Commonality in traits and hierarchical structure of vertebrate establishment success

Abstract

Aim We sought to (1) identify commonalities in functional species traits among organisms of multiple vertebrate classes introduced between Europe and North America, and (2) identify causal hierarchical structure (if any) among key mechanisms determining vertebrate establishment success. Location Europe and North America. Methods We updated a portion of the dataset originally compiled by Jeschke and Strayer (2006, Global Change Biology, 12, 1608) to model establishment success of 139 vertebrates (birds, mammals and bony fishes) introduced between Europe and North America. We used conditional inference trees (CITs) to classify introduced species as either failing or succeeding to become established. We then developed a conceptual hypothesis of hierarchical structure among invasion mechanisms in which species traits influence establishment success (1) directly, and (2) indirectly, by affecting propagule pressure (approximated by the number of introductions) and native range size. We evaluated this hypothesis using path analysis. Results Conditional inference trees identified number of introductions as the most important classifier of vertebrate establishment success. Secondarily, several standardized species traits operated across taxa to predict establishment success. Likewise, number of introductions and native range size were the only direct predictors of vertebrate establishment success in path models. However, these variables were also directly affected by a suite of species traits. Species that were introduced more often had greater reproductive allocation, longer lifespans and broader diets; species with larger native range sizes had greater thermal tolerance. Cumulative indirect effects of most traits were 2–3 times stronger than direct effects of other factors. Main Conclusions We show that vertebrates share several traits that contribute to invasiveness across taxa. Using a hierarchical approach to quantify indirect effects of traits on establishment success accounts for existing empirical disparity regarding the relative role of traits versus other factors contributing to establishment success of introduced vertebrates.

Relationships between landscape constraints and a crayfish assemblage with consideration of competitor presence

“…Surprisingly, ringed crayfish and gapped ringed crayfish were negatively associated with the presence of other strong competitors. Virile crayfish tend to be larger, more fecund and have a wider distribution than both ringed crayfish and gapped ringed crayfish (Pflieger, ), which suggests they may be superior competitors (Larson & Olden, ; Peoples & Goforth, ). Of course, there are several population characteristics that contribute to the invasion potential of crayfish (e.g., aquaculture production, parthenogenesis; Souty‐Grosset, ).…”

Where we've been and where we're going: the importance of source communities in predicting establishment success from phylogenetic relationships

“…Focusing on species traits instead of, or in combination with, phylogeny may eventually improve our ability to predict establishment success. Traits related to body size, reproduction, migration, environmental tolerances and diet have all been shown to influence establishment success (Forsyth et al 2004, Blackburn et al 2009b, Kempel et al 2013, Arndt and Schembri 2015, Mahoney et al 2015, Peoples and Goforth 2017). However, as with approaches based on phylogenetic metrics, trait‐based approaches typically fall short of linking establishment success with a particular coexistence mechanism (but see Godoy and Levine 2014).…”

“…The question of whether establishment is predictable has naturally received considerable attention (Elton 1958, Vermeij 1996, Davis et al 2001, Devin and Beisel 2007, Hayes and Barry 2008, Blackburn et al 2009a, Lockwood et al 2009, van Wilgen and Richardson 2012, Kempel et al 2013). Despite a growing literature of clade‐specific studies on traits that may increase success (Forsyth et al 2004, Blackburn et al 2009b, Kempel et al 2013, Arndt and Schembri 2015, Mahoney et al 2015, Peoples and Goforth 2017), few general correlates of establishment or invasion success have been found (Hayes and Barry 2008), with perhaps the most notable being propagule pressure (Blackburn et al 2015). Due to this lack of general predictors of invasion success there is a growing interest in using the phylogenetic distance between introduced and native species to predict the success of introductions (Strauss et al 2006, Thuiller et al 2010, Van Wilgen and Richardson 2011, Violle et al 2011, Maitner et al 2012, van Wilgen and Richardson 2012, reviewed by Ma et al 2016).…”