Immigration prevents extinction in a patch; this phenomenon is called:
“Rescue effect” for immigration prevents extinction in a patch; this phenomenon is called. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Island biogeography explains species richness as a dynamic balance between immigration and extinction. Immigration generally declines as an island fills with species, whereas extinction rises as more species divide finite area and maintain smaller populations. The remaining alternatives—“Founder effect”, “Genetic drift”, “Colonization effect”—refer to different
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology