Associations with habitat versus geographic cohesiveness: size and shape of Bembicium vittatum Philippi (Gastropoda: Littorinidae) in the Houtman Abrolhos Islands

In the Houtman Abrolhos Islands, Western Australia, the direct-developing littorine snail Bembicium vittatum occupies a wide range of habitats, which are replicated across the three major groups of islands. Earlier studies showed that allozyme similarities followed patterns related to gene flow, independent of habitat, providing an excellent opportunity to test for associations with habitat for traits more likely to be adaptively important. As the first test for adaptive divergence, we examined variation in size and shape of shells among 131 populations in the Abrolhos Islands. Two-fold variations were found in width of adults, the allometric coefficient of height with width, and shell height scaled to a standard width. Quantification of habitat characteristics was summarized by principal components analysis. In contrast with the patterns of divergence for allozymes, shell height, adjusted for width, was strongly associated with habitat: flatter shells are found on exposed, vertical shores, while domed, more globose shells predominate in sheltered sites. This association was stronger for shape of adult-sized snails than for height scaled to an arbitrary size, highlighting the importance of using biologically relevant measures. Even highly isolated and allozymically less variable populations in tidal ponds conformed to this association. Because differences in shape are highly heritable in B. vittatum , this association of shape with habitat, independent of patterns of gene flow, indicates local adaptation. Shell size also varied with habitat, but because growth rate is highly plastic, variation in size cannot be interpreted simply in terms of adaptation. Nevertheless, the pattern of variation indicates that, within realized limits, larger size is generally favourable, but may be constrained by local conditions. Thus, variation in size signals the potential for adaptive divergence of life histories among the many, isolated populations of this species.     

NERVOUS CONTROL OF OVULATION AND EJACULATION IN HELIX ASPERSA

The ovotestis duct transports male and female gametes from theovotestis, through the seminal vesicle, and into the fertilizationpouch-spermathecal complex. All these structures are innervatedby small branches of the intestinal nerve. Electrical stimulationof the nerve increased the rate at which gametes were transportedin the duct and caused autosperm to flow into the fertilizationpouch-spermathecal complex. These events were accompanied bystimulation-induced peristaltic contractions along the ductand activation of the cilia lining the interior of the duct.Acetylcholine and serotonin were identified as excitatory transmittersin this system, while FMRFamide was identified as a muscle relaxant.The nervous control of ejaculation may contribute to optimizingthe size of the ejaculate in a context of sperm competition,while the involvement of the nervous system in ovulation maystem from a requirement for sensory integration that is peculiarto the Stylommatophora. (Received 16 December 2004; accepted 31 March 2005)     

Sequences of sex allocation and mortality in clutches of Metaphycus parasitoids of soft scale insects and the prevalence of all‐female broods

1. In many gregarious or quasi‐gregarious parasitoids that experience local mate competition, precise sex ratios with low variance are observed. Precise sex ratios can be achieved by laying male and female eggs in non‐random sequences. 2. Developmental mortality can also alter sex ratios of emerging offspring, and subsequently influence sex ratio optima. 3. The present study investigates sex allocation by Metaphycus flavus Howard, M. luteolus Timberlake, and M. angustifrons Compere (Hymenoptera: Encyrtidae), endoparasitoids of soft scale insects, in the laboratory. 4. All three Metaphycus species had precise secondary sex ratios when parasitising brown soft scale, Coccus hesperidum, L. in the laboratory. Moreover, we documented that all three species lay fertilised (= female) eggs first followed by unfertilised (= male) eggs at the end of the oviposition bout. However, there were significant differences in sex allocation sequences among species. 5. Mortality rates of eggs allocated within an oviposition bout also varied considerably, indicating that there is a significant interspecific variation in sequence position‐specific mortality. 6. Using a stochastic Monte Carlo simulation approach, we provide evidence that the incidence of all‐female broods in these parasitoid wasps appears mainly due to developmental mortality and not due to decisions by the ovipositing female. In two species the prevalence of all‐female broods was independent of clutch size, contrary to what is expected from theory. The influence of mortality on optimal sex allocation in these parasitoids is discussed.     

Sex in Development: Science, Sexuality, and Morality in Global Perspective

Sex in Development: Science, Sexuality, and Morality in Global Perspective. Vincanne Adams and Stacy Leigh Pigg, eds. Durham, NC: Duke University Press, 2005. 342 pp.     

