Phenotypes In Evolution Research Articles

The Language of Shape: Biological Reactions are Dramatically Affected by the Shape of Lipid Membranes

To date the fields of biophysics, biochemistry, molecular and cellular biology and have established exhaustive correlations between the lipid composition of membranes and its impact on membrane properties and protein function. However, in addition to composition the shape of cellular membranes appears to be a well-conserved phenotype in evolution. The characteristic membrane topology of organelles e.g. the folded structure of the endoplasmatic reticulum, is strictly retained in most types of cells. Nevertheless we largely ignore what are the consequences of membrane shape/curvature to biological functions that make it so critical for sustaining life. The lack of information on the significance of membrane shape has predominantly been due to the absence of reliable assays that allow us to perform systematic experiments as a function of membrane shape/curvature. We have recently demonstrated the possibility to construct a high throughput array of unique nanoscale membrane curvatures. The assay is based on unilamellar liposomes of different diameters (30 nm to 700 nm), and therefore curvature, that are immobilized on a surface at dilute densities allowing for imaging of single liposomes with fluorescence microscopy.Here I will discuss published and unpublished data on two important classes of biomolecular interactions that exhibited dramatic curvature dependence: i) SNARE-mediated docking of single lipid vesicles and ii) membrane anchoring of lipidated proteins, and reveal previously unsuspected consequences of membrane curvature to biological function.

Niche construction, genetic evolution and cultural change

In evolution, adaptation is traditionally viewed as a process by which natural selection moulds organisms to fit pre-established environmental templates. The changes organisms cause in environments are seldom thought evolutionarily significant. However, organisms partly create their own environments by ‘niche construction’. A formal model of niche construction is discussed. It focusses on two genetic loci, E and A. It assumes: 1. (i) a population's capacity for niche construction is influenced by genes at the E locus; 2. (ii) the amount of an environmental resource, R, depends on niche construction; 3. (iii) changes in R affect selection at the A locus. This model produces some surprising results. For example, timelags occur between the spread of niche construction and the response to the selection it generates. Niche construction also enhances the role of phenotypes in evolution. Organisms not only carry and propagate genes, but they also modify the selection pressures that select those genes. This dual role changes the relationship between genetic evolution; individual development; learning; and cultural processes in human beings.