Temperate Ones Research Articles

Temporal variation of phytoplankton in a small tropical crater lake, Costa Rica

The temporal variation in lake's phytoplankton is important to understand its general biodiversity. For tropical lakes, it has been hypothesized that they follow a similar pattern as temperate ones, on a much accelerated pace; nevertheless, few case studies have tried to elucidate this. Most studies in Costa Rica have used a monthly sampling scheme and failed in showing the expected changes. In this study, the phytoplankton of the small Barvas's crater lake was followed for more than three years, first with monthly and later with weekly samplings, that covered almost two years. Additional information on temperature and oxygen vertical profiles was obtained on a monthly basis, and surface temperature was measured during weekly samplings around noon. Results showed that in spite of its shallow condition (max. depth: 7m) and low surface temperature (11 to 19 degrees C), the lake stratifies at least for brief periods. The phytoplankton showed both, rapid change periods, and prolonged ones of relative stasis. The plankton composition fluctuated between three main phases, one characterized by the abundance of small sized desmids (Staurastrum paradoxum, Cosmarium asphaerosporum), a second phase dominated by equally small cryptomonads (Chryptochrysis minor, Chroomonas sp.) and a third phase dominated by the green alga Eutetramorus tetrasporus. Although data evidenced that monthly sampling could miss short term events, the temporal variation did not follow the typical dry and rainy seasons of the region, or any particular annual pattern. Year to year variation was high. As this small lake is located at the summit of Barva Volcano and receives the influence from both the Caribbean and the Pacific weather, seasonality at the lake is not clearly defined as in the rest of the country and short term variations in the local weather might have a stronger effect than broad seasonal trends. The occurrence of this short term changes in the phytoplankton of small tropical lakes in response to weather variations needs to be further explored in other lakes.

Analysis of the response of two tall fescue cultivars of different origin to P deficiency

Soil phosphorus (P) availability commonly limits crop growth and forage production. Furthermore, there is a concern about the use of fertilizers, both because of the risk of environmental degradation and P being a non-renewable resource. Some experimental evidence would indicate that certain cultivars of tall fescue of Mediterranean origin would have a higher root:shoot ratio than temperate ones. This characteristic could improve P efficiency. Since P fertilization is a crucial issue in forage production, enabling grass crops to use the soil resources more efficiently represents an important agronomical goal. The objective of the present work was to compare the response of two tall fescues of different origin to low P availability and to analyze the interactions between morphological traits, P uptake efficiency and P use efficiency. Two cultivars of tall fescue ( Schedonorus phoenix (Scop.) Holub (formerly Festuca arundinacea (Schreb.)), one of temperate origin, Palenque Plus INTA (PP), and the other of Mediterranean origin, Fraydo (F), subjected to three different P treatments (P1, P2 and P3 obtained by adding 0; 10 or 100 mg P kg −1 soil–sand mixture 1:1 by weight) were studied in a glasshouse experiment. Four destructive harvests were performed from 24 to 54 days after emergence (dae) and the following determinations were performed: root and shoot components dry matter (DM), leaf area, tiller production, root length and diameter, root and shoot components P concentration. Tissue turnover measurements were performed from 19 to 53 dae. In general, responses to low P availability were in agreement with the literature (e.g. low DM accumulation, higher root:shoot ratio, low leaf elongation rate, low tiller production). Conversely to what was expected, PP had a higher root:shoot ratio than F under low P availability and tended to show higher values of P uptake during the whole experimental period. However, the P uptake efficiency per unit of root length was higher in F than in PP. By the end of the experimental period PP accumulated a higher amount of total biomass than F under P2 and P3. Under moderate P deficiency (P2), shoot growth was less reduced in PP than in F. Under the experimental conditions of the present study PP showed a higher growth potential and a more plastic response to P availability. Experiments at lower temperatures that would favor Mediterranean cultivars growth should be performed to study possible effects of P-temperature interactions on these cultivars.

