Some costs of reproduction for male bushcrickets,Requena verticalis (Orthoptera : Tettigoniidae) allocating resources to mate attraction and nuptial feeding

Summary The cost of reproductive effort is known to result in a trade-off between current and future reproduction. Similarly, trade-offs in energy allocation may occur between components of reproductive effort, mating and parental effort, within a single reproductive episode. We investigated the energy allocated to mating effort (calling to attract females) and parental effort (donation of spermatophore nutrients at mating) by male bushcrickets, Requena verticalis, under two dietary regimes. Males provided with a low quality diet reduced the daily energy allocated to calling activity while maintaining their investment in spermatophores. Males provided with a high quality diet did not allocate more resources per day to their spermatophores but stored excess energy for future reproduction. Thus, on a per day basis, males appear to hold constant their investment in the spermatophore at the cost of reduced mating effort when resources are limited. Males on both diets, however, increased the size of their spermatophore donations when the interval between female encounters was increased. One explanation for this pattern could be a frequency-dependent optimization of spermatophore size. Correspondence to: L.W. Simmons     

Optimal maternal investment in the dung beetle<Emphasis Type="Italic"> Onthophagus taurus</Emphasis>?

Optimal investment theory is based on the assumption that the proximate constraint acting on parental investment is resource based. A trade-off between per offspring investment and total investment seems intuitive. Consequently, a parents investment strategy is expected to represent a trade-off between the benefits of investment for current offspring and the costs to future reproduction for parents. In this study, we provide clear evidence that the costs and benefits of maternal provisioning in the dung beetle Onthophagus taurus influence the amount of provisions provided by the mother. Horse dung is typically of a higher nutritional value than cow dung and females were shown to provide 20% less dung to offspring when provisioning with horse dung. By reducing their investment per offspring and exhibiting a clear preference to provision offspring with horse dung, females were able to produce significantly more offspring. Females provisioning with horse dung received greater fitness returns per unit of investment and experienced lower provisioning costs, in terms of the minimum amount of dung required to produce a surviving offspring, than females provisioning with cow dung. Females provisioning in soil of low moisture content were found to have higher tunneling costs than those provisioning in soil of high moisture content, while the fitness returns per unit of investment did not differ. We adopted a marginal value theorem (MVT) approach to calculate the theoretical optimal level of investment for each dung type and for each soil moisture. Predicted levels of provisioning were lower for horse dung than for cow dung and for moist soil than for dry soil. Therefore, the results of this study are in qualitative agreement with MVT predictions and provide empirical support for the proposal that females can adaptively adjust their level of investment in response to resource and/or habitat quality. However, the theoretically predicted optimal investment yielded a poor quantitative fit with our observed levels of investment, with females providing over twice the investment predicted by the MVT approach. We suggest that this difference may reflect either our inability in directly quantifying all the necessary costs and benefits of investment in O. taurus and/or the applicability of the underlying assumptions of MVT.Communicated by D. Gwynne     

Thermal and oxidative disproportionation in amine degradation—O2 stoichiometry and mechanistic implications

Three modes of amine degradation have been previously identified—direct oxidation by metal ions, thermal disproportionation and autoxidation. Results are presented in which products of disproportionation reactions of quaternary compounds are compared to those seen in the thermal degradation of methyldiethanolamine, MDEA. This strongly suggests a role of a quaternary or a protonated amine intermediate in this reaction. Products of MDEA autoxidation at 140 °C also show characteristics of disproportionation reactions. Potential mechanisms are presented to account for the products seen.     

Estimates of Ground Level TSP,S02 and HCI for a Municipal Waste Incinerator to be Located at Tynes Bay—Bermuda

The computer model Industrial Source Complex Short Term (ISCST) was used to study the stack emissions from a refuse Incinerator proposed for the island of Bermuda. The model predicts that the highest ground level pollutant concentrations will occur near Prospect, 800 m to 1000 m due south of the stack. We installed a portable laboratory and instruments at Prospect to begin making air quality baseline measurements. By comparing the model’s estimates of the incinerator contribution to the background levels measured at the site we predict that stack emissions will not cause an Increase In TSP or SO₂. The incinerator will be a significant source of HCI to Bermuda air with ambient levels approaching air quality guidelines.     

The social viability and environmental sustainability of direct action land reform settlements in the Amazon

State-led agrarian reform (SLAR) settlements established in the Amazon in the 1970s led to environmental degradation and mixed socioeconomic outcomes. More recently, direct-action land reform (DALR) settlements have proliferated, which are leading to new forest clearing in the name of agrarian reform. The emergence of DALR begs questions about social and environmental outcomes in recent Amazon settlements. This paper compares DALR settlements in two different regions of the eastern Amazon: the South of Pará and the Transamazon. Analysis of household survey data shows that DALR settlements in the two study areas differ substantially in terms of their histories of formation and regional contexts. However, social and environmental outcomes do not always differ among the two study areas, which in turn resemble older SLAR settlements.     

