“…This feedback effect is discussed in greater detail in the following sections. 9 See, for instance, Koch (1974), Butler & Waltman (1981), Smith (1982), Cushing (1984), Gardini, Lupini & Messia (1989), Hofbauer & So (1994), Korobeinikov & Wake (1999), Hsu, Hwang & Kuang (2001), Loladze, Kuang, Elser & Fagan (2004), Feng & Hinson (2005; a collection of results for a class of such systems might be found in Zeeman (1993) and Zeeman & Zeeman (2002); for a more general discussion in the context of dynamical possibilities in three-dimensional differential equation systems, see Kuznetsov (1997).…”