Nesting preferences of common buzzard Buteo buteo and goshawk Accipiter gentilis in forest stands of different structure (Niepolomice Forest, Southern Poland)

Studies on nesting preferences of common buzzard and goshawk were carried out in two distinctly different parts of the Niepolomice Forest (S Poland): deciduous (oak-hornbeam wood) and coniferous. Characteristics of nest sites were determined on three spatial scales, separately for: (1) nest tree; (2) nest tree area (0.07 ha circle centred at nest tree) and (3) nest stand (15 ha circle centred at nest tree). Nesting preferences discovered for the nest tree and its surroundings, included height and diameter of trees, age of the forest stand, distance to the nearest open area or forest road and occurrence of open areas in the vicinity of the nest. In the diverse habitat of oak-hornbeam wood, more similar to natural woods, nest site selection operated on several levels, possibly starting at the most extensive end of the scale before narrowing to the selection of a particular nest tree. In the more homogeneous habitat of commercially exploited coniferous forest, the surrounding of the nest were found to be insignificant, and the nesting decisions were likely to be based principally on individual characteristics of a tree i.e. its shape and size, being suitable for nesting.     

Use of random amplified polymorphic DNA to identify several novel markers for sex identification in the crested serpent eagle and crested goshawk

The crested serpent eagle (Spilornis cheela hoya) has no distinct sexual dimorphic traits. In the current study, we report the results of an EE0.6 (EcoRI 0.6-kb fragment) sequence applied to S. cheela hoya and a novel random amplified polymorphic DNA (RAPD) marker that can be used to sex individuals within the species S. cheela hoya and Accipiter trivigatus formosae (crested goshawk). We used sex-specific primers for the avian CHD1 (chromo-helicase-DNA-binding 1) gene and the EE0.6 sequence in PCR assays to determine sex. In addition, 120 random primers were used for RAPD fingerprinting to search for novel sex-specific fragments of S. cheela hoya. The OPBB08 random primer generated a 1241-bp sex-specific fragment in all female S. cheela hoya. From the nucleotide sequence, PCR primers were designed to amplify 553-, 895-, and 194-bp sex-specific fragments present in all female S. cheela hoya. One of these primer pairs (ScBB08-7F/R) also amplified a male/female common fragment that can be used as an internal control (543 bp). Moreover, one of the primer pairs (ScBB08-5aF/5bR) could be used to identify genders of A. trivigatus formosae. In conclusion, we identified novel sex-specific DNA markers of S. cheela hoya and A. trivigatus formosae that can be used for rapid and accurate sex identification.     

The Mhc class II of the Black grouse (Tetrao tetrix) consists of low numbers of B and Y genes with variable diversity and expression

We found that the Black grouse (Tetrao tetrix) possess low numbers of Mhc class II B (BLB) and Y (YLB) genes with variable diversity and expression. We have therefore shown, for the first time, that another bird species (in this case, a wild lek-breeding galliform) shares several features of the simple Mhc of the domestic chicken (Gallus gallus). The Black grouse BLB genes showed the same level of polymorphism that has been reported in chicken, and we also found indications of balancing selection in the peptide-binding regions. The YLB genes were less variable than the BLB genes, also in accordance with earlier studies in chicken, although their functional significance still remains obscure. We hypothesize that the YLB genes could have been under purifying selection, just as the mammal Mhc-E gene cluster.     

