to the interactions between habitat heterogeneity, habitat preferences and interspecific

competition (e.g., Vasconcelos and Davidson 2000, Yu et al. 2001, Palmer 2003).

Nesting space may be a limiting resource in these relationships (Fonseca 1999), and

therefore ants commonly compete to maintain occupancy of a plant, often to the point of

mutual exclusion, as the host plant grows (Janzen 1966, Davidson et al. 1989, Stanton et

al. 2002). Because ant species often differ dramatically in their ability to defend their

host plants, variation in occupancy could significantly influence plant performance

(Janzen 1975, McKey 1984, Itioka et al. 2000, Heil et al. 2001a, Bruna et al. 2004).

Addressing the factors that affect ant community composition as myrmecophytes grow

and the consequent effects on herbivore damage sustained by the host plant is a critical

component of understanding the temporal dynamics of ant-plant protection relationships

and is the focus of this study.

 Cordia alliodora is a fast-growing myrmecophytic tree common in secondary

forests and fields throughout much of Central America and northern South America. The

ant associates of C. alliodora inhabit naturally hollow swellings, known as domatia,

produced by the plants at most branch nodes (Figure 1-1). In Costa Rica, more than ten

different ant species have been recorded occupying the domatia of C. alliodora, including

both specialists to that myrmecophyte and stem-nesting generalists (Wheeler 1942,

Longino 1996, Tillberg 2004). Unlike many other myrmecophytes, mature C. alliodora

trees often host colonies of multiple ant species simultaneously, making this system

particularly suitable to studies of species coexistence (Longino 1996; Tillberg 2003,

2004).