CH 18 - Biodiversity
Q. Explain how variation in ecosystem lead to biodiversity?
– Different habitats
– Different niches
– Many different species —> species diversity
– Genetic variation in each species
– Different selection pressures
– Therefore they adapt
Q. Explain why it is important to control invasive alien species.
– compete with native species ;
– for, food / same niche / light / resources
– feed on / predators of, native species ;
– can cause extinction in native species ;
– can breed more successfully than native species ;
– often have no, natural predator / grazers ;
– may disrupt, habitats / ecosystems / food webs / food chains
– cause reduction in biodiversity ;
– May introduce diseases
Niche : a role of an organism in an ecosystem
Biodiversity :
● Variation in ecosystems or habitats
● Number of species and their relative abundance (species density)
● Genetic Variation within each species
Biological Species concept : a group of organisms with similar morphology
and physiology, which can breed together to produce fertile offspring and are
reproductively isolated from other species
● Problems :
○ Cannot determine for asexual organisms
○ For fossil/extinct organisms
○ Often not possible to observe reproductive behaviour
○ time required for mating behaviour may take too long (to be
observed)
Morphological Species Concept: a group of organisms that share many
physical features that distinguish them from other species
Ecological Species Concept : When there is a population of similar organisms
living in the same area at the same time, they can be described as an
ecological species
Threats to the biodiversity of aquatic ecosystems
1) overfishing, example of overexploitation of resources, fishing younger fishes
therefore taking away population that has yet to breed
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