Interactions between population processes in a cyclic species: parasites reduce autumn territorial behaviour of male red grouse

The causes of population cycles fascinate and perplex ecologist. Most work have focused on single processes, whether extrinsic or intrinsic, more rarely on how different processes might interact to cause or mould the unstable population dynamics. In red grouse (Lagopus lagopus scoticus), two causal mechanisms have been supported: territorial behaviour (changes in autumn aggressiveness) and parasites (parasite induced reduction in fecundity). Here, we report on how these two regulatory processes might interact, by testing whether the parasite suspected to cause the grouse cycles, the nematode Trichostrongylus tenuis, reduces male autumn territorial behaviour. We either treated males with an anthelmintic, to remove parasites (dosed or D-males), or challenged them with infective T. tenuis larvae, to increase parasite intensity (challenged or C-males). We first show that dosing was effective in removing T. tenuis parasites, while parasite intensities increased in challenged birds during the autumn. Because old males initially had more parasites than young males, the treatments generated greater differences in parasite intensity in old than in young males. We also show that various aspects of territorial behaviour (increase in testosterone-dependent comb size in autumn, territorial call rate, likelihood of winning territorial interactions and over-winter survival) were significantly higher in dosed than in challenged males, but in old birds only. Our data thus supported the hypothesis that parasites reduce male aggressiveness during the autumn territorial contests, and could thereby influence recruitment. Our results also highlight that the territorial behaviour of young males, which have fewer parasites, is not as limited by parasites as that of old, previously territorial males. We discuss the implications of these findings for our understanding of the processes regulating red grouse populations and causing their complex, unstable population dynamics.     

Ammonia switch-off of nitrogenase from Rhodobacter sphaeroides and Methylosinus trichosporium: no evidence for Fe protein modification

In vivo switch-off of nitrogenase activity by NH ₄ ⁺ is a reversible process in Rhodobacter sphaeroides and Methylosinus trichosporium OB3b. The same pattern of switch-off in Rhodospirillum rubrum is explained by ADP-ribosylation of one of the Fe protein subunits, however, no evidence of covalent modification could be found in the subunits from either R. sphaeroides or M. trichosporium. Fe protein subunits from these organisms showed no variant behaviour on SDS-PAGE, nor were they ³²P-labeled following switch-off. These observations suggest either that the attachment of the modifying group to the Fe protein in these organisms is quite labile and does not survive in vitro manipulation, or that the mechanism of switch-off is different than that seen in Rhodospirillum.     

Stomatal numbers of soybean and response to water stress

The relationship among stomatal density, photosynthetic rate, leaf conductance, plant growth, bean yield and kaempferol triglucoside (K9) in the leaves of soybean (Glycine max (L.) Merr.) was examined in two field tests. K9 in the leaves was associated with reduced stomatal density, reduced photosynthetic rate, reduced stomatal conductance, reduced plant weight and lower bean yield. Plants with high stomatal frequency (lacking K9) were better able to take advantage of increased water supply by increasing stomatal conductance (upper surface), transpiration and bean yield. Plants with low stomatal frequency (with K9) were unresponsive to irrigation and in this sense were more tolerant of water stress, but their overall yield was low.     

Regulation of population size: evidence from Columbian ground squirrels

The hypothesis that food resources regulate population size was tested in Columbian ground squirrels, Spermophilus columbianus, from 1981 to 1986 in southwestern Alberta, Canada. Two replicate populations received supplemental food resources from 1981 to 1983, and were subsequently monitored until 1986. Two reference (unmanipulated) populations were monitored throughout the 6 years. During the experiment, dramatic increases in population size of about 500% occurred. After supplementation, spring populations declined by about 20% per year, under conditions that produced stressful shortages of food (as evidenced by significant decreases in body mass of ground squirrels). The demographic process that contributed most to increasing and decreasing experimental populations was production of yearlings, through changes in reproductive success and survival of young. Changes in migration contributed secondarily to changes in population size, and changes in adult survival were least important. While similarities of demographic processes were evident between replicates during population increases, a dramatic decrease in survival of young contributed to population decline at one replicate, and normal levels of reproduction and survival were sufficient to produce a decline in the other replicate. Demographic mechanisms may vary, but population regulation of mammalian populations appears strongly dependent on food resources.     

