Strategies to protect biological diversity and the evolutionary processes that sustain it

Conservation planning has tended to focus more on pattern (representation) than process (persistence) and, for the former, has emphasized species and ecosystem or community diversity over genetic diversity. Here I consider how best to incorporate knowledge of evolutionary processes and the distribution of genetic diversity into conservation planning and priority setting for populations within species and for biogeographic areas within regions. Separation of genetic diversity into two dimensions, one concerned with adaptive variation and the other with neutral divergence caused by isolation, highlights different evolutionary processes and suggests alternative strategies for conservation. Planning for both species and areas should emphasize protection of historically isolated lineages (Evolutionarily Significant Units) because these cannot be recovered. By contrast, adaptive features may best be protected by maintaining the context for selection, heterogeneous landscapes, and viable populations, rather than protecting specific phenotypes. A useful strategy may be to (1) identify areas that are important to represent species and (vicariant) genetic diversity and (2) maximize within these areas the protection of contiguous environmental gradients across which selection and migration can interact to maintain population viability and (adaptive) genetic diversity. These concepts are illustrated with recent results from analysis of a rainforest fauna from northeast Australia.     

Two distinct visual motion mechanisms for smooth pursuit: evidence from individual differences

Smooth-pursuit eye velocity to a moving target is more accurate after an initial catch-up saccade than before, an enhancement that is poorly understood. We present an individual-differences-based method for identifying mechanisms underlying a physiological response and use it to test whether visual motion signals driving pursuit differ pre- and postsaccade. Correlating moment-to-moment measurements of pursuit over time with two psychophysical measures of speed estimation during fixation, we find two independent associations across individuals. Presaccadic pursuit acceleration is predicted by the precision of low-level (motion-energy-based) speed estimation, and postsaccadic pursuit precision is predicted by the precision of high-level (position-tracking) speed estimation. These results provide evidence that a low-level motion signal influences presaccadic acceleration and an independent high-level motion signal influences postsaccadic precision, thus presenting a plausible mechanism for postsaccadic enhancement of pursuit.     

Terminal investment: individual reproduction of ant queens increases with age

The pattern of age-specific fecundity is a key component of the life history of organisms and shapes their ecology and evolution. In numerous animals, including humans, reproductive performance decreases with age. Here, we demonstrate that some social insect queens exhibit the opposite pattern. Egg laying rates of Cardiocondyla obscurior ant queens increased with age until death, even when the number of workers caring for them was kept constant. Cardiocondyla, and probably also other ants, therefore resemble the few select organisms with similar age-specific reproductive investment, such as corals, sturgeons, or box turtles (e.g., [1]), but they differ in being more short-lived and lacking individual, though not social, indeterminate growth. Furthermore, in contrast to most other organisms, in which average life span declines with increasing reproductive effort, queens with high egg laying rates survived as long as less fecund queens.     

Visual pursuit: an instructive area of cortex

Recent experiments have revealed an area of visual cortex that provides a velocity error signal which enables the eye to learn to pursue targets when they move in a predictable way.     

genhet: an easy-to-use R function to estimate individual heterozygosity

genhet is an R function which calculates the five most used estimates of individual heterozygosity. The advantage of this program is that it can be applied to any diploid genotype dataset, without any limitation in the number of individuals, loci or alleles. Its detailed manual should allow people who have never used R before to make the function work quite easily. The program is freely available at http://www.aureliecoulon.net/research/ac-computer-programs.html.     

Energy dissipation is an essential mechanism to sustain the viability of plants: The physiological limits of improved photosynthesis

In bright sunlight photosynthetic activity is limited by the enzymatic machinery of carbon dioxide assimilation. This supererogation of energy can be easily visualized by the significant increases of photosynthetic activity under high CO₂ conditions or other metabolic strategies which can increase the carbon flux from CO₂ to metabolic pools. However, even under optimal CO₂ conditions plants will provide much more NADPH + H⁺ and ATP that are required for the actual demand, yielding in a metabolic situation, in which no reducible NADP⁺ would be available. As a consequence, excited chlorophylls can activate oxygen to its singlet state or the photosynthetic electrons can be transferred to oxygen, producing highly active oxygen species such as the superoxide anion, hydroxyl radicals and hydrogen peroxide. All of them can initiate radical chain reactions which degrade proteins, pigments, lipids and nucleotides. Therefore, the plants have developed protection and repair mechanism to prevent photodamage and to maintain the physiological integrity of metabolic apparatus. The first protection wall is regulatory energy dissipation on the level of the photosynthetic primary reactions by the so-called non-photochemical quenching. This dissipative pathway is under the control of the proton gradient generated by the electron flow and the xanthophyll cycle. A second protection mechanism is the effective re-oxidation of the reduction equivalents by so-called “alternative electron cycling” which includes the water-water cycle, the photorespiration, the malate valve and the action of antioxidants. The third system of defence is the repair of damaged components. Therefore, plants do not suffer from energy shortage, but instead they have to invest in proteins and cellular components which protect the plants from potential damage by the supererogation of energy. Under this premise, our understanding and evaluation for certain energy dissipating processes such as non-photochemical quenching or photorespiration appear in a quite new perspective, especially when discussing strategies to improve the solar energy conversion into plant biomass.     

