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Variety in ecosystems
Biodiversity – the number and variety of different species in any
ecosystem.
Species – a group of organisms capable of interbreeding to produce
fertile offspring.
The greater the biodiversity, the more stable an ecosystem is. A
stable ecosystem has a wide range of species and food webs.
Organisms are adapted to specific habitats e.g.
Darwin’s finches on the Gallapagos Islands have evolved over a long
period of time to fill specific niches on the different islands. They
varied as to beak shape and size depending on their diet.
Eats large seeds
Eats cactus seeds
and nectar
Eats buds and
fruits
Eats flying insects
Large chunky beaks are used for crushing seeds while small fine beaks
show an insect based diet.
Desert plants are adapted to survive in very dry conditions. They have
specially adapted roots, reduced leaf surface area (spines) and thick
waxy cuticles on the leaves.
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Effects of grazing
High intensity grazing increases species diversity while very high or low
intensity grazing will decrease diversity.
Habitat destruction
Destruction of the rainforest is rapidly reducing biodiversity and perhaps
contributing to climate change. It destroys the habitats of many plants
and animals many of which have yet to be studied.
Pollution
Air, soil and water are all affected by pollution as a result of the
activities of man. It reduces biodiversity and causes harm to the
environment.
Behavioural adaptations
Competition between organisms for resources such as food, water, light
is common in both plants and animals.
Woodlice in a choice chamber settle in damp and dark conditions which
they prefer. In such conditions they avoid predators and do not lose
water too quickly. To study them we control all variables except one at
a time. They move more rapidly and randomly when conditions are
unfavourable and slow down and rest more in preferred areas.
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