Significant genetic admixture after reintroduction of peregrine falcon (<Emphasis Type="Italic">Falco peregrinus</Emphasis>) in Southern Scandinavia

The peregrine falcon (Falco peregrinus) population in southern Scandinavia was almost extinct in the 1970’s. A successful reintroduction project was launched in 1974, using captive breeding birds of northern and southern Scandinavian, Finnish and Scottish origin. We examined the genetic structure in the pre-bottleneck population using eleven microsatellite markers and compared the data with the previously genotyped captive breeding population and contemporary wild population. Museum specimens between 53 and 130 years old were analyzed. Despite an apparent loss of historical genetic diversity, the contemporary population shows a relatively high level of genetic variation. Considerable gene introgression from captive breeding stock used to repopulate the former range of southern Scandinavian peregrines may have altered the genetic composition of this population. Both the historical and contemporary northern and southern Scandinavian populations are genetically differentiated. The reintroduction project implemented in the region and the use of non-native genetic stock likely prevented the southern Scandinavian population from extinction and thus helped maintain the level of genetic diversity and prevent inbreeding depression. The population is rapidly increasing in numbers and range and shows no indication of reduced fitness or adaptive capabilities in the wake of the severe bottleneck and the reintroduction.     

Factors contributing to the seasonal occurrence of the willow leaf beetle Plagiodera versicolora

We conducted a 3-year study of a natural population of the willow leaf beetle Plagiodera versicolora (Coleoptera: Chrysomelidae) on a river bank of the Inukami River, Shiga, central Japan, where four willow species (Salix chaenomeloides, S. eriocarpa, S. integra, and S. serissaefolia) occur sympatrically. Our survey showed that: (1) at the study site, the abundance of P. versicolora greatly varied among years and among willow species; (2) adult abundance changed seasonally with species-specific patterns on different willow species; and (3) the dispersal-settlement of adults had the most pronounced effects on the seasonal population growth rate of P. versicolora. Factors affecting these results were discussed.     

Phycomyces: Phototropism and light-growth response to pulse stimuli

The relationship between phototropism and the light-growth response of Phycomyces blakesleeanus (Burgeff) sporangiophores was investigated. After dark adaptation, stage-IVb sporangiophores were exposed to short pulses of unilateral light at 450 nm wavelength. The sporangiophores show a complex reaction to pulses of 30 s duration: maximal positive bending at 3·10^-4 and 10^-1 J m^-2, but negative bending at 30 J m^-2. The fluence dependence for the light-growth response also is complex, but in a different way than for phototropism; the first maximal response occurs at 1.8·10^-3 J m^-2 with a lesser maximum at 30 J m^-2. A hypertropic mutant, L85 (madH), lacks the negative phototropism at 30 J m^-2 but gives results otherwise similar to the wild type. The reciprocity rule was tested for several combinations of fluence rates and pulse durations that ranged from 1 ms to 30 s. Near the threshold fluence (3·10^-5 J m^-2), both responses increase for pulse durations below 67 ms and both have an optimum at 2 ms. At a fluence of 2.4·10^-3 J m^-2, both responses decrease for pulse durations below 67 ms. The hypertropic mutant (madH), investigated for low fluence only, gave similar results. In both strains, the time courses for phototropism and light-growth response, after single short pulses of various durations, show no clear correlation. These results imply that phototropism cannot be caused by linear superposition of localized light-growth responses; rather, they point to redistribution of growth substances as the cause of phototropism.     

Chromosome numbers and differentiation of centrospermous families

The patterns of variation of chromosome numbers in theCentrospermae suggest a common ancestry of centrospermous anthocyanin and betalain families. Phylogenetic divergence in the order may have originated with progenitors similar to extantMolluginaceae, Aizoaceae orPhytolaccaceae taxa with x = 9. Evolutionary radiation and advancement in several lines then seems to have been paralleled by trends for increasing chromosome base numbers through dysploidy and polyploidy, e.g. towardsCaryophyllaceae, Portulacaceae-Basellaceae, Hectorellaceae, Cactaceae, Didieraceae, Nyctaginaceae andChenopodiaceae-Amaranthaceae. Presented in the Symposium Evolution of Centrospermous Families, during the XIIth International Botanical Congress, Leningrad, July 8, 1975.     

