Statistical Confusion Among Graduate Students: Sickness or Symptom?

Abstract: Statistics is one of the most important yet difficult subjects for many ecology and wildlife graduate students to learn. Insufficient knowledge about how to conduct quality science and the ongoing debate about the relative value of competing statistical ideologies contribute to uncertainties among graduate students regarding which statistical tests are most appropriate. Herein, we argue that increased education of the available statistical tests alone is unlikely to ameliorate the problem. Instead, we suggest that statistical uncertainties among graduate students are a secondary symptom of a larger problem. We believe the root cause lies in the lack of education on how to conduct science as an integrated process from hypothesis creation through statistical analysis. We argue that if students are taught to think about how each step of the process will affect all other steps, many statistical uncertainties will be avoided.     

Loss and Recovery of Phenotypic Expression of Gross Leukaemia Virus

MEASUREMENTS reported by Klein and Phelps¹ and by Glasel² have been interpreted to cast doubt on the conclusion from previous nuclear magnetic resonance (NMR) studies^3–5 that water in neural and muscle tissue possesses more average structure than liquid water. This communication intends to point out that the data in these two articles provide no basis for such doubt.     

Responses of a beaded Arctic stream to short-term N and P fertilisation

1. Oligotrophic Arctic streams are likely to be sensitive to changes in hydrology and nutrient inputs predicted to occur as a consequence of future climate and land use change. To investigate the potential consequences of nutrient enrichment for low‐order Arctic streams, we added ammonium‐N and phosphorous to a second‐order beaded, tundra stream on Alaska's north slope. We measured responses in nutrient chemistry, chlorophyll a standing crop, and in the breakdown and macroinvertebrate colonisation of leaf litter over a 38‐day summer period. 2. During the addition, nutrient concentrations immediately downstream of the dripper averaged 6.4 μm ammonium‐N and 0.45 μm soluble reactive P. Concentrations upstream of the dripper averaged 0.54 μm ammonium‐N and 0.03 μm soluble reactive P. Uptake of both nutrients was rapid. Concentrations were reduced on average to 28% (ammonium‐N) and 15% (inorganic P) of maximum values within 1500 m. Standing crops of chlorophyll a on standardised samplers were significantly higher by the end of the experiment. Breakdown rates of senescent willow (Salix sp.) and sedge (Carex sp.) litter and associated fungal biomass were also significantly increased by nutrient addition. 3. Fertilisation resulted in four‐ to sevenfold higher macroinvertebrate abundance and two‐ to fourfold higher macroinvertebrate biomass in litter bags, as well as an increase in late‐summer body mass of larval Nemoura stoneflies. 4. Our results are consistent with those of similar studies of larger streams in the high‐Arctic region. Based on our short‐term experiment, increased inputs of nutrients into these ecosystems, whether caused by climate change or more local disturbance, are likely to have profound ecological consequences. Longer‐term effects of enrichment, and their interaction with other components of future change in climate or land use, are more difficult to assess.     

Genomic diversity,population structure,and migration following rapid range expansion in the Balsam Poplar,Populus balsamifera

Rapid range expansions can cause pervasive changes in the genetic diversity and structure of populations. The postglacial history of the Balsam Poplar, Populus balsamifera, involved the colonization of most of northern North America, an area largely covered by continental ice sheets during the last glacial maximum. To characterize how this expansion shaped genomic diversity within and among populations, we developed 412 SNP markers that we assayed for a range‐wide sample of 474 individuals sampled from 34 populations. We complemented the SNP data set with DNA sequence data from 11 nuclear loci from 94 individuals, and used coalescent analyses to estimate historical population size, demographic growth, and patterns of migration. Bayesian clustering identified three geographically separated demes found in the Northern, Central, and Eastern portions of the species’ range. These demes varied significantly in nucleotide diversity, the abundance of private polymorphisms, and population substructure. Most measures supported the Central deme as descended from the primary refuge of diversity. Both SNPs and sequence data suggested recent population growth, and coalescent analyses of historical migration suggested a massive expansion from the Centre to the North and East. Collectively, these data demonstrate the strong influence that range expansions exert on genomic diversity, both within local populations and across the range. Our results suggest that an in‐depth knowledge of nucleotide diversity following expansion requires sampling within multiple populations, and highlight the utility of combining insights from different data types in population genomic studies.     

Woven World: Neotraditional Symbols of Unity in Vanuatu

The importance of kastom to national identity in Vanuatu has been recognized. In this paper I identify plaiting technology in general and basketry in particular — which once served to distinguish ethnic groups in Vanuatu — as emerging symbols of ni-Vanuatu unity. I argue that unlike these kastom traditions often discussed in the literature, plaiting and basketry need not be reinvented. Plaiting is a customary practice which has rich contemporaneous expressions. Plaited products may be fully elaborated in local detail and yet, as shared productions of a technology with common features, can simultaneously represent ni-Vanuatu identity.