (L.) Nicolson & C. E. Jarvis and related species. A key to the group in South America is presented.     

Biostratigraphy of Lower Cretaceous microfossils from the Araripe basin, northeastern Brazil

A biostratigraphic study was carried out in the Lower Cretaceous Araripe basin, northeastern Brazil, allowing the recognition of several chronostratigraphic units: the Dom João (Jurassic?-Lower Cretaceous?), the Rio da Serra (Neocomian) and the Alagoas (Aptian/Albian) local stages. For the first time a large hiatus between the Rio da Serra and Alagoas local stages is carefully documented. The palynomorphs and the ostracode associations throughout the Jurassic?-Aptian/Albian sequence allow the interpretation of the paleoenvironmental evolution of the Araripe basin which otherwise confirms that a polycyclical sedimentation occurred in the basin, being one of the controlling factors on the distribution of ostracodes and palynomorphes.     

Pollinator diversity affects plant reproduction and recruitment: the tradeoffs of generalization

One outstanding and unsolved challenge in ecology and conservation biology is to understand how pollinator diversity affects plant performance. Here, we provide evidence of the functional role of pollination diversity in a plant species, Erysimum mediohispanicum (Brassicaceae). Pollinator abundance, richness and diversity as well as plant reproduction and recruitment were determined in eight plant populations. We found that E. mediohispanicum was generalized both at the regional and local (population) scale, since its flowers were visited by more than 100 species of insects with very different morphology, size and behaviour. However, populations differed in the degree of generalization. Generalization correlated with pollinator abundance and plant population size, but not with habitat, ungulate damage intensity, altitude or spatial location. More importantly, the degree of generalization had significant consequences for plant reproduction and recruitment. Plants from populations with intermediate generalization produced more seeds than plants from populations with low or high degrees of generalization. These differences were not the result of differences in number of flowers produced per plant. In addition, seedling emergence in a common garden was highest in plants from populations with intermediate degree of generalization. This outcome suggests the existence of an optimal level of generalizations even for generalized plant species.     

Nutrient limitation to the decomposition of water hyacinth ( Eichhornia crassipes)

The responses of decomposition to N and P supply were investigated in three leaf types of water hyacinth (Eichhornia crassipes (Mart.) Solms): dead green leaves collected from Donghu Lake; green, and brown leaves collected from outdoor tanks. The ratios of C:N, C:P, lignin:N and lignin:P were lowest in the green leaves collected from Donghu Lake, and highest in the brown leaves collected from outdoor tanks. Decomposition constant (k) of water hyacinth varied greatly, ranged from 0.006 to 0.099 d^–1. Leaf litters decayed most quickly within the initial two weeks during the experimental period, but decomposition rate decreased significantly in the following days. Decomposition and nutrient (N and P) release were fastest in the green leaves collected from Donghu Lake, intermediate in the green leaves collected from outdoor tanks, slowest in the brown leaves collected from outdoor tanks. Statistical analyses revealed that the effects of P-availability on decomposition rate and N, P release rate of the three litter types were significant, whereas the impacts of N-availability was insignificant (p > 0.05) except for the brown leaves collected from outdoor tanks. These results suggest that decomposition rate and nutrient content dynamics of water hyacinth differ with their growth habitats, and could partly be regulated by nutrient availability, especially by P-availability, in the environments.     

Effect of nitrogen and fiber content on the decomposition of the waterhyacinth (Eichhornia crassipes [Mart.] Solms)

In situ rates of waterhyacinth decomposition were found to vary with tissue nitrogen and fiber content. High nitrogen (2.8%), low fiber (49%) waterhyacinth aerial tissues collected from a eutrophic site decomposed more rapidly than low nitrogen (1.3%), high fiber (58%) aerial tissues collected from a nutrient-poor site. In addition, waterhyacinth roots (65% fiber) decomposed much more slowly than aerial waterhyacinth tissues (49% fiber). Because the biomass distribution (aerial/root) and nitrogen and fiber content of waterhyacinths fluctuate both seasonally and with nitrogen availability, considerable temporal and site-to-site variability in decomposition dependent processes (e.g., sedimentation, mineralization) exist in aquatic systems infested by this species.     

Pollinator attracting odour signals in sexually deceptive orchids of the Ophrys fusca group

We investigated patterns of volatiles of several allopatric and sympatric species of the Ophrys fusca group and one species of the O. mammosa/sphegodes group pollinated by either Andrena nigroaenea or A. flavipes, using electrophysiology (gas chromatography coupled with electroantennography; GC-EAD) and chemical analyses. We found 52 GC-EAD active compounds, mainly saturated and unsaturated hydrocarbons with chain lengths of 21 to 31, aldehydes, an ester, and an acid. Based on the relative proportions of all GC-EAD active compounds, the investigated species were compared using various statistical methods (ANOVA, principle component analyses, discriminant function analyses and cluster analyses). Our results show that Ophrys species with the same pollinator – independent of their phylogenetic relationship–use the same volatiles for pollinator attraction. Differences between the species mainly involve different quantitative patterns of volatiles. Our results are in congruence with previous studies that showed different odour bouquets to be responsible for the specific attraction of different pollinators and that alkanes and alkenes are most important for pollinator attraction.