Chapter 14 - Evolution: Changes Over Time Flashcards
relative dating (stratigraphy)
the oldest layer of rock is at the bottom and progressively younger layers lie above it
absolute dating
the age of the fossil is determined by use of methods such as radiometric dating
based on decay of certain radioactive elements
fossils
the remains or impressions of previously existing organisms usually preserved in sedimentary rocks
direct fossil evidence
bones, teeth, leaves and shells
indirect fossil evidence
“trace fossils”
footprints, tracks, toothmarks, burrows
biogeography
the study of plant and animal distribution
homologous structures
structures that have similar basic structure even though they may serve different functions
common ancestor
analogous structures
structures that carry out similar functions but are not necessarily similar in basic structure
convergence
vestigial organs
organisms have degenerate organs/structures that no longer perform the function they did in their ancestors
kiwi wings
comparative embryology
comparing the embryonic development of different vertebrates
molecular homology
the similarity of the nucleotide sequences of DNA or RNA molecules or amino acid sequences
DNA hybridisation
DNA unzipped and recombined to form hybrid DNA
heat used to seperate
more heat more related
cladogram
DNA sequencing
the sequence of DNA can be determined with technology
amino acid sequencing
similarity/difference between amino acid sequences of particular proteins
more differences less related
immunological techniques
can be used to indirectly measure the degree of similarity of proteins in different species
mtDNA
mitochondrial DNA
matrilineal patten of inheritance
phylogeny
the evolutionary history of organisms represented in a cladogram
allopatric speciation
the process of forming a new species
steps of allopatric speciation
variation - range of characteristics
isolation - geographic barrier, no gene flow
selection - different selection pressures
speciation - changes accumulate, can’t interbreed
convergent evolution
evolution that results in species that are of similar appearance that are not closely related
common selection pressures
divergent evolution
the accumulation of differences between groups of an ancestral species
different selection pressures
extinct
refers to a species of which no living members exist
Conditions of fossilisation
Low oxygen
Low acidity
Rapid burial
Sediment covering
