Frequency-dependent seed size selection on Cryptocarya alba (Mol.) Looser (Lauraceae): testing the effect of background

Seed size affects the probability of seed predation. Large seeds should be preferred over small seeds but the selective responses of seed predators may also be frequency-dependent. Seed predators may prefer the most common seed sizes (apostatic selection), the rarest ones (antiapostatic selection) or even be unresponsive to the size of seeds. Moreover, seed density may further modify the selective responses of seed predators. We expect that at a low seed density seed consumption should be concentrated on common seed sizes, and at high seed density it should be concentrated on rare seed sizes, as common ones act as a background that makes rare phenotypes more conspicuous (the effect of background). We tested this prediction in a field experiment with seeds of Cryptocarya alba (Lauraceae) at La Campana National Park, central Chile. We presented large and small seeds in two contrasting seed densities (ten and 100 seeds per m²) and at five frequencies of large seeds: 0.1, 0.25, 0.5, 0.75 and 0.9. After 28 days we measured the proportions of the two size classes in the remaining seeds. Large seeds were always preferred to small seeds, even when they were at low frequency. Contrary to the predictions, at low seed density consumption was antiapostatic whereas at high seed density selection was independent of frequency. We discuss the causes and consequences of such selective responses expressed by seed predators.  © 2005 The Linnean Society of London , Biological Journal of the Linnean Society , 2005, 84 , 137–142.     

The diversification of Nearctic mammals in the Mexican transition zone

The boundary between the Nearctic and Neotropical regions has been delineated using different approaches, methods and taxa. Using a panbiogeographical approach, identification of nodes can help understand the dynamics and evolution of the boundary. We analysed the distribution patterns of 46 Mexican land mammal species belonging to the Nearctic biotic component and delineated generalized tracks and nodes, in order to determine the southernmost boundary of the Nearctic region in Mexico. We found six generalized tracks and nine nodes; the latter located largely in the Sierra Madre Oriental, Transmexican Volcanic Belt, Sierra Madre del Sur and Chiapas biogeographical provinces. The highlands of Chiapas were found to represent the southernmost area inhabited by Nearctic taxa. The other biogeographical provinces, together with the Sierra Madre Occidental and Balsas Basin provinces, represent the Mexican transition zone in the strict sense. Instead of a classic static boundary, this transition zone represents an evolutionarily 'active' zone, where several speciation events have taken place in the past.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 327–339.     

Taxonomic revision of the genus Succisella (Dipsacaceae) in the Iberian Peninsula

A revision of the three endemic Iberian species of Succisella G. Beck ( S. carvalhoana , S. microcephala and S. andreae-molinae ), based on herbarium studies, SEM photographs and field observations, is presented utilizing morphological, palynological, karyological, biogeographical and ecological characters. The distribution of the species in the Iberian Peninsula is shown in a grid map. Full synonymy is given for all taxa.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 351–364.     

Coral successions in Upper Tortonian reefs in SE Spain

Martin, Jose M., Braga, Juan C. & Rivas, Pascual 1989 07 15: Coral successions in Upper Tortonian reefs in SE Spain. Lethaia , Vol. 22, pp. 271–286. oslo. ISSN 0024–1164,
During the Upper Tortonian (Upper Miocene), the Almanzora river corridor, a small Neogene basin in SE Spain, harboured coral reefs growing in three different environments: in fan deltas, beyond the influence of coarse terrigenous sedimentation; in the abandoned lobes of a delta complex; and on coastal margins. All of these reefs are composed of several successive beds, each of which may be made up mainly of Porites embedded in silt or of an initial Porites level followed by a silt-free Tarbellastraea level on top. Porites may be associated with corallines. This structure is interpreted as being the result of an ecological succession repeated over and over again. A pioneer association consisting mainly of Porites . by colonizing the substrate and continuing to grow through relatively adverse silt-deposition conditions, prepares the ground for Tarbellastraea to take over. A return to the previous conditions halts the growth of the Tarbellastraea colonies and the Porites association once more establishes itself in the silt, or else the renewed rate of deposition is sufficiently heavy to suffocate the whole bioconstruction.* Ecological succession. coral reefs, Tortonian, southeast Spain .     

A new species of Tetrastemma (Nemertea: Enopla: Monostiliferoidea) from Ria de Foz, north-western Spain, found living in the mantle cavity of the bivalve mollusc Scrobicularia plana

A new species of monostiliferoidean nemertean, Tetrastemmafozensis , from the mantle cavity of the bivalve mollusc Scrobicularia plana , in the Ría de Foz, north-western Spain, is described and illustrated. Other nemerteans from the mantle cavity of Scrobicularia collected in Poole Harbour, southern England, are provisionally identified as conspecific with the Ria de Foz material, but show certain anatomical differences whose taxonomic significance cannot at present be assessed.     

