Fall 2025: Spatiotemporal dynamics

Physics 282: Spatiotemporal Dynamics in Biological Systems 

Instructor: Prof. Terry Hwa; office: Urey 7222
phone: 4-7263; e-mail:  
Time: Tu/Th 11:00am – 12:20 pm
(make-up lectures: Nov 10, Nov 24 at 3-4:20pm)
Location: 6120 Urey Hall
Office Hour: after class or by appointment
Course URL: this page (https://matisse.ucsd.edu/courses/f25-biodynamics/)
Grade 4-5 problem sets (to be assessed in person)
Prerequisite: a solid first course in ordinary differential equation; exposure to partial differential equation; interest in biological phenomena. 

Reference Books

Course description: 

This course is aimed for advanced undergraduates and beginning graduate students in biophysics and bioengineering, and for quantitative-minded BIO students. The course teaches and applies basic concepts in dynamical systems (phase plots, stability analysis, Lyapunov function) and fronts and patterns in spatially extended systems (Fisher wave, Keller-Segel, Turing instability, excitable systems, etc) on topics taken from microbial ecology and evolution, and developmental biology. Lessons learned from the analysis will be gleaned for biological insight.

Course outline

  • Introduction to bacterial growth, population dynamics, and ecology
  • Lotka-Volterra model and its generalization: fixed points and phase diagrams
  • Consumer-Resource model: coexistence and global stability
  • Trophic interactions, cross-feeding, cooperation, and cheating
  • Spatial range expansion: Fisher-Kolmogorov equation and the stability criterion
  • Chemotaxis: Keller-Segel equation; coordination of migration with growth
  • Population genetics: birth-death process, genetic drift, selection
  • Turing instability and patterns in developmental biology
  • Excitable systems: pulses and spiral waves

Tentative course outline:

  Date Topics assignment
L1 Tu, Sept 30 course overview and intro to population dynamics; logistic equation; qualitative effect of predation  [note  
L2 Th, Oct 2 two species interaction: fixed point, flow and phase diagram [note] HW1 due Oct 16
L3 Tu, Oct 7 generalized Lotka-Volterra model: competition and cooperation; phase diagram [note]  
L4 Th, Oct 9 stability of random gLV models; oscillation from realistic predator-prey model  [note]  
L5 Tu, Oct 14 oscillatory dynamics and stable limit cycles [note]  
L6 Th, Oct 16 FitzHugh-Nagumo model: excitable systems; relaxational oscillators [note]; intro to Consumer Resource model [note] HW2 due Oct 30
  Mon, Oct 20 Review of HW1   [soln1] [note on SIR model]  
L7 Tu, Oct 21 review of bacterial growth physiology [note]  
L8 Th, Oct 23  nutrient utilization and growth dynamics in chemostat [note]  
  Tu, Oct 28 no class  
L9 Th, Oct 30 CR model of two-species coexistence [note] HW3 due Nov 13
  Mon, Nov 3 Review of HW2 [soln2]  
L10 Tu, Nov 4 Tilman’s graphical solution to CR-model [note]  
L11 Th, Nov 6 Generalized CR model: MacArthur’s exclusion principle [note]  
L12 Mon, Nov 10
(makeup)
Ecological and phenotypical landscapes [note  
  Tu, Nov 11 no class (Veteran’s Day)  
L13 Th, Nov 13 Synergistic interaction: Cross-feeding and mutualism [note] HW4 due Dec 2
  Mon, Nov 17 Review of HW3 [soln3]  
L14 Tu, Nov 18 Trophic structure; cooperation and cheating [note]  
L15 Th, Nov 20 Front propagation: Fisher wave and trigger wave [note]  
L16 Mon, Nov 24
(makeup)
Chemotaxis: Keller-Siegel equation; growth-expansion model [note]  
L17 Tu, Nov 25 Turing patterns: Turing instability, Turing space and mode selection [note] [biological background]  
  Th, Nov 27 no class (Thanksgiving)  
L18 Mon, Dec 1
Amplitude fluctuation and secondary instabilities [note]  
L19 Tu, Dec 2 2D pattern selection: stripes, squares, and hexagons [note]
 
  Th, Dec 4 Review of HW4 [soln4-1] [soln4-2] [soln4-3] [soln4-4]