Taxonomy Species Concepts,

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TaxonomySpecies Concepts, Biological Diversity

• EEOB 661
• 27 September 2004

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Hierarchical Indicators of Biodiversity

• Genetics (population)
• Population Species
• Community- Ecosystem
• Landscape
• Each with Composition, Structure,
  Function (MC Fig. E4A)

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Levels of Biological Diversity
Genetic
Population
Demographic
Community
Landscape
From Temple 1991, drawing by T. Sayre
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Genetic (population)

• Composition
• Allelic diversity
• Presence/absence of rare alleles
• Structure
• Heterozygosity genetic structure
• Phenotypic polymorphism
• Function
• Inbreeding outbreeding rate

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POPULATION-SPECIES(demographics)

• Composition
• Absolute and relative abundance, density,
• Structure
• Sex ratio, age distribution
• Distribution
• Function
• Natality, Mortality, Immigration, Emigration
• Population growth and fluctuation
• Behavioral patterns and processes

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COMMUNITY-ECOSYSTEM

• Composition
• Species richness
• Species diversity (evenness, e.g.,Shannon-Weiner
  Index)
• Gilds associations
• Structure
• horizontal vertical foliage profiles
• Range of ages and seral stages
• Function
• Frequency intensity of disturbances
• Flow of energy and Cycling of nutrients

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LANDSCAPE

• Composition
• Variety and distribution of Communities
• Structure
• Patch size frequency distribution
• Edge zone interior zone ratio
• Function
• Rates of nutrient energy, and biological
  transfer between different communities

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SYSTEMATICS and TAXONOMY

• Systematics study of phenotypic variation
  within
• between taxa to reveal phylogenetic
  relationships
• Taxonomy Naming ranking of taxa with a goal
  of stable, universal nomenclature and a system
  for information storage retrieval.
• Several schools but phylogenetics (cladistics) is
  most widely practiced and accepted
• Taxon a group of organisms recognized as a
  formal unit in a hierarchial system of
  classification

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Central Position of Species in Biodiversity

• Importance compared to taxa in higher categories,
  i.e., genus, family, or class
• Species are real and distinct (?). Real because
  they are functional units in nature. Distinct
  because of common gene pool and limit gene flow
  between species
• Species are also real because many can be
  recognized by both laymen professional biologists
• Typological vs. populational views of species

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Species Concepts Definitions

• Biological species concept (traditional)
• Reproductive isolation of sexually reproducing
  species
• Practical and widely used (basis for nearly all
  alpha taxonomy)
• Problems limitations?
• Cladistic Species Concept
• The smallest cluster of organisms diagnosable by
  a synapomorphy
• Popular among systemitists
• Less so among alpha taxonomists
• Provides valid basis for sup-specific taxa (
  subspecies)

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Cladogram of Chordates Hickman et al Fig.15.3
(2003) - See also, MC Fig.3.3
Synapomorphies
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Wilson 1992 Diversity of Life
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Patterns in Biodiversity

• Taxonomic Diveristy (richness of higher taxa)
• Species richness of higher taxa
• i.e., number species per taxon
• Richness of taxa over geological time
• Patterns of local species richness
• Global patterns in species richness

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Hickman et al. 2003
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Patterns in Biodiversity

• Taxonomic Diversity (richness of higher taxa)
• Species richness of higher taxa
• i.e., number species per taxon
• Richness of taxa over geological time
• Patterns of local species richness
• Point richness number in single spot (sample
  plot) a total number in a small, homogeneous
  area
• ß rate of change/ turnover across a landscape

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Estimates of number of species on Earth

• Based on the rate at which new species are being
  discovered per taxon.
• Projection of a regression line based on body
  size and species richness
• Terry Erwins projection from tropical
  rainforest beetle species richness

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Estimating number of species from rate of new
discoveries
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Estimates of number of species on Earth

• Based on the rate at which new species are
  discovered per taxon.
• Projection of a regression line based on body
  size and species richness
• Terry Erwins projection from tropical
  rainforest beetle species richness
• Dr. Terry Erwin, Entomologist, Smithsonian
  Institution

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/ 70 species x 41,389
Calculations based on 70 tree species/ha, which
projects to about 30 million arthropods
worldwide Erwin, TL 1982. Tropical forests
Their richness in Coleoptera and other arthropod
species. Coleopt. Bull. 3674-75.
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Patterns in Biodiversity

• Taxonomic Diversity (richness of higher taxa)
• Species richness of higher taxa
• i.e., number species per taxon
• Richness of taxa over geological time
• Patterns of local species richness
• Global patterns in species richness

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Patterns in Alpha richness

• Why are there so many species in the tropics?
• High Primary Productivity
• Habitat size (island biogeography)
• Habitat complexity (heterogeneity)

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