Identifying management opportunities to combat climate,land, and marine threats across less climate exposed coral reefs

Conserving coral reefs is critical for maintaining marine biodiversity, protecting coastlines, and supporting livelihoods in many coastal communities. Climate change threatens coral reefs globally, but researchers have identified a portfolio of coral reefs (bioclimatic units [BCUs]) that are relatively less exposed to climate impacts and strongly connected to other coral reef systems. These reefs provide a proactive opportunity to secure a long-term future for coral reefs under climate change. To help guide local management efforts, we quantified marine cumulative human impact (CHI) from climate, marine, and land pressures (2013 and from 2008 to 2013) in BCUs and across countries tasked with BCU management. Additionally, we created a management index based on common management measures and policies for each pressure source (climate, marine, and land) to identify a country's intent and commitment to effectively manage these pressures. Twenty-two countries (79%) had increases in CHI from 2008 to 2013. Climate change pressures had the highest proportional contribution to CHI across all reefs and in all but one country (Singapore), but 18 BCUs (35%) and nine countries containing BCUs (32%) had relatively high land and marine impacts. There was a significant positive relationship between climate impact and the climate management index across countries (R² = 0.43, p = 0.02), potentially signifying that countries with greater climate impacts are more committed to managing them. However, this trend was driven by climate management intent in Fiji and Bangladesh. Our results can be used to guide future fine-scale analyses, national policies, and local management decisions, and our management indices reveal areas where management components can be improved. Cost-effectively managing local pressures (e.g., fishing and nutrients) in BCUs is essential for building a climate-ready future that benefits coral reefs and people.     

Male genital morphology influences paternity success in the millipede <Emphasis Type="Italic">Antichiropus variabilis</Emphasis>

The genitalia of internally fertilizing animals are among the most diverse of all sexual characters. It is currently argued that genitalia evolve rapidly and divergently due to intense post-copulatory sexual selection. If true, male genital morphology should be subject to directional selection, whereby males with particular genital morphologies achieve greater paternity success. There is mounting evidence that male genital morphology can influence competitive fertilization success; however, the form of selection acting on genitalia has rarely been explored. We conducted competitive fertilization experiments using Antichiropus variabilis millipedes. Using microsatellite loci, we determined the paternity of offspring following double matings. The last male to mate had a significant paternity advantage. While no aspect of the behavior of last males was correlated with paternity success, variation in genital morphology did account for variation in last male paternity. Male genitalia were subject to nonlinear selection, with both convex (stabilizing) selection and concave (disruptive) selection acting on genital shape. This is the first study to provide evidence for sperm precedence in a millipede and only the second to document the form of post-copulatory sexual selection operating on male genital morphology. We discuss the implications of our results for the evolution of genitalia in A. variabilis and, more broadly, how our findings relate to alternative theories of genital evolution.     

Brood-provisioning strategies in Dawson's burrowing bee, Amegilla dawsoni (Hymenoptera: Anthophorini)

Males of Dawson's burrowing bee are dimorphic in size. Although large (major) males defeat smaller ones in competition for emerging females and therefore are more likely to mate, majors are greatly outnumbered by half-sized (minor) males. Nesting females might produce many minor males, despite their low reproductive value, because female behaviour is governed by a mixed evolutionarily stable strategy (ESS), in which case the ratio of majors to minors should not be affected by changes in female condition. In contrast, a conditional-strategy hypothesis predicts that older, wing-worn or stressed females unable to forage efficiently should be especially likely to produce minor offspring, which require less brood provisions. To test these alternative hypotheses, we manipulated the condition of nesting female bees by the addition of weights and the removal of their wing margins. These manipulations, done early in the flight season, failed to increase the production of minor males, a result consistent with the mixed-ESS hypothesis. However, unmanipulated females were far more likely to produce minor males if they were small or if they were nesting late in the season, when foraging conditions had deteriorated, findings that are consistent with a conditional provisioning strategy. Thus it appears that the abundance of minor males is the result of a conditional provisioning strategy of nesting females, which may be superimposed on a fixed tendency to produce large offspring early in the season and small ones later.     

The challenge of biased evidence in conservation

Efforts to tackle the current biodiversity crisis need to be as efficient and effective as possible given chronic underfunding. To inform decision-makers of the most effective conservation actions, it is important to identify biases and gaps in the conservation literature to prioritize future evidence generation. We used the Conservation Evidence database to assess the state of the global literature that tests conservation actions for amphibians and birds. For the studies in the database, we investigated their spatial and taxonomic extent and distribution across biomes, effectiveness metrics, and study designs. Studies were heavily concentrated in Western Europe and North America for birds and particularly for amphibians, and temperate forest and grassland biomes were highly represented relative to their percentage of land coverage. Studies that used the most reliable study designs—before-after control-impact and randomized controlled trials—were the most geographically restricted and scarce in the evidence base. There were negative spatial relationships between the numbers of studies and the numbers of threatened and data-deficient species worldwide. Taxonomic biases and gaps were apparent for amphibians and birds—some entire orders were absent from the evidence base—whereas others were poorly represented relative to the proportion of threatened species they contained. Metrics used to evaluate effectiveness of conservation actions were often inconsistent between studies, potentially making them less directly comparable and evidence synthesis more difficult. Testing conservation actions on threatened species outside Western Europe, North America, and Australasia should be prioritized. Standardizing metrics and improving the rigor of study designs used to test conservation actions would also improve the quality of the evidence base for synthesis and decision-making.