Reduced vertebrate diversity independent of spatial scale following feral swine invasions

Abstract

Biological invasions often have contrasting consequences with reports of invasions decreasing diversity at small scales and facilitating diversity at large scales. Thus, previous literature has concluded that invasions have a fundamental spatial scale‐dependent relationship with diversity. Whether the scale‐dependent effects apply to vertebrate invaders is questionable because studies consistently report that vertebrate invasions produce different outcomes than plant or invertebrate invasions. Namely, vertebrate invasions generally have a larger effect size on species richness and vertebrate invaders commonly cause extinction, whereas extinctions are rare following invertebrate or plant invasions. In an agroecosystem invaded by a non‐native ungulate (i.e., feral swine, Sus scrofa ), we monitored species richness of native vertebrates in forest fragments ranging across four orders of magnitude in area. We tested three predictions of the scale‐dependence hypothesis: (a) Vertebrate species richness would positively increase with area, (b) the species richness y‐intercept would be lower when invaded, and (c) the rate of native species accumulation with area would be steeper when invaded. Indeed, native vertebrate richness increased with area and the species richness was 26% lower than should be expected when the invasive ungulate was present. However, there was no evidence that the relationship was scale dependent. Our data indicate the scale‐dependent effect of biological invasions may not apply to vertebrate invasions.

The Stages of Invasion: How does a nonnative species transition to an invader?

“…Their behavior-feeding, rooting in the soil for food, wallowing in water or mud to stay cool-alters the ecosystem by degrading the natural habitat and lowering biodiversity (Singer et al 1984). One study determined that mammal and bird diversity declined 26% where feral hogs were present (Ivey et al 2019). Feral hogs are also known to carry diseases, including foot and mouth disease, which can have serious impacts on native mammals and domesticated livestock (Morgan et al 2021).…”

Estimating body mass of wild pigs (Sus scrofa) using body morphometrics

“…For example, in the United States, wild pigs have colonized at least 35 states and continue to expand their range (Lewis et al 2019;McKee et al, 2020). Their expansion into non-native ranges has resulted in widespread economic losses and negatively impacted flora and fauna (Barrios-Garcia & Ballari, 2012;Ivey et al, 2019;McDonough et al, 2022;McKee et al, 2020;Pimentel, 2007). Because of their economic and ecological impacts, wild pigs are frequently the target of eradication efforts (e.g., trapping, aerial gunning, ground shooting; Gaskamp et al, 2021;Massei et al, 2011;McKee et al, 2020), but several factors such as high reproductive rates, general dietary habits, and dispersal capability make this species extremely challenging to eradicate (Ditchkoff et al, 2017).…”

Population genetic characteristics of Aedes aegypti in 2019 and 2020 under the distinct circumstances of dengue outbreak and the COVID-19 pandemic in Yunnan Province, China

“…Biological invasion is closely related to human health and genetic factors of invasive species, such as genetic variation and diversity ( Ivey et al, 2019 ). These factors are important indicators for revealing the status of invasive species ( Rasheed et al, 2013 ; Chown et al, 2015 ).…”