Temperate and virulent Lactobacillus delbrueckii bacteriophages: Comparison of their thermal and chemical resistance

The aim of this work was to study the efficiency of diverse chemical and thermal treatments usually used in dairy industries to control the number of virulent and temperate Lactobacillus delbrueckii bacteriophages. Two temperate (Cb1/204 and Cb1/342) and three virulent (BYM, YAB and Ib3) phages were studied. The thermal treatments applied were: 63 °C for 30 min (low temperature – long time, LTLT), 72 °C for 15 s (high temperature – short time, HTST), 82 °C for 5 min (milk destined to yogurt elaboration) and 90 °C for 15 min (FIL-IDF). The chemical agents studied were: sodium hypochlorite, ethanol, isopropanol, peracetic acid, biocides A (quaternary ammonium chloride), B (hydrogen peroxide, peracetic acid and peroctanoic acid), C (alkaline chloride foam), D (p-toluensulfonchloroamide, sodium salt) and E (ethoxylated nonylphenol and phosphoric acid). The kinetics of inactivation were drew and T 99 (time necessary to eliminate the 99% of phage particles) calculated. Results obtained showed that temperate phages revealed lower resistance than the virulent ones to the treatment temperatures. Biocides A, C, E and peracetic acid showed a notable efficiency to inactivate high concentrations of temperate and virulent L. delbrueckii phages. Biocide B evidenced, in general, a good capacity to eliminate the phage particles. Particularly for this biocide virulent phage Ib3 showed the highest resistance in comparison to the rest of temperate and virulent ones. On the contrary, biocide D and isopropanol presented a very low capacity to inactivate all phages studied. The efficiency of ethanol and hypochlorite was variable depending to the phages considered. These results allow a better knowledge and give useful information to outline more effective treatments to reduce the phage infections in dairy plants.

Top-down and bottom-up regulation of planktonic communities in a warm temperate wetland

This field experimental study simultaneously analysed the effects of predation (top-down) and nutrients (bottom-up) on planktonic communities (phytoplankton, zooplankton, heterotrophic nanoflagellates and ciliates) in a warm temperate wetland in South America. The top-down and bottom-up controls were investigated by assessing the impact of omnivorous-planktivorous fish (Jenynsia sp.) and the effects of nutrient input from natural lake sediments, respectively Three treatments and a control were run in triplicate in mesocosms and samples were taken at Days 0, 3, 7 and 15. The control contained all the planktonic components while treatments included all planktonic components plus the addition of either planktivorous fish (F), natural wetland sediments in dialysis bags (S) or both of them (SF). A bottom-up effect due to nutrient release from sediment (mainly total phosphorus) was noticed in treatments S and SF. Phytoplankton abundance increased in all treatments compared with the control. Thus, phytoplankton appeared to be bottom-up controlled while fish exerted a strong predation pressure on zooplankton (top-down), because treatments F and SF showed a marked decrease in mesozooplankton abundance. The results obtained in this study agree with the hypothesis that phytoplankton regulation by zooplankton might be weaker in warm temperate systems than in temperate ones.

Local Variation in Shredder Distribution can Explain their Oversight in Tropical Streams

ABSTRACTStream shredders play an important role in the breakdown of allochthonous leaf litter—a well‐known, key process in temperate headwater streams. In contrast, it has been suggested that litter breakdown in tropical streams is driven by microorganisms, shredders being scarce or absent. We propose that shredders have been overlooked in some tropical streams for two reasons: (1) assuming that tropical shredders belong to the same taxa as temperate ones, without determining the diet of tropical litter fauna; and (2) the small spatial scale of most tropical stream studies, which do not account for intra‐ and inter‐site comparisons. We explored shredder abundance and species richness in six streams in each of two tropical regions, the Australian wet tropics (AWT) and Panama (PAN), finding 734 individuals of 12 shredder species in AWT and 391 individuals of 16 species in PAN. Shredder species richness was positively related to altitude in AWT, but not in PAN. Shredder contribution to total leaf breakdown in the field was 24±3 SE percent in AWT and negligible in PAN, but this was probably due to the unsuccessful colonization of experimental cages by PAN shredders. In the laboratory, shredder contribution to total leaf breakdown was higher than in the field (35%±2 SE in AWT and 64%±3 SE in PAN) and varied with leaf decomposability. Our results support earlier indications that shredders are not scarce or functionally unimportant in the tropics, and suggest that their contribution to litter processing should be determined along altitudinal gradients.

