Showing papers by "Leo W. Beukeboom published in 2003"

Gene flow between arrhenotokous and thelytokous populations of Venturia canescens (Hymenoptera).

Abstract: In the solitary parasitoid wasp Venturia canescens both arrhenotokously (sexual) and thelytokously (parthenogenetical) reproducing individuals occur sympatrically. We found in the laboratory that thelytokous wasps are able to mate, receive and use sperm of arrhenotokous males. Using nuclear (amplified fragment length polymorphism, virus-like protein) and mitochondrial (restriction fragment length polymorphism) markers, we show the occurrence of gene flow from the arrhenotokous to the thelytokous mode in the field. Our results reinforce the paradox of sex in this species.

Genetics of courtship behaviour: A selection experiment in Nasonia vitripennis (Hymenoptera: Pteromalidae): Proc. Exper. Appl. Entomol. NEV Amsterdam

Abstract: The three sibling species from the Nasonia group (N. vitripennis, N. longicornis, N. giraulti) broadly show similar courtship behaviour patterns but with species-specific variations. Previous studies on hybrids between N. vitripennis and N. longicornis have shown a tendency of hybrid males to behave as the (grand) paternal species. It is not known whether this 'grandfather effect' occurs within species. A selection experiment in N. vitripennis was performed to obtain lines with extreme values for a particular behavioural character within this species. Although in previous studies evidence for a genetic basis of courtship behaviour was found, the component under selection (head nods number) showed only a weak response. In recently diverged species, the study of behaviour may explain how reproductive isolation evolved, or how it has been maintained. In the Nasonia sibling species group, composed of N. vitripennis, N. giraulti and N. longicornis, infection with different strains of Wolbachia bacteria cause the reproductive isolation, through cytoplasmic incompatibility in interspecific crosses (Bordenstein & Werren, 1998). However, after treatment with antibiotics, and despite some hybrid breakdown, viable and fertile offspring can be obtained from interspecies crosses (Breeuwer & Werren, 1995). Courtship and mating behaviour of Nasonia has been well studied (Van den Assem, 1986; Van den Assem & Werren, 1994). A male mounts on top of a female and starts the courtship, performing strong movements with the head that coincide with the release of pheromones. These movements are the so-called head nods, and are performed in consecutive series. Other components come along with the courtship display such as 'feet rubbing' (legs movement 'sweeping' the females eyes), and 'minus nods' (inconspicuous head movements). The three species show many similarities in courtship components, but some differences are species-specific. For example, the mean number of head nods in the first nods series is species-specific, and feet rubbing and minus nods are only present in N. longicornis (Van den Assem & Werren, 1994). The study of N. vitripennis x N. longicornis hybrids' behaviour showed a peculiar outcome. As expected by general mendelian laws of inheritance, hybrid behaviour was intermediate to both parental species, but it showed a significant bias towards the grandfathers' species in both reciprocal crosses ('grandfather effect', Beukeboom & Van den Assem, 2001). This cannot be explained by cytoplasmic factors, because in that case it would show a bias towards the grandmothers' species behaviour. It has not yet been established whether this grandfather effect is restricted to hybrids, or if it also occurs in pure species. This would be of special interest, since '… the possibility that the maternal and paternal genomes of hymenopteran females are nonequivalents could prompt a rethink of three decades of theoretical models on the evolution of social behavior in ants, wasps and bees' (Haig, 1988). To answer this question, behavioural lines with quantitatively different characters are needed. In N. vitripennis, most natural lines show similar behavioural features (Peire-Morais unpublished results). It is therefore necessary to artificially generate divergent behavioural lines, to subsequently cross them and test for the grandfather effect. For this purpose, a selection experiment was performed in N. vitripennis. The character under selection was the number of head nods in the first series. Four lines were selected for a high number of nods, and four for a low number of nods for four generations.

Genetics of courtship behaviour: A selection experiment in Nasonia vitripennis (Hymenoptera: Pteromalidae)

Abstract: The three sibling species from the Nasonia group (N. vitripennis, N. longicornis, N. giraulti) broadly show similar courtship behaviour patterns but with species-specific variations. Previous studies on hybrids between N. vitripennis and N. longicornis have shown a tendency of hybrid males to behave as the (grand) paternal species. It is not known whether this 'grandfather effect' occurs within species. A selection experiment in N. vitripennis was performed to obtain lines with extreme values for a particular behavioural character within this species. Although in previous studies evidence for a genetic basis of courtship behaviour was found, the component under selection (head nods number) showed only a weak response. In recently diverged species, the study of behaviour may explain how reproductive isolation evolved, or how it has been maintained. In the Nasonia sibling species group, composed of N. vitripennis, N. giraulti and N. longicornis, infection with different strains of Wolbachia bacteria cause the reproductive isolation, through cytoplasmic incompatibility in interspecific crosses (Bordenstein & Werren, 1998). However, after treatment with antibiotics, and despite some hybrid breakdown, viable and fertile offspring can be obtained from interspecies crosses (Breeuwer & Werren, 1995). Courtship and mating behaviour of Nasonia has been well studied (Van den Assem, 1986; Van den Assem & Werren, 1994). A male mounts on top of a female and starts the courtship, performing strong movements with the head that coincide with the release of pheromones. These movements are the so-called head nods, and are performed in consecutive series. Other components come along with the courtship display such as 'feet rubbing' (legs movement 'sweeping' the females eyes), and 'minus nods' (inconspicuous head movements). The three species show many similarities in courtship components, but some differences are species-specific. For example, the mean number of head nods in the first nods series is species-specific, and feet rubbing and minus nods are only present in N. longicornis (Van den Assem & Werren, 1994). The study of N. vitripennis x N. longicornis hybrids' behaviour showed a peculiar outcome. As expected by general mendelian laws of inheritance, hybrid behaviour was intermediate to both parental species, but it showed a significant bias towards the grandfathers' species in both reciprocal crosses ('grandfather effect', Beukeboom & Van den Assem, 2001). This cannot be explained by cytoplasmic factors, because in that case it would show a bias towards the grandmothers' species behaviour. It has not yet been established whether this grandfather effect is restricted to hybrids, or if it also occurs in pure species. This would be of special interest, since '… the possibility that the maternal and paternal genomes of hymenopteran females are nonequivalents could prompt a rethink of three decades of theoretical models on the evolution of social behavior in ants, wasps and bees' (Haig, 1988). To answer this question, behavioural lines with quantitatively different characters are needed. In N. vitripennis, most natural lines show similar behavioural features (Peire-Morais unpublished results). It is therefore necessary to artificially generate divergent behavioural lines, to subsequently cross them and test for the grandfather effect. For this purpose, a selection experiment was performed in N. vitripennis. The character under selection was the number of head nods in the first series. Four lines were selected for a high number of nods, and four for a low number of nods for four generations.