How development affects evolution

How development affects evolution. A mathematical framework that explicitly integrates development into evolution has recently been derived. Here we use this framework to analyse how development affects evolution. We show that, whilst selection pushes genetic and phenotypic evolution uphill on the fitness landscape, development determines the admissible evolutionary pathway, such that evolutionary outcomes occur at path peaks, which need not be peaks of the fitness landscape. Development can generate path peaks, triggering adaptive radiations, even on constant, single-peak landscapes. Phenotypic plasticity, niche construction, extra-genetic inheritance, and developmental bias variously alter the evolutionary path and hence the outcome. Selective development, whereby phenotype construction may point in the adaptive direction, may induce evolution either towards or away landscape peaks depending on the developmental constraints. Additionally, developmental propagation of phenotypic effects over age allows for the evolution of negative senescence. These results help explain empirical observations including punctuated equilibria, the paradox of stasis, the rarity of stabilizing selection, and negative senescence, and show that development has a major role in evolution.

History of English as punctuated equilibria? A meta-analysis of the rate of linguistic change in Middle English

In this paper, we explore the rate of language change in the history of English. Our main focus is on detecting periods of accelerated change in Middle English (1150–1500), but we also compare the Middle English data with the Early Modern period (1500–1700) in order to establish a longer diachrony for the pace at which English has changed over time. Our study is based on a meta-analysis of existing corpus research, which is made available through a new linguistic resource, the Language Change Database (LCD). By aggregating the rates of 44 individual changes, we provide a critical assessment of how well the theory of punctuated equilibria (Dixon, Robert M. W. 1997. The rise and fall of languages. Cambridge: Cambridge University Press) fits with our results. More specifically, by comparing the rate of language change with major language-external events, such as the Norman Conquest and the Black Death, we provide the first corpus-based meta-analysis of whether these events, which had significant societal consequences, also had an impact on the rate of language change. Our results indicate that major changes in the rate of linguistic change in the late medieval period could indeed be connected to the social and cultural after-effects of the Norman Conquest. We also make a methodological contribution to the field of English historical linguistics: by re-using data from existing research, linguists can start to ask new, fundamental questions about the ways in which language change progresses.

Policy Innovations Can Relax Political Constraints

Development requires institutional change. This chapter suggests a ray of hope. Policy innovations, according to hypothesis 5, can enhance capacities for resolving CAPs, relaxing political impediments to development—notably, CAPs from hypotheses 3 and 4. South Korea’s 1950s land reform policy established foundations for subsequent development. Innovations, however, emerge and spread within political contexts; institutional change presents formidable CAPs. Distinct individual as opposed to organizational capacities for information processing, combined with asymmetric distributions of power, typically generate relatively long periods of institutional and policy stability that occasionally succumb to rapid change: punctuated equilibria. Within such contexts, coalitions vie for influence, using policy narratives and images (mini ideologies) to legitimate their influence and discredit opponents.

On ideas of evolution and the evolution of ideas: communicating traditions of scientific enquiry

That there was variation in the theories expounded by the major early thinkers on evolution is well established. What is less effectively articulated is how their intellectual ambitions and approaches to interpreting evidence reflect a deep-rooted difference in their views on what sort of systems, and problems evolution deals with; insights which speak directly to contemporary debates about how we communicate the nature of science with consequences for learning practice. We provide a re-reading of the perspectives adopted by those who formulated the central concepts of evolutionary theory to expose slender but persistent differences of emphasis. Our analysis contrasts the approaches to enquiry of three voyaging naturalists; Charles Darwin, Thomas Henry Huxley, and Alfred Russel Wallace. This potted history is used to illustrate the relationship between different traditions of scientific enquiry, specifically the natural philosophy approach characteristic of Wallace’s work and the later Neo-Darwinists; Huxley’s more empirical, natural history approach that anticipated punctuated equilibria, and Darwin’s emphasis on agency and choice, which suggests a more humanistic mind-set. These understandings are used to propose a model of the structure of evolutionary science which has broader value as a motif for exploring and communicating the transitions between different modes of enquiry.

Transposable elements activity reveals punctuated patterns of speciation in mammals

ABSTRACTTransposable elements (TEs) play an essential role in shaping eukaryotic genomes and generating variability. Our “Cold Genome” hypothesis postulates that speciation and TEs activity are strongly related in mammals. In order to test this hypothesis, we created two new parameters: the Density of Insertion (DI) and the Relative Rate of Speciation (RRS). The DI is the ratio between the number of TE insertions in a genome and its size, whereas the RRS is a conditional parameter designed to identify potential speciation bursts. Thus, by analyzing TEs insertions in mammals, we defined the genomes as “hot” (low DI) and “cold” (high DI). Then, comparing TEs activity among 16 intra-order pairs of mammalian species, 4 superorders of Eutheria and 29 taxonomical families of the whole Mammalia class, we showed that taxa with positive RRS correlate with “hot” genomes, whereas taxa with negative RRS correlate with “cold” genomes. In addition, our study supports the “Punctuated Equilibria” theory in mammals for both adaptive radiation and stasis.