Ants on plants: a meta-analysis of the role of ants as plant biotic defenses

We reviewed the evidence on the role of ants as plant biotic defenses, by conducting meta-analyses for the effects of experimental removal of ants on plant herbivory and fitness with data pooled from 81 studies. Effects reviewed were plant herbivory, herbivore abundance, hemipteran abundance, predator abundance, plant biomass and reproduction in studies where ants were experimentally removed (n = 273 independent comparisons). Ant removal exhibited strong effects on herbivory rates, as plants without ants suffered almost twice as much damage and exhibited 50% more herbivores than plants with ants. Ants also influenced several parameters of plant fitness, as plants without ants suffered a reduction in biomass (-23.7%), leaf production (-51.8%), and reproduction (-24.3%). Effects were much stronger in tropical regions compared to temperate ones. Tropical plants suffered almost threefold higher herbivore damage than plants from temperate regions and exhibited three times more herbivores. Ant removal in tropical plants resulted in a decrease in plant fitness of about 59%, whereas in temperate plants this reduction was not statistically significant. Ant removal effects were also more important in obligate ant-plants (=myrmecophytes) compared to plants exhibiting facultative relationships with hemiptera or those plants with extrafloral nectaries and food bodies. When only tropical plants were considered and the strength of the association between ants and plants taken into account, plants with obligate association with ants exhibited almost four times higher herbivory compared to plants with facultative associations with ants, but similar reductions in plant reproduction. The removal of a single ant species increased plant herbivory by almost three times compared to the removal of several ant species. Altogether, these results suggest that ants do act as plant biotic defenses, but the effects of their presence are more pronounced in tropical systems, especially in myrmecophytic plants.

Anguilla marmorata larval migration plasticity as revealed by otolith microstructural analysis

The oceanic early-life history of Anguilla marmorata was examined in the southwestern Indian Ocean in Mayotte, Mauritius, and Réunion islands through otolith microstructural analysis. The study of the hatching dates, the first feeding check diameter (FFD), the leptocephalus (LD) and metamorphosis (MD) durations, the age at recruitment (AR), and the leptocephalus otolith growth rate (OGR) of glass eels revealed great variations in early-life traits and relationships between them. An agglomerative nesting analysis discriminated three early-life histories, differently represented according to the locality: (i) fast migrants with short LD, short MD, young AR, large FFD, and high OGR dominated in Réunion and Mayotte; (ii) midspeed migrants with intermediate LD, MD, AR, FFD, and OGR dominated in Mauritius; (iii) slow migrants with long LD, long MD, old AR, small FFD, and low OGR were recorded only in Mauritius. All possible strategies were not observed and therefore not successful at the sampling time. However, several were simultaneously expressed, which suggests larval migration plasticity at the population level. This evidence is crucial information regarding both the species dispersal capabilities and the evolution from short-migratory tropical species towards long-migratory temperate ones in the genus Anguilla .

Role of atelomixis in replacement of phytoplankton assemblages in Dom Helvécio Lake, South-East Brazil

Scale and frequency of changes in a lake’s physical structure, light dynamics, and availability of nutrients are closely related to phytoplankton ecology. Since phytoplankton assemblages were first described, phytoplankton ecologists concluded that these assemblages provide insight into phytoplankton responses to environmental changes. Objectives of this study were to investigate ecology of phytoplankton during a complete hydrological cycle in the deepest natural lake in Brazil, Dom Helvécio, and to sort species into the list of assemblages, checking its accordance with environmental changes in a tropical system within the middle Rio Doce Lake district, South-East Brazil. Canonical Correspondence Analysis, t-test, Mann–Whitney U-test, and Kruskal–Wallis test were used to analyze climatological, environmental, and plankton data, which were obtained monthly in 2002. A new phytoplankton assemblage, NA (atelomixis-dependent desmids), is suggested because atelomixis (robust movement of water occurring once a day) contributed to replacement of species in Dom Helvécio Lake. Stability of stratification, water chemistry, and composition of phytoplankton assemblages characterized two periods. The first period occurred in six rainy months (Jan–Mar and Oct–Dec) when the lake was stratified and phytoplankton was dominated by two assemblages: NA and F. The second period occurred in six dry months (Apr–Sep) when the lake was nonstratified and phytoplankton was dominated by four assemblages: S2, X1, A, and LO. Results suggest that phytoplankton in Dom Helvécio Lake was shaped by seasonal and daily changes of water temperature, even with its lower amplitude of variation within 2002 (El Niño year). These changes promoted water column stratification or mixing, reduced light, and increased nutrient availability. Temperature, therefore, is similarly important to phytoplankton ecology in tropical regions as it is in temperate ones. Sorting phytoplankton species into assemblages matched well with environmental changes and periods identified so it is also suggested that this can be further used as an appropriate tool to manage water quality when evaluating tropical lakes.

