Obesity and the rate of time preference: is there a connection?

It is hypothesized that recent trends in US and worldwide obesity are, in part, related to an increase in the marginal rate of time preference, where time preference refers to the rate at which people are willing to trade current benefit for future benefit. The higher the rate of time preference, the larger is the factor by which individuals discount the future health risks associated with current consumption. Data from the United States, as well as international evidence, suggest that a relationship between these two variables is plausible. The authors encourage researchers to explore the possible link between obesity and time preference, as important insights are likely to result.     

Physiological variation along a geographical gradient: is growth rate correlated with routine metabolic rate in Rana temporaria tadpoles?

Shorter season length and lower temperature towards higher latitudes and altitudes often select for intraspecific clines in development and growth rates. However, the physiological mechanisms enabling these clines are not well understood. We studied the relationship between routine metabolic rate (RMR) and larval life-history traits along a 1500-km latitudinal gradient across Sweden. In a laboratory common garden experiment, we exposed eight common frog Rana temporaria populations to two experimental temperatures (15 and 18 °C) and measured RMR using flow-through respirometry. We found significant differences among populations in RMR, but there was no evidence for a linear relationship between latitude and RMR in either temperature treatment. However, we found a concave relationship between latitude and RMR at the lower experimental temperature. RMR was not correlated with growth rate at population or at individual levels. The results obtained suggest that, unlike in growth and development rates, there is no latitudinal cline in RMR in R. temporaria tadpoles.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 217–224.     

Partitioning the components of relative growth rate: how important is plant size variation?

Plant growth plays a key role in the functioning of the terrestrial biosphere, and there have been substantial efforts to understand why growth varies among species. To this end, a large number of experimental analyses have been undertaken; however, the emergent patterns between growth rate and its components are often contradictory. We believe that these conflicting results are a consequence of the way growth is measured. Growth is typically characterized by relative growth rate (RGR); however, RGR often declines as organisms get larger, making it difficult to compare species of different sizes. To overcome this problem, we advocate using nonlinear mixed-effects models so that RGR can be calculated at a standard size, and we present easily implemented methods for doing this. We then present new methods for analyzing the traditional components of RGR that explicitly allow for the fact that (log)(RGR) is the sum of its components. These methods provide an exact decomposition of the variance in (log)(RGR). Finally, we use simple analytical and simulation approaches to explore the effect of size variation on growth and its components and show that the relative importance of the components of RGR is influenced by the extent to which analyses standardize for plant size.     

Can the false-discovery rate be misleading?

The decoy-database approach is currently the gold standard for assessing the confidence of identifications in shotgun proteomic experiments. Here, we demonstrate that what might appear to be a good result under the decoy-database approach for a given false-discovery rate could be, in fact, the product of overfitting. This problem has been overlooked until now and could lead to obtaining boosted identification numbers whose reliability does not correspond to the expected false-discovery rate. To overcome this, we are introducing a modified version of the method, termed a semi-labeled decoy approach, which enables the statistical determination of an overfitted result.     

What is parallelism?

Although parallel and convergent evolution are discussed extensively in technical articles and textbooks, their meaning can be overlapping, imprecise, and contradictory. The meaning of parallel evolution in much of the evolutionary literature grapples with two separate hypotheses in relation to phenotype and genotype, but often these two hypotheses have been inferred from only one hypothesis, and a number of subsidiary but problematic criteria, in relation to the phenotype. However, examples of parallel evolution of genetic traits that underpin or are at least associated with convergent phenotypes are now emerging. Four criteria for distinguishing parallelism from convergence are reviewed. All are found to be incompatible with any single proposition of homoplasy. Therefore, all homoplasy is equivalent to a broad view of convergence. Based on this concept, all phenotypic homoplasy can be described as convergence and all genotypic homoplasy as parallelism, which can be viewed as the equivalent concept of convergence for molecular data. Parallel changes of molecular traits may or may not be associated with convergent phenotypes but if so describe homoplasy at two biological levels-genotype and phenotype. Parallelism is not an alternative to convergence, but rather it entails homoplastic genetics that can be associated with and potentially explain, at the molecular level, how convergent phenotypes evolve.     

Variation in courtship rate in the fiddler crab Uca annulipes: is it related to male attractiveness?

