Biology: life on earth notes. Well written, easy to understand, aesthetic notes covering topics of evolution, classification, diversity, beginning of life on earth, cnidarians, insects etc in detail.
Classification, evolution, diversity, beginning of life on earth, invertebrates, vertebrates
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biology
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University of KwaZulu-Natal (UKZN)
Life on Earth (BIOL102)
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BIODIVERSITY, CLASSIFICATION AND EVOLUTION
CLASSIFICATION
Learning Outcomes: Binomial Nomenclature:
o Understand the origin and diversity of life. Every species has a two-part name (Binomen) :
o Grasp the different domains of life. o Genus: The first part, always capitalized.
o Comprehend the Linnaean classification system. o Specific Epithet: The second part, lowercase.
o Interpret phylogenies, cladograms, and spindle o Both parts are italicized or underlined if hand
diagrams. written.
o Learn about natural selection, evolution, and o Example: Panthera leo (Lion)
speciation.
• The system helps avoid confusion caused by
Introduction to Classification: common names, which can vary across
languages and regions.
The diversity of life is vast, with an estimated 8 million
species, though only about 2 million have been Hierarchy of Classification:
described. Classification organizes this diversity,
Levels of Classification:
aiding in understanding evolutionary relationships.
Domain > Kingdom > Phylum > Class > Order >
Taxonomy: The science of Family > Genus > Species
classification, crucial for organizing
biological diversity.
Taxon: a group of organisms placed within a
taxonomic category such as phylum, family, order
etc.
Biological classification: a process of cataloguing
organisms – delimiting, ordering & ranking organisms
into groups.
Carolus Linnaeus: Introduced binomial
nomenclature in 1758, a standardized system for
naming organisms using two-part scientific names.
Example: Homo sapiens (Human)
Mnemonic to Remember: "Dear King Philip
Came Over For Good Soup."
,Example:
Linnaean Classification System:
Organisms are grouped based on shared
characteristics, reflecting evolutionary relationships.
• Spindle Diagrams: Used to show the
diversity and evolutionary history of different
Domains of Life:
groups, often illustrating the rise and fall of
Three Domains: species over time.
o Bacteria: Single-celled prokaryotes,
characterized by the absence of a nucleus and
organelles.
o Archaea: Also single-celled prokaryotes, often
found in extreme environments, with distinct
biochemistry.
o Eukarya: Organisms with complex cells
Caminalcules:
containing a nucleus and organelles, including
plants, animals, fungi, and protists. • Imaginary creatures invented by Joseph
Camin used in classification exercises to
Concepts in Phylogenetics:
demonstrate the principles of phylogeny and
• Phylogenetic Trees: Visual representations taxonomy.
of evolutionary relationships, showing how
Why Classify Life?
species diverged from common ancestors.
• Classification provides a framework to study
and communicate about biodiversity.
• It helps scientists understand evolutionary
processes and relationships, making it easier
to predict characteristics of organisms.
• Natural Selection: The process by which
organisms better adapted to their
environment tend to survive and produce
more offspring.
• Evolution: The change in the heritable traits
of a population over generations.
• Cladograms: Branching diagrams that
represent the evolutionary relationships • Speciation: The formation of new and
among a group of organisms. distinct species in the course of evolution.
, The Tree of Life:
• Represents the evolutionary relationships 6. Animalia (Metazoa): Multicellular, ingestive
among all organisms. heterotrophs, includes vertebrates and
invertebrates.
• Shows the hierarchy of life from common
ancestors to present-day species.
• Branching Diagrams (Cladograms): Used to
illustrate the evolutionary pathways and
relationships between species.
HIERARCHY OF LIFE:
Life is divided into three domains and six kingdoms.
• Domains:
o Prokaryotes: Eubacteria and Archaea
o Eukaryotes: Protista, Plantae, Fungi,
Taxonomic Classification:
Animalia
Two natural groups:
• Kingdoms:
o Prokaryotes: Lack membrane-bound organelles,
o Prokaryotes:
no nucleus, have circular chromosomes & no
1. Eubacteria: True bacteria, including cytoskeleton
cyanobacteria (use chlorohyll-based
o Eukaryotes: Have membrane-bound organelles,
photosynthesis). None are methanogens
a nucleus, linear chromosomes & cyto.
2. Archaea: Anerobic or aerobic. Extremophiles,
Debates in Classification:
often methane producers, non-photosynthetic.
Some sources recognize five kingdoms, others
o Eukaryotes:
recognize six, combining different domains and
3. Protista: Unicellular, autotrophic, or kingdoms based on criteria like molecular data and
heterotrophic. cell structure.
4. Fungi: Multicellular, saprotrophic heterotrophs Phylogenetics and Cladistics:
(e.g., molds, yeasts).
• Phylogenetic Trees: Show evolutionary
5. Plantae (Metaphyta): Multicellular, relationships and divergence times.
photosynthetic (autotrophic), develops through
• Cladograms: Illustrate shared characteristics
embryonic layering.
among species and their common ancestors.
EVOLUTIONARY THEORY
Morphology: Genetics:
o Homology: Similarities due to shared o Similar nucleic acid sequences indicate
ancestry. relatedness.
o Analogy: Similarities due to convergent o Slight differences suggest close relation; large
evolution. differences suggest distant relation.
o Example: The forelimbs of humans, whales, o Divergence: The greater the differences, the
cats, and bats share the same basic structure, more time since the species diverged from a
indicating common ancestry. common ancestor.
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