When should we save the most endangered species?

At the heart of our efforts to protect threatened species, there is a controversial debate about whether to give priority to cost-effective actions or whether focusing solely on the most endangered species will ultimately lead to preservation of the greatest number of species. By framing this debate within a decision-analytic framework, we show that allocating resources solely to the most endangered species will typically not minimise the number of extinctions in the long-term, as this does not account for the risk of less endangered species going extinct in the future. It is only favoured when our planning timeframe is short or we have a long-term view and we are optimistic about future conditions. Conservation funding tends to be short-term in nature, which biases allocations to more endangered species. Our work highlights the need to consider resource allocation for biodiversity over the long-term; 'preventive conservation', rather than just short-term fire-fighting.     

When does selective hunting select,how can we tell,and what should we do about it?

Potential evolutionary consequences of selective hunting of mammals are controversial because of limited evidence and important socio‐economic impacts. Several ecological and management variables facilitate evolutionary responses to selection for horn, tusk or antler size, including strong selective hunting pressure; harvest of males with large horns, tusks or antlers before they can breed; unavailable or ineffective sources of unselected immigrants; and age‐dependent relationships between horn, tusk or antler size and male mating success. Plastic responses of male horns, tusks and antlers to environment are probably more common than evolutionary changes. Evidence for evolutionary effects of selective hunting is strong for large mammals where biological characteristics and hunting regulations combine to favour them.     

Estimating bird species richness: How should repeat surveys be organized in time?

Abstract Estimates of species richness for a given area require that repeat surveys be taken, so that the statistical robustness of the estimate can be assessed. But how should these repeat surveys be organized in time? Here we present a case study of Australian woodland birds, surveyed using the ‘active timed area search’ method, which has become the standard unit for the Australian Bird Atlas, a continental‐scale bird survey. To date, there has been no assessment of how estimates of species richness derived from this method are affected by the temporal organization of the repeat surveys. For instance, can conducting the repeat surveys in sequence on the same day effectively capture richness, or will additional species be obtained by repeating the surveys on different days within a season? If so, does the spacing of the repeat visits throughout the season have an effect? To answer these questions, we surveyed woodland birds in the Mount Lofty Ranges, South Australia, during late spring–summer 1999–2000, and compared the performance of two different temporal configurations of repeat visits to sites: (i) six repeat surveys performed on the same day; and (ii) three repeat surveys on different days. For both, we calculated the average number of species actually sighted and also estimated total species richness. The data supported our hypothesis that the same‐day surveys would yield fewer species and underestimate total species richness. The different‐day repeats captured significantly more species per unit of survey effort, and yielded a higher richness estimate. However, the timespan over which different‐day surveys were conducted within a season did not have a significant influence on species richness estimates, evincing a qualitative advantage to surveying on different days, regardless of the spacing of repeat visits. These results may be of assistance to conservation managers when planning cost‐efficient monitoring regimes.     

When do localized natural enemies increase species richness?

The Janzen–Connell hypothesis states that local species‐specific density dependence, mediated through specialist enemies of offspring such as fungal pathogens and insect seed predators, can facilitate coexistence of species by preventing recruitment near conspecific adults. We use spatially explicit simulation models and analytical approximations to evaluate how spatial scales of offspring and enemy dispersal affect species richness. In comparison with model communities in which both offspring and enemies disperse long distances, species richness is substantially decreased when offspring disperse long distances and enemies disperse short distances. In contrast, when both offspring and enemies disperse short distances species richness more than doubles and adults of each species are highly spatially clumped. For the range of conditions typical of tropical forests, locally dispersing specialist enemies may decrease species richness relative to enemies that disperse long distances. In communities where dispersal distances of both offspring and enemies are short, local effects may enhance species richness.     

Detecting climate change induced range shifts: Where and how should we be looking?

Abstract: Global climate warming is expected to cause systematic shifts in the distribution of species and consequently increase extinction risk. Conservation managers must be able to detect, measure and accurately predict range shifts in order to mitigate impacts on biodiversity. However, important responses to climate change may go unnoticed or be dismissed if we fail to collect sufficient baseline data and apply the most sensitive analytical tests. Here we use randomizations of a contemporary data set on rainforest birds of north‐eastern Australia to quantify the sensitivity of three measures for assessing range shifts along altitudinal gradients. We find that smaller range shifts are detectable by analysing change in the mean altitude of presence records rather than upper or lower range boundaries. For a moderate survey effort of 96 surveys, measurements of change in the mean altitude of 34 species have the capacity to provide strong inference for a mean altitudinal range shift as small as 40 m across the species assemblage. We also show that range shifts measured at range boundaries can be potentially misleading when differences in sampling effort between contemporary and historical data sets are not taken into account.     

