describes the strengths and weaknesses of the different classification systems proposed by different scientists

1. strengths and
weakness of the
classification systems

2. Linnaeus weakness
Two kingdom system of classification was acceptable
to many scientist due the diversity among the
organisms and many other limitations the main
weakness are
• Many protozoans posses characteristics of both
plants and animals eg euglena
• Bacteria and cyanobacteria(blue and green
algae)hev many similarities btwn em and are quite
different from other organisms.thus it is difficult to
place em in eir plant or animal kingdom
• Fungi and moulds were placed under kingdom
Plantae but ey poses many characters not common
to plants

3. • Two kingdom system is not based upon natural selection
upon natural ancestral relationships(eg DNA sequencing
places fungi closer to animals than plants)
• Linnaeus didn’t take into account for the similariti4s that
evolved by which distant species developed similarities thou
they were not closely related, in this classification physical
similarities btwn species were taken as a result of species
being closely related

4. • This system is based mainly on 2 modes of nutriition,such as
assimilation and ingestion.the 3rd type abssorption was
recognized subsequently.

5. Linnaeus Strengths
• Allows for a comparison of how closely related organisms
are based on which level of organisation ey hold in common
• It serves as a common language for the word,reducing
confusion btwn regional names for certain animals
• Differentiation btwn closely related organisms wen
separation occurs
• Based on observable traits
• You mek a dichotomous key based on it to determine what
an organism is.

6. Whittaker strengths
• It reflects better relationship among organisms with regard
to levels of organisation and mode of nutrition
• It reflects bettter evolutionary trend indicating gradual
evolution of complex organisms from simpler ones
• Better placement of certain controversial groups like
cyanobacteria,fungi,euglena etc

7. • Seperation of kingdom fungi from plants seems to be
justified as fungi bear own type of structural,physiological as
well as biochemical characteristics

8. Whittaker weakness
• The position of virus is not clear
• Kingdom protista includes organisms hevin diverse form
,structure and life cycle,hence does not seem to be proper
grouping
• Some organisms included under protista(eg dinoflagellates)
are not eukaryotic rather mesokaryotic
• Slime moulds placed under protista differ considerably from
the rest of protists

9. • The 3 higher kingdoms:plantae,fungi and animalia seem to be
polyphyletic

10. Carl Woase classification system
strengths
• . Based on rRNA gene sequences.
• all of life can be grouped into three domains. Branch lengths
are proportional to the amount of genetic change in each
lineage
• It shows the lineages within Eukarya that are dominated by
multicellular organisms (plants. fungi. and animals) and also
the other lineages consist solely or primarily of single-celled
organisms are also classified in their own lineages

11. Presentation by Leon .N.
Tshuma and Vonai Muripira