Hydrographic and biological patterns across the Angola–Benguela Frontal Zone under undisturbed conditions

A detailed, multi-disciplinary investigation of the Angola–Benguela Frontal Zone (ABFZ) was carried out in the austral autumn of 2004. Both satellite remote monitoring and hydrographic observations demonstrate an unusually stable state of affairs before and during this survey, suggesting that it was representative of the frontal system during undisturbed – or average – conditions at the time. Sea surface temperatures from satellite were mirrored by distributions of near surface salinities and nutrients. Upwelled water was Eastern South Atlantic Central Water (ESACW) at the two southern transects, and thermocline water in the north. Between the thermocline and the level of the Antarctic Intermediate Water (AAIW), South Atlantic Central Waters (SACW) were oxygen-deficient and nutrient-rich along the two northern transects, and also within gyral disturbances at the offshore parts of the southern transects. In the southwest ESACW occurred, and Angola Current water covered the offshore and upper part of the northernmost transect. Seaward of the upwelling front the depth of the thermo- and halocline decreased toward the north, and their vertical gradients increased. The predominant meridional geostrophic flow was northward, except for the area within and north of the ABFZ. Isopleths indicate a poleward undercurrent along the shelf edge. This undercurrent was shallow at the two northern transects, and at shelf-edge depth in the south. The undercurrent's direction stayed constant during the cruise and transported oxygen-deficient, nutrient-rich SACW as well as tropical fish larvae – adapted to low oxygen conditions – southwards to at least 22° S. This is in contrast to earlier theories of spawning here. Geostrophy and distribution patterns of indicator species indicate transport offshore within and along the ABFZ. Except for the undercurrent and gyral disturbances, the offshore ABFZ separates the tropical fish larval community from temperate and Southern Ocean ones. These gyral disturbances had an anticyclonic surface expression, and on the basis of water mass, nutrients, and biological composition they were most likely spawned from the undercurrent. A comparison with earlier surveys made during a Benguela Niño showed that the ABFZ responded hydrographically and faunistically to that warm event by a southward displacement of at least four degrees of latitude and the intrusion of tropical, shallow-living fish larvae into Namibian waters. Historical abundance data of fish larvae for species of commercial importance were in part overestimates, and some historical cumulative distributions seem to have been mistaken for “higher abundances” in the past. When compared with our autumnal data, historical data do not indicate any decadal decline.

Petrochemistry of the Paleoproterozoic Udokan copper-bearing sedimentary complex

The maturity of terrigenous material of the Paleoproterozoic Udokan copper-bearing sedimentary complex is considered. The average values of hydrolyzate module (HM), alumina-silica module (AM), and Pettijohn’s coefficient of maturity appreciably vary throughout the Udokan Complex. Among cupriferous sandstones, rocks of the Aleksandrovka Formation are characterized by the highest maturity, whereas rocks of the Chitkanda Formation are distinguished by the lowest maturity. The maturity of cupriferous sandstones of the Sakukan Formation corresponds to that of host rocks. The maturity of cupriferous sandstones from the Aleksandrovka Formation is much higher than that of host rocks. In the Chitkanda Formation, the cupriferous sandstones are much less mature than host rocks. Climatic conditions in provenances estimated from the Nesbitt index of chemical weathering or chemical index of alteration (CIA) may be characterized as temperate ones without prominent climatic features. Most CIA values range from 46 to 66. The formation of copper-bearing sediments was closely related to the periods of volcanic activity.

