Bill colour and body condition in the Moorhen Gallinula chloropus

Capsule We found yellow to be an honest signal of health status.     

Seasonal reproductive success of the Moorhen Gallinula chloropus: the importance of male weight

During a three-year study of 82 pairs of Moorhens Gallinula chloropus, seasonal reproductive success (SRS) varied greatly between pairs. Pairs on big territories had a higher SRS than pairs on small territories, probably because clutch survival was higher on big territories. Pairs that began breeding early had a higher SRS than pairs that began late because early breeders laid larger clutches and could attempt more broods. Pairs with heavy males had bigger territories and began breeding earlier than pairs with light males. Heavy males therefore had a higher SRS than light males. Female weight did not affect territory size, timing of breeding, or female SRS. Assuming SRS to be a good predictor of lifetime reproductive success, selection should favour heavy males but not heavy females. Male Moorhens are significantly heavier than female Moorhens. Finally, pairs with breeding experience had a higher SRS than pairs without, because they had bigger territories and began breeding earlier. However, males in inexperienced pairs were not lighter than males in experienced pairs, so it is not clear why they defended smaller territories or laid later.     

Gene flow from multiple sources maintains high genetic diversity and stable population history of Common Moorhen Gallinula chloropus in China

In this study, we used mitochondrial control sequences and microsatellite data from 231 Common Moorhen Gallinula chloropus individuals sampled from 19 sites in China to analyse their genetic structure and evolutionary history. High genetic diversity was found for all populations, although microsatellite analysis showed that the genetic diversity in non‐migratory populations was significantly higher than in migratory populations. High gene flow occurred between neighbouring populations, although long‐distance gene flow also occurred. The Huazhong population was the single greatest genetic source for other populations. High gene flow probably led to the shallow genetic structure that we observed. Demographic expansion was found in migratory populations, non‐migratory populations and with all individuals combined. The expansion time for all populations combined was estimated to be 221 000 years ago. The Common Moorhen population grew rapidly during the interglacial before the last glacial maximum (LGM), then remained generally stable from the LGM to the present.     

Juvenile helping in the moorhen,Gallinula chloropus

In a 3-year study of the moorhen, Gallinula chloropus, some chicks from first broods stayed on their natal territory once they had reached independence, and helped to rear their younger, second brood, siblings. Juvenile dispersal was constrained by habitat saturation, and first brood young were forced to stay on their natal territory. Juveniles that hatched early in the year were forced to stay longer, and helped more than those that hatched late. The total feeding rates to broods with and without juvenile helpers were the same, but parents with helpers reduced their feeding rates relative to parents without helpers. Pairs with helpers (=pairs attempting second broods) reared more chicks per nesting, attempt than pairs rearing chicks at the same time of year without helpers (=pairs attempting first clutch renests). This was true both for all clutches, and for hatched clutches only, even when controlling for parental quality, territory size and scasonal effects.     

Age differences in the feeding ability of Moorhens Gallinula chloropus

Numerous studies have shown that juvenile birds obtain food at a slower rate than do adults (Norton-Griffiths 1968, Recher & Recher 1969, Orians 1969, Dunn 1972, Davies& Green 1976, Groves 1978), We compared the foraging behaviour of adult and juvenile Moorhens Gallinula chloropus and tried to assess the relative importance of different components of feeding in determining the intake rate.     

Observational Learning in the White-Eared Hummingbird (Hylocharis leucotis): Experimental Evidence

The adoption of new food resources can be facilitated by the ability to learn through observation of other individuals who use them. This behavior, termed observational learning, applies to any problem solving in which a naive individual who has observed an experienced individual learns a behavior faster than another who has not. Hummingbirds consume nectar from flowers of a large number of plant species, which are very diverse in morphology and color. During their local or migratory movements, they can observe the use of floral resources by conspecifics and heterospecifics which may change their foraging preferences. Although there is evidence that hummingbirds can use observational learning to exploit new floral resources, it is necessary to generate additional information by studying different hummingbird species. In this work, the learning performance of White‐eared hummingbirds (Hylocharis leucotis) was studied in the presence or absence of a knowledgeable tutor. In a first experiment, naïve hummingbirds learned to feed on arrays of artificial flower of two colors: red (previously known resource) and yellow (novel resource), where only one color had nectar. Naive hummingbirds visited red flowers faster and more often than rewarded yellow flowers. Individuals with the best performance on each color were further trained to ensure that they only visited flowers of a specific color, and were then used as tutors in the next experiment, in which new naive hummingbirds, caged individually, were allowed to observe them foraging on the artificial arrays. These naïve individual were then exposed alone to the same array used by their tutor. Tutored hummingbirds learned to feed faster and more frequently from nectar‐containing flowers of the array than naive individuals. Likewise, all tutored individuals only visited flowers of the color that had been previously visited by their tutors. This study provides experimental evidence that hummingbirds taken directly from the field can use observational learning as an efficient strategy to access new floral resources.     

