higher biology - unit 3.8: threats to biodiversity

threats to biodiversity

over-exploitation, habitat loss and fragmentation, invasive species

over-exploitation

the consumption of resources at a rate faster than they can be replaced

what happens if over-exploitation is stopped?

if halted rapidly, then populations can recover

bottleneck effect

when small populations lose their genetic variation necessary to enable evolutionary responses to environmental change

can the bottleneck effect be critical?

in small populations the loss of genetic diversity can be critical as inbreeding can result in poor reproductive rates

habitat loss and fragmentation

the clearing of habitats has led to habitat fragmentation

habitat fragmentation can be caused by?

geographical processes that slowly alter the layout of the physical environment / human activity that is more rapid

habitat fragments may...

have a smaller total surface area that the original habitat

degradation of the edges of habitat fragments results in...

increased competition between species as the fragment becomes smaller

habitat fragmentation leads to a...

decrease in biodiversity and lower species diversity

to remedy habitat fragmentation, isolated fragments can be linked with...

habitat corridors

habitat corridors allow for...

increased access to food, mates and recolonization of small fragments after local extinctions, gene flow

introduced (non-native) species

species that humans have moved either intentionally or accidentally to new geographic locations

naturalised species

species that become established within wild communities - that live and breed in it's new habitat

invasive species

naturalised species that spread rapidly and eliminate the native species

invasive species increase rapidly but especially if...

they are free of predators, pathogens, parasites and competitors that limit their population in their native habitat

invasive species may...

prey on native species, out-compete them for resources or hybridise with them