Overyielding and species diversity: what should we expect?

Recent empirical studies have found evidence of increased biomass production ('overyielding') in species mixtures relative to monoculture, but the interpretation of these results remains controversial, in part, because of the lack of a theoretical expectation. Here, we examined the expected frequency and stability of overyielding species mixtures using Lotka-Volterra models of species dynamics in two- and four-species systems in conjunction with community, population, and specific rate of biomass production (SRP) definitions of overyielding. Overyielding plant mixtures represented > 55% of potential species assemblages under community definitions and approximately 100% of species were either overyielding or underyielding under the population definition. Our species simulations approached their equilibria in 1-2 yr, supporting the relevancy of an equilibrial analysis. The range of parameter space that we explored produced realistic values of plot biomass, supporting their biological relevance. We show that overyielding is expected to be common under community definitions and population definitions. Overyielding, under community or population definitions, does not imply an actual increase in the specific rate of biomass production. In addition, assemblages of overyielding and underyielding species under all three definitions can be stable over time with underyielding species persisting in the presence of overyielding species.     

What is speciation and how should we study it?

To understand speciation, we first need to know what species are. Yet debates over species concepts have seemed endless, with little obvious relevance to the study of speciation. Recently, there has been progress in resolving these debates, favoring a lineage-based, evolutionary species concept. This progress calls for reconsideration of the study of speciation. Traditional speciation research based on the biological species concept has led to great advances in understanding how nonallopatric speciation occurs and how species diverge and remain separate from each other. However, this research has neglected the question of how new species arise in the first place for the most common geographic mode (allopatric). A new and very different research program is needed to understand the ecological and evolutionary processes that split an ancestral species into new allopatric lineages. This research program will connect speciation to many other fundamental questions in evolutionary biology, ecology, biogeography, and conservation biology.     

Nonhost resistance: how much do we know?

Nonhost disease resistance is the most common form of disease resistance exhibited by plants against the majority of potentially pathogenic microorganisms. Recently, several components of nonhost disease resistance have been identified. Nonhost resistance exhibited against bacteria, fungi and oomycetes can be of two types. Type I nonhost resistance does not produce any visible symptoms whereas type II nonhost resistance results in a rapid hypersensitive response with cell death. Strong similarities exist between nonhost and gene-for-gene resistance responses but it is still not clear if the same mechanism is involved in producing these resistance responses.     

Analytical quality--what should we be aiming for?

ISO 15189 5.5.1 "The laboratory shall use examination procedures, ... which meet the needs of the users of laboratory services and are appropriate for the examinations. Requirements for analytical quality include: understanding the analytical goal; seeking an assay that fulfills those goals; establishing your own performance with that assay; setting warning and action limits for your assay; applying quality control tools to every important step.     

Community genetics: what have we accomplished and where should we be going?

Research in community genetics seeks to understand how the dynamic interplay between ecology and evolution shapes simple and complex communities and ecosystems. A community genetics perspective, however, may not be necessary or informative for all studies and systems. To better understand when and how intraspecific genetic variation and microevolution are important in community and ecosystem ecology, we suggest future research should focus on three areas: (i) determining the relative importance of intraspecific genetic variation compared with other ecological factors in mediating community and ecosystem properties; (ii) understanding the importance of microevolution in shaping ecological dynamics in multi-trophic communities; and (iii) deciphering the phenotypic and associated genetic mechanisms that drive community and ecosystem processes. Here, we identify key areas of research that will increase our understanding of the ecology and evolution of complex communities but that are currently missing in community genetics. We then suggest experiments designed to meet these current gaps.     

Investigating physiological changes in the aerial parts of AM plants: what do we know and where should we be heading?

Research in the field of arbuscular mycorrhizal (AM) symbiosis has taken a giant leap in the past two decades, as demonstrated by the large amount of literature being published every year. Most of the research efforts have been put towards the understanding of the mechanisms of this symbiosis. However, there are still several unknowns on the systemic effects of the AM symbiosis, and our understanding of non-nutritional effects on the physiological changes occurring in the aerial parts of the host plant is yet quite limited. In this short note, I briefly address the question, if there are any changes in metabolic activities that are triggered by AM fungi, and assess the importance of such changes for mycorrhizal research and application.