Experimental Evidence for the Isotope Effect in Photorespiration

Recent data on carbon isotope fractionation in photosynthesis are reviewed. Analysis of the carbon isotope composition in photosynthates and derivative products supports the hypothesis of the isotope effect in photorespiration. This hypothesis envisages the existence in a photosynthesizing cell of two carbon flows differing in isotope composition. One of these flows is enriched in ¹²C and associated with the assimilation pathway of photosynthesis. The other flow enriched in ¹³C circulates in the photorespiratory pathway. The relation between stimulated photorespiration and the carbon isotope composition of biomass supports this view. Our hypothesis of two interrelated isotope effects in photosynthesis leads to the conclusion that photosynthesis and photorespiration are coupled processes subject to periodical oscillations, where Rubisco acts as a main switch regulating these two pathways.     

Body Colors Indicate the Reproductive Status of Female Common Chameleons: Experimental Evidence for the Intersex Communication Function

Female common chameleons, Chamaeleo chamaeleon , show temporary body color changes during the reproductive season, probably in synchrony with their reproductive status. In a field study, the color changes of 21 radio-tagged females were monitored for the apparent effects that three selected colorations (green body with yellow lines, green body with yellow spots and black body with yellow spots, abbreviated to GYL, GYS and BYS, respectively) had on the reproductive behavior of both sexes. In a field experiment, females naturally displaying GYL were artificially painted to resemble GYL (or control), GYS and BYS. They were released in the wild and the response of males was recorded. The frequency of male-female behaviors, the pairing time and the outcome of male copulation attempts were consistent with the respective neutral (GYL), receptive (GYS) and gravid (BYS) functions of female color phases since a high percentage of copulations occurred during the short-term GYS phase, whereas all copulation attempts by males were violently rejected during the BYS phase. In addition, BYS females also displayed specific behavioral postures to prevent matings. In the field experiment, the number of approaching males and the strength of the response by males were significantly higher for painted GYS females. The data show strong evidence that temporary body color changes in female common chameleons are associated with changes in their reproductive status and hence, function as signals used in inter-sex communication.     

Behaviour of the Common Moorhen in Rio Grande do Sul, Brazil

This study presents data on behavioural acts performed by the Common Moorhen Gallinula chloropus in southern Brazil, and compares these with the behaviours previously reported for other populations. Focal observations of individuals were conducted in the municipality of Santa Maria, in the central region of the state of Rio Grande do Sul, Brazil. The sampling was done in 2-hour sessions, between January and March of 2007. A total of 20 behavioural acts, grouped in seven categories, were identified and described: locomotion (N = 5 acts), grooming (N = 4), intra-specific behaviour (N = 2), inter-specific behaviour (N = 3), foraging (N = 2), reproduction (N = 2) and rest (N = 2). Among the observed behaviours were acts that are not described in the literature such as greeting of offspring and some feeding acts. Regarding the use of habitat, we observed that this species has a preference for water or aquatic macrophytes, which is contrary to other reports. In the analysis of behavioural daily variation, overall behavioural categories did not vary significantly throughout the day, whereas we observed a significant difference in the use of categories during the periods 11:00 am–1:00 pm, 1:00–3:00 pm and 5:00–7:00 pm. The contrasting data between studies indicate that the variation between habitats and ecological interactions may generate different selective pressures on the behaviour of G. chloropus.     

First Experimental Evidence for Zoophagy in the Hepatic Colura

Abstract: Some hepatics, especially epiphytic species, possess lobules or water sacs on their leaves that appear to function as stores. In Pleurozia and Colura, these water sacs have very complex openings that can be closed by a movable lid, which prompted the hypothesis that these water sacs could function as a trap-like mechanism for small animals, which are occasionally found in these organs. Experiments revealed that protozoa (ciliata), which feed on bacteria on the surface of the plants, are trapped in the water sacs. We propose that these trap mechanisms function for zoophagy, but there is no clear evidence that the protozoa are specifically attracted to the hepatic.     

Evidence for alpha-Tocopherol Function in the Electron Transport Chain of Chloroplasts

The effect of three different stable radicals-2,2-diphenyl-1-picrylhydrazyl, 1,3,5-triphenyl-verdazyl, and galvinoxyl-was studied in photosystem II of spinach (Spinacia oleracea) chloroplasts. Inhibition by the three was noted on dimethylbenzoquinone reduction in presence of 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB) and on silicomolybdate reduction in presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) in photosystem II and on the H₂O → methylviologen reaction encompassing both photosystems. Inhibition of all photosystem II reactions except silicomolybdate reduction could be partially restored by α-tocopherol or by 9-ethoxy-α-tocopherone but not by other quinones or radical chasers. On this basis, a functional role for α-tocopherol in the electron transport chain of spinach chloroplasts between the DCMU and DBMIB inhibition sites is postulated.     

