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ORGANISMS ARE RELATED THROUGH EVOLUTIONARY HISTORY - Coggle Diagram
ORGANISMS ARE RELATED THROUGH EVOLUTIONARY HISTORY
Organisms are grouped according to their evolutionary relationships
The taxonomic classification system is hierarchical
Taxon:
Kingdom
Phylum
Class
Order
Family
Genus
Species
Example
:
Animalia
Chordata
Mammalia
Primates
Hominidae
Homo
Homo sapiens
A
species
can be
defined as a group of organisms that can interbreed to produce fertile offspring.
Species have a two-word (binomial) latin name, made up of genus and species.
An advantage of binomial names is that it can indicate close evolutionary relationships.
For example, the binomial name for lion is Panthera Leo, indicating that it is in the same genus as, and therefore closely related to, tigers. Also allows scientists to communicate clearly without relaying on common names, which can vary in different areas.
Phylogenetic trees
can show the interrelatedness of organisms. Each 'branching point' of the tree is a common ancestor two organisms have.
The more recent the ancestor two organisms have, the more closely related the organisms are.
Hierarchical taxonomy
means that
larger groups can be subdivided into smaller groups
, with the organisms becoming more closely related the smaller the group.
All living things are placed in one of five kingdoms.
The five kingdom system:
Prokaryote
Unicellular
Autotrophic and heterotrophic
No membrane-bound organelles; DNA is free in the cytoplasm.
Protoctista
Mostly unicellular but some multicelluar
Autotrophic and heterotrophic
No tissue differentition.
Plantae
Multicellular
Autotrophic
Photosynthetic
Fungi
Multicellular and unicellular
Heterotrophic
Reproduce by spores; most have filiments called hyphae.
Animalia
Multicellular
Heterotrophic
Have nervous coordination.
New biochemical evidence led to the three-domain classification system
There are in fact two distinct groups of prokaryotes that are fundamentally different from each other.
Led to the prokaryotes being split into two separate groups and the development of the three-domain classification system.
All living organisms are divided into three domains:
Bacteria (Eubacteria)
- Prokaryotes that are 'true' bacteria.
Archaea (Archaebacteria)
- the extremophile prokaryotes. extremophiles can live in a wide range of different extreme environments, including extreme pressure, pH, salinity and temperature.
Eukarya/eukaryota
- all eukaryotic organisms, i.e. animals, plants, fungi and protoctista.
Biochemical methods can be used to determine the relatedness of organisms
Used to measure the proportion of DNA shared between species and how similar the amino acids in proteins are.
The more similar the DNA base sequence of the two organisms, the more closely rlated the two organisms are.
The amino acid sequence of enzymes are often compared. Many organisms have the same enzymes but the amino acids sequence of the enzymes will vary depending on how closely related the organisms are.
The more similar the amino acid sequence of the enzyme, the more closely related the organisms are:
The DNA or proteins are extracted and then separated.
The DNA fragments or proteins are usually displayed as bands on an electrophoresis gel.
In the case of DNA, this creates a genetic footprint.
Organisms that are more closely related will have bands in similar positions on the electrophoresis gel.
Similar features do not infer relatedness
Mistakes in classifications can be due to convergent evolution. This is where a similar feature evolves independently in different organisms in response to similar selection pressures.
Homologous features:
Features that have evolved from the same original structure but have different functions.
An example:
pentadactyl limb
. This is a limb wiith five digits that is found in a wide range of different organisms such as birds and reptiles. These homologous features are evidence of a common ancestor from which all these organisms evolved.
Analogous features
:
Similar features that carry out the same function but have not evolved from a common ancestor.
An example: of analogous features are the dorsal fins on dolphins and sharks. These are features that have evolved to carry out the same function but did not evolve from a recent common ancestor of dolphins and sharks.
Biodiversity refers to all species in a specific ecosystem
Biodiversity:
A measure of the number and variety of organisms found within a specified geographic region.
Biodiversity varies over both space and time,
for example: biodiversity is generally higher at the equator and decreases as you move towards the poles.
Biodiversity can be measured in different ways
We can assess the biodiversity in a habitat in a number of ways:
Species richness
- the number of species present. The more species, the higher species richness.
Species evenness
- the number of individuals within each species populations. An environment that is dominated by a single species would have a low species evenness.
Biodiversity can also be studied within a species at the genetic and molecular level
Biodiversity at the genetic level can be assessed by studying the variety of alleles within the gene pool of population - the proportion of polymorphic loci across the genome.
Polymorphism
The presence of different types of individuals within a species.
Polymorphism is due to the presence of polymorphic genes. Polymorphic genes are multiple alleles of the same gene.
Genetic biodiversity can be assessed by determining the number of alleles at a locus (location of a chromosome) and the proportion of the population that have a particular allele.
Biodiversity is generated by natural selection
An example of this process is selective predation.
Organisms that are better adapted to an environment are less likely to killed by predators, this means that they are more likely to survive, breed and pass on their alleles to their offspring.
Camouflage would be an example of this.
Natural selection leads to species being uniquely adapted to the environment in which they live.
Adaptions include anatomical, physiological and behavioural adaptions:
Anatomical adaptions
- mammals in cold environments often have thick fur, thick layers of adipose (fat) tissue and reduced surface area:volume ratios, all to reduce heat loss.
Physiological adaptions
- many plants, such as nettles, produce poison to ratios, all reduce heat loss.
Behavioural adaptions
- Many desert animals are nocturnal, staying hidden in burrows during the day and emerging at night when it is cooler.