Post-intervention epidemiology of STH in Bangladesh: Data to sustain the gains

In 2008, Bangladesh initiated Preventive Chemotherapy (PCT) for school-age children (SAC) through bi-annual school-based mass drug administration (MDA) to control Soil-Transmitted Helminth (STH) infections. In 2016, the Ministry of Health and Family Welfare’s Program on Lymphatic Filariasis Elimination and STH (ELFSTH) initiated district-level community impact assessments with Children Without Worms (CWW) using standardized, population-based sampling to measure the post-intervention STH burden across all ages (≥ 1 yr) for the three STH species. The Integrated Community-based Survey for Program Monitoring (ICSPM) was developed by CWW and was used to survey 12 districts in Bangladesh from 2017–2020. We excluded the first two district data as piloting caused some sampling errors and combined the individual demographic and parasite-specific characteristics from the subsequent 10 districts, linking them with the laboratory data for collective analysis. Our analysis identified district-specific epidemiologic findings, important for program decisions. Of the 17,874 enrolled individuals, our results are based on 10,824 (61.0%) stool samples. Overall, the prevalence of any STH species was substantially reduced to 14% from 79.8% in 2005. The impact was similar across all ages. STH prevalence was 14% in 10 districts collectively, but remained high in four districts, despite their high reported PCT coverage in previous years. Among all, Bhola district was unique because it was the only district with high T.trichuris prevalence. Bangladesh successfully lowered STH prevalence across all ages despite targeting SAC only. Data from the survey indicate a significant number of adults and pre-school age children (PSAC) were self-deworming with purchased pills. This may account for the flat impact curve across all ages. Overall prevalence varied across surveyed districts, with persistent high transmission in the northeastern districts and a district in the central flood zone, indicating possible service and ecological factors. Discrepancies in the impact between districts highlight the need for district-level data to evaluate program implementation after consistent high PCT coverage.     

Milk sharing: from private practice to public pursuit

After only six months, a commerce-free internet-based milk-sharing model is operating in nearly 50 countries, connecting mothers who are able to donate breast milk with the caregivers of babies who need breast milk. Some public health authorities have condemned this initiative out of hand. Although women have always shared their milk, in many settings infant formula has become the "obvious" alternative to a mother's own milk. Yet an internationally endorsed recommendation supports mother-to-mother milk sharing as the best option in place of a birth mother's milk. Why then this rejection? Several possibilities come to mind: 1) ignorance and prejudice surrounding shared breast milk; 2) a perceived challenge to the medical establishment of a system where mothers exercise independent control; and 3) concern that mother-to-mother milk sharing threatens donor milk banks. We are not saying that milk sharing is risk-free or that the internet is an ideal platform for promoting it. Rather, we are encouraging health authorities to examine this initiative closely, determine what is happening, and provide resources to make mother-to-mother milk sharing as safe as possible. Health authorities readily concede that life is fraught with risk; accordingly, they promote risk-reduction and harm-minimisation strategies. Why should it be any different for babies lacking their own mothers' milk? The more that is known about the risks of substituting for breast milk, the more reasonable parental choice to use donor milk becomes. We believe that the level of intrinsic risk is manageable through informed sharing. If undertaken, managed and evaluated appropriately, this made-by-mothers model shows considerable potential for expanding the world's supply of human milk and improving the health of children.     

