1. A species of wasp is outcompeted by several other species and goes extinct; Natural causes.
2. A species of wildflower goes extinct after land is cleared for agriculture; Human intervention.
3. A population of grubs decreases as the population of moles, a predator of the grubs, increases; Natural causes.
4. Three populations of migratory fish decline after the construction of a hydroelectric dam; Human intervention.
5. The number of offspring produced by a population of frogs decreases after pesticides enter their pond. Human intervention.
6. A mass extinction occurs after several volcanic eruptions; Natural causes.
The changes in biodiversity can be influenced both, by the humans and their activity, and the natural events that are taking place on our planet. Throughout the geologic history, lots of natural events. like asteroid collisions, super-volcano eruptions, changes in the composition of the atmosphere etc, have resulted in the dying out of millions of species, and even though this process of natural selection continues, it is not the dominant cause anymore. Nowadays, the biggest cause of loss and changes of biodiversity is the human activity. Lots of living organism have lost their habitats and food sources and went extinct because of the human activity, and also some species have died out or are on the verge of extinction because of the introduction of non-native species to certain places, and that has been devastating to the local wildlife.
