Parasites and Bright Male Plumage in the Satin Bowerbird (Ptilonorhynchus violaceus)

Results from our field studies of the satin bowerbird (Ptilonorhynchusviolaceus) suggest that females choose males as mates basedon their level of infection with the ectoparasite (Myrsideaptilonorhynchi: Menoponidae). We evaluated predictions fromthree hypotheses for why this pattern of choice might evolve.The bright male and correlated infection models both suggestthat females choose parasite free males because these malesare more likely to sire parasite resistant offspring. The brightmale hypothesis suggests that females are able to gauge infectionbased on plumage brightness. The correlated infection hypothesisclaims that females assess resistance to endoparasites througha correlated effect on ectoparasites. In the parasite avoidancemodel female choice is shaped by the proximate benefits of avoidinginfection. Six predictions from these models were tested usinginformation on patterns of infection in satin bowerbirds. Ofthese models the parasite avoidance model was best supportedby the available data.     

The functional morphology of the praying mantis forelimb (Dictyoptera: Mantodea)

The structure and function of the forelimbs of praying mantids are discussed. A large spine on the femur and the spine on the end of the tibia were shown experimentally to be important in the capture of unrestrained flies. These spines may function to narrow the gap through which a fly may escape while the tibia is closing on the femur. Some of the spines on the femur are hinged at their base; the structure, properties and possible functions of these spines are discussed.
Similar hinged spines are reported on the lorelimbs of Stomatopoda (CrustaceaI but were not found in the Mantispidac (Neuroptera:Insecta). The variation of forelimb structure within the Mantodea is briefly discussed. The theory that the optimum prev size can be predicted from the geometry of the mantid forelimb is critically discussed.     

GLYCOGEN METABOLISM AND CHANGES IN THE ACTIVITIES OF PHOSPHORYLASE, PHOSPHOFRUCTOKINASE AND PYRUVATE KINASE DURING DEVELOPMENT OF SEA URCHIN EGGS

The glucose and glycogen contents of sea urchin eggs and embryos were measured enzymatically. Unfertilized eggs of Hemicentrotus pulcherrimus and Anthocidaris crassispina contain about 20.9 and 24.4 μg of glycogen per mg protein, respectively. As for glucose, unfertilized eggs of Hemicentrotus and Anthocidaris contain about 0.7 and 1.9 μg per mg protein, respectively. Glycogen consumption during embryonic development differs with different species of sea urchins. In Anthocidaris , glycogen decreases significantly after fertilization. The oxidation of glucose and glycogen accounts for about 50% of oxygen consumed until the early blastula stage in this species. The contribution ratio of glucose and glycogen to the overall energy pool becomes less than 10% at later stages. In Hemicentrotus , however, the glycogen content remains unchanged until the early blastula stage and thereafter decreases. The importance of glucose and glycogen as an energy fuel seems little throughout the development of Hemicentrotus. Activities of phosphorylase (EC 2.4.1.1), phosphofructokinase (EC 2.7.1.11) and pyruvate kinase (EC 2.7.1.40) were measured at various embryonic stages in both species of sea urchins. The difference between two species in the consumption of glucose and glycogen can not be elucidated by the differences in the activities of these enzymes.     

STUDIES ON A CAROTENE-PROTEIN COMPLEX ISOLATED FROM GREEN LEAVES

1. Two new methods of preparing a carotene-protein complex fromchloroplasts were described, in addition to the one previouslyreported by the present authors.
2. Light-scattering measurementswere performed and from the dissymmetryratio of the scattering,the particle size of the complex wascalculated. The mean radiuscorresponding to the weightaverageparticle weight was foundto be 56 mµ. This result wasdiscussed with referenceto the previously reported values obtainedfrom sedimentationmeasurements and electron micrographic determinations.
3. Thedepolarization of scattered light was measured. Large valuesobtained for the degree of depolarization of the incident lightrevealed a high degree of anisotropy in the particle of thecarotene-protein complex.