A predictive model for the growth rate of Bacillus cereus in broth by response surface methodology

A response surface methodology (RSM) was developed for predicting the growth rate of Bacillus cereus in a tryptic soy broth medium as a function of temperature (10 to 40°C), pH (5.5 to 8.5), and the NaCl concentration (0 to 8%). The primary model showed a good fit (r² = 0.920 to 0.999) to a Gompertz equation to obtain growth rates each condition. The quadratic polynomial model was found to be significant (p < 0.0001) and predicted values were found to be in good agreement with experimental values (R² value of 0.9486). The evaluation of RSM for describing the growth rate of B. cereus used the bias factor (B_f) and the accuracy factor (A_f). Both the B_f value (1.11) and the A_f value (1.50) were within acceptable ranges. This model was provided an efficient and accurate method for predicting the growth of B. cereus as a function of the controlling factors.     

Long-term investigation of the degree of exposure of German peregrine falcons ( Falco peregrinus) to damaging chemicals from the environment

The contamination of German peregrine falcons (Falco peregrinus) with organochlorine (CHC) biocides and mercury (Hg) was investigated over the years 1955–2002. A total of 960 unhatched eggs from eastern Germany, Baden-Württemberg (BW) and North Rhine-Westphalia/Rhineland Palatinate (NRW/RP) were analysed for the biocides DDE, HCB, PCB, etc., and for shell index and shell thickness. Hg analyses from 367 samples (unhatched eggs, moulted and nestling feathers, tissue samples) complete the investigation. The results confirm that the collapse of the German peregrine populations is correlated with the application of the insecticide DDT. The mean DDE values in BW over the years 1970–1976 were above the relevant threshold values of 70–100 g/g (all concentrations refer to the dry sample mass), with single analyses showing values above 100 g/g until as late as 1987. The mean contamination levels in the 1960s can be retrospectively assumed to have lain above 200 g/g. With the help of thorough conservation measures it was possible after a fall in numbers of about 80% to stabilise the remnant population in BW . Following the West German DDT ban in 1972 and the resulting decline in environmental CHC contamination, this core population was able to recover from about 1980 onwards and has since increased tenfold. The shell index improved steadily from 1.48 (1970–1971) to a normal value of 1.80–1.88 (2000–2002). Hg contamination in western Germany stayed under toxic threshold values over the period 1969–1991. The significantly more intense application of DDT in eastern Germany, continuing until 1989, led to the extinction of the peregrine falcon, of both the cliff- and tree-nesting populations. This phenomenon is described with respect to DDE analysis data and shell thickness/index studies, complemented by observations of breeding biology. In addition, the employment in the GDR of methyl/phenyl Hg as seed treatments had dramatic local toxic effects on embryo survival and shell thickness. Hg burdens reached very high levels in feathers (147 µg/g) and eggs (65 g/g). The combination of DDT and Hg was responsible for the species extinction in this region. The current peregrine falcon population of eastern Germany even now shows biocide contaminant burdens up to 3 times higher than in samples from western German falcons. Shell index and shell thickness had, however, normalised to a large extent by 2002. The tree-nesting habit of the peregrines formerly breeding in the forested lowlands of Central and Eastern Europe, a tradition which had been passed on by imprinting, has been completely eradicated as a result of the effects of the environmental contamination. In NRW/RP unhatched eggs over the period 1989–2002 show uncritical DDE contamination levels in the region of 4–20 g/g with normal shell index values. PCB analyses from all three regions confirm the highest levels of contamination from industrial centres with no clear trend so far. HCB burdens peaked at a maximum of 80 g/g and have been stable at <1 g/g since 1983. Population parameters did not improve in BW until 1976, after DDE and HCB contamination levels had started to decrease as a result of the bans on use. In East Germany and NRW/RP, the documented recolonisation and increases in breeding success parameters were only possible after the DDE levels (and in East Germany additionally the Hg levels) had fallen to below toxic threshold levels.Communicated by F. Bairlein     

