1) Evolutionary systematics
The method of reconstructing the evolutionary history (phylogeny) of a taxon by analyzing the evolution of major features along with the distribution of both shared primitive and shared derived characteristics
GEOGRAPHY 316: BIOGEOGRAPHY
B. Holzman, PhD
10/30/02
Lecture
Historical Biogeography
I. Definition
II. Systematics
III. Fossils
problems with fossil record
why fossils are important
IV. Phylogeny
definition
assumption
V. Phenetics
VI.. Phylogentic Classification
Disjunctions debunked:
Examples: Helodermatidae, Porcupines, Proteacea
VII. Evolutionary Systematics
vs. Phylogentic Systematics
VIII. Cladistics
Assumptions
Examples
Criticisms
Historical Biogeography is concerned with relationships among
and between species—the true genetic relationship of taxa.
Systematics: Classification of organisms into hierarchical groups (or taxa) that summarize patterns of similarities
Fossils are important because..
1) ages of taxon
2) can document extinction from an area or of
a major group
3) can aid in determining primitive features
and evolutionary trends
4) can give an idea of the diversity of early life
Problems with the fossil record:
1) Known fossil record is incomplete
a) animals lacking hard tissue and plants
w/o durable chemicals in their cell walls
are poorly represented
b) fossil record is biased in favor of easily
preserved organisms
2)Fossils that are preserved may have
actually been side branches of evolutionary
tree that became extinct w/o giving rise to
new species
Phylogeny: the evolutionary relationship between an ancestor and all known descendants
Three basic assumptions:
1) evolution has occurred
2) patterns of inheritance exist
3) at least some features may be used to show
relationships between taxa and determine
evolutionary sequence
Phenetics: Overall similarity of organisms
(can sometimes cause the wrong conclusions or relationships to be made)
examples: Organisms that seem related but really are very distant
Helodermatidae (gila monster) vs. Varanus (monitor lizard)
Old and New World Porcupines
g. Histrix (old world) vs. g. Erethion (new world)
Proteacea
(link here for web article: Proteaceae sp. A new
genus with a long fossil history)
Gondwana distribution but S. Am and S. Africa probably orginated from
Australia
Phylogentic Systems
1) Evolutionary systematics
The method of reconstructing the evolutionary history (phylogeny) of
a taxon by analyzing the evolution of major features along with the distribution of both
shared primitive and shared derived characteristics
2) Cladistics: the method of reconstructing evolutionary history (phylogeny) of a taxon by identifying the branching sequences of differentiation through analysis of shared (nested) derived character states.
Assumptions of cladistics:
1) speciation is allopatric in the majority of
cases
2) features analyzed are homologous
3) parallel evolution of individual
characteristics is rare
4) organisms with derived characteristics
generally do no rise to more primitive ones.
Angiosperm phylogeny came out in 1960, still in its infancy, still
changing.........
Here's
a link to an article about one of the most ancient angiospems (Proteaceae) just recently
rediscovered
Vicariance biogeography: study of distribution patterns
of organisms that attempt to reconstruct historical events through cladistic
methods (little or no attention to dispersal capabilities or ecological properties)
Vicariants: two disjunct species that are most closely related
to each other and that are assumed to have been created when an initial range of the
ancestor was split by some historic event
Dispersal biogeography: study of the distribution patterns of organisms that places strong emphasis on the dispersal capabilities and ecological properties of each species. When evaluation of the origin of element of a particular biota.
Issues to be addressed:
1) stochastic nature
2) assume common pattern have common causes
3) stability of ranges
