QLS guest seminar - Tuesday 19 April

[Quantitative Life Sciences]

Tuesday, 19 April at 14:00

ICTP, Central Area, 2nd floor, old SISSA building

Speaker: Gyuri BARABAS - Department of Ecology and Evolution, The 
University of Chicago, USA

Title: " Self-regulation and the stability of large biological networks"

Abstract:
Biological networks are many and varied, including food webs describing 
who eats whom in an ecosystem, gene regulation networks in which genes 
are connected through suppression and enhancement, or mutualistic 
networks in which plants are connected to their pollinators. What they 
have in common is that they are all large (containing thousands of 
nodes) and possess definite structure, deviating considerably from 
simple random graphs. In these networks the nodes interact with one 
another, but also with themselves: when the nodes represent species, a 
negative self-effect (self-regulation) generally arises from 
intraspecific competition for limited resources. One important question 
concerns the role of self-effects in stabilizing network dynamics. While 
it is easy to construct networks which can be stabilized by only a 
handful of nodes exhibiting self-regulation, their structure is highly 
special, and quite different from what is observed empirically. Here I 
show that, in general, the vast majority of nodes must exhibit 
substantial self-regulation in order to stabilize dynamics. The argument 
holds for both random and highly structured empirical networks. I show 
that in the case of competitive networks the arrangement of 
self-interactions leading to the most/least stabilized configurations 
can be justified analytically, and are confirmed by thorough simulations.

Web page: http://indico.ictp.it/event/7852/

-- 
Erica Sarnataro
Group Secretary
Quantitative Life Sciences
The Abdus Salam International Centre for Theoretical Physics (ICTP)
Trieste,  Italy
Tel. +39-040-2240623
e-mail:qls at ictp.it