Markov models of territory occupancy: implications for the management and conservation of competing species

Markov chains have been frequently used in community ecology to model successional changes, but little attention has been paid to its application in population ecology as a tool to explore the outcomes of species interactions. Markov models can be regarded as “null models” that provide predicted values under a no-change scenario against which the consequences of changes in variables of interest can be assessed. Here we explore Markov chains’ potential to project population trends of competing species and derive sensible management strategies. To do that we use six years of field data on territory occupancy and turn-over of two competing top predators in a Mediterranean landscape: the golden and Bonelli’s eagles. The results suggest that long-term coexistence of both species in the study area is likely, with the main limitation for their coexistence being the difficulties Bonelli’s eagles have in colonising new territories that become available. To avoid future declines in the population of Bonelli’s eagle, it is important to take into account that the positive effects of conservation strategies focused on encouraging colonization (e.g. decreasing disperser mortality) are likely to be larger than those focused on avoiding territory abandonment (e.g. decreasing adult mortality). Markov chains are likely to be useful to evaluate the relative merit of alternative management options in other territorial species when patterns of territory occupancy are the only reliable data available, as often happens with large predators.     

Per-capita productivity in a social wasp: no evidence for a negative effect of colony size

Optimal colony size in eusocial insects likely reflects a balance between ecological factors and factors intrinsic to the social group. In a seminal paper Michener (1964) showed for some species of social Hymenoptera that colony production of immature stages (productivity), when transformed to a per-female basis, was inversely related to colony size. He concluded that social patterns exist in the social insects that cause smaller groups to be more efficient than larger groups. This result has come to be known as “Michener’s paradox” because it suggests that selection on efficiency would oppose the evolution of the large and complex societies that are common in the social insects. Michener suggested that large colony size has other advantages, such as improved defense and homeostasis, that are favored by selection. For his analysis of swarm-founding wasps, Michener combined data from colonies of different species and different developmental stages in order to obtain adequate sample sizes; therefore, his study did not make a strong case that efficiency decreases with increasing colony size (across colonies) in these wasps. We tested Michener’s hypothesis on the Neotropical swarm-founding wasp Parachartergus fraternus, while controlling for stage of colony development. We found that small colonies were more variable in percapita productivity relative to larger colonies, but found no evidence for a negative relationship between efficiency and size across colonies. Received 1 February 2006; revised 5 May 2006; accepted 11 May 2006.     

Chromosome numbers and their systematic implications in Australian marine angiosperms: ThePosidoniaceae

Somatic chromosome numbers of 2n = 20 are reported for all eight species of AustralianPosidonia: P. angustifolia, P. australis, P. coriacea, P. denhartogii, P. kirkmanii, P. ostenfeldii, P. robertsonae, andP. sinuosa. All species apparently have five larger and five smaller pairs of chromosomes. There is no evidence that speciation inPosidonia, which is relatively prolific in comparison to other seagrasses, is accompanied by change of chromosome number.     

Leaf dynamics of a deciduous forest canopy: no response to elevated CO<Subscript>2</Subscript>

