How Biological Diversity Evolves

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Chapter 13

• How Biological Diversity Evolves

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Macroevolution
The large patterns of evolution are called
macroevolution These are things like speciation
and extinction
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Biological Species

• A species is a group of interbreeding natural
  populations that are reproductively isolated from
  other such groups
• Examples painted trillium, humans, horse
• Visual variation occurs between species and
  diversity exists within species

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Reproductive Barriers
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Speciation
Species can arise from a single population either
by spatial separation or other means
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Allopatric Speciation
Physical structures can interrupt and population
and lead to genetic differentiation
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Sympatric Speciation
Species can arise within a population if genetic
alterations occur that lead to reproductive
isolation
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Speciation Tempo
Gradualist models predict slow changes,
Punctuated Equilibirum models predict sudden
bursts of speciation
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Biological Novelty

• Exaptation structures that evolve in one context
  but become adaptive for another function ex.
  Light bones in bird ancestors
• Paedomorphosis retention of juvenile
  characteristics in adults ex. Retention of
  juvenile external gills in a salamander

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The evolution of current life forms took a long
time, we are youngsters
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Radiometric Dating
Using the abundance of decaying materials to
estimate the age of a fossil
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Continental Drift
The separation of continents over geological time
has led to allopatric speciation
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Mass Extinctions
Dramatic changes in the environment can lead to
the extinction of many species The striking of a
meteor into the Earth may have lead to the
decline of dinosaurs What changes are happening
now?
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Taxonomy (Naming)
We use binomial nomenclature to identify
species Each organism fits into a spot in a
hierarchical classification scheme (like nested
bowls)
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Phylogeny
Phylogenetics attempts to relate hierarchical
naming to the evolutionary trail that made the
species
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Cladistics
Cladistics uses computers to identify similar
adaptations and indicate related organisms in
clades (branches of the tree) Cladistics may or
may not yield the same results as phylogenetics
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Five Kingdoms, Three Domains
Five Kingdoms
Three Domains
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Topic Summary

• Origin of Species Species, Reproductive
  Barriers, Mechanisms of Speciation, Tempo of
  Speciation
• Biological Novelty exaptation, paedomorphosis
• Macroevolution Geological Time, Continental
  Drift, Mass Extinction
• Classification Taxonomy, Phylogeny, Cladistics,
  Groupings of Life