Male attractiveness covaries with fighting ability but not with prior fight outcome in house crickets

In many species males that tend to win fights against othermales are more attractive to females. There are three ways inwhich male fighting ability and attractiveness may be associated:(1) attractiveness and fighting ability are influenced by thesame underlying traits (e.g., body size), (2) females prefermales that have directly observed winning fights, or (3) winningprevious fights indirectly improves a male's chance of beingpreferred by females. The last possibility may arise as a consequenceof the "loser effect"; in many species when a male loses a fighthis probability of losing subsequent fights increases. Thereare, however, no studies testing whether such a "loser effect"also influences male attractiveness. Here we show that maleattractiveness and fighting ability are positively correlatedin the house cricket, Acheta domesticus. Our experiment wasdesigned so that females could not directly observe the outcomeof fights, thus eliminating possibility (2) above. We then testedbetween possibilities (1) and (3) by making use of the factthat in some cricket species the "loser effect" can be eliminatedexperimentally by ‘shaking’ a male and stimulatingthe motor program for flying. We showed that in A. domesticus‘shaking’ does affect the outcome of subsequentfights. Males that had won two previous fights were less likelyto win a fight after being ‘shaken’ than when subjectto a control treatment. In contrast, males that had lost twoprevious fights were more likely to win a fight after being‘shaken’ than when they were not shaken. There was,however, no effect of ‘shaking’ on male attractiveness.We conclude that the "loser effect" does not alter the tendencyfor large, dominant males to be attractive to females. Instead,it appears that there are traits correlated with both fightingability and attractiveness. One such trait is body size. Fightwinners were significantly larger than losers and attractivenesswas positively correlated with male body size.     

The Modification of Ancient Woodland Ground Flora at Arable Edges

The last five decades have witnessed an intensification of agriculture with a marked increase in the use of agrochemicals. This study investigated whether arable edges affect ancient woods and the extent of any modifications to the ground flora. Plant species were recorded from a total of 84 transects into the centre of the woods, of which 59 were taken from the arable–woodland interface and 25 were taken from non-arable land or woodland rides. Ellenberg indicator and CSR values were used to infer fertility and features of the environment. Results suggested that, after adjusting for light and moisture conditions, elevated nitrogen levels might occur in ancient woodlands to a distance of at least 100 m from arable farmland. Furthermore, the transects from the arable fields had a substantially altered herb-layer with respect to species composition, notably a greater percentage cover of ruderal and nitrophilous species, and a lower cover of stress tolerator species. Smaller woods contained a greater cover of competitor and nitrophilous species and a lower cover of stress tolerators and ancient woodland indicator species. We conclude that farming may be unwittingly modifying the ground flora of ancient woodlands adjacent to arable land and that small and irregularly shaped woods are most at risk. It is recommended that farmers apply agrochemicals in such a way that drift is minimised, and that large, valuable ancient woods be protected by a substantial buffer zone.     

Impact of Juvenile Stocking Size on the Major Carp Production in a Minor Reservoir,Bibinagar, India

The present study deals with the impact of juvenile stocking sizes of the major carp on production in a minor reservoir, Bibinagar, Nalgonda, India. Reservoir surface area equaled over 23.8 ha and water from the reservoir was used for irrigation and fisheries. Four experiments were conducted for 4 years from 2000–2001 to 2003–2004. The experiments were planned in such a way that every year juvenile stocking size was held constant and subsequent fish production analyzed. During the first year’s experiment (2000–2001) a stocking size of 25–30 mm (fry) was maintained. Similarly 50–55 (advanced fry), 75–80 mm (fingerling) and 100–105 mm (advanced fingerling) were stocked during 2001–2002, 2002–2003 and 2003–2004 respectively. Uniform yearly stocking densities (2000/ha) were established in each experiment in the month of July and fish were harvested in June of the subsequent year. Major carp production was enhanced with larger stocking size. Yearly productions equaled 144.00, 231.48, 632.91 and 1005.03 kg/ha/year with the above stocking sizes. Variation in stocking sizes had significant (P<0.05) effects on fish production. The number of fish per kg production decreased gradually with increases in stocking size with an average value of 3.97. Reservoir production of catla was the most abundant species, followed by rohu, common carp, mrigal and grass carp. These results show that stocking size has a great impact on fish production and the stocking of advanced fingerlings will provide maximum carp production in minor reservoirs in India.     

Microsatellite variation and structure of 28 populations of the common wetland plant, Lychnis flos-cuculi L., in a fragmented landscape

Habitat fragmentation is known to cause genetic differentiation between small populations of rare species and decrease genetic variation within such populations. However, common species with recently fragmented populations have rarely been studied in this context. We investigated genetic variation and its relationship to population size and geographical isolation of populations of the common plant species, Lychnis flos-cuculi L., in fragmented fen grasslands. We analysed 467 plants from 28 L. flos-cuculi populations of different sizes (60 000-54 000 flowering individuals) in northeastern Switzerland using seven polymorphic microsatellite loci. Genetic differentiation between populations is small (F(ST) = 0.022; amova; P < 0.001), suggesting that gene flow among populations is still high or that habitat fragmentation is too recent to result in pronounced differentiation. Observed heterozygosity (H(O) = 0.44) significantly deviates from Hardy-Weinberg equilibrium, and within-population inbreeding coefficient F(IS) is high (0.30-0.59), indicating a mixed mating breeding system with substantial inbreeding in L. flos-cuculi. Gene diversity is the only measure of genetic variation which decreased with decreasing population size (R = 0.42; P < 0.05). While our results do not indicate pronounced effects of habitat fragmentation on genetic variation in the still common L. flos-cuculi, the lower gene diversity of smaller populations suggests that the species is not entirely unaffected.     

