Chapter 14 -- Macroevolution: the long run p. 432

  • Macroevolution examines patterns above the species level, such as rates of origination and extinction of species.

14.1 Microevolution and Macroevolution p. 434

  •  Microevolution
    • evolution within species and populations.
    • Adaptive and neutral changes in allele frequencies
  • Macroevolution
    • gives rise to the patterns above the species
    • Origination, diversification, and extinction
Chapter 18

 The Motors of Macroevolution: Speciation and Extinction p. 435

  • Speciation and extinction rates produce changing levels of diversity.
  1. Interplay between speciation and extinction determines diversity
    1. D1 (diversity) + originations – extinctions = D2 (new diversity)

Rates of Origination and Extinction p. 436

  • Paleontologists measure rates of origination and extinction by calculating the duration of species in the fossil record.
  1. Calculating rates of origination and extinction (Fig. 14.2)
    1. Standing diversity
    2. Turnover
  2. Diverse taxa have higher origination rate than extinction rate (Fig. 14.3)
  3. An inordinate fondness for beetles  J.B.S. Haldane
  4. Extinction rate often tracks origination rate (Fig. 14.4)
  5. Causes of decline in diversity
    1. Diversity can decline when extinction increases or origination decreases
    2. Drop in origination rate contributed to dinosaur extinction
  6. Key Concepts
    1. Extinction occurs when the last member of a clade dies
      1. Can be species or group of species
    2. Mass extinction in a clade can have two causes:
      1. Drop in origination rate
      2. Increase in extinction rate
Chapter 18

14.2 Biogeography: Mapping Macroevolution p. 439

  • The geographical distribution of species is the result of dispersal and vicariance.
  1. Biogeography: the study of geographical patterns of diversity (Fig. 14.5)
  2. Map of biogeographical regions (Fig. 14.6)
  3. Clades can become isolated through vicariance (Fig. 14.7)
  4. Marsupials evolved through a mix of vicariance and dispersal (Fig. 14.8)
  5. Key Concepts
    1. Biogeography is a multidisciplinary field that explores the roles of geography and history in explaining the distribution of species

Physical Isolation as a Barrier to Gene Flow

  1. Allopatric Speciation (Mayr 1942, 1963).
    1. Two major patterns [Fig. 16 .5] 
      1. Vicariance (splitting of range)
      2. Dispersal 

Geographic Isolation through Dispersal and Colonization 

  1. Hawaiian Drosophila [Fig. 16.6]
  2. Founder hypothesis 
  3. Geological history of the Hawaiian Islands [Fig. 16.7].
    1. Evidence for speciation and dispersal events 

Geographic Isolation through Vicariance

  1. Vicariance
  2. Panamanian isthmus and snapping shrimp (Knowlton et al.) [Fig. 16.8].
    1. Shrimp on Caribbean versus Pacific side of 4 Ma Isthmus of Panama. 

14.3 Measuring Diversity through Time p. 443

  •  Measuring long-term changes in diversity requires taking into account the bias introduced through imperfections in the fossil record.
  1. Box 14.1 Punctuated Equilibria and the Species Concept in Paleontology
    1. Anagenesis
    2. Cladogenesis
    3. Punctuated equilibria
    4. Phyletic gradualism
  2. Estimating diversity through time is a complicated task (Figs. 14.9, 14.10)
  3. Chance fluctuations in diversity can produce trend-like patterns (Fig. 14.11)
  4. Some ecological marine communities have become more diverse (Fig. 14.12)
  5. Three “evolutionary faunas” (Fig. 14.13)
  6. Caveats to diversity studies
    1. Most taxa studied are not species
      1. Assignments to higher taxonomic groups somewhat arbitrary
    2. Phylogenetic relationships among groups uncertain
    3. Large-scale patterns may obscure interesting regional patterns

Chapter 18

14.4 Adaptive Radiations: When α Eclipses Ω p. 450

  •  Many species evolved during rapid bursts of diversification brought about through new ecological opportunities.
  1. Adaptive radiation in Hawaiian honeycreepers  (Fig. 14.14)
  2. Phylogenetic signatures of adaptive radiation  (Fig. 14.15)
    1. Hawaiian silversword alliance
  3. Adaptive radiation and convergent evolution 
    1. Lake Victoria cichlids
    2. Convergent evolution of African Rift Valley cichlids  (Fig. 14.16)
  4. Adaptive radiation of animals  (Fig. 14.17)
    1. Ediacaran
    2. Cambrian "explosion"
  5. Fossil record reveals how major transitions occurred  (Fig. 14.18)
  6. Rapid diversification of animals corresponds to major environmental changes  (Fig. 14.19)
    1. Warming and retreat of glaciers
    2. Oxygenation of ocean
  7. Table 14.1 Examples and presumed causes of Adaptive Radiations
  8. Key Concepts
    1. Most adaptive radiations involve exploitation of environments not occupied by competitors
    2. Key innovations can transform how organisms interact with their environment –Paves the way for adaptive radiation
Chapter 18

14.5 The Pace of Extinctions p. 457

  • Species have become extinct at a roughly regular rate.
  • Five pulses of extinctions claimed 75 percent or more of all species.
  • Their potential causes include volcanoes, impacts, sea-level change, and rapid changes of the climate
  1. Pace of extinctions
    1. Background extinction: the normal rate of extinction for a taxon or biota
    2. Mass extinction: a statistically significant increase above background extinction rate


Chapter 18

14.6 The “Big Five” Mass Extinctions p. 458

  1. Five large mass extinctions  (Fig. 14.20)
  2. Mass extinction can result from climate change  (Fig. 14.21)
  3. Rising carbon dioxide from volcanic activity may have led to Permian extinction  (Fig. 14.22)
  4. K-T boundary extinction may have been caused by asteroid impact  (Fig. 14.23)
  5. Traces of impact along Mexican coast  (Fig. 14.24)
  6. Table 14.2 Proposed Causes of the Big Five Mass Extinctions
  7. Key Concepts
    1. The big five extinctions had different causes that impacted different organisms
Marine extinction intensity during the Phanerozoic eon
Millions of years ago

From Wikipedia:  Percentage of marine animal genera becoming extinct during any given time interval

14.7 Macroevolution and the “Sixth Mass Extinction” p. 464

  • Human activity has raised extinction rates far higher than average, and we may soon enter the sixth round of mass extinctions.
  1. Humans may be driving a sixth mass extinction  (Fig. 14.25)
  2. Habitat loss contributes to extinction   (Fig. 14.26)
  3. Current extinction rates are on par with previous mass extinctions  (Fig. 14.27)
  4. Increasing carbon dioxide leads to warming temperatures  (Fig. 14.28)
  5. Increasing carbon dioxide acidifies the ocean  (Fig. 14.29)
  6. Key Concept
    1. Although a single extinction event may have minimal impacts on an ecosystem a mass extinction can have cascading effects




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