Seasonal development of secondary xylem and phloem in Schizolobium parahyba (Vell.) Blake (Leguminosae: Caesalpinioideae)

The cambial activity and periodicity of secondary xylem and phloem formation have been less studied in tropical tree species than in temperate ones. This paper describes the relationship between seasonal cambial activity, xylem and phloem development, and phenology in Schizolobium parahyba, a fast growing semideciduous seasonal forest tree from southeastern Brazil. From 2002 to 2003, wood samples were collected periodically and phenology and climate were recorded monthly in the same period. S. parahyba forms annual growth increments in wood, delimited by narrow initial parenchyma bands. The reduction of the cambial activity to a minimum correlates to the dry season and leaf fall. The higher cambial activity correlates to the wet season and the presence of mature leaves. In phloem, a larger conductive region was observed in the wet season, when the trees were in full foliage. The secondary phloem did not exhibit any incremental zone marker; however, we found that the axial parenchyma tends to form irregular bands.

Causes for the intriguing presence of tRNAs in phages

Phages have highly compact genomes with sizes reflecting their capacity to exploit the host resources. Here, we investigate the reasons for tRNAs being the only translation-associated genes frequently found in phages. We were able to unravel the selective processes shaping the tRNA distribution in phages by analyzing their genomes and those of their hosts. We found ample evidence against tRNAs being selected to facilitate phage integration in the prokaryotic chromosomes. Conversely, there is a significant association between tRNA distribution and codon usage. We support this observation by introducing a master equation model, where tRNAs are randomly gained from their hosts and then lost either neutrally or according to a set of different selection mechanisms. Those tRNAs present in phages tend to correspond to codons that are simultaneously highly used by the phage genes, while rare in the host genome. Accordingly, we propose that a selective recruitment of tRNAs compensates for the compositional differences between the phage and the host genomes. To further understand the importance of these results in phage biology, we analyzed the differences between temperate and virulent phages. Virulent phages contain more tRNAs than temperate ones, higher codon usage biases, and more important compositional differences with respect to the host genome. These differences are thus in perfect agreement with the results of our master equation model and further suggest that tRNA acquisition may contribute to higher virulence. Thus, even though phages use most of the cell's translation machinery, they can complement it with their own genetic information to attain higher fitness. These results suggest that similar selection pressures may act upon other cellular essential genes that are being found in the recently uncovered large viruses.

Identifying potentially suitable nesting habitat for golden eagles applied to ‘important bird areas’ design

AbstractGeographic information systems (GIS)‐based habitat‐suitability modelling is becoming an essential tool in conservation biology. A multi‐scale approach has been proposed as a particularly useful way to identify different factors affecting habitat preferences. In this paper, we developed predictive models of potentially suitable habitat for golden eagles Aquila chrysaetos at three spatial scales in a representative Mediterranean area on the Iberian Peninsula. We used logistic regression through a generalized linear model (GLM) to model golden eagle breeding habitat preferences. The best‐occurrence GLM models were those that involved topographic factors as independent predictors. Golden eagles seemed to prefer rugged and higher places of the study area for nesting. Climatic factors identified cold temperatures in January and temperate ones in July as the best predictors of eagles' occurrence. This was also higher in places with less agricultural areas and higher surface of pine forests. The distribution of potentially suitable area matches the distribution of mountain ranges, mainly in inner sectors of the study area. In contrast, potentially suitable nest sites in coastland areas remain unoccupied by golden eagles. Avoidance of coastland places for nesting may be due to the synergistic effects of human avoidance and the occurrence of potential competitors, like the endangered Bonelli's eagle Hieraaetus fasciatus. When mapped at a fine spatial resolution, the best GLM model identified large areas that fall outside the current network of protected areas. We therefore propose three new important bird areas for the region.