¹Present address: Johnson Foundation, University of Pennsylvania,Philadelphia, Pa., U.S.A. (Received July 8, 1960; )     

The utilization of dead wood resources by woodpeckers in Britain

Dead wood is important for woodpeckers, providing foraging, roost and nest-sites. In this paper, data from long-term studies of woodpeckers and dead wood in oakwoods in southern England are used to examine the dead wood requirements of the three British resident woodpecker species. Both Great Dendrocopos major and Lesser Spotted Woodpeckers Dendrocopos minor select dead trees for nest-sites although the former is able to nest in living trees too. On the other hand a smaller fraction of Lesser Spotted Woodpecker nests are in living trees. Green Woodpecker Picus viridis shows no selection for dead nesting trees. Hence the smallest woodpecker species appears to be most dependent on dead and decaying trees for nest-sites. Great and Lesser Spotted Woodpeckers show no preference for foraging on dead trees although they both make use of dead branches on living trees. Lesser Spotted Woodpeckers forage on smaller branches higher in the tree than Great Spotted Woodpeckers. There has been a trend for increasing dead wood resources in the study woods with both dead wood on the ground and standing dead trees (snags) increasing in the last 20 years. The levels of dead wood are shown to be the result of continual processes of creation and decay. Around 0.5% of oak Quercus spp., Ash Fraxinus excelsior and Hornbeam Carpinus betulus and 3.4% of the birch Betula spp. trees die each year in the woods resulting in a continuity of new dead snags and fallen trees. There is a high turnover of standing dead snags of oak and birch with 95% and 80% annual survival, respectively. Snags are only suitable for nesting Great Spotted Woodpeckers for a few years after their creation. It is suggested that these stand and dead wood dynamics are likely to provide habitats more favourable for the Great Spotted than the Lesser Spotted Woodpecker.     

Differentiation in phenotypic plasticity among populations of Arabis serrata Fr. & Sav. (Brassicaceae)

Studies on divergence of phenotypic plasticity in closely related species have suggested that character means and plasticity of these characters may evolve independently. Similar patterns of divergence between populations within a species have been reported although few plant species have been studied. Thus, in this paper, the patterns of differentiation between character means and phenotypic plasticity among eight populations of Arabis serrata are documented. Mean response and magnitude and pattern of phenotypic plasticity were measured and compared in plants growing under an environmental gradient of nutrients. Differences in means and coefficients of variation (CV as indicators of plasticity) among populations were compared using the Canberra metric and generating unrooted Wagner trees. Populations showed significant differences in character means in nine morphological traits. Magnitude and patterns of phenotypic plasticity showed a complex pattern of differentiation for each trait and population. Biomass traits were more plastic, in general, than characters associated with linear size. Comparisons between pairs of populations for nine morphological traits showed that in 28.6% of 252 possible cases, populations differed in means, magnitude and patterns of phenotypic plasticity. In almost 90% of the cases, populations differed in magnitude and/or pattern of plasticity. Considering all characters together, populations from similar habitats and with common life history features tended to respond in similar ways. The patterns of divergence, however, suggest that character means and character plasticities among populations are able to evolve independently.     

An examination of phytochemical variation in Aloe elgonica Bullock

Compounds in the leaf exudates from 43 individuals of A. elgonica collected on Mount Elgon on the Kenya-Uganda border and raised at Kew were examined by two-dimensional thin-layer chromatography. The compounds reacting with Fast Blue B to give coloured zones showed patterns of variation throughout the species. These patterns could not be correlated with the considerable variations in chromosome form and leaf surface anatomy. The two major compounds in the leaf exudates were the anthrone C-glycosides, barbaloin and homonataloin, which were never observed together in the same plant. Aloenin occurs throughout the species in every plant examined, varying only in amount as detected by staining.     

Limb Development and Regeneration

Experiments on developing and regenerating vertebrate limbshave led to the idea that pattern formation and growth controlare causally linked. The mechanism by which position-specificgrowth occurs is termed intercalation, and evidence is presentedthat implicates intercalation in the initiation, maintenanceand cessation of growth during limb formation. We conclude thatamong the variety of cell types present in limbs, only fibroblastshave been shown to possess the positional information necessaryfor intercalation. Hence we propose that the limb pattern isgenerated by intercalation between fibroblasts to give riseto a connective tissue scaffold, which in turn dictates thepositioning and morphogenesis of all of the differentiated celltypes of the limb. Finally, we review evidence that regenerativefailure among higher vertebrates is linked to defects in theintrinsic cellular mechanisms of growth control (intercalation)and conclude that progress towards the goal of stimulating regenerativelimb outgrowth in non-regenerating vertebrates will be contingentupon a better understanding of these intrinsic mechanisms.