por Erik L Peterson
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De ontsnapping van de natuur
by Thomas Oudman & Theunis Piersma
Is social transmission a forgotten force in coevolution?
During the last decade it has become impossible to ignore that social transmission of information occurs across the animal kingdom:1 humans and non-human animals alike learn by observing others. An explosion of studies demonstrate that species as diverse as Drosophila fruit flies to humpback whales either copy the behavior of others, or use it to alter their behavioral responses at a later date (social learning). If female fruit flies observe males attracting other females, any other males that share similar markings also become sexier,2 for example, while new methods for catching fish spread rapidly among humpback whale populations, mapping on to social networks of interacting individuals.3 Interestingly, social transmission does not seem to be a hallmark of socially-complex species.4 In fact, even solitary fish species are just as likely to use social information as those that live in shoals.5
United fronts: Unity, organization, and syntheses in the life sciences
In his book Consilience, E.O. Wilson described science as he saw it: one moving ever closer to shared agreement on theories, principles, concepts, and standards of evidence. For Wilson, the indications that science was unifying were obvious; “disciplinary boundaries within the natural sciences are disappearing, to be replaced by shifting hybrid domains in which consilience is implicit.” (1998, pp. 11) Yet it wasn’t just that the conciliation of science was underway. For Wilson, unification was something that should happen. Consilience went hand in hand with a humanistic vision of science: “when we have unified enough certain knowledge, we will understand who we are and why we are here.” (pp. 7)
‘Lá vou eu outra vez’ – As esperanças de Waddington finalmente serão cumpridas? Parte I
por Erik L Peterson
The variational ratchet: Intuiting the variational approach to niche construction
The principle of evolution by natural selection provides a solid conceptual tool to understand adaptive design. It operates like a ratchet, to retain and build upon functional variation. Pull down, ‘click’! Variation. Hold tight, lock it! Retention and differential fitness. Push up! Inheritance, and ratchet your way up towards peaks in the adaptive landscape. As this process is repeated over phylogenetic time, the organism-environment complementarity will tend to get tighter and tighter, often leading to enhancements in the properties of adaptations.
Pleiotropy allows the evolutionary maintenance of positive niche construction in the face of free-riders
In our paper published recently in American Naturalist, we used mathematical models to help us understand how positive niche construction can be maintained. Many animals, plants and other organisms engage in niche construction, that is, they modify the environment and the subsequent selective pressures to which they are exposed. Positive niche construction occurs when organisms modify the environment to their advantage; for example, beavers create dams to provide shelter and other benefits. So-called free-riders can emerge who don’t contribute to the costly niche construction but still benefit from the niche-constructing activities of others. This raises an evolutionary problem of how positive niche construction can emerge and be maintained if it is constantly challenged by free-riders.
Conference on Complex Systems 2018
23-28 September 2018
What’s hiding in Waddington’s epigenetic landscape? A case study in baby cichlids
In his 1957 book entitled The Strategy of the Genes, British scientist Conrad Hal Waddington noted that the genetic sequence does not map directly onto the phenotype we can observe in nature. Contrary to the gene-centric views held by many of his contemporaries, Waddington emphasised that phenotypes ultimately depend on the interaction between genes and an array of often environment-sensitive developmental factors he labelled as ‘epigenetic’.1,[*] Using Waddington’s famous ‘epigenetic landscape’ metaphor, the process that connects genotype to phenotype can be described as travelling downhill through a series of valleys from a starting point at the top of the landscape. Some valleys are deep and narrow, which means that the ultimate phenotype will be robustly produced across a wide range of rearing environments. In other cases, the directing landscape is flat and can lead to a variety of end points (i.e. different phenotypes) because the development of a trait is sensitive to environmental influences, often mediated by epigenetic factors.2 Waddington went on to propose that epigenetic factors could play a role in evolution, by allowing organisms to adjust to environmental conditions. Such adaptive phenotypes are subsequently stabilised through selection on genetic variation,3 a hypothesis now known as ‘plasticity-first’ evolution.4