Undesirable side‐effects of water hyacinth control in a shallow tropical reservoir

Summary1. Based on a comprehensive data set collected monthly during 8 years (1997–2004), we evaluated the effects of mechanical removal ofEichhornia crassipeson the limnological characteristics and algal biomass of a polymictic shallow tropical reservoir.2. Interrupted time series analyses indicated that the limnological responses to macrophyte removal can be classified as an ‘abrupt permanent impact’ implying that the overall mean of the time‐series shifted promptly after intervention. These analyses indicated a significant increase for pH, total phosphorus, total phytoplankton and cyanobacterial biomass, and a decrease in water transparency and CO2concentrations in the surface water; also, the increase in water stability, increase of bottom soluble reactive phosphorus (SRP) and decrease in bottom oxygen levels.3. Cyclic anoxic periods previously observed during springs and summers were replaced by a persistent period of anoxic conditions in the sediment overlying water. Anoxic conditions were suitable for SRP release from sediments. Heavy cyanobacterial blooms became more persistent, maximum biomass (4229 mm3 L−1) was 30 times larger, the blooms frequently reached 2 m and sometimes the bottom of the reservoir, contrasting to the preremoval period in which it reached at most 1 m deep.4. The long‐term P dynamics in the system, initially driven by allochthonous nutrient loadings were replaced by internal ecological processes. Water hyacinth removal markedly accelerated the process of eutrophication due to internal feedback mechanisms, leading to a switch to a more turbid state. Biological feedback mechanisms were driven by cyanobacterial blooms by enhancing water stability, oxygen anoxia at the bottom and by increasing suitable conditions for P internal loading. These data support the hypothesis of the role of cyanobacterial blooms as an important factor impairing water quality and driving the ecosystem towards a stable degraded state.5. These findings have important implications for the restoration of shallow stratifying eutrophic lakes, as the alternative degraded state is most likely to occur when compared with their non‐stratifying counterparts. Moreover, feedback mechanisms in tropical and subtropical shallow lakes seem to be stronger than in temperate ones, as stratification events are more likely to occur over the year, intensifying system resilience to restorative strategies.

A year‐long plant‐pollinator network

Abstract In this work we analyse the pollination community in a South American forest known as ‘talar’. This is a vegetal woody community that inhabits fossil coastal banks characterized by seasonal temperate weather and calcareous soil, at the coast of the Río de la Plata, in the province of Buenos Aires, Argentina. We obtained data of the interactions between anthophylous insects and entomophylous flowering plants over an extensive period of time. We showed that pollination system parameters, such as partners’ identity, system size, and connectance, fluctuated among months, when sampled year‐long. Maximal network size occurred in early spring and early autumn, when both the number of mutualistic species and the number of interactions peaked, and this was also when network asymmetry was higher than average. Monthly connectance of the plant‐flower visitor matrix decreased to its lowest values at these peaks. Available data suggest that cumulative traditional connectance (i.e. the connectance calculated as the whole number of interactions registered in the community divided by the full size system) underestimates actual connectance values by a factor of c. 3 ×. Monthly values of connectance decreased exponentially as system size increased, and the distribution of interactions per species followed power‐law regimes for animals, and truncated power‐law regimes for plants, in accordance with patterns previously deduced from among‐network cumulative communities studies. We think that either within or and among pollination networks, systems that are organized as power‐law regimes may be a basic property of these webs, and provide examples of the fact. Both seasonal changes and interactions between mutualists like competition, and some degree of facilitation, may be very important to understand the performance of the system as a whole, and the role and importance of different species in the community. We suggest that communities of plant – pollinators that exhibit extended activity, such as temperate or tropical seasonal ones, should be studied through consecutive plant‐pollinator webs rather than cumulative ones. The partition of the system into smaller serial parts allows us to obtain outstanding information of every short period. This information is flattened by the average effect when we considered the combined analysis of the whole data.