Differential investment and costs during avian incubation determined by individual quality: an experimental study of the common eider (Somateria mollissima)

Individuals of different quality may have different investment strategies, shaping responses to experimental manipulations, thereby rendering the detection of such patterns difficult. However, previous clutch-size manipulation studies have infrequently incorporated individual differences in quality. To examine costs of incubation and reproductive investment in relation to changes in clutch size, we enlarged and reduced natural clutch sizes of four and five eggs by one egg early in the incubation period in female common eiders (Somateria mollissima), a sea duck with an anorectic incubation period. Females that had produced four eggs (lower quality) responded to clutch reductions by deserting the nest more frequently but did not increase incubation effort in response to clutch enlargement, at the cost of reduced hatch success of eggs. Among birds with an original clutch size of five (higher quality), reducing and enlarging clutch size reduced and increased relative body mass loss respectively without affecting hatch success. In common eiders many females abandon their own ducklings to the care of other females. Enlarging five-egg clutches led to increased brood care rate despite the higher effort spent incubating these clutches, indicating that the higher fitness value of a large brood is increasing adult brood investment. This study shows that the ability to respond to clutch-size manipulations depends on original clutch size, reflecting differences in female quality. Females of low quality were reluctant to increase investment at the cost of lower hatch success, whereas females of higher quality apparently have a larger capacity both to increase incubation effort and brood care investment.     

Conditioning individual mosquitoes to an odor: sex, source, and time

Olfactory conditioning of mosquitoes may have important implications for vector-pathogen-host dynamics. If mosquitoes learn about specific host attributes associated with pathogen infection, it may help to explain the heterogeneity of biting and disease patterns observed in the field. Sugar-feeding is a requirement for survival in both male and female mosquitoes. It provides a starting point for learning research in mosquitoes that avoids the confounding factors associated with the observer being a potential blood-host and has the capability to address certain areas of close-range mosquito learning behavior that have not previously been described. This study was designed to investigate the ability of the southern house mosquito, Culex quinquefasciatus Say to associate odor with a sugar-meal with emphasis on important experimental considerations of mosquito age (1.2 d old and 3-5 d old), sex (male and female), source (laboratory and wild), and the time between conditioning and testing (<5 min, 1 hr, 2.5 hr, 5 hr, 10 hr, and 24 hr). Mosquitoes were individually conditioned to an odor across these different experimental conditions. Details of the conditioning protocol are presented as well as the use of binary logistic regression to analyze the complex dataset generated from this experimental design. The results suggest that each of the experimental factors may be important in different ways. Both the source of the mosquitoes and sex of the mosquitoes had significant effects on conditioned responses. The largest effect on conditioning was observed in the lack of positive response following conditioning for females aged 3-5 d derived from a long established colony. Overall, this study provides a method for conditioning experiments involving individual mosquitoes at close range and provides for future discussion of the relevance and broader questions that can be asked of olfactory conditioning in mosquitoes.     

Not an innocent pursuit: the politics of a 'Jewish' genetic signature

This commentary questions the presumption in genetic research that a biological connection exists between populations identified as Jewish. The author emphasises that identifying individuals as Jewish based on biological criteria is a sociological process that can draw attention away from other social mechanisms affecting identity construction. She also encourages critical consideration of the possible racialised thinking behind genetic anthropology studies, and the language used to express genetic findings. In conclusion, she calls for a radical cultural shift in the kind of knowledge valued as significant, relevant, and beneficial to the people on whom genetic ancestry studies are carried out and she asks for attention to the political contexts surrounding all such research.     

Sustainable agriculture: how to sustain a production system in a changing environment

During the past 10-15 years, sustainable agriculture has progressed from a focus primarily on a low-input, organic farming approach with a major emphasis on small fruit or vegetable production farms, often described as Low Input Sustainable Agriculture, to the current situation where sustainability is an important part of mainstream animal and plant production units. The US Department of Agriculture programmes cover a broad range of activities, including conserving the natural resource base, enhancing environmental quality, and sustaining productivity of the nation's farms. The use of Geographic Information Systems technology to direct application of fertilisers, pesticides, and herbicides is one example of a rapidly emerging technology that can reduce use of external inputs, protect the agricultural environment, and improve economic returns. This Geographic Information Systems technology also is being used to localise animal pest and disease problems, assist in regulatory or control measures, and identify high risk areas that might need different management systems or should be avoided as sites for animal production. Use of intensive grazing systems also has increased markedly over the past 5-6 years. These systems will allow longer grazing seasons in southern parts of the USA, provide more efficient use of the forages being produced and reduce labour costs in the typical dairy operation. Major animal and plant production agriculture-oriented programmes at the US Department of Agriculture focus on integrated production systems, use of Integrated Pest Management techniques, and development of alternative methods to manage pests and diseases that reduce or avoid the use of drugs and chemicals. The US Department of Agriculture has a programme for sustainable agriculture, the Sustainable Agriculture Research and Education programme, which emphasises alternative approaches for animal and plant production systems.