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 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 chronotype?

Sleep and Biological Rhythms -     

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.     

What is macroevolution?

Definitions of macroevolution fall into three categories: (1) evolution of taxa of supraspecific rank; (2) evolution on the grand time-scale; and (3) evolution that is guided by sorting of interspecific variation (as opposed to sorting of intraspecific variation in microevolution). Here, it is argued that only definition 3 allows for a consistent separation of macroevolution and microevolution. Using this definition, speciation has both microevolutionary and macroevolutionary aspects: the process of morphological transformation is microevolutionary, but the variation among species that it produces is macroevolutionary, as is the rate at which speciation occurs. Selective agents may have differential effects on intraspecific and interspecific variation, with three possible situations: effect at one level only, effect at both levels with the same polarity but potentially different intensity, and effects that oppose between levels. Whereas the impact of all selective agents is direct in macroevolution, microevolution requires intraspecific competition as a mediator between selective agents and evolutionary responses. This mediating role of intraspecific competition occurs in the presence of sexual reproduction and has therefore no analogue at the macroevolutionary level where species are the evolutionary units. Competition between species manifests both on the microevolutionary and macroevolutionary level, but with different effects. In microevolution, interspecific competition spurs evolutionary divergence, whereas it is a potential driver of extinction at the macroevolutionary level. Recasting the Red Queen hypothesis in a macroevolutionary framework suggests that the effects of interspecific competition result in a positive correlation between origination and extinction rates, confirming empirical observations herein referred to as Stanley's rule.     

What is altruism?

Altruism is generally understood to be behavior that benefits others at a personal cost to the behaving individual. However, within evolutionary biology, different authors have interpreted the concept of altruism differently, leading to dissimilar predictions about the evolution of altruistic behavior. Generally, different interpretations diverge on which party receives the benefit from altruism and on how the cost of altruism is assessed. Using a simple trait-group framework, we delineate the assumptions underlying different interpretations and show how they relate to one another. We feel that a thorough examination of the connections between interpretations not only reveals why different authors have arrived at disparate conclusions about altruism, but also illuminates the conditions that are likely to favor the evolution of altruism.     

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.