Julian Wuerth - Kant's Immediatism, Pre-Critique

Kant's Immediatism, Pre-Critique Julian Wuerth As the author of a copernican revolution in philosophy, 1 Kant argues that philosophy begins with the study of the self. 2 To grasp the scope and nature of [End Page 489] knowledge in natural science, ethics, and aesthetics, we must first understand the self and its faculties of representation, pleasure, and desire, respectively. 3 While the literature acknowledges the foundational role of Kant's account of the self in his system of philosophy, it typically focuses on Kant's isolated conclusions about a priori concepts, or on the ontology of the self solely as Kant presents it in his rejection of rational psychology. The result is a gap in the commentary. The place of these conclusions in a single, broader account of the self, and the positive ontological status of this self, remains largely a mystery. These shortcomings are related: Kant's account of the ontology of the self provides the background for understanding the unity and interrelations of the many different powers of the self and their accidents, including a priori concepts. [End Page 490] A recent spate of literature on Kant's account of the self addresses important components of this account but perpetuates some traditional methodological weaknesses. The often original commentaries by Patricia Kitcher, Thomas Powell, and Wayne Waxman stick to frontline issues such as Kant's Paralogisms, his accounts of different faculties of representation, and his Transcendental Deduction, for example; they do not examine Kant's underlying positive ontology of the self, his more general ontology of substance, powers, and accidents, or the other faculties that Kant ascribes to the self. 4 This traditional orientation reflects a problematic research methodology: these accounts do not consider any of Kant's voluminous recorded thought from before the Critique of Pure Reason (1781), even though Kant published the Critique when he was already fifty-seven years old, after decades of detailed, systematic, and largely consistent studies of the self. These interpretations instead rely almost exclusively on the Critique and rarely even consult Kant's many other post-1781 sources. They accordingly focus on the faculties highlighted in the Critique, namely the various faculties of representation and not the faculties of pleasure or desire, and they take the Critique's pithy and notoriously cryptic chapter on the Paralogisms as a full statement of the soul's ontology. Unfortunately, the Paralogisms present only a negative account of the soul's ontology, not a complete one. These interpretations therefore understand Kant's rejection of [End Page 491] the intemperate rationalist arguments—which hold that the conclusions of the soul's simplicity and substantiality imply the soul's permanence, incorruptibility, and immortality—as Kant's rejection of all ontologically significant conclusions of the soul's substantiality and simplicity, even more temperate ones that do not imply the soul's permanence, incorruptibility, and immortality. Although these interpretations—united in their view that Kant rejects the substantiality of the soul in any ontologically significant sense—may at first seem viable if we consider only the Paralogisms, a closer look at the Paralogisms reveals significant problems, a look beyond the Paralogisms shows that these interpretations are repeatedly contradicted, and application of these interpretations when approaching other doctrines in Kant's philosophy repeatedly leads us down dead-ends. Thus Kant states in the Paralogisms, and in many other places after the Critique, that the soul is a substance, understood in the most basic ontological sense of the pure category of substance. 5 And Kant claims that the soul has powers and accidents, while at the same time repeatedly making clear that accidents (unlike mere logical predicates) are a form of existence and that all existence is grounded in substance, either being substance or a determination, or mode, of substance. Without Kant's concept of noumenal substance, his concepts of the soul's accidents and powers are rendered incoherent, frustrating our understanding of many other Kantian doctrines, including Kant's critique of rational psychology...

Male sterility at extreme temperatures: a significant but neglected phenomenon for understanding Drosophila climatic adaptations

The thermal range for viability is quite variable among Drosophila species and it has long been known that these variations are correlated with geographic distribution: temperate species are on average more cold tolerant but more heat sensitive than tropical species. At both ends of their viability range, sterile males have been observed in all species investigated so far. This symmetrical phenomenon restricts the temperature limits within which permanent cultures can be kept in the laboratory. Thermal heat sterility thresholds are very variable across species from 23 degrees C in heat sensitive species up to 31 degrees C in heat tolerant species. In Drosophila melanogaster, genetic variations are observed among geographic populations. Tropical populations are more tolerant to heat induced sterility and recover more rapidly than temperate ones. A genetic analysis revealed that about 50% of the difference observed between natural populations was due to the Y chromosome. Natural populations have not reached a selection limit, however: thermal tolerance was still increased by keeping strains at a high temperature, close to the sterility threshold. On the low temperature side, a symmetrical reverse phenomenon seems to exist: temperate populations are more tolerant to cold than tropical ones. Compared to Mammals, drosophilids exhibit two major differences: first, male sterility occurs not only at high temperature, but also at a low temperature; second, sterility thresholds are not evolutionarily constrained, but highly variable. Altogether, significant and sometimes major genetic variations have been observed between species, between geographic races of the same species, and even between strains kept in the laboratory under different thermal regimes. In each case, it is easily argued that the observed variations correspond to adaptations to climatic conditions, and that male sterility is a significant component of fitness and a target of natural selection.