Refuge from cannibalism in complex-structured habitats: implications for the accumulation of invertebrate predators

Abstract.  1. Like many invertebrate predators, the wolf spider Pardosa littoralis Banks (Araneae: Lycosidae) accumulates in complex-structured habitats replete with leaf litter (thatch). Here we test the hypothesis that P. littoralis accumulates in complex habitats to gain refuge from cannibalism.
2. A laboratory experiment examined the effects of habitat complexity (thatch present or absent) and size-class pairing of conspecific spiders (large vs. small, small vs. small, and large vs. large) on the incidence of cannibalism. Spider survival was significantly higher (22%) in complex-structured habitats with thatch than in simple-structured habitats lacking thatch. Furthermore, cannibalism occurred more frequently in P. littoralis when the size of conspecifics was asymmetric (large vs. small spiders) than when spiders were of equal size. There was no interactive effect of habitat complexity and size-class pairing on spider survival.
3. A field experiment examined the effects of habitat complexity, conspecific density, and access to alternative prey on the prevalence of cannibalism in P. littoralis . Access to alternative prey significantly increased the number of spiders recovered from field enclosures, as did the presence of leaf litter thatch. That fewer spiders were recovered when thatch and alternative prey were absent suggests that cannibalism was most prevalent under these conditions.
4. Overall, results suggest that habitat complexity reduces agonistic interactions and cannibalism among wolf spiders, providing encouragement to pest managers that the structure of agricultural habitats can be managed to maximise densities of generalist predators for enhanced pest suppression.     

CLONING, PARENTHOOD, AND GENETIC RELATEDNESS

In this paper I examine what I take to be the best case for reproductive human cloning, as a medical procedure designed to overcome infertility, and argue that it founders on an irresolvable tension in the attitude towards the importance of being ‘genetically related’ to our children implied in the desire to clone. Except in the case where couples are cloning a child they have previously conceived naturally, cloning is unable to establish the right sort of genetic relation to make couples the parents of their cloned child. If anybody is the genetic parent of a cloned child it is the natural parent(s) of the DNA donor. Paradoxically, in order to resist the claims of the parents of the donor to the cloned child, the argument for human reproductive cloning must place more weight on the intention to parent a child, than we do in cases of ordinary reproduction. It must insist that the parental relation is established by the intentions of the couple who bring a clone into the world and not by their genetic relation to the child. The emphasis placed on intention as establishing the parental relationship works to undermine the justification for cloning in the first place. For cloning to play a useful role as a reproductive technology, it must allow couples to become parents who could do so no other way. However, to the extent that intention is sufficient to establish parenthood, adoption or surrogacy, which are existing alternatives to cloning, will serve equally well to allow couples to become parents.     

Spatial and temporal assessment of sources contributing to the annual austral spring mid-tropospheric ozone maxima over the tropical South Atlantic

The primary source of the annual austral spring mid‐tropospheric ozone maxima over the tropical South Atlantic has generally been assumed to be biomass burning. However, ozone precursor emissions from biogenic, lightning, and anthropogenic sources in subequatorial Africa before and during the ozone peak are shown to be comparable, if not greater, in magnitude to regional biomass burning production. Moreover, an investigation of the spatial and temporal characteristics of these ozone precursor sources (i.e. vegetative and microbial activity, lightning‐induced generation, and anthropogenic emissions) suggests that these alternative sources can potentially make a substantial contribution to the seasonal ozone peak. This argument is supported by the practical limitations of atmospheric transport available to regionally produced ozone and ozone precursors.     

Transferring Research to Endangered Species Management

ABSTRACT In the natural resource and wildlife profession, we face difficulties in the production, diffusion, and transfer of rigorously tested science, especially when facing entrenched management paradigms. We present 3 case studies to illustrate the challenges in changing entrenched management paradigms for endangered species. Here we examine specifically what factors helped or hindered the adoption of management practices through the theoretical framework developed for the dissemination of technologies. An examination of 3 case studies suggests that active communication and advocacy of scientific findings, along with simple, visible results, will aid researchers in the acceptance and adoption of their research. Management agencies that increase openness and communication with outside experts, reduce bureaucratic procedures, and localize decision making increase the likelihood that new scientific ideas will be adopted by the agency. We also suggest adaptive resource management as a strategy for endangered species management may foster many of the characteristics that aid in the adoption of scientific ideas into management activities.     

Morphometric analysis of the Taxus wallichiana complex (Taxaceae) based on herbarium material

We used morphological and geographical data of 128 herbarium specimens of the Taxus wallichiana complex in eastern Asia to investigate their utilization in discriminating and identifying taxa included in the complex. One bud scale and 26 leaf characters were used to separate T. fuana , T. wallichiana var. wallichiana , T. wallichiana var. mairei , T. wallichiana var. chinensis and T. sumatrana by K-means clustering and dendrograms using Ward's distance. Out of the 27 characters examined 21 were found to be well correlated with geographical patterns. T. fuana was morphologically the most distant taxon, while T. sumatrana clustered among the T. wallichiana varieties. After correcting misidentifications of the specimens in T. wallichiana , its varieties occupied discrete geographical ranges, except for some limited sympatry of varieties mairei and chinensis east of the Tanaka–Kaiyong line and the Sichuan Basin, China. Our analysis demonstrates the importance of consistency in character selection and definition in the identification of morphologically difficult taxa and the power of combining morphometric and geographical data in clarifying their spatial distribution.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 307–335.