Improbable but true: the invasive inbreeding ambrosia beetle Xylosandrus morigerus has generalist genotypes

Abstract

The wide distribution and dominance of invasive inbreeding species in many forest ecosystems seems paradoxical in face of their limited genetic variation. Successful establishment of invasive species in new areas is nevertheless facilitated by clonal reproduction: parthenogenesis, regular self-fertilization, and regular inbreeding. The success of clonal lineages in variable environments has been explained by two models, the frozen niche variation (FNV) model and the general-purpose genotype (GPG) model. We tested these models on a widely distributed forest pest that has been recently established in Costa Rica—the sibling-mating ambrosia beetle Xylosandrus morigerus. Two deeply diverged mitochondrial haplotypes coexist at multiple sites in Costa Rica. We find that these two haplotypes do not differ in their associations with ecological factors. Overall the two haplotypes showed complete overlap in their resource utilization; both genotypes have broad niches, supporting the GPG model. Thus, probable or not, our findings suggest that X. morigerus is a true ecological generalist. Clonal aspects of reproduction coupled with broad niches are doubtless important factors in the successful colonization of new habitats in distant regions.

New Plant-Parasitic Nematode from the Mostly Mycophagous Genus Bursaphelenchus Discovered inside Figs in Japan

“…and the two or three different paraphyletic Schistonchus lineages suggest other possible scenarios, such as rogue introductions of fungal feeding nematodes by other fig-associating insects or other unknown aspects concerning fig biology. For example, the new species is close to the species associated with ambrosia beetles ( B. kiyoharai ) [48] and stag beetles ( B. tadamiensis ) [49], and some ambrosia beetles invade the petiole of living trees in tropical region [73], [74]. Given the relatively short branch length (genetic distance) between B. sycophilus n. sp.…”

Tracing the origin of a cryptic invader: phylogeography of theEuwallacea fornicatus(Coleoptera:Curculionidae:Scolytinae) species complex

“…However, deep intraspecific divergence in the COI of bark and ambrosia beetles may not be uncommon (Jordal & Kambestad, ). Within the Xyleborini, levels of intraspecific divergence higher than 9.5% have been reported in COI sequences of Xylosandrus morigerus , Xyleborinus crassiusculus and Xyleborinus saxeseni (Dole et al ., ; Andersen et al ., ; Jordal & Kambestad, ). However, in each of these examples, divergence in the nuclear ribosomal 28S gene was reported to be minimal (0–0.2%).…”

Explaining biogeographical range size and measuring its effect on species diversification in bark beetles

“…Being functionally similar, inbreeding which is very common among invasive species (Price & Jain, 1981;Jordal et al, 2001;Allendorf & Lundquist, 2003;Terhivuo & Saura, 2006)has a similar effect. Both asexually reproducing and inbreeding organisms are preadapted for dispersal in that single (mated, in the case of inbreeding species) individuals are sufficient for establishment in a new area (Baker, 1955;Andersen et al, 2012). Also, with their immunity to inbreeding depression (Peer & Taborsky, 2005), inbreeders are more likely to have high fitness in their new environment.…”

“…The second potential predictor of dispersal ability is inbreeding, which is very common among invasive plants and animals (Price & Jain, 1981;Jordal et al, 2001;Allendorf & Lundquist, 2003;Terhivuo & Saura, 2006). The kind of inbreeding seen in certain bark beetle groups is betweensiblings mating within the nests prior to dispersal, which enables single inseminated females to establish new populations (Baker, 1955;Andersen et al, 2012). While most other bark and ambrosia beetles locate mates at the entrance of a newly started nest, females from species that mate before dispersal save time and reduces the risk of predation.…”