LifeHistory Type, Speciation

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Life-History Type, Speciation Adaptation of
Chaparral Species
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Mediterranean-type ecosystems (MTEs)
maquis
chaparral
matorral
fynbos
mallee
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Convergent Evolution

• Evolution of similar features among distantly
  related species in response to similar selective
  pressures (environment).
• MTEs
• Many distantly related plant species
• Widely separated for a long time
• Similar form
• Evergreen sclerophyllous shrubs

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Climate
-Winters rainy cool
-Summers dry hot
Dallman 1998
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Nutrients
DiCastri 1981
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High biodiversity in MTEs
Globally 2 of land area with 16 of plant
species
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MTE in CA
Atlas of the biodiversity of CA 2003
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Biodiversity in CA
Atlas of the biodiversity of CA 2003
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Wildfires
Wildfires occur every 12-50 years
-accelerating Keeley and Fotheringham Minnich
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Life-History Types For Chaparral Species in a
Post-Fire Environment

• Life-history type or strategy
• Survival, growth, and reproduction
• How does selection schedule these three
• Life span
• Phenology
• Reproductive allocation

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Life-History Types For Survival in a Post-Fire
Environment
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Obligate-Sprouter Recruitment
Non-Sprouter (NS)
Facultative-Sprouter (FS)
Obligate-Sprouter (OS)
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Non-Sprouters
Sprouters
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Evolution of Chaparral Life-History Types

• Ability to sprout (FS OS)
• Ancestral
• Loss of sprouting (NS)
• Derived

Bond and Midgely 2001 Feild 2003
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Speciation
Life-History Speciation

• Development of reproductive isolation between
  populations

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Life-History Speciation
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Life-History Speciation
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Life-History Speciation (Wells)

• Selection in non-sprouting species
• Frequency of selection (greater genetic
  variation)
• NS gt FS OS
• Intensity of selection (greater adaptive
  divergence)
• NS gt FS OS
• Greater speciation in non-sprouting species

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Non-Sprouting Species

• Arctostaphylos spp.
• NS 59
• FS 16
• OS 0
• Ceanothus spp.
• NS 46
• FS 12
• OS 0

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Post-fire recruitment
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Adaptive divergence in Ceanothus

• Leaf size
• FS gt NS

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Adaptive divergence in Ceanothus

• Sclerophylly
• FS lt NS
• Support without turgor

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Adaptive divergence in Ceanothus

• Stomatal crypts
• No FS Yes NS

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Adaptive divergence in Ceanothus

• Corky stipules
• FS lt NS

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Adaptive divergence in Ceanothus

• Lignotuber
• Yes FS No NS

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Adaptive divergence in Ceanothus

• Xylem density
• FS lt NS

Jacobsen et al. submitted
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Adaptive divergence in Ceanothus

• Cavitation resistance
• FS lt NS

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Greater survival for NS
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Summary

• Life-History strategy and speciation
• Frequency intensity of selection
• NS gt FS OS
• Adaptive divergence for drought tolerance
• NS gt FS OS

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