Improving biodiversity monitoring

Effective biodiversity monitoring is critical to evaluate, learn from, and ultimately improve conservation practice. Well conceived, designed and implemented monitoring of biodiversity should: (i) deliver information on trends in key aspects of biodiversity (e.g. population changes); (ii) provide early warning of problems that might otherwise be difficult or expensive to reverse; (iii) generate quantifiable evidence of conservation successes (e.g. species recovery following management) and conservation failures; (iv) highlight ways to make management more effective; and (v) provide information on return on conservation investment. The importance of effective biodiversity monitoring is widely recognized (e.g. Australian Biodiversity Strategy). Yet, while everyone thinks biodiversity monitoring is a good idea, this has not translated into a culture of sound biodiversity monitoring, or widespread use of monitoring data. We identify four barriers to more effective biodiversity monitoring in Australia. These are: (i) many conservation programmes have poorly articulated or vague objectives against which it is difficult to measure progress contributing to design and implementation problems; (ii) the case for long‐term and sustained biodiversity monitoring is often poorly developed and/or articulated; (iii) there is often a lack of appropriate institutional support, co‐ordination, and targeted funding for biodiversity monitoring; and (iv) there is often a lack of appropriate standards to guide monitoring activities and make data available from these programmes. To deal with these issues, we suggest that policy makers, resource managers and scientists better and more explicitly articulate the objectives of biodiversity monitoring and better demonstrate the case for greater investments in biodiversitymonitoring. There is an urgent need for improved institutional support for biodiversity monitoring in Australia, for improved monitoring standards, and for improved archiving of, and access to, monitoring data. We suggest that more strategic financial, institutional and intellectual investments in monitoring will lead to more efficient use of the resources available for biodiversity conservation and ultimately better conservation outcomes.     

Melanin Standard Method: Empirical Formula 2

Natural melanins are composed of two distinct portions; a protein fraction and a chromophoric backbone. There is no unequivocal evidence for covalent bonding between these two fractions, and standard protocols used in protein purification have failed to separate the protein fraction from the chromophoric fraction. In order to study the chromophoric backbone, many workers have resorted to harsh isolation and purification protocols that are now known to degrade and damage the chromophoric portion. These artifactual melanin preparations are poor models for valid chemical, physical, and biological studies. We have developed a mild isolation and purification protocol for melanins that takes into consideration both the particulate nature of natural melanins and the stability characteristics of the chromophoric fraction. Mathematical factoring of the quantitative amino acid data into the elemental analysis was used to obtain the empirical formula of the chromophoric backbone of melanins. The analyses have shown that melanins from various sources have significantly different amino acid compositions and contents, molar C/N ratios, and empirical formulae. This method successfully differentiates melanins from a variety of sources, namely, human hair, Sepia officinalis, Sigma Chemical Company (cat. no. M8631), autoxidation of dopa, and from the feathers of Rhode Island Red chickens. Analytical results from these studies are presented and discussed.     

Floral resources,body size,and surrounding landscape influence bee community assemblages in oak‐savannah fragments

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Morphology and fine structure of the gravid uterus of three hymenolepidid tapeworm species (Platyhelminthes: Cestoda)

Summary

The ultrastructure of the uterus in gravid proglottids of Hymenolepis citelli, Vampirolepis nana and Vampirolepis microstoma was examined using transmission and scanning electron microscopy. The cellular and subcellular structures were similar in all three species, consisting basically of a syncytial layer attached to a basal extracellular matrix. All nuclei were juxtaluminal and each contained a single large centrally located nucleolus and prominent masses of central and peripheral heterochromatin. The cytoplasm showed evidence suggesting a high level of protein synthesis and secretion. It consisted primarily of granular endoplasmic reticulum with moderately dilated cisternae; most cisternae were completely filled with an electron-lucent flocculent material, but others contained electrondense granules. Free ribosomes and mitochondria were also present. The apical plasma membrane and a small amount of enclosed cytoplasm were folded into long microlamellae that extended into the uterine lumen. Larger epithelial folds and villi consisting of folded portions of the entire epithelium projected into the uterine lumen. The uterine epithelium along with its basul extracellular matrix and underlying cellular parenchyma were folded into the lumen at several points, forming epitheliomesenchymal folds and villi that closely apposed many of the eggs.     

