Evidence for enemy release in invasive common daceLeuciscus leuciscusin Ireland: a helminth community survey and systematic review

Abstract

Invasive species lose parasites in the process of invasion and tend to be less parasitized than conspecifics in the native range and sympatric native species in the invasive range (enemy release). We evaluated enemy release in an invasive freshwater fish in Ireland, common dace Leuciscus leuciscus, using helminth parasite community surveys at the core and front of the invasive range of common dace. Furthermore, we undertook a systematic literature review of helminth infection in common dace across its native range in Great Britain and Europe and invasive range in Ireland. The helminth parasite community survey revealed that invasive common dace were infected with fewer helminth species at the invasion front than at the core. Four helminth taxa – Acanthocephala, Monogenea, Digenea and Nematoda – were present in dace at the invasion core compared to only a single helminth species (Pomphorhynchus tereticollis) at the front. The systematic review revealed that invasive common dace in Ireland hosted fewer species of helminths than common dace in the native range. We report a total of three helminth species in common dace in Ireland compared to 24 in Great Britain and 84 in Continental Europe. Our results support the hypotheses that invasive populations are less parasitized than native populations and that more recently established populations host fewer parasites. However, we demonstrate that invasive species may continue to experience release from parasites long after initial invasion.

Prey naïveté rather than enemy release dominates the relation of an invasive spider toward a native predator

“…As one of the most predominant and intuitive, the enemy release hypothesis posits that nonindigenous species are released from the pressure of predators and parasites once introduced to their exotic ranges (Elton, 1958 ; Keane & Crawley, 2002 ). Introduced species might have advantages over resident species against native enemies by, for example, not being recognized as prey or hosts for parasites in the exotic range (e.g., Cottrell & Shapiro‐Ilan, 2003 ; Gozzi et al., 2020 ; Montes et al., 2020 ; Tierney et al., 2020 ). However, Elton ( 1958 ) mentions that species leaving coevolved predators and parasites from the native areas immediately meet novel potential enemies once introduced in the exotic range.…”

“…Therefore, the enemy release hypothesis as a driving force behind successful invasions should be tested for already established invasive species that are in their spreading phase (i.e., abundant or dominant) in the exotic range. Furthermore, studies investigating the role of enemy release as a causal mechanism of invasiveness are mainly based on invasive plant and vertebrate species (e.g., Carpenter & Cappuccino, 2005 ; Gozzi et al., 2020 ; Hawkes, 2007 ; Hierro et al., 2005 ; van Kleunen et al., 2010 ; Lankau et al., 2004 ; Liu & Stiling, 2006 ; Meijer et al., 2016 ; Montes et al., 2020 ; Schultheis et al., 2015 ; Tierney et al., 2020 ), whereas only a limited number is focused on arthropods (e.g., Aliabadi & Juliano, 2002 ; Juliano et al., 2010 ; Paula et al., 2021 ; Zuharah & Lester, 2010 ).…”