When are genetic methods useful for estimating contemporary abundance and detecting population trends?

The utility of microsatellite markers for inferring population size and trend has not been rigorously examined, even though these markers are commonly used to monitor the demography of natural populations. We assessed the ability of a linkage disequilibrium estimator of effective population size (Ne) and a simple capture-recapture estimator of abundance (N) to quantify the size and trend of stable or declining populations (true N = 100–10,000), using simulated Wright–Fisher populations. Neither method accurately or precisely estimated abundance at sample sizes of S = 30 individuals, regardless of true N. However, if larger samples of S = 60 or 120 individuals were collected, these methods provided useful insights into abundance and trends for populations of N = 100–500. At small population sizes (N = 100 or 250), precision of the Ne estimates was improved slightly more by a doubling of loci sampled than by a doubling of individuals sampled. In general, monitoring Ne proved a more robust means of identifying stable and declining populations than monitoring N over most of the parameter space we explored, and performance of the Ne estimator is further enhanced if the Ne ⁄N ratio is low. However, at the largest population size (N = 10,000), N estimation outperformed Ne. Both methods generally required ≥ 5 generations to pass between sampling events to correctly identify population trend

Neglect of Genetic Diversity in Implementation of the Convention on Biological Diversity

Genetic diversity is the foundation for all biological diversity; the persistence and evolutionary potential of species depend on it. World leaders have agreed on the conservation of genetic diversity as an explicit goal of the Convention on Biological Diversity (CBD). Nevertheless, actions to protect genetic diversity are largely lacking. With only months left to the 2010-biodiversity target, when the 191 parties to the CBD have agreed on achieving a significant reduction of the rate of biodiversity loss, gene-level diversity is still not being monitored, and indicators and thresholds that can be used to devise strategies to conserve this important component of biodiversity are missing. Immediate action is needed to ensure that genetic diversity is not neglected in conservation targets beyond 2010. The risks associated with depletion of genetic diversity were recognized in classic publications 4 decades ago (Frankel 1970, 1974), and this message has been repeatedly stressed ever since (e.g., Schonewald-Cox 1983; Ryman & Utter 1987; Frankham 1995; Allendorf & Ryman 2002; Hughes et al. 2008). In that time, a body of theory (Lynch & Lande 1993; Lande 1995; Lynch et al. 1995) and empirical work has emerged that demonstrates how populations and even species can collapse due to loss of genetic diversity (e.g., Newman & Pilson 1997; Briskie & Mackintosh 2004; Frankham 2005). Evidence supporting the importance of maintaining genetic variation to sustain species and ecosystems continues to accumulate (Wimp et al. 2004; Crutsinger et al. 2006; Whitham et al. 2006). Gene-level biodiversity is recognized in the CBD (www.cbd.int) as one of three levels of diversity— ecosystems, species, and genes—that are to be conserved and sustainably used. Since its adoption in 1992, this convention has become the most important international political instrument for halting biodiversity loss. At present, 192 nations are parties to the CBD, representing every nation in the world except for Andorra, the Holy See (the Vatican), Somalia (party from mid December 2009), and the United States. Integral to the CBD is the task of “monitor[ing], through sampling and other techniques, the components of biological diversity” to “identify processes and categories of activities which have or are likely to have significant adverse impacts on the conservation and sustainable use of biological diversity, and monitor their effects.” In 2002 parties to the CBD committed themselves to reduce significantly by 2010 the current rates of biodiversity loss at global, regional, and national levels as a “contribution to poverty alleviation and to the benefit of all life on Earth.” This 2010 biodiversity target was subsequently endorsed by the World Summit on Sustainable Development and the United Nations General Assembly and incorporated as a new target under the UN Millennium Development Goals (http://www.un.org/millenniumgoals/). To evaluate progress toward the 2010 biodiversity target for genetic variation it is necessary to assess and monitor this critical level of diversity. The CBD is not a mandatory instrument; it is the responsibility of each country to develop and implement a National Biodiversity Strategy and Action Plan (NBSAP). To assess the extent to which genetic diversity is currently recognized in national biodiversity policy programs, we used information available at the convention’s website to review NBSAPs of a subset of countries party to the CBD (http://www.cbd.int; subheading: Countries; assessed January–March 2009). Our aim was to investigate whether individual parties state in their strategies and action plans that genetic variation of wild animals and plants is to be conserved in their country and whether they explicitly recognize the need for developing monitoring programs for this diversity. For our analysis we selected every 10th country ranked according to its gross national product (GNP; http:// www.studentsoftheworld.info/infopays/rank/PN B2.html). If a country was not part of the CBD or not a sovereign nation, or if a document was missing, not searchable, or not in English, we chose the next country on the list. We reviewed 24 NBSAPs. Of these, 67% (16 countries) state that genetic variation should be conserved. Nevertheless, 38% (six) of these plans focus only on the genetic diversity of domesticated populations compared with 62% (10) that also recognize the genetic diversity of wild animals and plants as a conservation concern. Although most (90%; 21 countries) of the reviewed NBSAPs state that monitoring of biodiversity should be carried out, only 21% (five) explicitly acknowledge the need for developing means for monitoring diversity at the genetic level. These five countries all grouped in the upper 20% of the GNP ranking (i.e., larger countries with strong economic performance). In contrast, countries sharing the general goal of conserving genetic diversity represent the full spectrum of GNP ranks

Lithic raw material units based on magnetic properties: A blind test with Armenian obsidian and application to the Middle Palaeolithic site of Lusakert Cave 1

Classification of lithic artifacts’ raw materials based on macroscopic attributes (e.g., color, luster, texture) has been used to pull apart knapping episodes in palimpsest assemblages by attempting to identify artifacts produced through the reduction of an individual nodule. These classes are termed “raw material units” (RMUs) in the Old World and “minimum analytical nodules” in the New World. RMUs are most readily defined for lithic artifacts in areas with distinctive cherts and other siliceous raw materials, allowing pieces from different nodules to be recognized visually. Opportunities to apply RMUs, however, are strongly limited at sites where lithic material visual diversity is low. The magnetic properties of obsidian, which result from the presence of microscopic iron oxide mineral grains, vary spatially throughout a flow. Consequently, obsidian from different portions of a source (i.e., different outcrops or quarries) can vary in magnetic properties. This raises the possibility that magnetic-based RMUs (mRMUs) for obsidian artifacts could be effective to distinguish individual scatters from multiple production episodes and offer insights into spatial patterning within a site or specific occupation periods. First, we assess the potential of mRMUs using obsidian pebbles from Gutansar volcano in Armenia. Second, we evaluate the validity of this approach based on a double-blind test involving an experimental assemblage of Gutansar obsidian flakes. Cluster analysis can successfully discern flakes from obsidian specimens containing high concentrations of iron oxides. Obsidian with more magnetic material has more opportunities for that material to vary in unique ways (e.g., grain size, morphology, physical arrangement). Finally, we apply the mRMU approach to obsidian artifacts from the Middle Palaeolithic site of Lusakert Cave 1 in Armenia and compare the results to traditional RMU studies at contemporaneous sites in Europe. In particular, we seek – but do not find – differences between retouch flakes (which re