Competitive displacement of the native species Bursaphelenchus mucronatus by an alien species Bursaphelenchus xylophilus (Nematoda: Aphelenchida: Aphelenchoididae): a case of successful invasion

Abstract

The presence of alien invasive species has serious negative impact on endemic biodiversity, especially on native species that occupy the same niche in the ecosystem. To study the influence of the alien invasive species Bursaphelenchus xylophilus on its native sister species B. mucronatus, the two nematode species were mix-cultured in a fungal mat and mix-inoculated into a susceptible host. By comparing the propagation parameters of both species under competitive and noncompetitive conditions it was shown that the propagation level of B. xylophilus was clearly higher than that of B. mucronatus under laboratory culture. Furthermore, the propagation capacity of B. xylophilus under competitive conditions was much higher than that under noncompetitive conditions, both in laboratory culture and with host inoculation. Bursaphelenchus xylophilus also excluded B. mucronatus when the two species were cultured as a mixture for a longer time. The relative abundance ratios of the two species in natural pinewoods were also determined by random sampling of dying pine trees from regions with different invasion histories. It was noted that with an increase in invasion years the distribution frequency of B. xylophilus increased while that of B. mucronatus decreased. Experimental tests verified our hypothesis that because of its high fecundity and strong competitive ability, the invasive species B. xylophilus out-competed the native species B. mucronatus and displaced it in natural ecosystems. The successful invasion of B. xylophilus is attributed to competitive displacement, which may be one of the ecological invasive mechanisms.

Island biogeography as a test of reproductive interference

“…Instead, the invasion by V. persica probably brought about the habitat alteration of V. p. lilacina on the mainland. The exclusion of native plants by aliens has been claimed in some species to date (Ogawa and Mototani 1985;Cheng et al 2009;Takakura 2012). The present study differs from most prior studies in the following respect.…”

Competition between invasive and indigenous species: an insular case study of subterranean termites

“…Although competition is often difficult to study, it has been clearly demonstrated that invasive species may affect indigenous species by competitive exclusion and niche substitution (Byers 2000;Cheng et al 2009;Gherardi and Daniels 2004;Holway 1999;McNatty et al 2009;Petren and Case 1996;Shinen and Morgan 2009). However, it has been shown that indigenous species can sometimes be more competitive than introduced species (Paini et al 2008), suggesting that the presence of an indigenous competitor may slow and perhaps even prevent the spatial and demographical expansion of invaders.…”

Rapid species displacement during the invasion of Florida by the tropical house gecko Hemidactylus mabouia

“…Studies of species displacement during invasion have shown that it occurs slowly if resource competition is the driving mechanism (Byers and Goldwasser 2001;Cheng et al 2009). While rapid reduction of the abundance of resident species has been documented to occur following predation by invaders (\5 years; (Grosholz et al 2000;Lohrer and Whitlatch 2002), similarly rapid rates of displacement resulting from competition are rarely reported.…”

“…While rapid reduction of the abundance of resident species has been documented to occur following predation by invaders (\5 years; (Grosholz et al 2000;Lohrer and Whitlatch 2002), similarly rapid rates of displacement resulting from competition are rarely reported. While a few studies have documented significant declines in resident species due to competition with invaders in \5 years (Ekesi et al 2009;Ricciardi et al 1998;Rilov et al 2004), typical time spans for such declines are several decades (Bohn et al 2008;Byers and Goldwasser 2001;Cheng et al 2009;Moyer et al 2005;Ricciardi and Whoriskey 2004), and sometimes involve significant lag periods before any declines are observed (Byers and Goldwasser 2001;Rilov et al 2004). The displacement rates we observed in geckos are unusually rapid compared to previously published rates of displacement during invasion.…”

“…Competition, and exploitation in particular, is less asymmetric than predation, because interactions are indirect and mediated through resources. Studies have shown that invasion can result in species displacement through exploitation or interference (Byers 2000;Holway 1999;Juliano 1998;Petren and Case 1996), but it rarely results in displacement of natives over time scales comparable to those for predation (Byers and Goldwasser 2001;Cheng et al 2009;Rilov et al 2004, but see Ekesi et al 2009;Ricciardi et al 1998).…”