Modern Synthesis Review

Douglas Futuyma's article , "How does phenotypic plasticity fit into evolutionary theory?", delves into a fascinating crossroads between development and adaptation, where the malleability of phenotypes dances with the rigidity of genes. In this essay, we will explore the intricate tapestry of phenotypic plasticity, its role in evolution, and its implications for understanding the dynamic nature of life. Defining Plasticity: At its core, phenotypic plasticity refers to the ability of a single genotype to express different phenotypes in response to varying environmental cues. Imagine a chameleon adjusting its skin color for camouflage, or a tadpole developing into a swimming or burrowing individual depending on the presence of predators. These are just a few examples of the remarkable diversity of plastic responses observed across the spectrum of life. Plasticity and Natural Selection: Futuyma argues that phenotypic plasticity can be both a friend and foe of natural selecti...

The article "The tree of one percent" by T. Dagan and W. Martin challenges the traditional view of the tree of life as a single, bifurcating tree. The authors argue that the vast majority of genes in microbial genomes are not universally distributed, but have been transferred between different lineages through lateral gene transfer (LGT). This means that the tree of life as we know it is based on only a small fraction of the genes in microbial genomes, and that the true evolutionary relationships between microbes are much more complex than a simple tree can represent. The authors support their argument by analyzing the distribution of 5,833 human proteins in prokaryotic genomes. They found that only 31 of these proteins were universally distributed, meaning that they were present in all of the prokaryotic genomes that they analyzed. The remaining 5,797 proteins were either absent from some genomes, or were present in only a subset of genomes. This suggests that the vast majo...

The article "The industrial melanism mutation in British peppered moths is a transposable element" by Van't Hof et al. (2016) provides evidence that the mutation that caused industrial melanism in peppered moths was a transposable element. Transposable elements (TEs) are pieces of DNA that can move around the genome. They are often called "jumping genes". TEs can cause mutations by inserting themselves into genes, disrupting their function. TE's are outside of NeoDarwinism as they are noncoding DNA. This means if a mutation occurs to them the will not be selected for. In the case of the peppered moth, the transposable element inserted itself into the gene cortex. This gene is involved in the production of melanin, the pigment that gives moths their color. The insertion of the transposable element caused the moths to produce more melanin, making them darker. This means NeoDarwinism was not the cause of this change. The increase in melanin pigmentation made t...

The study of biology has long been anchored by the Modern Synthesis, the mid-20th-century unification of Darwinian natural selection and Mendelian genetics. This framework posits that evolution is driven almost exclusively by changes in DNA sequences (mutations) that occur randomly and are filtered by environmental pressures over vast timescales. However, the article “Generational stability of epigenetic transgenerational inheritance facilitates adaptation and evolution” presents a profound challenge to this orthodoxy. By demonstrating that epigenetic marks—chemical modifications to DNA and histones that do not change the underlying code—can be stably inherited across many generations, it introduces a mechanism for "soft inheritance" that allows for rapid, directed adaptation. The Core Premise: Beyond the Genetic Code At the heart of the Modern Synthesis is the Weismann Barrier, the principle that information flows only from the germline to the body cells, and never back. T...