Sociable Weaver biometrics and primary moult

The biometric and primary moult data housed at the South African Bird Ringing Unit (SAFRING) were analysed for the Sociable Weaver Philetairus socius. The average body mass and wing length was 27.9g (SD = 2.2) and 74.1mm (SD = 2.5), respectively. Variation in these parameters is not clearly correlated with region, season or climate, other than a negative correlation of body mass with average annual water deficiency. Body mass of Sociable Weavers near Kimberley showed a longterm decrease of 2.9g, probably due to stabilising selection on mass. Primary moult duration varied from 152 days to 169 days and started between 26 January and 31 December in two populations (socius and South African eremnus respectively). Individual primaries moulted mainly one at a time, each taking 20–28 days to grow fully. Prolonged moult duration in this species is probably an adaptation to reduce energy expenditure, and to grow more durable feathers due to abrasion in entering the nest. The lack of clear patterns of geographical variation in biometrics indicates that the contiguous populations of Sociable Weaver should belong to the nominate species. The biometric and primary moult data housed at the South African Bird Ringing Unit (SAFRING) were analysed for the Sociable Weaver Philetairus socius. The average body mass and wing length was 27.9g (SD = 2.2) and 74.1mm (SD = 2.5), respectively. Variation in these parameters is not clearly correlated with region, season or climate, other than a negative correlation of body mass with average annual water deficiency. Body mass of Sociable Weavers near Kimberley showed a longterm decrease of 2.9g, probably due to stabilising selection on mass. Primary moult duration varied from 152 days to 169 days and started between 26 January and 31 December in two populations (socius and South African eremnus respectively). Individual primaries moulted mainly one at a time, each taking 20–28 days to grow fully. Prolonged moult duration in this species is probably an adaptation to reduce energy expenditure, and to grow more durable feathers due to abrasion in entering the nest. The lack of clear patterns of geographical variation in biometrics indicates that the contiguous populations of Sociable Weaver should belong to the nominate species.     

Mutations in EZH2 cause Weaver syndrome

We used trio-based whole-exome sequencing to analyze two families affected by Weaver syndrome, including one of the original families reported in 1974. Filtering of rare variants in the affected probands against the parental variants identified two different de novo mutations in the enhancer of zeste homolog 2 (EZH2). Sanger sequencing of EZH2 in a third classically-affected proband identified a third de novo mutation in this gene. These data show that mutations in EZH2 cause Weaver syndrome.     

The Weaver Wasp: Spinning Fungus into a Nest

Wasp nests range from simple to complex structures made of paper or mud. Here, we show that a Neotropical wasp of the genus Nitela builds its nest entirely by weaving endophytic fungal hyphae and spider silk harvested from the leaves growing in the understory of the rain forest in French Guiana.     

Alterations In Serotonin Receptors in the Neostriatum of Weaver Mutant Mice

Mice that carry the autosomal recessive gene weaver show a distinctive loss of nigrostriatal dopamine innervation, with the greatest deficits in the dorsal caudate-putamen and almost complete sparing in the nucleus accumbens and ventral caudate. In addition to loss of dopamine in this model, it has recently been shown that markers of serotonin (5-hydroxytryptamine, 5-HT) innervation including 5-HT content, synaptosomal uptake of [³H]5-HT and [³H]citalopram binding were elevated in the dorsal neostriatum of the weaver mutant mouse. Using quantitative autoradiography of specific ligands for dopamine and 5-HT uptake sites as well as serotonin 5-HT₁ and 5-HT_2A receptors, we found an increased density of 5-HT uptake sites and 5-HT₁ receptors restricted to the dorsal portion of the neostriatum of the weaver mouse. In contrast, 5-HT_2A receptors were increased in both the dorsal and ventral portions of the rostral neostriatum as well as the nucleus accumbens. The behavioural and functional relevance of these receptor changes is unclear, although, adaptations in 5-HT may play a role in certain aspects of spontaneous behaviour in the weaver mutant mouse.     

Patterns of Sperm Transfer in the Golden Orb‐Weaver Nephila edulis

Sperm competition studies typically identify copulation duration as an important predictor of paternity as it may determine the quantity of sperm transferred and thus paternity success. This study explores the relationship between copulation duration, male body size, male age and sperm transfer in the golden orb‐weaving spider, Nephila edulis. Paternity in this species is strongly associated with the relative frequency and duration of copulation, which is also influenced by male size. We determined the number of sperm transferred during copulation, by performing sperm counts in both the male copulatory organs (palps) and female sperm receptacle (spermatheca) of recently mated pairs. The total number of sperm recorded (the sum in the male palps and female spermathecae) was greater for younger males than older males, but did not vary with male body size. In general, younger males transferred more sperm and a greater proportion of their sperm supplies than older males and, among these younger males, larger individuals transferred more sperm. However, there were no significant size effects for older males. More sperm was transferred with longer copulations, but in contrast with previous studies, we found that larger males copulated for longer. The rate of sperm transferred was negatively correlated with the duration of copulation, suggesting that the variation in copulation duration in N. edulis may represent strategic investment by males to alter patterns of paternity, in addition to transferring additional sperm.     

2-Deoxyglucose Incorporation in the Cerebellum of Weaver and Nervous Mutant Mice

Abstract: The 2-deoxyglucose autoradiographic method has been used to study activity in cerebellum of the weaver and nervous mutant mice. Patterns of 2-deoxyglucose incorporation into the cerebral hemispheres from weaver and nervous strains did not differ significantly from those of the controls. In the normal cerebellum, 2-deoxyglucose incorporation was maximal in the granular layer, where mossy fibers form synapses with the dendrites of granule cells. In the cerebellum of nervous mice, which lacks Purkinje cells, the incorporation of the 2-deoxyglucose was maximal in the granular layer, but the incorporation into the molecular layer appeared less than in the control. The incorporation into the cerebellum from weaver, which lacks granule cells, was much higher than that of the control, the maximal incorporation being found in the Purkinje cell layer and in cell masses located in the white matter. These data suggest that the heterologous synapses that mossy fibers or climbing fibers form with the cells in the Purkinje cell layer and the cells in the white matter in the weaver cerebellum are functional.