BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Marco Tulio Angulo (UNAM - México) DTSTART:20220218T160000Z DTEND:20220218T170000Z DTSTAMP:20260423T022916Z UID:GEOTOP-A/13 DESCRIPTION:Title: Coexistence holes in ecological systems\nby Marco Tulio Angulo (UNAM - México) as part of GEOTOP-A seminar\n\n\nAbstract\nA central challenge of Ecology is to explain the enormous biodiversity of species that we fin d on Earth\, from the diversity of plant and animal species that stably co exist in tropical forests to the variety of microbial species that coexist in our gut. Ecologists have focused on characterizing the "limits" of spe cies coexistence ---that is\, the maximum number of different species that can coexist under given constraints. Yet\, little is known about the stru cture of species coexistence below such limits. Namely\, is it possible to assemble an ecological system by adding one species at a time until reach ing the coexistence limits? Or is it possible to find obstructions where s pecies coexistence abruptly breaks before reaching the limits? To address these questions\, we built a novel formalism based on hypergraphs and Alge braic Topology to show that\, below its limits\, species coexistence in ec ological systems has ubiquitous obstructions that we call "coexistence hol es". A coexistence hole occurs during an assembly process when a species c ollection does not coexist\, although we can assemble it from sub-collecti ons that coexist. Using theoretical and experimental ecological systems\, we provide direct evidence showing that coexistence holes obey regularitie s. Namely\, their diversity is constrained by the internal structure of sp ecies interactions\, while their frequency can be explained by external fa ctors acting on these systems. Overall\, our work provides one of the firs t applications of Algebraic Topology to Ecology\, unveiling how biodiversi ty is a discontinuous process driven by internal design constraints.\n\nTh is is joint work with Aaron Kelley (IM-UNAM)\, Luis Montejano (IM-UNAM)\, Chuliang Song (McGill/Toronto University) and Serguei Saavedra (MIT).\n\nR eferences:\n[1] Angulo\, Marco Tulio\, et al. "Coexistence holes character ize the assembly and disassembly of multispecies systems." Nature Ecology & Evolution (2021): 1-11.\n[2] Letten\, A. D. (2021). "Coexistence holes f ill a gap in community assembly theory." Nature Ecology & Evolution\, 1-2. \n LOCATION:https://researchseminars.org/talk/GEOTOP-A/13/ END:VEVENT END:VCALENDAR