We investigated among-male variation in courtship waving inthe fiddler crab Uca annulipes. Wave rate is positively correlatedwith both male carapace size and relative claw size (controlledfor body size), and relative claw size is positively correlatedwith an index of body condition. An experimental reduction inthe availability of food decreased male wave rate. These datasuggest that some of the variation in wave rate among malesis due to variation in male condition combined with energeticcosts to waving (differential costs). However, we also foundthat the correlation between male size and wave rate decreasedover the semilunar cycle. Later in the cycle, smaller malesincrease their wave rate relative to that of larger males. Previouswork has shown that females are more likely to accept a smallermale as a mate later in the cycle. We suggest that smaller malesinvest disproportionately more in courtship later in the cyclebecause the potential benefits are greater due to their increasedattractiveness to females (differential benefits). Alternativeexplanations for the observed temporal trend are also discussed.     

What is emotion?

There is no consensus in the literature on a definition of emotion. The term is taken for granted in itself and, most often, emotion is defined with reference to a list: anger, disgust, fear, joy, sadness, and surprise. This article expands on a thesis that motivational states can be compared to each other by means of a common currency (Philos. Trans. Roy. Soc. Lond. 270 (1975) 265-293). I have previously argued that this common currency is pleasure. Such a conclusion is based not on introspective intuition, as with early pre-scientific psychology (), but on experimental methods. As a follow-up to a definition of consciousness (Neurosci. Biobehav. Rev. 20 (1996) 33-40) as a four-dimensional experience (quality, intensity, hedonicity, and duration), I propose here that emotion is any mental experience with high intensity and high hedonic content (pleasure/displeasure).     

What is macroecology?

The symposium ‘What is Macroecology?’ was held in London on 20 June 2012. The event was the inaugural meeting of the Macroecology Special Interest Group of the British Ecological Society and was attended by nearly 100 scientists from 11 countries. The meeting reviewed the recent development of the macroecological agenda. The key themes that emerged were a shift towards more explicit modelling of ecological processes, a growing synthesis across systems and scales, and new opportunities to apply macroecological concepts in other research fields.     

What is Chondriolejeunea?

Chondriolejeunea, the former subgenus of Cololejeunea is raised to the generic rank on the base that the supposed large styli are in reality underleaves, inserted alternately to the two cell rows of ventral merophytes and having rhizoid initials at their base. Chondriolejeunea pseudostipulata (Schiffn.) Kis & Pócs, Chondriolejeunea shimizui (N. Kitag.) Kis & Pócs, Chondriolejeunea shimizui var. phangngana (N. Kitag.) Kis & Pócs, Chondriolejeunea chinii (Tixier) Kis & Pócs, comb. et stat. nov. Cololejeunea shimizui subsp. shihuishanensis M.L. So & R.L. Zhu, syn. nov. Speculation on the possible ways of evolution of tribe Cololejeuneae.     

What is metamorphosis?

Metamorphosis (Gr. meta- "change" + morphe "form") as a biologicalprocess is generally attributed to a subset of animals: mostfamously insects and amphibians, but some fish and many marineinvertebrates as well. We held a symposium at the 2006 Societyfor Integrative and Comparative Biology (SICB) annual meetingin Orlando, FL (USA) to discuss metamorphosis in a comparativecontext. Specifically, we considered the possibility that theterm "metamorphosis" could be rightly applied to non-animalsas well, including fungi, flowering plants, and some marinealgae. Clearly, the answer depends upon how metamorphosis isdefined. As we participants differed (sometimes quite substantially)in how we defined the term, we decided to present each of ourconceptions of metamorphosis in 1 place, rather than attemptingto agree on a single consensus definition. Herein we have gatheredtogether our various definitions of metamorphosis, and offeran analysis that highlights some of the main similarities anddifferences among them. We present this article not only asan introduction to this symposium volume, but also as a referencetool that can be used by others interested in metamorphosis.Ultimately, we hope that this article—and the volume asa whole—will represent a springboard for further investigationsinto the surprisingly deep mechanistic similarities among independentlyevolved life cycle transitions across kingdoms.     

What is life?

Background

Many traditional biological concepts continue to be debated by biologists, scientists and philosophers of science. The specific objective of this brief reflection is to offer an alternative vision to the definition of life taking as a starting point the traits common to all living beings.

Results and Conclusions

Thus, I define life as a process that takes place in highly organized organic structures and is characterized by being preprogrammed, interactive, adaptative and evolutionary. If life is the process, living beings are the system in which this process takes place. I also wonder whether viruses can be considered living things or not. Taking as a starting point my definition of life and, of course, on what others have thought about it, I am in favor of considering viruses as living beings. I base this conclusion on the fact that viruses satisfy all the vital characteristics common to all living things and on the role they have played in the evolution of species. Finally, I argue that if there were life elsewhere in the universe, it would be very similar to what we know on this planet because the laws of physics and the composition of matter are universal and because of the principle of the inexorability of life.