- Created by: charlotte
- Created on: 19-01-11 10:36
Biodiversity in crisis ..
There is a growing loss of biodiversity and many species have declined to critical levels. Its estimated the current extinction rate is between 1000 and 10000 times higher than is naturally the case.
Why so many different organisms?
Charles Darwins voyage on H M S beagle took him to many countries. He discovered many new species he discovered many species on islands just outside south america that were similar but not the same to the species on the mainland - he published his idea's in a book called .. ' The origin of the species'.
Biodiversity refers too -
The varity of different organisms..
The Genetic diversity ( this is the diversity within species)..
and the diversity of ecosystems..
The 1992 international convetion defined biodiversity as - . The variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecocystems, and the ecological complexes of which they are part. This includes diversity within species, between species and ecosystems.
We still have no accurate estimate on the amount of species on the earth because the task is so large.
A species is - a group of organisms with similar morphology, physiology, and behaviour. Which can interbreed and produce fertile offspring.
Estimates for the total number of species are done by 'guestimates'.
The bynomail system -
This refers to Carolus Linnaeus's technique of how to catologue species into a 2 part Latin name.
The first part is the - Genus. It is shared by all closely related species - for example all horses and zebras are - equus. The second part of the name defines the species in the genus . Together these 2 words make a unique species name.
A dichotomous key is a text based key that gives two options at each stage and you follow the path to find the unfimiliar name of organisms. The newer technique is ( C A T ) computer assisted taxonomy. This uses computer based keys and electronic techniques - meaning it is easily updated.
Sorting and grouping ..
Placing organisms into groups based on shared features is known as - classification or taxonomy, This results in a more manageable number of categories and is the principal aim of all classification systems.
It starts from a kingdom at the biggest group and is narrowed down through - Phylum . class . Order . Family . Genus . Species .
The taxonomic hierarchy is a nested group of - taxa. All members share common features also known as homologies.
The 5 kingdoms. .
Kingdom Animalia - These include multicellular Eukaryotes with differentiated cells organised into organs. They have no cell walls or vacuoles , They are heterotrophic ( this means they rely on other organism's for nutrition ). and they cannot photo synthesize. Eg / Phyla such as Jellyfish..
Kingdom Plantae - Multicellular eukaryotes with differentiated cells organised into organs. Cell walls contain Cellulose . Cells contain chloroplasts and large vacuoles. They are Autotrophic…