CETACEA Quintessential Mammals? Mammalogy – EEOB 625 27 February 2004.
Taxonomy Species Concepts, & Biological Diversity EEOB 661 27 September 2004.
-
Upload
bridget-goodwin -
Category
Documents
-
view
216 -
download
0
Transcript of Taxonomy Species Concepts, & Biological Diversity EEOB 661 27 September 2004.
TaxonomySpecies Concepts, & Biological Diversity
EEOB 661
27 September 2004
Hierarchical Indicators of Biodiversity
• Genetics – (population)
• Population – Species
• Community- Ecosystem
• Landscape –
* Each with: Composition, Structure, & Function (M&C Fig. E4A)
Population
Community
Landscape
Levels of Biological Diversity
Genetic
Demographic
From Temple 1991, drawing by T. Sayre
Genetic (population)Composition• Allelic diversity
• Presence/absence of rare alleles
Structure• Heterozygosity & genetic structure
• Phenotypic polymorphism
Function • Inbreeding & outbreeding rate
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
COMMUNITY-ECOSYSTEM
Composition• Species richness• Species diversity (evenness, e.g.,Shannon-Weiner Index)
• Gilds & associationsStructure • horizontal & vertical foliage profiles • Range of ages and seral stages Function• Frequency & intensity of disturbances• Flow of energy and Cycling of nutrients
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
SYSTEMATICS and TAXONOMY
Systematics: study of phenotypic variation within & between taxa to reveal phylogenetic relationshipsTaxonomy: 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
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
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)
Cladogram of ChordatesHickman et al Fig.15.3 (2003) - See also, M&C Fig.3.3
Synapomorphies
Wilson 1992 – Diversity of Life
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
Hickman et al. 2003
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)
α = total number in a small, homogeneous area
β = rate of change/ turnover across a landscape
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 Erwin’s projection from tropical rainforest beetle species richness
Estimating number of species from rate of new discoveries
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 Erwin’s projection from tropical rainforest beetle species richness
Dr. Terry Erwin, Entomologist, Smithsonian Institution
*
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. 36:74-75.
/ 70 species x 41,389 =
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
Patterns in Alpha richness:
Why are there so many species in the tropics?• High Primary Productivity• Habitat size (island biogeography)• Habitat complexity (heterogeneity)