Parthenogenetic populations of the freshwater snail Campeloma limum occupy habitats with fewer environmental stressors than their sexual counterparts

1. Sexual organisms should have half the reproductive rate of their parthenogenetic counterparts (i.e. twofold cost of sex), so the plethora of sexual species relative to parthenogenetic species remains an evolutionary paradox. The rarity of parthenogenesis may in part be due to the accumulation of deleterious mutations. Indeed, parthenogenetic populations of the freshwater snail Campeloma limum have a greater mutation load relative to sexual populations of C. limum, although this does not directly affect their reproductive fitness. We hypothesise that although parthenogenesis has no direct effect on fitness in C. limum, mutation accumulation and environmental stress act synergistically to limit the distribution of parthenogenetic populations. 2. We evaluated this hypothesis, predicting that parthenogenetic populations of C. limum would inhabit sites with fewer environmental stressors than their sexual counterparts. We collected water quality, population density and individual size data at multiple time points from eight parthenogenetic and five sexual populations in the south‐eastern United States (Georgia and South Carolina). 3. Consistent with our hypothesis, sexual populations of C. limum inhabited poorer‐quality areas (sites with significantly lower dissolved oxygen and significantly more faecal coliform bacteria) than parthenogenetic populations. Despite these stressors, sexual populations still exhibited significantly higher population density than parthenogenetic populations. 4. Our findings support the hypothesis that mutation‐laden parthenogenetic C. limum populations occupy habitats with fewer environmental stressors relative to their sexual counterparts. Moreover, sexual C. limum populations inhabit lower‐quality habitats where they can presumably evade the twofold cost of sex in the absence of competition from their parthenogenetic counterparts.     

Quantifying the benefits and costs of parental care in assassin bugs

1. Which sex should care for offspring depends on the cost and benefits of the behaviour for each sex. Understanding these differences between the sexes is a fundamental step to explain the evolution of animal societies, but it is often difficult to quantify them empirically. A possible approach is to investigate two closely related species that perform a very similar type of care but in which the caring sex differs. 2. Using field and laboratory data, we estimated the benefits and costs of parental care in two species of assassin bugs with very similar ecologies: Rhinocoris tristis, which has exclusive paternal care, and Rhinocoris carmelita, which has exclusive maternal care. 3. In both species, the main benefit of care was a reduction in parasitism and predation of eggs. Guarding R. tristis males consumed eggs (filial cannibalism), and thus managed not to lose weight, but R. carmelita females paid the full energetic cost of care. Guarding male R. tristis incurred survival costs relative to non‐guarding male and female conspecifics. 4. Very high population density and female preference for males already guarding eggs (a preference previously recorded in fish) minimised the promiscuity cost of paternal care in R. tristis, explaining the difference in care pattern between the two species.     

Defining the limits to local density: alternative views of abundance–environment relationships

1. In many ecosystems, the local abundance of organisms is spatially heterogeneous. Ecologists often seek to explain this variation by modelling the central tendency of abundance as a function of a single dominant factor (central response, CR). An alternative approach is to model maximum and minimum abundance in relation to the dominant factor (limiting response, LR), thereby acknowledging that multiple factors may constrain abundance and create scatter in the relationship. In many ecosystems, including streams, abundance–environment relationships are traditionally expected to be CR models with a single dominant factor determining local abundance, but this hypothesis lacks rigorous test. This omission is of concern because CR modelled relationships form the foundations of many ecological tests, predictive and management tools that, consequently, may provide erroneous interpretations. 2. In a survey designed to minimise variance in the data, we related densities of three taxa of stream invertebrates to near‐bed flow. Data were analysed using both ordinary least squares (OLS) regression and quantile regression, which have different characteristic results depending on whether the relationship is better described as a CR or LR model. For all three taxa, invertebrate responses to flow conformed most closely to LR models and were best described by quantile regression, although OLS regression revealed broadly similar general trends in this case. 3. Based on the statistically modelled relationships, we were able to hypothesise which ecological mechanisms limited maximum abundance at this site, including dislodgement with high flow (Heptageniidae, Leuctridae), reduced oxygen uptake at low flow (Baetidae) and reduced provision of interstitial spaces at high flow (Leuctridae). Scatter in the relationships was attributable to multiple factors that may operate at different scales, including inter‐individual variation, alternative environmental gradients and biotic processes at the patch scale, and potential constraints of dispersal and settlement operating outside the patch. 4. We illustrate how the choice of CR or LR model to describe abundance–environment relationships may affect tests of ecological theory and applied ecology. If our results are typical of other streams and other types of systems, greater use of LR models may transform the way many ecologists view ecosystems, thus having positive consequences for survey and experimental designs and highlighting weaknesses in existing management tools that are underpinned by CR models.