Practice question

In a core–satellite, or mainland–island, metapopulation, a large persistent core population provides a continuing supply of emigrants to smaller peripheral populations. The core has low extinction risk because of its size or superior habitat quality, whereas satellite patches may frequently disappear and be recolonized. Regional persistence therefore depends heavily on propagule production from the core. Equal gene flow among all patches is not required; movement is often asymmetric from core to satellites. A high extinction rate in satellites may characterize the system but does not maintain it without compensating colonization. Mutation is not the ecological process supporting patch occupancy. The model differs from the classic Levins structure, which treats patches as more similar, and from a source–sink framework, although a core often functions as a demographic source. Protecting only satellites while degrading the core can therefore destabilize the entire network. Conversely, conserving the large persistent population and its dispersal routes can sustain otherwise transient local populations across a fragmented landscape.