EX 3 Evolution Speciation
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What is taxonomy?
Identification,naming and classification of species
Biological vs morphological species
concepts- what are they
- species concept: recognizes species based on genetic interbreeding. A biological species members can interbreed
- with each other in nature to produce fertile offspring
- -Advantages: strong
- evolutionary significance, genetically based
- large information requirement. What abut
- asexual species or fossils?
- species concept: recognizes species based on differences in appearance
- low information requirement, easily understood by everyone
- some very different organisms have similar appearances, and other organisms in
- interbreeding populations may look very different from each other
What are prezygotic reproductive
barriers, and what are the types (be able to recognize from examples)?
Prezygoticreproductive barriers: preventing mating or fertilization between species
What are the postzygotic barriers and generally what do they involve?
- isolation: individuals do not mate at the same time of year
- isolation: individuals do not live in the same place and therefore do not
- encounter one another to mate
- isolation: individuals do not use the same cues to mate (ex. Fireflys blinking
- isolation: sexual organs are incompatible
- isolation: sperm and egg do not fuse due to cellular incompatibility (surface
Allopatric vs sympatric speciation
- Allopatric speciation: speciation due togeographical isolation
- Sympatric speciation: speciation withoutgeographical isolation
What has to happen for speciation to occur using the biological species concept?
What are the two ideas about the rate of speciation? Which is
supported by the evidence?
Rate ofspeciation: two contrasting patterns1. gradual paceof speculation: big changes (speciation) occur by the steady accumulation ofmany small changes2. puncturedequilibria: long periods of little noticeable changes interrupted (punctuated)by brief periods of rapid change
What is exaptation?
When oldstructures are used for new functions
What is paedomorphosis?
Retention of juvenile in and adult
What are homeotic genes, and why do they explain major changes
in body form in evolution?
Homeotic genes: regulate the rate, timing andspatial pattern of development
-a homeotic gene mutation can drastically changebody plans
What is macroevolution?
majorevolutionary change. The term applies mainly to the evolution of wholetaxonomic groups over long periods of time.
4 eras for life on Earth: names, relative order, what marks their start/end, relative time span, major landmarks (only the information provided in class)
- Precambrian era: 46000-542 Million yrs ago
- -very long-4.1 billion yrs
- -age of prokaryotes
- -algae and aquatic invertabrates
- -oldest animals and eukaryoktes
- Paleozoic era: 542-241 million yrs ago
- -second longest -291 million years
- -most animal groups appear
- -colonization of land
- -age of invertabrates and amphibians
- -ends in Permian extinction (96% marine animals died)
- Mesozoic era: 241-65 million yrs ago
- -3rd longest ~186 million yrs
- -age of dinosaurs
- -flowering plants appear near the end
- -ends in Cretaceous extinction, which opened the
- way for mammals to diversify
- Cenozoic era: 65 million yrs ago to present
- -age of mammals
- -origin of man
Why are plate tectonics important in understanding the distribution of species on Earth?
What are mass extinctions? Why are they often followed by
Linnaeus’ system for naming organisms: binomial
-genus capitalized, species not
0must be unique for each species
Taxonomic hierarchies, and their relationship to one another
(nested system from Domain to species).
Species in genus are more closely related thatthose in the same class
Relatedness based on DNA sequences or proteins
- -traits must be homologous (from common
- ancestor), not analogous
- -molecular systematics use DNA or RNA or amino
- acids sequences to determine relationships among organisms
- 0the more recently two species their nucleotides
- and amino acids sequence should be
Basis of cladistic analysis- what is parsimony, and how do you use it to make decisions about common ancestors?
- Cladistics: groups of organisms by common
- Clade: ancestral species and all its evolutionary
- -to identify clades, scientists compare an
- ingroup with and outgroup (which tells them what the ancestors looked like)
Potential exam question: Provide and explain two reasons why scientists need more than one species concept.
What would you like to do?
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