Refractive index-based determination of detergent concentration and its application to the study of membrane proteins

The concentration of detergent in membrane protein preparations can have a critical role on protein stability, function, and the potential for crystallization. Unfortunately, dialysis or protein concentration can lead to an unknown amount of detergent in the final membrane protein preparations. Here we present a method for the determination of detergent concentration based on refractive index of the detergent solution. This method was applied to quantitate the amount of detergent remaining in solution after concentration in various concentrators. We found that the ability of the tested detergents to pass through the molecular weight cutoff membrane correlates well with detergent micelle size. Therefore, the micelle size can be used as a rough guide to estimate the retention of a given detergent in various molecular weight cutoff concentrators. The refractive index method is exceptionally informative when coupled with size exclusion chromatography and light scattering, and can be used to determine the oligomeric state of the membrane protein, the size of a protein-associated micelle, as well as the amount and size of the unbound detergent micelle.     

Genetic structure in the coral-reef-associated Banggai cardinalfish, Pterapogon kauderni

In this study, we used 11 polymorphic microsatellite loci to show that oceanic distances as small as 2-5 km are sufficient to produce high levels of population genetic structure (multilocus F(ST) as high as 0.22) in the Banggai cardinalfish (Pterapogon kauderni), a heavily exploited reef fish lacking a pelagic larval dispersal phase. Global F(ST) among all populations, separated by a maximum distance of 203 km, was 0.18 (R(ST) = 0.35). Moreover, two lines of evidence suggest that estimates of F(ST) may actually underestimate the true level of genetic structure. First, within-locus F(ST) values were consistently close to the theoretical maximum set by the average within-population heterozygosity. Second, the allele size permutation test showed that R(ST) values were significantly larger than F(ST) values, indicating that populations have been isolated long enough for mutation to have played a role in generating allelic variation among populations. The high level of microspatial structure observed in this marine fish indicates that life history traits such as lack of pelagic larval phase and a good homing ability do indeed play a role in shaping population genetic structure in the marine realm.     

Efficient construction of a highly useful phage-displayed human antibody repertoire

We have constructed a highly useful phage-displayed human antibody repertoire with limited cloning efforts. Our strategy was to maximize diversity during the first steps of library construction through the use of various lymphoid sources from several donors, inclusion of different immunoglobulin isotypes, and performance of multiple separate amplification reactions with all possible combinations within a complex primer set. The resulting variable region collections were cloned to form a moderate size library, composed by 4.25x10(8) single chain antibody fragments. This repertoire was successfully used to retrieve binders to seven model antigens: six proteins and one 12 aa peptide. Binding affinities reached nanomolar and even subnanomolar range. Sequence diversity and V-gene usage variability among binders were proven. Our approach was not focused on absolute library size, but on a high quality sampling of variable regions from the human antibody repertoire.     

GEOGRAPHICAL VARIATION IN THE RATE OF EVOLUTION: EFFECT OF AVAILABLE ENERGY OR FLUCTUATING ENVIRONMENT?

In a recent paper, Wright et al. (2003) argue for the hypothesis that greater biologically available energy elevates the rate of molecular evolution. However, their results are also consistent with alternative hypotheses that invoke either environmentally driven variation in effective population sizes, or natural selection, or both. The available energy gradient cited by Wright et al. is linearly correlated with temperature fluctuations, and the observed rate heterogeneity could be a consequence of this environmental variability. The distribution of phylogenetic branch lengths alone is insufficient to distinguish between the hypotheses, and complementary approaches are suggested.     

Negative effects of elevated testosterone on female fecundity in zebra finches

Although factors influencing androgen deposition in the avian egg and its effects on nestling fitness are recently receiving considerable attention, little is known about the potential costs of high testosterone levels in the females. Our study aimed at determining the effect of injections of testosterone (T) in female zebra finches (Taeniopygia guttata), on clutch size, egg mass, yolk mass, and yolk androgen content. Females were given a single bolus injection of T in a range of doses after laying the first egg. Results show that administration of T negatively affected clutch size; the strength of this effect increased with increasing doses of T. Females injected with the highest testosterone dose showed suppressed oviposition of the third and the fourth eggs. Interestingly, testosterone administration made females produce eggs with relatively large yolks, suggesting that T may mediate the trade-off between number and size of eggs. Testosterone injection resulted in elevated levels of androgen in the eggs, in contrast to control clutches, which showed a decreasing pattern of androgen concentration along the laying sequence. We conclude that high androgen investment in eggs may be limited by physiological requirements of the ovulatory process.