Reproductive asynchrony and population divergence between two tropical bird populations

High-latitude vertebrates generally breed seasonally and synchronously as the primary environmental cue used to time seasonal processes is photoperiod. Investigations of tropical vertebrates have also documented seasonal reproduction, but it is unclear how synchronous reproduction is, both within and between populations. In this study, we investigated whether seasonal reproduction in a tropical species is synchronous between two populations in close proximity and, if not, whether asynchrony is correlated with genetic and cultural differentiation. We describe two equatorial populations of rufous-collared sparrows (Zonotrichia capensis), at the same latitude and separated by 25 km, that each breed seasonally but out of phase with each other. This asynchronous reproductive phenology is associated with local weather patterns and is independent of photoperiod. At a finer scale, reproductive timing is more highly synchronized within monogamous pairs than within the population as a whole. Associated with the difference in reproductive phenologies, we document that males in each population sing different song dialects. Using microsatellite DNA analysis, we found limited gene flow and significant genetic differentiation between the two populations. From these results we hypothesize that cultural and genetic differentiation between populations, which can be greater in tropical populations than temperate ones, can be associated with locally adapted reproductive phenologies. Key words: biodiversity, bird, dialects, DNA, estrogen, evolution, microsatellite, migration rate, reproduction, song, speciation, testosterone, tropics, Zonotrichia capensis. [Behav Ecol]

The impact of climate change on the fish community structure of the eastern continental shelf of the Bay of Biscay

Abstract Many fish species are at the southern or northern limit of their distribution range in the Bay of Biscay, where large-scale hydroclimatic changes have occurred in recent decades. We attempt here to identify the impact of these changes on the fish community of the eastern continental shelf of the Bay of Biscay. Data collected during 14 autumn groundfish surveys in 1973 and from 1987 to 2002 are used. The study area is between latitudes 48°30′N and 43°30′N while the depth ranges from 15 to 200 m. Annual abundance indices (number of individuals per km2) of 56 fish taxa present on average in at least 5% of the tows are computed. Multivariate analysis is used to detect temporal trends in these species' abundance indices. Assuming that increased water temperature may favour subtropical species and hinder temperate ones, knowledge about the latitudinal distribution range is used to interpret time trends. Results show an increasing abundance trend with time for fish species having a wide distribution range in latitude (mainly subtropical ones), whereas the abundance of temperate and the least widely distributed species decreased steadily.

Microbiologia de farinhas de mandioca (Manihot esculenta Crantz) durante o armazenamento

Este trabalho foi realizado com o objetivo de avaliar as características microbiológicas em farinhas de mandioca (Manihot esculenta Crantz) simples e temperadas, armazenadas durante 180 dias. Os materiais consistiram de cinco amostras, sendo uma de farinha de mandioca sem mistura (simples) e as demais de farinhas de mandioca temperadas. A farinha simples foi embalada em sacos de polietileno de baixa densidade com capacidade de 1,0kg e as farinhas temperadas foram embaladas em sacos plásticos de polipropileno pigmentado, com capacidade 0,5kg. Em todas as amostras, foram realizadas contagens de coliformes fecais, Staphylococcus aureus, bactérias mesófilas, bolores e leveduras e pesquisa de Salmonella sp. As análises foram realizadas em intervalos de 30 dias. Não foram detectadas diferenças entre as características microbiológicas das amostras simples e das temperadas. O armazenamento não alterou os padrões microbiológicos das amostras. As amostras apresentaram esterilidade para coliformes fecais, Salmonella sp. e Staphylococcus aureus. Os valores encontrados para coliformes fecais, Salmonella sp., Staphylococcus aureus, bactérias mesófilas e para bolores e leveduras estavam dentro dos padrões fixados pela legislação brasileira.