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Université de Neuchâtel

How does breeding system variation modulate sexual antagonism?

Bedhomme, Stéphanie ; Bernasconi, Giorgina ; Koene, Joris M. ; Lankinen, Åsa ; Arathi, H. S. ; Michiels, Nico K. ; Anthes, Nils

In: Biology Letters, 2009, vol. 23, no. 5, p. 660-662

The study of sexually antagonistic (SA) traits remains largely limited to dioecious (separate sex), mobile animals. However, the occurrence of sexual conflict is restricted neither by breeding system (the mode of sexual reproduction, e.g. dioecy or hermaphroditism) nor by sessility. Here, we synthesize how variation in breeding system can affect the evolution and expression of intra- and...

Université de Neuchâtel

Repeatability of sperm size in outbred and inbred Scathophaga stercoraria (Diptera: Scathophagidae)

Bernasconi, Giorgina ; Ward, P.I. ; Hellriegel, B.

In: Canadian Entomologist (The), 2007, vol. 139, no. 2, p. 228-234

Variability in male gametic traits can depend on several genetic and environmental factors such as developmental instability as a consequence of inbreeding, developmental noise during spermatogenesis, or age- or condition-dependent changes in allocation to sperm cells. Variation in sperm size is particularly evident in species that produce more than one sperm morph but also occurs among males in...

Université de Neuchâtel

Effect of queen phenotype and social environment on early queen mortality in incipient colonies of the fire ant, Solenopsis invicta

Bernasconi, Giorgina ; Keller, Laurent

In: Animal Behaviour, 1999, vol. 57, no. 2, p. 371-377

In many ant species, including the fire ant Solenopsis invicta, queens can found their colonies alone or in associations of two or more. Colonies founded by associations produce a larger worker brood, have higher survival and mature earlier than colonies founded by solitary queens. However, cofoundresses almost invariably fight after the eclosion of the first workers. As a result, only one...

Université de Neuchâtel

Fertilization competence and sperm size variation in sperm-heteromorphic insects

Bernasconi, Giorgina ; Hellriegel, B.

In: Evolutionary Ecology, 2005, vol. 19, no. 1, p. 45-54

Between species, variation in sperm size has been related to male–female coevolution and male–male competition. In contrast, variation within species is poorly understood. A particular case of intraspecific sperm-size variation occurs in sperm-heteromorphic species, where males produce distinct sperm morphotypes, usually only one of which is fertile. This allows to investigate sperm size...

Université de Neuchâtel

Seed paternity in flowering plants: an evolutionary perspective

Bernasconi, Giorgina

In: Perspectives in Plant Ecology, Evolution and Systematics, 2003, vol. 6, no. 3, p. 149-158

The ultimate importance of paternal contributions to fitness and of post-pollination selection in flowering plants have remained elusive, largely because of the technical difficulty of assigning paternity. I review empirical studies that use heritable markers to investigate per-fruit seed paternity in natural populations and after experimental multiple-donor pollination. Thirty-one studies...

Université de Neuchâtel

Sperm survival in the female reproductive tract in the fly Scathophaga stercoraria (L.)

Bernasconi, Giorgina ; Hellriegel, B. ; Heyland, A. ; Ward, P. I.

In: Journal of Insect Physiology, 2002, vol. 48, no. 2, p. 197-203

While sperm competition risk favours males transferring many sperm to secure fertilizations, females of a variety of species actively reduce sperm numbers reaching their reproductive tract, e.g. by extrusion or killing. Potential benefits of spermicide to females include nutritional gains, influence over sperm storage and paternity, and the elimination of sperm bearing somatic mutations that...

Université de Neuchâtel

Cooperation among unrelated individuals: the ant foundress case

Bernasconi, Giorgina ; Strassmann Joan E.

In: Trends in Ecology and Evolution, 1999, vol. 14, no. 12, p. 477-482

Ant foundress associations are an example of cooperation among non-kin. Across a dozen genera, queens able to found a colony alone often join unrelated queens, thereby enhancing worker production and colony survivorship. The benefits of joining other queens vary with group size and ecological conditions. However, after the first workers mature, the queens fight until only one survives. The...

Université de Neuchâtel

Reply from G. Bernasconi and J.E. Strassmann

Bernasconi, Giorgina ; Strassmann Joan E.

In: Trends in Ecology and Evolution, 2000, vol. 15, no. 3, p. 117

Université de Neuchâtel

Microgametophyte population sizes and plant reproductive output in the insect-pollinated Prunella grandiflora (Lamiaceae)

Bernasconi, Giorgina ; Lang, Daniela J. ; Schmid, Bernhard

In: New Phytologist, 2006, vol. 173, no. 1, p. 393-400

• Intraspecific variation in pollen deposition and number of pollen tubes per style is rarely quantified, but is essential for assessing the occurrence of pollen limitation and pollen competition and their evolutionary implications. Moreover, pollen deposition, pollen tube growth, and the fate of fertilized ovules are rarely distinguished in field studies. Here we present such a study in eight...

Université de Neuchâtel

Female polyandry affects their sons' reproductive success in the red flour beetle Tribolium castaneum

Bernasconi, Giorgina ; Keller, Laurent

In: Journal of Evolutionary Biology, 2001, vol. 14, no. 1, p. 186-193

A potential benefit to females mating with multiple males is the increased probability that their sons will inherit traits enhancing their pre- or post-mating ability to obtain fertilizations. We allowed red flour beetle (Tribolium castaneum) females to mate on three consecutive days either repeatedly to the same male or to three different males. This procedure was carried out in 20...