Classification and evolution Flashcards
Why do we classify things?
for our convenience
make study of living things more manageable
easier to identify organisms
help see relationships between species
Classification
process of placing living things into groups
The 8 taxonomic levels:
Domain Kingdom Phylum Class Order Family Genus Species
Domain - Kingdom - Phylum - Class - Order - Family - Genus - Species -
Archaea, Eubacteria, Eukaryotae
Plantae, Animalia, Fungi, Protoctista (all eukaryotes), Prokaryotae
group with same body plan
same general traits
additional info like meat-eating (Carnivora)
closely related genera (genus)
closely related species
all essentially the same with some variations
As you descend to the lower taxonomic groups….
becomes increasingly difficult to separate closely related species and place species accurately, more detailed description of species needed
Binomial system
uses genus name and species name to avoid confusion when naming organisms (genus always in capital, and name underlined/italics)
Used Latin for binomial system as using a common name doesn’t work because…. (4)
same organisms may have different common name in different parts of one country
different common names used in different countries
translation of language may give different names
same common name may be used for different species in other parts of the world
Biological definition of species
group of organisms that can freely interbreed to produce fertile offspring
Phylogenetic definition of a species
group of individual organisms that are very similar in appearance, anatomy, physiology, biochemistry, genetics
Aristotle’s early classification
plant or animal
animal further into live and move in water, live and move on land, more through air
Prokaryotae
no nucleus, loop of DNA, naked DNA no membrane-bound organelles smaller ribosomes cells smaller than eukaryotes free-living or parasitic
Protoctista
eukaryotic mostly single-celled wide variety of forms, only thing in common is don't belong to any other kingdom plant-like or animal-like features mostly free-living autotrophic or heterotrophic nutrition
Fungi
eukaryotic
single cells or have mycelium that consists of hyphae
chitin walls
multinucleate cytoplasm
mostly free-living and saprophytic (cause decay of organic matter)
Plantae
eukaryotic multicellular cellulose cell wall autotrophic contain chlorophyll
Animalia
eukaryotic
multicellular
heterotrophic
move
Convergent evolution
organisms not closely related independently evolve similar traits as a result of being adapted to similar environments or ecological niches.
(unrelated species look very similar)
If we assume that ______________________ then differences seen today are result of ___________.
Differences between molecules in different species reflect ______________.
the earliest living things had identical versions of certain biological molecules
evolution
evolutionary relationships.
What protein used in respiration do all living things that respire have?
How do we compare it?
Draw conclusions on what?
cytochrome c amino acids in protein identified, compare sequence sequence same=species closely related sequences different=not closely related more differences=less closely related
Another molecule used to classify species?
DNA
more similar sequence in part of DNA=more closely related species
many differences=evolved separately for long time
Bacteria are different from Archaea and Eukaryotae because………
different cell membrane structure
flagella with different internal structure
different enzymes for synthesising RNA
no proteins bound to genetic material
different mechanisms for DNA replication and synthesising RNA
features that Archaea share with Eukaryotes
similar enzymes for synthesising RNA
similar mechanisms for DNA replication, RNA synthesis
production of some proteins that bind to their DNA
Phylogeny
use what?
study of evolutionary relationships between organisms
phylogenetic tree
Artificial classification
based on few characteristics
doesn’t reflect evolutionary relationships
limited info
stable
Natural classification
uses many characteristics
reflects evolutionary relationships
lots of useful info
may change with advancing knowledge
Monophyletic
all evolved from same species
Intraspecific variation
variation between members of the same species
Interspecific variation
differences between species
Continuous variation
2 extremes and full range of values in between
e.g. height, length of leaves, number of flagella
Discontinuous variation
distinct categories and nothing in between
e.g. gender, flagella or not, blood group
Student’s t-test
compare 2 means