Genetic Evidence for Two T Complex Tail Interaction (Tct) Loci in T Haplotypes

The t complex on chromosome 17 of the house mouse is an exceptional model for studying the genetic control of transmission ratio, gametogenesis, and embryogenesis. Partial haplotypes derived through rare recombination between a t haplotype and its wild-type homolog have been essential in the genetic analysis of these various properties of the t complex. A new partial t haplotype, which was derived from the complete tw71 haplotype and which is called tw71Jr1, was shown to have unexpected effects on tail length and unique recombination breakpoints. This haplotype, either when homozygous or when heterozygous with the progenitor tw71 haplotype, produced short-tailed rather than normal-tailed mice on certain genetic backgrounds. Genetic analysis of this exceptional haplotype showed that the recombination breakpoints were different from those leading to any other partial t haplotype. Based on this haplotype, a model is proposed that accounts for genetic interactions between the brachyury locus (T), the t complex tail interaction (tct) locus, and their wild-type homolog(s) that determine tail length. An important part of this model is the hypothesis that the tct locus, which enhances the tail-shortening effect of T mutations, is in fact at least two, genetically separable genes with different genetic activities. Genetic analysis of parental and recombinant haplotypes also suggests that intrachromosomal recombination involving an inverted duplicated segment can account for the variable orientation of loci within an inverted duplication on wild-type homologs of the t haplotype.     

Cytoplasmic Tail Regulates the Intercellular Adhesion Function of the Epithelial Cell Adhesion Molecule

Ep-CAM, an epithelium-specific cell-cell adhesion molecule (CAM) not structurally related to the major families of CAMs, contains a cytoplasmic domain of 26 amino acids. The chemical disruption of the actin microfilaments, but not of the microtubuli or intermediate filaments, affected the localization of Ep-CAM at the cell-cell boundaries, suggesting that the molecule interacts with the actin-based cytoskeleton. Mutated forms of Ep-CAM were generated with the cytoplasmic domain truncated at various lengths. All of the mutants were transported to the cell surface in the transfectants; however, the mutant lacking the complete cytoplasmic domain was not able to localize to the cell-cell boundaries, in contrast to mutants with partial deletions. Both the disruption of the actin microfilaments and a complete truncation of the cytoplasmic tail strongly affected the ability of Ep-CAM to mediate aggregation of L cells. The capability of direct aggregation was reduced for the partially truncated mutants but remained cytochalasin D sensitive. The tail truncation did not affect the ability of the transfectants to adhere to solid-phase-adsorbed Ep-CAM, suggesting that the ability to form stable adhesions and not the ligand specificity of the molecule was affected by the truncation. The formation of intercellular adhesions mediated by Ep-CAM induced a redistribution to the cell-cell boundaries of α-actinin, but not of vinculin, talin, filamin, spectrin, or catenins. Coprecipitation demonstrated direct association of Ep-CAM with α-actinin. Binding of α-actinin to purified mutated and wild-type Ep-CAMs and to peptides representing different domains of the cytoplasmic tail of Ep-CAM demonstrates two binding sites for α-actinin at positions 289 to 296 and 304 to 314 of the amino acid sequence. The results demonstrate that the cytoplasmic domain of Ep-CAM regulates the adhesion function of the molecule through interaction with the actin cytoskeleton via α-actinin.     

Evidence for Transceptor Function of Cellodextrin Transporters in Neurospora crassa

Neurospora crassa colonizes burnt grasslands and metabolizes both cellulose and hemicellulose from plant cell walls. When switched from a favored carbon source to cellulose, N. crassa dramatically up-regulates expression and secretion of genes encoding lignocellulolytic enzymes. However, the means by which N. crassa and other filamentous fungi sense the presence of cellulose in the environment remains unclear. Previously, we have shown that a N. crassa mutant carrying deletions of three β-glucosidase enzymes (Δ3βG) lacks β-glucosidase activity, but efficiently induces cellulase gene expression and cellulolytic activity in the presence of cellobiose as the sole carbon source. These observations indicate that cellobiose, or a modified version of cellobiose, functions as an inducer of lignocellulolytic gene expression and activity in N. crassa. Here, we show that in N. crassa, two cellodextrin transporters, CDT-1 and CDT-2, contribute to cellulose sensing. A N. crassa mutant carrying deletions for both transporters is unable to induce cellulase gene expression in response to crystalline cellulose. Furthermore, a mutant lacking genes encoding both the β-glucosidase enzymes and cellodextrin transporters (Δ3βGΔ2T) does not induce cellulase gene expression in response to cellobiose. Point mutations that severely reduce cellobiose transport by either CDT-1 or CDT-2 when expressed individually do not greatly impact cellobiose induction of cellulase gene expression. These data suggest that the N. crassa cellodextrin transporters act as “transceptors” with dual functions - cellodextrin transport and receptor signaling that results in downstream activation of cellulolytic gene expression. Similar mechanisms of transceptor activity likely occur in related ascomycetes used for industrial cellulase production.