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Replenishment of local populations of reef fishes typically occurs via settlement of planktonic larvae, a process that is variable in space and time. We examined spatial variation in settlement of three species of damselfishes (genus Dascyllus) in relation to variation in average near-field current speed. Although the larvae of these species colonized at the same times, they repeatedly exhibited qualitatively...
The goal of this study was to assess the relative importance of food availability and its quality for the spatial distribution of a folivorous lemur species, Lepilemurruficaudatus, from the highly seasonal dry deciduous forest of Madagascar. Males and females of this species showed opposite changes of body mass and body condition during the dry and the wet season. Male body mass declined during the...
We investigated the relationship between the δ13C signal in current-year and 1-year-old needle bulk material, starch extracts, and early- or late-wood in mature spruce trees (Picea abies) to identify the modifying influence of climatic conditions on the different δ13C signals. Seasonal patterns of δ13C were determined in total bulk needle material from 1998 to 2000, and in acid soluble starch extracts...
High irradiances, high air temperatures and low relative humidities characterize the seasonal savannas of central Brazil, locally known as cerrados. In the present study, we investigated the implications to photoprotection of diurnal adjustments in photochemical and non-photochemical processes in five cerrado woody species that differed in photosynthetic capacity and in the duration and extension...
Plant hybrids can be more, less, or equally resistant to herbivores compared to their parental species. These patterns in resistance can be critical determinants of the fitness of plant hybrids and may also influence distribution of the herbivore. We examined resistance to a pre-dispersal seed predator by natural and experimental hybrids between Ipomopsisaggregata and I.tenuituba. These species and...
Unusually among reptiles, Australian carpet pythons (Morelia spilota) display substantial geographic variation in mating systems and sexual size dimorphism. We studied a population of the south-western subspecies (M. s. imbricata) of this widely distributed taxon, on Garden Island near Perth, Western Australia. Our data greatly expand the range of variation previously documented for populations of...
This study presents novel evidence that 15N natural abundance can be used as a robust indicator to detect pollutant nitrogen in natural plant communities. Vegetation from the heavily polluted industrial area of Cubatão in São Paulo State, SE Brazil, was strongly 15N depleted compared to plants at remote sites. Historic herbarium samples from Cubatão were significantly less 15N depleted than extant...
We investigated the particle size distribution in 245 faecal samples of 81 species of captive ruminants by a wet-sieving procedure. As a comparative measure, the modulus of fineness (MOF; Poppi et al. 1980) was used. Species were classified as frugivores (n=5), browsers (BR, n=16), intermediate feeders (IM, n=35) and grazers (GR, n=25). BR generally had a higher proportion of large particles, i.e...
Forest defoliation by insects can lead to severe disruptions of the nitrogen (N) cycle resulting in elevated NO3– levels in stream water. To trace the movement of insect-mobilized N in a forest soil, 15N-labeled gypsy moth frass or 15N-labeled oak leaf litter was added to trenched plots in an oak forest over 29 months. Nitrogen movement from the frass or litter was measured in the available, mineralizable,...
Despite the importance of dispersal to ecology, accurate estimates of dispersal rates are often difficult to obtain, especially for organisms that rely on passive dispersal of propagules to colonize new sites. To investigate potential dispersal vectors and relative colonization rates of zooplankton, we conducted a field experiment in which we restricted potential dispersal vectors (insects, birds,...
We examined the seasonal variation in total non-structural carbohydrate (TNC) concentrations in branch, trunk, and root tissues of Anacardiumexcelsum, Lueheaseemannii, Cecropialongipes, and Ureracaracasana growing in a seasonally dry forest in Panama. Our main goals were: (1) to determine the main sites of carbohydrate storage, and (2) to determine if seasonal patterns of carbohydrate storage are...
This study examined the ability of the Photochemical Reflectance Index (PRI) to track seasonal variations in carotenoid pigments and photosynthetic activity of mature evergreen chaparral shrubs. Our results confirm that PRI scales with photosystem two (PSII) photochemical efficiency across species and seasons, as demonstrated by PRI's strong correlation with de-epoxidized (photoprotective) xanthophyll...
We compared foliar and soil nutrients in tundra between two different landscapes in the foothills of the Brooks Range, Alaska, that were deglaciated >50,000 and >11,500 years ago, respectively. Our goal was to determine whether foliar nutrients reflect differences in soil nutrient availability, or whether species and/or growth forms have characteristic foliar nutrient concentrations regardless...
A range of cues may be used by parasites in selecting hosts, yet few studies have examined multiple cues simultaneously. We investigated the proximate cues involved in spawning decisions of the European bitterling, Rhodeus sericeus, a species of fish which lays its eggs in four species of freshwater mussel. When offered a choice of both live and artificial mussels within a single species, females...
Nutrients obtained by epiphytes may either be of atmospheric origin or from organic matter in the canopy, which decomposes to form canopy soil on large branches. We hypothesised that the N supply for epiphytes on small branches was lower, and a larger proportion provided by rainwater, than for epiphytes rooting in canopy soil. We tested this by measuring the N concentration and isotopic composition...
We examined soil and vegetation N isotopic composition (δ15N) and soil inorganic N availability in an intact Mojave desert ecosystem to evaluate potential effects of elevated atmospheric CO2 on N cycling. Vegetation from the dominant perennial shrub Larrea tridentata under elevated CO2 was enriched in 15N. Over a 7-month sampling period, Larrea δ15N values increased from 5.7±0.1‰ to 9.0±1.1‰ with...
Studies have increasingly shown that the constitutive or induced expression of resistance in plants is costly to fitness in the absence of enemy attack. If such costs are based on resource allocation tradeoffs, it has been hypothesized that resource limitation associated with plant competition increases the fitness costs of resistance. In two greenhouse studies, I examined the expression and costs...
Parasitic plants are common in natural communities, but are largely ignored in plant community theory. Interactions between parasitic plants and hosts often parallel those between herbivores and plants: both types of consumers display host preferences, reduce host biomass and alter host allocation patterns, modify plant community structure and dynamics, and mediate interactions between host plants...
In this paper we tested the hypothesis that ant mosaics are generated and maintained by stochastic processes, against the general idea that deterministic processes, such as competition, are the main forces that structure these communities. We analysed 14 published ant mosaics, described for crops and natural forests, transforming their data in presence/absence matrices. These matrices were submitted...
While growth rates of pelagic larvae have been argued to be one of the principal determinants of the recruitment success of temperate marine fishes, it is not known if this is the case in the tropics. Here, we use larval growth histories derived from otoliths of a Caribbean reef fish to show that monthly variation in the intensity of settlement and recruitment of pelagic juveniles onto reefs is positively...
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