Use ecological examples and population data to distinguish competition, mutualism, parasitism, predation and pathogenicity in IB Biology SL C4.1.11.
The images show a southern cassowary (Casuarius casuarius johnsonii) and the fruit of Ryparosa kurrangii. The fruit grow suspended from the main trunk of the tree on long stems.
The southern cassowary is a large, flightless bird found in New Guinea and Queensland, Australia, which feeds on the fruits of rainforest trees. Many of these tree species contain large seeds that are stripped of their flesh as they pass along the cassowary gut, and may be transported long distances before being ejected in fecal material.
The graph shows the results of an investigation in which seeds of the rainforest tree species Ryparosa kurrangii were exposed to one of three conditions before being transferred to soil to assess the effects of consumption by the cassowary on seed germination:
- seeds left intact inside the fruit (control)
- some flesh roughly removed
- seeds consumed by cassowaries and passed through their gut.
Populations of the southern cassowary are experiencing serious decline as a result of collision with road vehicles which kills many adults, wild dogs which kill chicks and juveniles, and wild pigs which destroy cassowary habitat. Deduce two effects of this decline on R. kurrangii.
1.
2.