Leaf area index (LAI) and its seasonal dynamics are key determinants of terrestrial productivity and, therefore, of the response of ecosystems to a rising atmospheric CO₂ concentration. Despite the central importance of LAI, there is very little evidence from which to assess how forest LAI will respond to increasing [CO₂]. We assessed LAI and related leaf indices of a closed-canopy deciduous forest for 4 years in 25-m-diameter plots that were exposed to ambient or elevated CO₂ (542 ppm) in a free-air CO₂ enrichment (FACE) experiment. LAI of this Liquidambar styraciflua (sweetgum) stand was about 6 and was relatively constant year-to-year, including the 2 years prior to the onset of CO₂ treatment. LAI throughout the 1999–2002 growing seasons was assessed through a combination of data on photosynthetically active radiation (PAR) transmittance, mass of litter collected in traps, and leaf mass per unit area (LMA). There was no effect of [CO₂] on any expression of leaf area, including peak LAI, average LAI, or leaf area duration. Canopy mass and LMA, however, were significantly increased by CO₂ enrichment. The hypothesized connection between light compensation point (LCP) and LAI was rejected because LCP was reduced by [CO₂] enrichment only in leaves under full sun, but not in shaded leaves. Data on PAR interception also permitted calculation of absorbed PAR (APAR) and light use efficiency (LUE), which are key parameters connecting satellite assessments of terrestrial productivity with ecosystem models of future productivity. There was no effect of [CO₂] on APAR, and the observed increase in net primary productivity in elevated [CO₂] was ascribed to an increase in LUE, which ranged from 1.4 to 2.4 g MJ^–1. The current evidence seems convincing that LAI of non-expanding forest stands will not be different in a future CO₂-enriched atmosphere and that increases in LUE and productivity in elevated [CO₂] are driven primarily by functional responses rather than by structural changes. Ecosystem or regional models that incorporate feedbacks on resource use through LAI should not assume that LAI will increase with CO₂ enrichment of the atmosphere.     

Variability of kokanee and rainbow trout food habits,distribution, and population dynamics,in an ultraoligotrophic lake with no manipulative management

Crater Lake is a unique environment to evaluate the ecology of introduced kokanee and rainbow trout because of its otherwise pristine state, low productivity, absence of manipulative management, and lack of lotic systems for fish spawning. Between 1986 and 2004, kokanee displayed a great deal of variation in population demographics with a pattern that reoccurred in about 10 years. We believe that the reoccurring pattern resulted from density dependent growth, and associated changes in reproduction and abundance, driven by prey resource limitation that resulted from low lake productivity exacerbated by prey consumption when kokanee were abundant. Kokanee fed primarily on small-bodied prey from the mid-water column; whereas rainbow trout fed on large-bodied prey from the benthos and lake surface. Cladoceran zooplankton abundance may be regulated by kokanee. And kokanee growth and reproductive success may be influenced by the availability of Daphnia pulicaria, which was absent in zooplankton samples collected annually from 1990 to 1995, and after 1999. Distribution and diel migration of kokanee varied over the duration of the study and appeared to be most closely associated with prey availability, maximization of bioenergetic efficiency, and fish density. Rainbow trout were less abundant than were kokanee and exhibited less variation in population demographics, distribution, and food habits. There is some evidence that the population dynamics of rainbow trout were in-part related to the availability of kokanee as prey.     

Phylogenetics of Quiinaceae (Malpighiales): evidence from trnL-trnF sequence data and morphology

We present the first parsimony analyses of the Neotropical family Quiinaceae using nucleotide sequence data from the non-coding trnL intron and trnL-trnF intergenic spacer of the plastid genome, analysed separately as well as in combination with morphology. Both molecules and combined data recover Quiinaceae as a well-supported monophyletic group. Quiinaceae form a polytomy together with their potential sister groups, the monophyletic Ochnaceae s.str. and the monotypic Medusagynaceae from the Seychelles in the Indian Ocean. Froesia is resolved as sister to the rest of the family. Other members of the family, Lacunaria, Quiina, and Touroulia, are all recovered as monophyletic despite the inclusion of strikingly distinctive representatives (L. oppositifolia and Q. pteridophylla). Relationships among the last three genera, however, are yet uncertain. Optimising characters of breeding system onto the molecular phylogeny reveals that bisexual flowers (Froesia) are the ancestral state in Quiinaceae, whereas androdioecy (Quiina, Touroulia) and dioecy (Lacunaria) are derived breeding systems.