Threats to Biodiversity

(a) Exploitation and recovery of populations and the impact on their genetic diversity. Small populations may lose the genetic variation necessary to enable evolutionary responses to environmental change (the bottleneck effect).
(b) Habitat loss, habitat fragments and their impact on species richness.
Habitat fragments suffer from degradation at their edges and this may further reduce their size; species adapted to the habitat edges (edge species) may invade the habitat at the expense of interior species. To remedy widespread habitat fragmentation, isolated fragments can be linked with habitat corridors allowing species to feed, mate and recolonise habitats after local extinctions.
(c) Introduced, naturalised and invasive species and their impact on indigenous populations. Introduced (non-native) species are those that humans have moved either intentionally or accidentally to new geographic locations. Those that become established within wild communities are termed naturalised species. Invasive species are naturalised species that spread rapidly and eliminate native species. Invasive species may well be free of the predators, parasites, pathogens and competitors that limit their population in their native habitat. They may prey on native species, out-compete them for resources or hybridise with them.
(d) Climate change and its impact on biodiversity