Behavioral and genetic characteristics of a new species of Nasonia

Abstract

Nasonia (Hymenoptera: Pteromalidae) is a genus of parasitoid wasps, which is fast emerging as a model system for evolutionary, genetic, developmental and host-endosymbiont interaction studies. In this study, we report a new species, Nasonia oneida, distinguish its behavioral, genetic and morphological features, and characterize its pre-mating and post-mating isolation with the other Nasonia species. Phylogenetic analyses indicate that N. oneida is the sister species to Nasonia giraulti with its own uniquely distinct cuticular hydrocarbon profiles, behavioral characteristics and subtle morphological differences. An important characteristic of N. oneida is the strong mate discrimination shown by the females against all the other Nasonia species. A genetic analysis of this phenotype by interspecies hybridization indicates that this strong discriminating phenotype is recessive. A formal species description of N. oneida Raychoudhury & Desjardins is also provided.

Figure 1

The MrBayes tree of the concatenated nuclear data set comprising of nine genes (5408 base pairs), showing N. oneida to be an independent but closely related lineage of Nasonia.

Figure 2

Haplotype networks of concatenated sequences for the nuclear genes (2A) and the mitochondrial cox1 gene (2B). The size of each node represents its frequency (not to scale). The haplotypes representing the two species are separated by a dashed line.

Figure 2

Haplotype networks of concatenated sequences for the nuclear genes (2A) and the mitochondrial cox1 gene (2B). The size of each node represents its frequency (not to scale). The haplotypes representing the two species are separated by a dashed line.

Figure 3

Discriminant analysis of cuticular hydrocarbon profiling of N. oneida and N. giraulti, showing clear separation by sex and species.

Figure 4

Behavioral observations of N. oneida (O) with A) N. giraulti (G), B) N. longicornis (L) and C) N. vitripennis (V), showing N. oneida females to be strongly isolated from the other three species. F1 hybrids between species have significantly reduced levels of mate discrimination. Hybrid crosses were done in both directions and cytoplasm of F1 hybrids are indicated by []. Two different N. oneida and N. giraulti strains were used for these observations (O1, O2 and G1, G2, respectively) while hybrid females were established only with the Wolbachia-free strain O1U. (Light grey bars: acceptance of conspecific males. Black bars: acceptance of heterospecific males. Dark grey bars: hybrid female acceptance.) See text for details.

Figure 5

Mean numbers of male offspring obtained from virgins of the four species and their hybrids. Family sizes of hybrid females are indicated with grey bars. (V, G, L, and O are N. vitripennis, N. giraulti, N. longicornis and N. oneida respectively). Hybridizations were done in both directions and cytoplasm is indicated by []. See text for details.

Figure 6

Crosses between Wolbachia infected N. oneida (O) and N. giraulti (G) showing no effects of cytoplasmic incompatibility between the species.

Figure 7

Morphological differences between N. oneida and the other Nasonia species. N. oneida has an angulate scape (a) as does N. giraulti (b), while N. vitripennis has a spindle-shaped scape and N. longicornis has a cylindrical scape. N. oneida has the narrowest male antennal flagellum (a), with a length to width ratio of ~10.4:1 (a). N. longicornis, N. giraulti and N. vitripennis have progressively wider antennal flagella, with length to width ratios of ~9.5:1, ~8.3:1, and ~8.0:1, respectively (b, c, and d). N. oneida females tend to have a slighty curved stigmal vein on the forewing (e), which is more similar to the straight stigmal vein of N. vitripennis (h) than to the stongly arched stigmal vein of N. giraulti (f) or the elbowed stigmal vein of N. longicornis (g). The forewings of N. oneida males are broad and rounded (i), similar to those of N. giraulti (j), while the forewings of N. longicornis are triangular (k) and those of N. vitripennis are short and narrow.

Figure 7

Morphological differences between N. oneida and the other Nasonia species. N. oneida has an angulate scape (a) as does N. giraulti (b), while N. vitripennis has a spindle-shaped scape and N. longicornis has a cylindrical scape. N. oneida has the narrowest male antennal flagellum (a), with a length to width ratio of ~10.4:1 (a). N. longicornis, N. giraulti and N. vitripennis have progressively wider antennal flagella, with length to width ratios of ~9.5:1, ~8.3:1, and ~8.0:1, respectively (b, c, and d). N. oneida females tend to have a slighty curved stigmal vein on the forewing (e), which is more similar to the straight stigmal vein of N. vitripennis (h) than to the stongly arched stigmal vein of N. giraulti (f) or the elbowed stigmal vein of N. longicornis (g). The forewings of N. oneida males are broad and rounded (i), similar to those of N. giraulti (j), while the forewings of N. longicornis are triangular (k) and those of N. vitripennis are short and narrow.

Figure 7

Morphological differences between N. oneida and the other Nasonia species. N. oneida has an angulate scape (a) as does N. giraulti (b), while N. vitripennis has a spindle-shaped scape and N. longicornis has a cylindrical scape. N. oneida has the narrowest male antennal flagellum (a), with a length to width ratio of ~10.4:1 (a). N. longicornis, N. giraulti and N. vitripennis have progressively wider antennal flagella, with length to width ratios of ~9.5:1, ~8.3:1, and ~8.0:1, respectively (b, c, and d). N. oneida females tend to have a slighty curved stigmal vein on the forewing (e), which is more similar to the straight stigmal vein of N. vitripennis (h) than to the stongly arched stigmal vein of N. giraulti (f) or the elbowed stigmal vein of N. longicornis (g). The forewings of N. oneida males are broad and rounded (i), similar to those of N. giraulti (j), while the forewings of N. longicornis are triangular (k) and those of N. vitripennis are short and narrow.