Biodiversity And Evolution
-Biodiversity = A measure of the number of species on the planet.
-Evolution = The process by which new species are formed over long periods of time.
At this moment of time it is argued that humanity is causing the extinction of many different species, a threat to biodiversity.
Darwin's theory of evolution was based on the information and evidence collected during his time in the Galapagos islands and other studies, he concluded that one species became physically isolated from eachother during a storm; and during different environments some of the species (finches) became under selective pressure, the ones with adaptation suited to food sources were more adapted to the new environment survived and passed on their favourable alleles to the next set of young; eventually becoming genetically isolated and a different species that couldn't mate with the other finches; this is known as adaptive radiation - which is the emergence of a new species from a common ancestor.
-Taxonomy is the branch of Biology concerned with naming and classifying diverse life.
A hierarchical system has been devised to classify based on ranking groups from large to small groups of organisms:
Kingdom - The largest (e.g. animals/plants).
Phylum - A large grouping with similar features (e.g. anthropods).
Class - A grouping of similar orders (e.g. insects).
Order - A group of related families.
Family - A group of several genera.
Genus - A group of similar species.
Species - A group of organisms that can freely breed to produce fertile offspring.
So relationship between organisms increases going down the groups.
-Phylogeny is the evolutionary relationship between organisms.
The taxonomic ranks are based on evolutionary relationships, shown as this:
A binomial system was set up to name each species, using latin. The genus comes first with a capital letter, and the species second without; usually in itallics.
Prokaryotae (e.g. bacteria)
-These are unicellular organisms.
-No internal membranes, ER, mitochondria or golgi body and a non-cellulose cell wall.
Proctoctista (e.g. algae/water moulds)
Fungi (e.g. yeast/mushrooms)
-Body consists of a network of hyphae.
-Chitin cell wall.
-Reproduction via spores.
Animals (e.g. cats)
-Multicellular, heterotrophic, with no cell walls and nervous coordination.
Plants (e.g. ferns)
-Multicellular, carry out photosynthesis; with cell walls, vacoules, and chloroplasts).
Examples Of Phyla
Annelida (e.g. earthworm)
-Long, thin, segmented body.
-Fluid filled body with a hydrostatic skeleton.
-Primitive brain, and closed-circulatory system.
Arthropoda (e.g. insects)
-Open circulatory system and paired jointed legs.
-Exoskeleton (Positive = waterproof / Negative = Vulnerbable when shedding it).
Vertabral column and well developed brain.
-Fish - Aquatic with scales and gills.
-Amphibians - Soft, moist skin; with eggs and only partially terrestrial.
-Reptiles - Mainly terrestrial, with dry skin and lungs.
-Mammals - skin with hair, born alive and feed on milk.
-Birds -Lay eggs, with feathers and fly.
Evidence Of Common Ancestory
Using physical features
-Homologous is having a common origin but serving a different function, a good example being pentadactyl limbs (e.g. whale flippers and hands of humans)
-Analogous is having the same function but a different origin (e.g. wings of insects/birds)
Using genetic evidence
-DNA analysis reduces the mistakes made by convergent evolution; which is the tendency for unrelated organisms to acquire similar structures.
-DNA hybridisation involves the extraction and comparison of it, the more alike the sequences the closer the relationship.
-Immunilogical comparisons are made by injecting antibodies into another species, which will react with corrsponding antigens; this will eventually form a precipitate - the bigger this is the closer the evolutionary relationship.