Altruism in populations at the extinction transition

Partial financial support has been received from the Agencia Estatal de Investigacion (AEI, Spain) and Fondo Europeo de Desarrollo Regional under project PACSS, No. RTI2018-093732-B-C21 (AEI/FEDER,UE), and the Spanish State Research Agency, through the Maria de Maeztu Program for units of Excellence in R&D (MDM-2017-0711). K.K. acknowledges funding from MINECO through the Ramon y Cajal program and through project SPASIMM, No. FIS2016-80067-P (AEI/FEDER, EU).