key: cord-0880435-n1gtqx3z authors: O'Brien, Stephen J.; Evermann, James F. title: Interactive influence of infectious disease and genetic diversity in natural populations date: 1988-10-31 journal: Trends in Ecology & Evolution DOI: 10.1016/0169-5347(88)90058-4 sha: d0fd13d1d91515d45a3572b5c73bf72abd93ac2b doc_id: 880435 cord_uid: n1gtqx3z Abstract The importance of infectious disease in the survival and adaptation of animal populations is rapidly becoming apparent. Throughout evolution, animal species have been continually afflicted with devastating disease outbreaks which have influenced the demographic and genetic status of the populations. Some general population consequences of such epidemics include selection for disease resistance, the occasional alteration of host gene frequencies by a genetic ‘founder effect’ after an outbreak, and genetic adaptation of parasites to abrogate host defense mechanisms. A wide variety of host cellular genes which are polymorphic within species and which confer a regulatory effect on the outcome of infectious diseases has recently been discovered. The critical importance of maintaining genetic diversity with respect to disease defense genes in natural populations is indicated by certain populations which have reduced genetic variability and apparent increased vulnerability to infectious disease. TREE vol. 3, no. IO, October 1988 Interactive influence of Infectious Disease and Genetic Diversity in Natural Populations Stephen J. O'Brien and James F. Evermann The importance of infectious disease in the survival and adaptatiofl of animal popu-latioMs is rapidly becoming apparent. Throughout evolution, animal species have Geen continually afflicted with devastating disease outbreahs which have influenced the demographic and genetic status of fhe populations. Some general population consequences of such epidemics include selection for disease resistance, the occasional alteration of host gene frequencies by a genetic 'founder effect' after an outbreak, and genetic adaptation of parasites fo abrogate host defense mechanisms. A wide variety of host cellular genes which are polymorphic within species and which confer a regulatory effect on the outcome of infectious diseases has recently Geen discovered. The critical importance of maintaining genetic diversity with respect to disease defense genes in natural populations is indicated 6y certain populatiofls which have reduced genetic variability and apparent increased vulnerability to infectious disease. A fundamental goal of evolutionary biology is the identification and understanding of specific ecological components that influence whether a species (or a population I flourishes, survives, stumbles or becomes extinct. The regulatory contribution of infectious disease to population dynamics was recognized by Darwin', who suggested that epidemics provided 'a limiting check' on geometric expansion of populations, but were, he speculated, 'independent of the struggle for life'. A century later, the geneticist and theoretician J.B.S. Haldane' introduced the concept that parasitic diseases must also be considered as a key part of the 'struggle for life' because of the intense selective pressures exerted by these agents on the afflicted populations. It has now become generally accepted that the In some of these instances, the endogenous viruses were pathologically defective and are thought to have conferred a novel form of virus defense mechanism to infected individuals and to their descendantss5. Possible biological mechanisms whereby cellular genes restrict or promote viral pathology are multiple, but in several cases they have been specifically defined. The maior histocompatibility (MHC) locus, encodes two classes of cell surface antigens (class I and class II) that play a key role in viral antigen presentation to circulating Tlymphocytes involved in immune surveillance5,7. The MHC is the most extensively polymorphic In summary, any discussion of evolving host and parasite genomes and their impact on each other is circular. Host population genetic structure both regulates epidemic prl,gression and isc;ften significantly modified by the event. Parasite genomes also endure rapid adaptation during outbreaks and the Population Biology of Infectious Diseases (Report on the Dahlem Workshop on Population Biology of Infectious Disease Agents 11976) Plaguesand People I9861 Natural History of the Major Histocompatibility Complex A. 11983) Hematology IO May. R.M. and Anderson, R.M. II9871 Nature326 RE(l9681Condor70 119781 in Viruses and Environment IKurstak I9841 in Evolutionary Dynamics of Genetic Diversity in Evolution and the I921 I Genetics6. I I I-178 in Conservation Biology, the Science of Scarcity and Diversity ISoule, M Proceedings Workshop on Reproductive Biology of Black-Footed Ferrets and Small Population Biology as They Relate to Conservation Cold Spring Harbor Press 35 Benveniste Group Report, Evolution of Parasites and Hosts I Population Biology of Infectious Diseases Report on the Dahlem Workshop on Population. Biology of Infectious Disease Agents We are grateful to Drs D Derse. L. Forman. 1. Heeney, C. Kozak and C. Winkler for critical discussions of the points reviewed here.