Great Ideas in science
Spring 2008
F. Levy
SPECIATION AS A PROCESS
Topic Outline
I. Species Concepts
Morphological - delineation
Phylogenetic - analysis using molecular tools
Biological Species Concept -gene pool assessment
II. Models of Allopatric Reproductive Isolation
Pleiotropy model--Selection driven
Epistatic model (Muller; Dobzhansky)--Neutral model
Chromosomal model--Drift driven (fitness trough)
III. Approaches to Study the Genetics of Reproductive Isolation
Genes, genomes, inheritance patterns
Crossing designs to estimate number of genes and intensity of effects and genome location
Reciprocal crosses and potential results
Backcrosses with marked chromosomes
IV. “Rules” of Speciation
Haldane’s rule
Pathway to RI - Orr’s rate paradigm
Useful Reference Books (Sherrod Library call number in parentheses)
Barigozzi, C. (ed.). 1981. Mechanisms of Speciation : Proceedings from the International Meeting on
Mechanisms of Speciation. Accademia nazionale dei Lincei, Rome, Italy. A.R. Liss, New York.
Coyne, JA and HA Orr. 2004. Speciation. Sinauer Assoc., Sunderland, MA. (QH380.C68.2004)
Dieckmann, J. (ed.). 2004. Adaptive Speciation. Cambridge Univ. Pr., Cambridge, UK (QH546.A34.2004)
Endler, J. A. and D. Otte (eds.). 1989. Speciation and its Consequences. Sinauer Associates, Sunderland, MA.
(SHERROD: QH83 .S685 1989)
Giddings, L. V., K. Y. Kaneshiro and W. Anderson (eds.). 1989. Genetics, Speciation, and the Founder
Principle. Oxford University Press, New York. (SHERROD: QH455 .G467 1989)
Grant, V. 1981. Plant Speciation, 2nd edition. Columbia University Press, New York.
SHERROD (has the first edition): 581.38 G767
Howard, D. J. and S. H. Berlocher (eds.). 1998. Endless Forms : Species and Speciation. Oxford
University Press, New York. (Sherrod QH380 .E54 1998)
Levin, D. A. 2000. The Origin, Expansion, and Demise of Plant Species. Oxford University Press, New
York. ( Sherrod QK 980 .L48 2000)
Powell, J. R. 1997. Progress and Prospects in Evolutionary Biology: The Drosophila Model. Oxford
University Press, New York.
Stebbins, G. L. 1950. Variation and Evolution in Plants. Columbia University Press, New York.
(SHERROD: 581.15 St31)
Great Ideas in science
Spring 2008
F. Levy
Outline for Discussion of Speciation Genetics
Be ready to discuss:
--The general or “big” question(s) the paper strives to address.
--The specific issues associated with the big questions.
--The approach used in the study.
This does not mean a detailed iteration of all methods. It does mean a concise explanation of how
they went about addressing the questions they raise. Are crosses used? If so, what types and why?
Molecular methods should be distilled to explain their purpose.
--Results
Without a table by table reading, summarize the results that have bearing on the question. You may
copy some tables to highlight points.
--What has the study accomplished. How has it contributed to an understanding of the big questions?
--What aspects of the question(s) remains open.
Some Questions to Address
**What approaches are used to understand the genetic basis of reproductive isolation (RI)?
**How many gene loci contribute to RI? Do they have major or minor effects on fertility?
**What has fine scale genetic mapping of RI factors shown that was not known previously?
**Where are the loci causing RI located (nucleus; cytoplasm; X chromosome; autosomes)?
**What are the genetic explanations for Haldane’s Rule and why is it important to distinguish among them?
**Are generalizations applicable and robust for speciation? If so, which?
**Is there a relationship between genetic distance, morphological divergence and reproductive isolation?
**How can theory and experimentation complement each other?