Block B - Exam Page studies (Biotic Interactions and control)

Core mechanism cluster: Competition / predation = affects populations / niches / coexistence

• Fruit pigeons – Bismark Achipelago Islands = closely related pigeons – questioned coexistence (required null model) 

• Greenwood (1986) - Duck and Skunks = 1600 nests – 5 skunk removal sites = higher hatch rate 

• McNaughton (1985) - Serengeti Plains = circular migration = suggested grazing facilitation 

Core Mechanism cluster: Plants - have defences against herbivorous populations

Oak trees - have chemical and structural defences

chemical - tannins increase in oak leaves from spring to autumn (adapting to insect life cycles)

Structural - altered leaf texture - old leaves are tougher than tender young ones

Core Mechamism cluster: Habitats - affected by allogenic (not themselves) vs autogenic (themselves)

• Stream communities - terrestrial and aquatic food webs linked

• Reichman and Seabloom (2002) - Pocket Gophers = ecosystem engineers through borrowing = gaps in plant matrix 

• Marczak, Roderick and Richardson (2007) - removal of aquatic insects = reduced riparian spiders = ecosystem connectivity 

..

..