evolution - populations, speciation and adaptive radiation population – a group of interbreeding...
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EVOLUTION -POPULATIONS, SPECIATION AND ADAPTIVE RADIATION
Population – a group of interbreeding organisms
Gene pool – the sum of all of the genetic componentsin a population
Speciation – the origin of new species
Species – a collection of populations within which thereis free flow of genes
EVOLUTION -POPULATIONS, SPECIATION AND ADAPTIVE RADIATION
Geographic barriers (Allopatric speciation)
KaibabSquirrel (left)
AbertsSquirrel (right)
EVOLUTION -POPULATIONS, SPECIATION AND ADAPTIVE RADIATION
Adaptive radiation Hawaiian honeycreepers
EVOLUTION -POPULATIONS, SPECIATION AND ADAPTIVE RADIATION
Adaptive radiation also occurs at other taxonomic levels
Adaptive radiation of mammals at beginning ofCenozoic Era
Evolution above the species level is macroevolution
THE FOSSIL RECORDPhyletic gradualism
Phyletic gradualism is the gradual progressive change by means of an almost infinite number of small,subtle steps
THE FOSSIL RECORDPhyletic gradualism
THE FOSSIL RECORDPunctuated equilibrium
Punctuated equilibrium is sudden changes interruptinglong periods of little change
Periods of little change are called stasis
Most change occurs over a short period of time
THE FOSSIL RECORDPunctuated equilibrium
THE FOSSIL RECORDPunctuated equilibrium
Punctuated equilibrium suggests that evolution occursin isolated areas around the limits of a populationsgeographic range
Groups in these areas are peripheral isolates and rapid speciation may occur here
Also known as allopatric speciation
When the new species expands into its original territory,it is seen as a sudden appearance
THE FOSSIL RECORDAllopatric speciation
THE FOSSIL RECORDAllopatric speciation
THE FOSSIL RECORDAllopatric speciation
THE FOSSIL RECORDPhylogeny
Phylogeny is the sequence of organisms placed inevolutionary order
THE FOSSIL RECORDPhylogenyDiagrams are used to illustrate ancestor-descendent
relationships.
Phylogenetic Tree
THE FOSSIL RECORDPhylogenyBranches on the diagram are called clades
THE FOSSIL RECORDPhylogeny
Cladograms are diagrams drawn to show ancestor-descendent relationships based on characteristicsshared by organisms
Do not include information on time or geologic ranges
THE FOSSIL RECORDPhylogeny - Cladogram
THE FOSSIL RECORDSequential Evolution
THE FOSSIL RECORDHomology
Homology is the similarity of body parts in regards toorigin, history and structure, without referenceto function
Homologous organs and bone configurations have acommon origin and ancestry
THE FOSSIL RECORDHomology
THE FOSSIL RECORDFossils and Stratigraphy
Principle of Fossil or Faunal SuccessionWilliam Smith
Used for
Age
Correlation
THE FOSSIL RECORDFossils and Stratigraphy
The geologic range of an organism is the interval between its first and last occurrence.
THE FOSSIL RECORDPaleontologic Correlation
Cosmopolitan species are found almost everywhere; they are not restricted to a single geographic location in their environment.
Endemic species are confined to a restricted area in the environment in which they live.
Cosmopolitan species are most useful in correlation because they have a geographically widespread distribution. Fossils found only in limited environments (endemics) are not as useful in matching up rock layers that are far apart.
Appearances and disappearances of fossils may indicate:
Evolution or Extinction Changing environmental conditions
that cause organisms to migrate into or out of an area
THE FOSSIL RECORDPaleontologic Correlation
THE FOSSIL RECORDIndex Fossils
Index fossils or guide fossils are useful in identifying time-rock units and in correlation.
They are: oabundant owidely distributed (cosmopolitan) oorganisms with short geologic ranges
(rapid evolution rates)
THE FOSSIL RECORDBiostratigraphic Zones
Biozone = a body of rock that is identified only on the basis of the fossils it contains. They are the basic unit for biostratigraphic classification and correlation (much as the formation is the fundamental unit for lithostratigraphy).
THE FOSSIL RECORDBiostratigraphic Zones
Range Zone = the part of the stratigraphic column containing the total geologic range of a species or other taxon
THE FOSSIL RECORDBiostratigraphic Zones
Assemblage Zone = the part of the stratigraphic column containing an assemblage or set of several associated fossils that coexist
THE FOSSIL RECORDBiostratigraphic Zones
Concurrent Range Zone = the rock where the ranges of two (or more) taxa overlap