Abstract : For the last 3.8 billion years, the large-scale structure of evolution has followed a patte rn of speciation that can be described by branching trees. Recent work, esp ecially on bacterial sequences, has established that despite their apparent complexity, these so-called phylogenetic or evolutionary trees exhibit two unexplained broad structural features which are consistent across evolutio nary time. The first is that phylogenetic trees exhibit scale-invariant top ology, which quantifies the fact that their branching lies in between the t wo extreme cases of balanced binary trees and maximally unbalanced ones. Th e second is that the backbones of phylogenetic trees exhibit bursts of dive rsification on all timescales. I present a coarse-grained statistical mecha nics model of ecological niche construction coupled to a simple model of sp eciation, and use renormalization group arguments to show that the statisti cal scaling properties of the resultant phylogenetic trees recapitulate bot h the scale-invariant topology and the bursty pattern of diversification in time. These results show in principle how dynamical scaling laws of phylog enetic trees on long time-scales may emerge from generic aspects of the int erplay between ecological and evolutionary processes, leading to scale inte rference.
Finally, if there is time, I will suggest that these sorts of simplistic, minimal arguments might have a pla ce in understanding other large-scale aspects of evolutionary biology. In p articular I will mention two questions where we do not have even a qualitat ive understanding let alone a quantitative one: (1) the spontaneous emergen ce of the open-ended growth of complexity; (2) the response of evolving sys tems to perturbations and the implications for their control. Even th ough biology is intimidatingly complex, "everything has an exception", and there are a huge number of undetermined parameters, statistical physics rea soning may lead to useful new insights into the existence and universal cha racteristics of living systems.
Work perfor med in collaboration with Chi Xue and Zhiru Liu and supported by NASA throu gh co-operative agreement NNA13AA91A through the NASA Astrobiology Institut e for Universal Biology.
CONTACT:Nigel Goldenfeld - University of California San Diego DTSTAMP:20260907T071646 DTSTART;TZID=America/New_York:20230222T104500 DTEND;TZID=America/New_York:20230222T114500 SEQUENCE:0 TRANSP:OPAQUE END:VEVENT END:VCALENDAR