Université de Neuchâtel

Complexity in quantitative food webs

Banašek-Richter, Carolin ; Bersier, Louis-Félix ; Cattin, Marie-France ; Baltensperger, Richard ; Gabriel, Jean-Pierre ; Merz, Yves ; Ulanowicz, Robert E. ; Tavares, Annette F. ; Williams, D. Dudley ; de Ruiter, Peter C. ; Winemiller, Kirk O. ; Naisbit, Russell. E.

In: Ecology, 2009, vol. 90, no. 6, p. 1470-1477

Food webs depict who eats whom in communities. Ecologists have examined statistical metrics and other properties of food webs, but mainly due to the uneven quality of the data, the results have proved controversial. The qualitative data on which those efforts rested treat trophic interactions as present or absent and disregard potentially huge variation in their magnitude, an approach similar to...

Université de Neuchâtel

Counter-intuitive developmental plasticity induced by host quality

Röder, Gregory ; Rahier, Martine ; Naisbit, Russell. E.

In: Proceedings of the Royal Society B, 2007, vol. 275, no. 1637, p. 879-885

Adaptation to different hosts plays a central role in the evolution of specialization and speciation in phytophagous insects and parasites, and our ability to experimentally rank hosts by their quality is critical to research to understand these processes. Here we provide a counter-intuitive example in which growth is faster on poor quality hosts. The leaf beetles Oreina elongata and...

Université de Neuchâtel

Glacial survival and local adaptation in an alpine leaf beetle

Margraf, Nicolas ; Verdon, Aline ; Rahier, Martine ; Naisbit, Russell. E.

In: Molecular Ecology, 2007, vol. 16, no. 11, p. 2333-2343

The challenge in defining conservation units so that they represent evolutionary entities has been to combine both genetic properties and ecological significance. Here we make use of the complexity of the European Alps, with their genetic landscape shaped by geographical barriers and postglacial colonization, to examine the correlation between ecological and genetic divergence. Montane species,...

Université de Neuchâtel

Coping with an antagonist: the impact of a phytopathogenic fungus on the development and behaviour of two species of alpine leaf beetle

Röder, Gregory ; Rahier, Martine ; Naisbit, Russell. E.

In: Oikos, 2007, vol. 116, no. 1, p. 1514-1523

Herbivorous insects and phytopathogenic fungi often share their host plants. This creates a network of direct and indirect interactions, with far-reaching consequences for the ecology and evolution of all three parties. In the Alps, the leaf beetles Oreina elongata and Oreina cacaliae (Coleoptera: Chrysomelidae), and the rust fungus Uromyces cacaliae (Uredinales:...

Université de Neuchâtel

Genetic and Environmental Sources of Variation in the Autogenous Chemical Defense of a Leaf Beetle

Triponez, Yann ; Naisbit, Russell. E. ; Jean-Denis, J. B. ; Rahier, Martine ; Alvarez, Nadir

In: Journal of Chemical Ecology, 2007, vol. 33, no. 11, p. 2011-2024

Chemical defense plays a central role for many herbivorous insects in their interactions with predators and host plants. The leaf beetle genus Oreina (Coleoptera, Chrysomelidae) includes species able to both sequester pyrrolizidine alkaloids and autogenously produce cardenolides. Sequestered compounds are clearly related to patterns of host-plant use, but variation in de novo...

Université de Neuchâtel

Disruptive sexual selection against hybrids contributes to speciation between Heliconius cydno and Heliconius melpomene

Naisbit, Russell. E. ; Jiggins, Chris D. ; Mallet, James

In: Proceedings of the Royal Society, 2001, vol. 268, no. 1478, p. 1849-1854

Understanding the fate of hybrids in wild populations is fundamental to understanding speciation. Here we provide evidence for disruptive sexual selection against hybrids between Heliconius cydno and Heliconius melpomene. The two species are sympatric across most of Central and Andean South America, and coexist despite a low level of hybridization. No-choice mating experiments show...

Université de Neuchâtel

Reproductive isolation caused by colour pattern mimicry

Jiggins, Chris D. ; Naisbit, Russell. E. ; Coe Rebecca L. ; Mallet, James

In: Nature, 2001, vol. 411, p. 302-305

Speciation is facilitated if ecological adaptation directly causes assortative mating, but few natural examples are known. Here we show that a shift in colour pattern mimicry was crucial in the origin of two butterfly species. The sister species Heliconius melpomene and Heliconius cydno recently diverged to mimic different model taxa, and our experiments show that their mimetic...

Université de Neuchâtel

Mimicry: developmental genes that contribute to speciation

Naisbit, Russell. E. ; Jiggins, Chris D. ; Mallet, James

In: Evolution & Development, 2003, vol. 5, no. 3, p. 269-280

Despite renewed interest in the role of natural selection as a catalyst for the origin of species, the developmental and genetic basis of speciation remains poorly understood. Here we describe the genetics of Müllerian mimicry in Heliconius cydno and H. melpomene (Lepidoptera: Nymphalidae), sister species that recently diverged to mimic other Heliconius. This mimetic shift...

Université de Neuchâtel

Sex-Linked Hybrid Sterility in a Butterfly

Jiggins, Chris D. ; Linares, Mauricio ; Naisbit, Russell. E. ; Salazar, Camilo ; Yang, Ziheng H. ; Mallet, James

In: Evolution, 2001, vol. 55, no. 8, p. 1631–1638

Recent studies, primarily in Drosophila, have greatly advanced our understanding of Haldane's rule, the tendency for hybrid sterility or inviability to affect primarily the heterogametic sex (Haldane 1922). Although dominance theory (Turelli and Orr 1995) has been proposed as a general explanation of Haldane's rule, this remains to be tested in female-heterogametic taxa, such as the...

Université de Neuchâtel

Conserved oviposition preferences in alpine leaf beetle populations despite host shifts and isolation

Verdon, Aline ; Margraf, Nicolas ; Davison, Anthony C. ; Rahier, Martine ; Naisbit, Russell. E.

In: Ecological Entomology, 2007, vol. 32, no. 1, p. 62-69

1. Choosing the plant on which to lay their eggs is the last act of care that most female herbivorous insects bestow upon their offspring. These decisions play a pivotal role in insect–plant interactions, placing host preference under strong selection and contributing to the diversity of phytophagous insects as one of the first traits to adapt to new hosts. 2. This study presents a test of...