View - ResearchGate

82
6.2 Hypotheses to Explain Biological Invasion
R.A. Hufbauer and M.E. Torchin
Demographic expansions of invasive species are influenced by multiple biotic
and abiotic factors. Our aim is to review ecological and evolutionary hypotheses
of invasion success, and to explain relationships among biotic factors,
including characteristics of both the invaded communities and the invaders
themselves (Table 6.1). We evaluate whether the hypotheses can help explain
strong invasion, or not. We first outline multiple hypotheses, and then focus
on four: two ecological (enemy release, biotic resistance) and two evolutionary
(evolution of increased competitive ability, hybridization). We further
explore links between these four hypotheses. Most existing work integrating
across hypotheses focuses on ecological hypotheses only (though see Facon et
al. 2006). We offer ideas connecting ecological and evolutionary hypotheses,
and suggest ways in which a more clear and integrated framework may help
explain seemingly contradictory results.
Table 6.1 Main ecological and evolutionary hypotheses to explain invader success following
introduction, and whether they can help explain strong invasion (R>1)
Hypotheses Selected early and recent references R>1
Ecological hypotheses
Preadaptation/disturbance Baker and Stebbins (1965), Sax and Brown (2000) No
Inherent superiority Elton (1958), Sax and Brown (2000) No
Novel weapons Callaway and Ridenour (2004) Yes
Empty niche Elton (1958), Hierro et al. (2005) No
Mutualist facilitation/ Simberloff and Von Holle (1999), No
invasional meltdown Richardson et al. (2000)
Biotic resistance Elton (1958), Levine et al. (2004) Yes
Enemy release Darwin (1859), Torchin and Mitchell (2004) Yes
Evolutionary hypotheses
Hybridization Ellstrand and Schierenbeck (2000) Yes
Evolution of increased Blossey and Nötzold (1995) Yes
competitive ability
Founder events Mayr (1954) Yes
Genetic architecture Lee (2002) No