endangered species and extinction Flashcards
define endangered species
those that are at serious risk of extinction
define extinction
when there are no living members of a species left
what type of process is extinction?
natural process
why are scientists worried about extinction at the moment?
occurring at a much faster rate than in the past
how is natural selection a threat to species?
humans are changing environments faster than new mutations allow organisms to adapt
how are non-contiguous populations a threat to species?
small populations are isolated from each other
unable to interbreed
may not be enough genetic diversity to ensure a healthy population
how is deforestation a threat to species?
permanent removal of trees removes habitats
how is drainage of wetlands a threat to species?
wetlands are drained to allow agriculture or building
destroys habitats
how is hedgerow loss a threat to species?
have separated fields for centuries
removes breeding sites, feeding sites and wildlife ‘corridors’
allow animals to move from one area to another
how is crop sowing seasons a threat to species?
sowing during autumn rather than spring
plants are unsuitable heights for birds to build nests
how is overhunting a threat to species?
for trophies
traditional medicine
‘bush meat’
overfishing
agricultural exploitation
how is competition from other introduced species a threat to species?
domestic animals and accidentally introduced animals predate or outcompete native species
how is pollution a threat to species?
kill organisms or make it more difficult for them to survive in their habitat
