Walk,swim or fly? Locomotor mode predicts genetic differentiation in vertebrates

Limited dispersal is commonly used to explain differences in diversification rates. An obvious but unexplored factor affecting dispersal is the mode of locomotion used by animals. Whether individuals walk, swim or fly can dictate the type and severity of geographical barriers to dispersal, and determine the general range over which genetic differentiation might occur. We collated information on locomotion mode and genetic differentiation (F_ST) among vertebrate populations from over 400 published articles. Our results showed that vertebrate species that walk tend to have higher genetic differentiation among populations than species that swim or fly. Within species that swim, vertebrates in freshwater systems have higher genetic differentiation than those in marine systems, which is consistent with the higher number of species in freshwater environments. These results show that locomotion mode can impact gene flow among populations, supporting at a broad‐scale what has previously been proposed at smaller taxonomical scales.     

Is it the athlete or the equipment? An analysis of the top swim performances from 1990 to 2010

O'Connor, LM and Vozenilek, JA. Is it the athlete or the equipment? An analysis of the top swim performances from 1990 to 2010. J Strength Cond Res 25(12): 3239-3241, 2011-Forty-three world record swims were recorded at the 2009 Fédération Internationale de Natation (FINA) World Championship meet in Rome. Of the 20 FINA recognized long-course (50-m pool) swimming events, men set new world records in 15 of those events, whereas women did the same in 17 events. Each of the men's world records and 14 of the 17 women's records still stand. These performances were unprecedented; never before had these many world records been broken in such a short period of time. There was much speculation that full-body, polyurethane, technical swimsuits were the reason for the conspicuous improvement in world records. Further analysis led the FINA to institute new rules on January 1, 2010, that limited the types of technical swimsuits that could be worn by athletes. No long-course world record has been broken since then. We sought to understand this phenomenon by analyzing publicly available race data and exploring other possible causes including improvements in other sports, improvements in training science, changes in rules and regulations, gender differences, anaerobic vs. aerobic events, unique talent, and membership data.     

Will All Americans Become Overweight or Obese? Estimating the Progression and Cost of the US Obesity Epidemic

We projected future prevalence and BMI distribution based on national survey data (National Health and Nutrition Examination Study) collected between 1970s and 2004. Future obesity-related health-care costs for adults were estimated using projected prevalence, Census population projections, and published national estimates of per capita excess health-care costs of obesity/overweight. The objective was to illustrate potential burden of obesity prevalence and health-care costs of obesity and overweight in the United States that would occur if current trends continue. Overweight and obesity prevalence have increased steadily among all US population groups, but with notable differences between groups in annual increase rates. The increase (percentage points) in obesity and overweight in adults was faster than in children (0.77 vs. 0.46-0.49), and in women than in men (0.91 vs. 0.65). If these trends continue, by 2030, 86.3% adults will be overweight or obese; and 51.1%, obese. Black women (96.9%) and Mexican-American men (91.1%) would be the most affected. By 2048, all American adults would become overweight or obese, while black women will reach that state by 2034. In children, the prevalence of overweight (BMI >/= 95th percentile, 30%) will nearly double by 2030. Total health-care costs attributable to obesity/overweight would double every decade to 860.7-956.9 billion US dollars by 2030, accounting for 16-18% of total US health-care costs. We continue to move away from the Healthy People 2010 objectives. Timely, dramatic, and effective development and implementation of corrective programs/policies are needed to avoid the otherwise inevitable health and societal consequences implied by our projections .     

Is the scaling of swim speed in sharks driven by metabolism?

The movement rates of sharks are intrinsically linked to foraging ecology, predator–prey dynamics and wider ecosystem functioning in marine systems. During ram ventilation, however, shark movement rates are linked not only to ecological parameters, but also to physiology, as minimum speeds are required to provide sufficient water flow across the gills to maintain metabolism. We develop a geometric model predicting a positive scaling relationship between swim speeds in relation to body size and ultimately shark metabolism, taking into account estimates for the scaling of gill dimensions. Empirical data from 64 studies (26 species) were compiled to test our model while controlling for the influence of phylogenetic similarity between related species. Our model predictions were found to closely resemble the observed relationships from tracked sharks, providing a means to infer mobility in particularly intractable species.     