The cost of incubation in relation to clutch-size in the Collared Flycatcher Ficedula albicollis

This study examines the importance of avian incubation costs as determinants of clutch-size variation by performing clutch-size and brood-size manipulations in the same population of Collared Flycatchers Ficedula albicollis during the same breeding season. In 2 5 cases when three or more clutches of the same size were completed on the same day, we moved two eggs on the day after the last egg had been laid from one randomly selected clutch (C) to another (C) and moved two other eggs from this to a third clutch (C⁺). In 20 other cases of simultaneously completed clutches of the same size, we moved two randomly selected young from one brood to a second and from that moved two other young to a third (B, B and B⁺groups). Most females were weighed the day after completion of the clutch and 1–4 days before hatching of the young, and some of them also 10–14 days after hatching of the young. We measured the daily energy expenditure of females incubating manipulated clutches of 4, 6 and 8 eggs by means of the doubly-labelled water (D₂¹⁸O) technique and also recorded their nest attendance. Hatching success of fertilized eggs was reduced in the enlarged clutches compared with control and reduced clutches. Females expired on average 3142.6 ml CO₂ and expended 78.6 kJ per day while incubating, which corresponds to a metabolic intensity of 3.3 times BMR. Daily energy expenditure increased with clutch-size due to higher costs while incubating, and not because of changed activity patterns. There were no significant differences in length of incubation, female mass or mass changes between phases for the C, C and C⁺groups. In both the C and B groups, enlarged broods produced significantly more fledged young than control broods, and those significantly more than reduced broods. Fledgling tarsus-length and mass did not differ significantly between treatments in either the C or B groups. There was no significant difference in breeding success between clutch and brood manipulations. In this season, incubation costs did not entail significant fitness losses, expressed either as fledgling production or female condition. Also, control females could have raised more young to fledging age than they did with no apparent costs.     

The influence of darkness and visual contrast on oviposition by Anopheles gambiae in moist and dry substrates

Abstract.  The influence of substrate brightness (value), contrast and colour (hue) on oviposition is quantified under low night-light levels of 1.2 × 10⁻⁴ w m⁻² in choice-tests using caged Anopheles gambiae sensu stricto laboratory strains and/or gravid An. gambiae sensu lato from a natural population in Western Kenya. Egg output increases as darkness of the substrate increases against a white background. Black substrates elicit the most oviposition by both laboratory and house-collected mosquitoes, whereas white elicits the least. Contrast between patches of substrate and background also influences egg placement. In four-choice tests, a black ovipositional dish against a white floor receives many more eggs than does black–black, white–white, and white–black dish vs. floor combinations. In a similar test presenting four grey vs. black combinations of dish vs. floor, females respond similarly to grey vs. black dishes and deposit nearly as many eggs on the dry floors as on wet dishes. Illumination at 2.1 × 10⁻³ w m⁻², equivalent to late dusk and early dawn, improves discrimination between black dishes and grey floors. Under the experimental conditions, An. gambiae females respond almost equally to dishes of water placed over red, yellow, green, blue and purple paper disks matching the brightness and saturation values of their neutral (grey) counterparts. Thus, no evidence is found for wavelength discrimination on oviposition. It is concluded that visual contrast strongly influences the search patterns for prospective ovipositional sites whereas darkness of substrate and moisture are strong releasers of oviposition.     

On the Politics of Theorizing in a Postmodern Academy

The authors outline a politics of academic theorizing that seeks pluralism and egalitarianism without relativism and nihilism. Their goal is to help transform the academy by knocking down the walls around institutionalized technoscience without dissolving the enterprise of academic theorizing. Postmodernist critiques have blurred the cultural boundaries between technoscience and popular science practices, calling into question the absolute legitimacy of the former. Yet the positive proposals of postmodernism have been less valuable than the critiques. The authors hope to recover some of the imaginative power of postmodernist criticism by formulating a different politics of academic theorizing, built around the language and practice of "partnering." In the process, they hope to build exchange relations between postmodernism and other forms of theorizing, such as feminism.     

Strengthening the Natural and National Park system of Iberia to conserve vascular plants

The diversity of the Iberian vascular flora has been investigated using WORLDMAP versions 3.08 and 3.18. Two data sets scoring plant distributions as presences within the Iberian Peninsula were compiled; one for 2133 species at 50 × 50 km grid and the other for 801 species at 10 × 10 km map grids. Patterns of biodiversity were determined using the diversity measures of species richness, range-size rarity and character richness diversity. Using the diversity measures, combined with an area selection method, maps of priority areas were calculated using iterative procedures. Near minimum sets (NMSs) for both scales were calculated. Comparison of the NMS for the 10 × 10 km grid with the near minimum set for existing reserves (NMSER) showed that at least 2% more of the land surface would be required above and beyond the existing protected area network, currently comprising 6% of the area, to ensure representation of all species at least once as listed within the present data-base. It is demonstrated that reserve systems selected on a variety of different criteria are suboptimal when compared to particular groups of target organisms with a definite goal of representation for conservation. Calculating efficiency of existing reserve systems and accounting for all taxa identifies precisely the extra required areas for the protected area system to satisfy particular goals of representation.