Evolution & Classification Flashcards
Timeline: How Long ago was the Earth formed?
4.5+ BYA
Timeline: How old are the oldest prokaryote fossils? What were they?
3.5 BYA
cyanobacteria
Timeline: How old are the oldest Unicellular eukaryote fossils? What were they?
1.8 BYA
dinoflagellates
Timeline: When did the earliest metazoa evolve?
670 MYA - 1.2 BYA ???
Timeline: How old are the oldest sponge & invertebrate embryo fossils?
570 MYA
Timeline: How old are the oldest vertebrate fossils?
550 MYA
Timeline: When did the cambrian explosion occur?
540 MYA
Timeline: the 1st terrestrial arthropods evolved how long ago?
425 MYA
Timeline: The 1st wingest insects and earliest terrestrial tetrapods (vertebrates) evolved how long ago?
413 MYA
Timeline: Dinosaurs appeared how long ago?
225 MYA
Timeline: Birds appeared how long ago?
185 MYA
Timeline: Hominids (“Ardi”) appeared how long ago?
4.4 MYA
Timeline: How long ago did Homo sapiens appear?
~0.4 MYA
What is classification?
arrangement into groups according to established criteria
What is Biological Classification?
grouping beings according to their actual evolutionary relationship.
What is systematics?
grouping of species by similarity & evolutionary relatedness
What is binomial nomenclature?
every species is given a 2 part name
species name = Genus + specific epithet
ex) Homo sapiens
What is a Biological species?
members of a species reproduce with each other but do not interbreed with other species. subspecies arising through geographic separation can still interbreed with viable offspring but slight gene diff
Name the hierarchical classification in order.
Kingdom, Phylum, Class, Order, Family, Genus, Species
What data is used for classification?
Morphology
Ecological characteristics
fossils
molecular information
What is morphology?
What is the problem with using it for classification?
external & internal anatomy,embryology
Problem: if similar morphology not due to close relationship
What is convergent evolution?
This is when 2+ species evolve the same feature, separate from one another.
(ie. they have a common ancestor w/o the feature)
When a feature evolves more than once, what is it called? Give an example.
analogous
“Wings” - birds & bats
What is a homologous feature? Give an example.
a feature present in a common ancestor
“forelimbs” - birds & humans
What are some ecological characteristics?
What is the problem with using this for classification?
Habitat, niche, behavior, phenology, geographic range
Problem: best for lower categories (ie. genus)
How is the fossil record useful in classification?
what is the problem with using it for classification?
Usefulness: helps determine sequence of appearance, useful for extinct species (common ancestors) & good record of taxa with hardened body
problem: only ~10% of invertebrates fossilize well
What is molecular evidence in classification?
Physiological: enzyme structure, biochemical pathways
Genetic: chromosonal banding patterns, DNA sequence
What is the problem with using molecular evidence for classification?
Difficult to detect convergent evolution
difficult to extract DNA
mutation rates not known for all taxa
rates very w/in geologic periods (punctuated equilibrium)
What is the exaptation concept?
New complex adaptations don’t appear in a single mutation.
Adaptations are modifications of preexisting inherited structure that may have evolved for other purposes.
New adaptations evolve in progression of useful intermediate stages
What is the evolution of feathers? State the possible intermediate stages.
Cold-blooded dinosaurs with flattened scale for protection.
IS: insulation for warm-blooded dinosaurs
IS: Sexual displays
Winged Dinosaur glides w/feathered forelimb
Birds diverge, specialized for flight
Explain the lifecycle of the Unionid Clam.
Adults nearly sessile
sperm is expelled & taken in by female
gravid female grows a fish lure
fish bites lure causing clam to spray larvae into its mouth
larvae attach to gills then drop at maturity
name the 3 classification methods
“Classical” taxonomy
Phenetics
Cladistics
What is the goal of Classical taxonomy?
What is the problem?
compares the morphology of “best” features (based on expert opinion) to find overall similarity and relatedness
problem: expert opinion is subjective. bad traits may be chosen (ex. “wings” belong to bats & birds; convergent evolution)
What is the goal of Phenetics?
made in 1950s
eliminate subjectivity, classify by similarity
not based on relatedness
as many traits as possible are used in computer programs to calculate similarity index; shows “best fit”
evolutionary biologists hate this
What is the diagram in Phenetics called?
Phenogram
What is the problem with phenetics?
- different computer programs calculate “best fit” differently
- ignores evolutionary relationships
- uses convergent characteristics
What is the goal of Cladistics?
made in 1950s-60s
Eliminate subjectivity, show relatedness
- uses many traits, but only ones showing evolutionary relationships
- computer programs estimate relatedness
What is the diagram in cladistics called?
cladogram
What is a monophyletic group?
a complete group and all their decendents that have the same ancestor
reptiles are not monophyletic, birds evolved from them
What is an apomorphic feature?
Wings, modified scales
feature that evolved within a group
What is a pleisiomorphic feature?
scales
feature that evolved at the base of a study group