Estimating mutation rate: how to count mutations?

Mutation rate is an essential parameter in genetic research. Counting the number of mutant individuals provides information for a direct estimate of mutation rate. However, mutant individuals in the same family can share the same mutations due to premeiotic mutation events, so that the number of mutant individuals can be significantly larger than the number of mutation events observed. Since mutation rate is more closely related to the number of mutation events, whether one should count only independent mutation events or the number of mutants remains controversial. We show in this article that counting mutant individuals is a correct approach for estimating mutation rate, while counting only mutation events will result in underestimation. We also derived the variance of the mutation-rate estimate, which allows us to examine a number of important issues about the design of such experiments. The general strategy of such an experiment should be to sample as many families as possible and not to sample much more offspring per family than the reciprocal of the pairwise correlation coefficient within each family. To obtain a reasonably accurate estimate of mutation rate, the number of sampled families needs to be in the same or higher order of magnitude as the reciprocal of the mutation rate.     

Isolated remnant or recent introduction? Estimating the provenance of Yellingbo Leadbeater's possums by genetic analysis and bottleneck simulation

Effective conservation management requires that genetically divergent populations potentially harbouring important local adaptations be identified and maintained as separate management units. In the case of the endangered Australian Leadbeater's possum (Gymnobelideus leadbeateri), an arboreal marsupial endemic to Victoria, uncertainty over the evolutionary origin of a potentially important extant wild population recently discovered in atypical habitat (lowland swamp) at Yellingbo is hampering such efforts. The population is rumoured to be a recent introduction. Microsatellite allele frequencies at Yellingbo differed substantially from those in sampled populations in montane ash forest (F_ST between 0.23 and 0.36), and Bayesian clustering analyses of genotypes strongly separated them (K = 2). We conducted a suite of bottlenecking tests which all indicated that Yellingbo had undergone a recent reduction in size. The extent to which the distinctiveness of Yellingbo animals might be expected solely through bottlenecking associated with a recent introduction, was tested by simulating population–history scenarios seeded with genotypes from candidate wild and captive sources. No bottleneck scenario reproduced anything approaching the genetic distinction of the Yellingbo population, with all structure analyses placing Yellingbo in a separate cluster to simulated populations (K = 2, minimum F_ST = 0.13). These results suggest that Yellingbo does not share recent ancestry with other extant populations and instead may be a remnant of an otherwise extinct gene pool. Importantly, this may include genes involved in adaptation to a lowland swamp environment, substantially adding to the conservation importance of this population, and suggesting that separate management may be prudent until evidence suggests otherwise.     

6 or 9?

In this article the author offers an original interpretation of patterns found on the world's most ancient felts (Fifth Century BCE). These artifacts have been recovered from frozen burial mounds in the Altai Mountains. The interpretation presented here constitutes a new approach to the study of ornamentation as a system of symbols.     

Heterosis or Neutrality?

Various statistics have been proposed on an ad hoc basis to test whether alleles at a locus are selectively neutral. By considering population models in which selection operates, this paper shows that the population homozygosity is a powerful test statistic for testing departures from neutrality, in the direction of heterozygote advantage or disadvantage. The sample homozygosity plays a similar role when only sample data are available. Some numerical examples are included, showing the application of the test.—An analysis is made of the effect of heterosis on such quantities as the expected number of alleles in the population or sample, the effective number of alleles, the expected homozygosity, and on the population and sample allele frequency distributions generally.     

Lost or forgotten?

Bonobo, the Forgotten Ape by F. de Waal University of California Press, 1997. ￡39.95 hbk (210 pages) ISBN 0 520 20535 9.