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Irreversible Processes in Ecological Evolution/Phenotypic evolution in the Anthropocene

From Complex Time

January 30, 2019
8:45 am - 9:45 am


Priyanga Amarasekare (UCLA)


Phenotypic traits constitute the interface between the organism and the environment. Adaptive evolution occurs when trait responses to the  environment maximize fitness subject to constraints. These constraints can be morphological, biochemical or genetic.  On the one hand, evidence of rapid evolution in response to environmental perturbations (e.g., pollution, habitat degradation, climate warming) suggests that evolution in response to these novel selection pressures can proceed unconstrained. On the other hand, evidence of extinctions and disruptions of species interactions suggests that constraints can impede evolution in response to novel selective regimes.  There is much we do not understand about the interplay between selection and constraints, particularly in light of anthropogenically-induced selection regimes.  I am particularly interested in the role of biochemical constraints in reaction norm evolution.  This interest is fueled by my work on temperature effects on ectotherm life history, population dynamics and species interactions.  I want to gain a mechanistic understanding of biochemical constraints all the way from protein folding to enzyme kinetics so that I can incorporate these mechanisms into models of reaction norm evolution.  There is a great deal I do not understand about these processes themselves and how they translate into the mathematics of population dynamics.  I do, however, entertain some speculations about the role of how biochemical constraints in irreversible outcomes in phenotypic evolution.    

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Post-meeting Reflection

Priyanga Amarasekare (UCLA) Link to the source page

  1. Presentation highlights: (i) The role of constraints in phenotypic evolution as means of generating irreversible evolutionary endpoints and set upper limits to evolutionary trajectories. (ii) Role of constraints in species' ability to adapt to changing environments. (iii) Species come up against hard limits to phenotypic plasticity under climate warming. (iv) In order for thermal reaction norms to evolve in the face of climate warming, there has to be genetic variation. Unclear that reaction norms under strong biochemical control (e.g., development) have sufficient amounts of variation for the upper thermal limit to evolve in response to warming.

2. Open questions:

2.1 Connection between Darwinian adaptationist evolution and the idea of increase in disorder (as in the second law of thermodynamics)

2.2 What exactly are irreversible evolutionary endpoints? Can we come up with a specific definition of irreversibility?

2.3 Selection and constraints are not the same thing. This needs to be clarified.

3. How my perspective has changed: I want to think more carefully and deeply about the connection between Darwinian evolution and the second law of thermodynamics.

4. Reflections on other presentations

4.1 Stephen Proulx - I very much liked this presentation about the population genetics of low-probability transitions. I was particularly interested in stochastic selection due to lottery competition that leads to alternative stable states making it possible for mutations of large effect to cause transitions between states in a directional manner. I also liked the models of stochastic tunneling or valley crossing, that provide possible avenues for transitions between states. The case of multiple independent mutations enabling valley crossing is equally fascinating. I particularly liked how the examples shown related to the central theme of irreversibility and transitions.

4.2 Dervis Can Vural - An elegant presentation of the evolution of cooperation against the backdrop of fluid dynamics. I would like the theory to be generalized to perturbations other than shear so that it can also apply to pathogenic microbes within a host and other situations that do not involve fluid as a medium. I think you also should take the plunge and try to connect this theory to Hamilton's theory of kin selection. It is hard, and perhaps not analytically tractable, but it would be worth doing.

4.3. Samraat Pawar - I like the connection between metabolic constraints on species interactions and carbon fluxes.

4.4 Fernanda Valdovinos - The idea that adaptive foraging by mutualists (e.g., pollinators) allowing the persistence of nested mutualistic networks is a novel and exciting finding that pushes the field forward.

Reference Material

Title Author name Source name Year Citation count From Scopus. Refreshed every 5 days. Page views Related file
Temperature dependence of the functional response Göran Englund, Gunnar Öhlund, Catherine L. Hein, Sebastian Diehl Ecology Letters 2011 226 13
The common patterns of nature S. A. Frank Journal of Evolutionary Biology 2009 117 2
Temperature dependence of the functional response2 Ecology Letters 2011 0 25 Download