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Titolo:
THE INFLUENCE OF HOST DEMOGRAPHY ON THE EVOLUTION OF VIRULENCE OF A MICROSPORIDIAN GUT PARASITE
Autore:
EBERT D; MANGIN KL;
Indirizzi:
UNIV BASEL,INST ZOOL,RHEINSPRUNG 9 CH-4051 BASEL SWITZERLAND UNIV OXFORD,DEPT ZOOL,ABRG OXFORD OX1 3PS ENGLAND UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,CTR POPULAT BIOL,NERC ASCOT SL5 7PY BERKS ENGLAND
Titolo Testata:
Evolution
fascicolo: 6, volume: 51, anno: 1997,
pagine: 1828 - 1837
SICI:
0014-3820(1997)51:6<1828:TIOHDO>2.0.ZU;2-K
Fonte:
ISI
Lingua:
ENG
Soggetto:
DAPHNIA-MAGNA; ECOLOGICAL INTERACTIONS; POPULATION-STRUCTURE; INFECTIOUS-DISEASES; NEMATODE PARASITES; FIG WASPS; SELECTION; MEIOSIS; COEVOLUTION; MAINTENANCE;
Keywords:
DAPHNIA; MICROSPORIDIA; MULTIPLE INFECTIONS; PARASITE; SELECTION; SPORE SIZE; TRADE-OFF; TRANSMISSION; VIRULENCE; WITHIN-HOST COMPETITION;
Tipo documento:
Article
Natura:
Periodico
Citazioni:
56
Recensione:
Indirizzi per estratti:
Citazione:
D. Ebert e K.L. Mangin, "THE INFLUENCE OF HOST DEMOGRAPHY ON THE EVOLUTION OF VIRULENCE OF A MICROSPORIDIAN GUT PARASITE", Evolution, 51(6), 1997, pp. 1828-1837

Abstract

It is predicted that host exploitation should evolve to maximize parasite fitness and that virulence ( parasite-induced host mortality) evolves along with the rate of host exploitation. If the life expectancy of a parasite is short, it is expected to evolve a higher rate of hostexploitation and therefore higher virulence because the penalty to the parasite for killing the host is reduced. We tested this hypothesis by keeping for 14 months the horizontally transmitted microsporidian parasite Glugoides intestinalis in mono-clonal host cultures (Daphnia magna) under conditions of high and low host background mortality. Highhost mortality, and thus parasite mortality, was achieved by replacing weekly 70-80% of all hosts in a culture with uninfected hosts from stock cultures (Replacement lines). In the low-mortality treatment no replacement took place. Contrary to our expectation, parasites from theReplacement lines evolved a lower within-host growth rate and virulence than parasites from the Nonreplacement lines. Across lines we founda strong positive correlation between within-host growth rate and virulence. We did further experiments to answer the question why our datadid not support the predictions. Sporophorous vesicles (SVs, spore clusters) were smaller in doubly infected than in singly infected host-gut cells, indicating that competition within cells bears costs for theparasite. Due to our experimental protocol, the average Life span of infections had been much higher in the Nonreplacement lines. Since thenumber of parasites inside a host increases with the time since infection, long-lasting infections led to high frequencies of multiply infected host-gut cells. Therefore, we speculated that within-cell competition was more severe in the Nonreplacement fines and may have led to selection for accelerated within-host growth. SVs in the Nonreplacementfines were indeed significantly larger. Our results point out that single-factor explanations for the evolution of virulence can lead to wrong predictions and that multiple infections are an important factor in virulence evolution.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 27/11/20 alle ore 22:28:30