Evolutionary Ecology

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Evolutionary Ecology
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Environmental or Genetic Variation in Yarrow?
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Creeping Bent Grass - Agrostis stolonifera
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Adaptation in Trinidad GuppiesPoecilia reticulata
Male and Female
Two males
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Adaptation and natural selection in guppy
populations
John Endler
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Cline Bergmanns Rule
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Cline Allens Rule
Arctic Cool Temperate Warm Temperate
Desert
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White clover Trifolium repens
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Cline in cyanide production by white clover
dark circle populations with cyanide white
circle lack cyanide
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Herring Gull
Lesser Black-backed Gull
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What is a species?

• Morphological species concept Assemblages of
  individuals with morphological features in common
  and separable from other such assemblages by
  correlated morphological discontinuities in a
  number of features.
• from Davis and Heywood

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Rubus - Blackberries
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Biological Species Concept
Comte de Buffon Ernst Mayr
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Biological species concept

• A species consists of a groups of organisms which
  can sexually interbreed or at least have the
  potential to sexually interbreed (if
  geographically isolated) that are reproductively
  isolated from other such groups.
• This is based on two criteria
• 1. do populations from the same locality
  normally interbreed?
• 2. if cross-fertilization does occur, are the
  hybrids viable and fertile?

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Sibling species

• Species which look almost identical
  morphologically but which do not interbreed.

Drosophila pseudoobscura
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Gilia tricolor
Gilia angelensis
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Polytypic species

• Species made up of populations which differ
  morphologically but which will interbreed in
  nature.

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Variation in Song Sparrows
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Phylogenetic species concept

• Species are defined based upon branching patterns
  in phylogenetic trees. Species are also defined
  based upon differences in evolutionary history.
  Species typically diverge when reproductively
  and/or geographically isolated.

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Western and Florida Scrub Jay
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Speciation

• Speciation is the formation of new species.
• Allopatric speciation - formation of new species
  occurs when populations of a species become
  geographically separated from each other and
  diverge so that when they co-occur they cannot
  interbreed.
• Sympatric speciation - occurs when reproductive
  isolation occurs within the range of a population
  before any differentiation of the two species can
  be detected.

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Allopatric Speciation Galapagos Islands Finches
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Darwins Finches
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Sympatric and Allopatric Speciation Picture
Winged Drosophila
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Eight Species of Picture- Winged Drosophila
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Founder Events with Picture Winged Drosophila
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Sympatric Speciation in Cichlids
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Variation in Lake Malawi and Lake Tanganyika
Cichlids
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Polyploidy in Spartina cordgrasses

• Polyploidy - an increase in the number of
  chromosomes beyond the typical diploid number -
  may be a doubling or greater - this happens most
  often in plants
• Polyploidy often occurs following the production
  of hybrids

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Spartina alterniflora marsh North Carolina
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Spartina alterniflora
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Spartina maritima
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Spartina x townsendii
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Spartina anglica
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Spartina anglica invasive in New Zealand