How a complex life cycle can improve a parasite's sex life

How complex life cycles of parasites are maintained is still a fascinating and unresolved topic. Complex life cycles using three host species, free‐living stages, asexual and sexual reproduction are widespread in parasitic helminths. For such life cycles, we propose here that maintaining a second intermediate host in the life cycle can be advantageous for the individual parasite to increase the intermixture of different clones and therefore decrease the risk of matings between genetically identical individuals in the definitive host. Using microsatellite markers, we show that clone mixing occurs from the first to the second intermediate host in natural populations of the eye‐fluke Diplostomum pseudospathaceum. Most individuals released by the first intermediate host belonged to one clone. In contrast, the second intermediate host was infected with a diverse array of mostly unique parasite genotypes. The proposed advantage of increased parasite clone intermixture may be a novel selection pressure favouring the maintenance of complex life cycles.

[1]  T. Reusch,et al.  Polymorphic microsatellite loci for the trematode Diplostomum pseudospathaceum , 2004 .

[2]  F. Prugnolle,et al.  Molecular ecology of Schistosoma mansoni transmission inferred from the genetic composition of larval and adult infrapopulations within intermediate and definitive hosts , 2004, Parasitology.

[3]  P. Hudson,et al.  Patterns of cercarial production from Diplostomum spathaceum: terminal investment or bet hedging? , 2004, Parasitology.

[4]  G. Parker,et al.  Evolution of complex life cycles in helminth parasites , 2003, Nature.

[5]  M. Tibayrenc,et al.  Multilocus enzyme electrophoresis analysis of Trypanosoma cruzi isolates from a geographically restricted endemic area for Chagas' disease in Argentina. , 2003, International journal for parasitology.

[6]  Sam P. Brown,et al.  Evolution of Trophic Transmission in Parasites: Why Add Intermediate Hosts? , 2003, The American Naturalist.

[7]  G. Snounou,et al.  Transmission of mixed Plasmodium species and Plasmodium falciparum genotypes. , 2003, The American journal of tropical medicine and hygiene.

[8]  M. Milinski,et al.  OUTCROSSING INCREASES INFECTION SUCCESS AND COMPETITIVE ABILITY: EXPERIMENTAL EVIDENCE FROM A HERMAPHRODITE PARASITE , 2002, Evolution; international journal of organic evolution.

[9]  D. Wakelin,et al.  Variation and immunity to intestinal worms , 2002, Parasitology.

[10]  D. Wakelin.  The Biology of Nematodes (ed. Lee, D. L.), pp. 635. Taylor & Francis, London, 2002. ISBN 0 415272114. £120.00. , 2002, Parasitology.

[11]  J. Piñero,et al.  Analysis of NLS and rRNA binding motifs in the L25 ribosomal protein from Leishmania (Viannia) braziliensis: investigation of its diagnostic capabilities , 2002, Parasitology.

[12]  D. Minchella,et al.  Schistosome genetic diversity: the implications of population structure as detected with microsatellite markers , 2002, Parasitology.

[13]  R. Poulin,et al.  Trematode life cycles: short is sweet? , 2002, Trends in parasitology.

[14]  Sam P. Brown,et al.  Evolution of trophic transmission in parasites: the need to reach a mating place? , 2001 .

[15]  A. Tait,et al.  Trypanosoma brucei: identification of trypanosomes with genotypic similarity to human infective isolates in tsetse isolated from a region free of human sleeping sickness. , 2000, Experimental parasitology.

[16]  E. Herniou,et al.  Phylogeny of the Platyhelminthes and the evolution of parasitism , 1999 .

[17]  P. Durand,et al.  Genetic diversity and recruitment pattern of Schistosoma mansoni in a Biomphalaria glabrata snail population: a field study using random-amplified polymorphic DNA markers. , 1999, The Journal of parasitology.

[18]  S. Morand,et al.  Distribution of schistosome genetic diversity within naturally infected Rattus rattus detected by RAPD markers , 1996, Parasitology.

[19]  W. G. Hill,et al.  Estimation of numbers of malaria clones in blood samples , 1995, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[20]  R. Paru,et al.  Mating patterns in malaria parasite populations of Papua New Guinea. , 1995, Science.

[21]  D. Minchella,et al.  Distribution of schistosome genetic diversity within molluscan intermediate hosts , 1995, Parasitology.

[22]  Susan A. Foster,et al.  The Evolutionary biology of the threespine stickleback , 1995 .

[23]  V. Connors,et al.  Complexity in parasite life cycles: population biology of cestodes in fish , 1995 .

[24]  K. Rohde,et al.  The origins of parasitism in the platyhelminthes. , 1994, International journal for parasitology.

[25]  K. Hughes,et al.  An experimental study of inbreeding depression in a natural habitat. , 1994, Science.

[26]  P. Onyango,et al.  Electrophoretic Analysis of Trypanosoma Brucei Sub-Group Stocks from Cattle, Tsetse and Patients from Lambwe Valley, Western Kenya , 1990 .

[27]  A. Dobson.  The Population Biology of Parasitic Helminths in Animal Populations , 1989 .

[28]  D. Gibson,et al.  Questions in digenean systematics and evolution , 1987, Parasitology.

[29]  S. O’Brien,et al.  Genetic basis for species vulnerability in the cheetah. , 1985, Science.

[30]  D. S. Trail.  Behavioral Interactions between Parasites and Hosts: Host Suicide and the Evolution of Complex Life Cycles , 1980, The American Naturalist.

[31]  D. Broom,et al.  Effects of the eyefluke, Diplostomum spathaceum, on the behaviour of dace (Leuciscus leuciscus) , 1980, Animal Behaviour.

[32]  D. Littlewood,et al.  Life cycle evolution in the digenea: a new perspective from phylogeny. , 2003, Advances in parasitology.

[33]  R. Siddall,et al.  Patterns of trematode parasitism in lymnaeid snails from northern and central Finland. , 2000 .

[34]  C. Combes.  Fitness of parasites: pathology and selection. , 1997, International journal for parasitology.

[35]  F. Bonhomme,et al.  GENETIX 4.05, logiciel sous Windows TM pour la génétique des populations. , 1996 .

[36]  A. Magurran.  Ecological Diversity and Its Measurement , 1988, Springer Netherlands.

[37]  Mark W. Denny,et al.  Nearshore Biomechanics. (Book Reviews: Biology and the Mechanics of the Wave-Swept Environment) , 1988 .

[38]  Deborah Charlesworth,et al.  INBREEDING DEPRESSION AND ITS EVOLUTIONARY CONSEQUENCES , 1987 .