BIOL5300-201 Topics in Ecology and Evolution:
Speciation
Fall 2004
Dr. Lev Yampolsky
http://faculty.etsu.edu/yampolsk/
yampolsk@mail.etsu.edu
Phone 423-439-4359
Syllabus
The purpose of this course is to discuss one of the most fundamental features of living systems –
ability to speciate and review the current knowledge of causes and mechanisms of speciation. We will start
with the idea of biodiversity and observe that conceptually similar mechanisms are responsible from
maintaining diversity on genetic and species levels. We will go on to discuss the general model of
speciation, which requires the following steps to work: stable polymorphism, a primary isolation barrier
(pre- or postzygotic) and selection against intermediates. In the following chapters of the course we’ll see
how specific versions of this model apply to allopatric, parapatric and sympatric speciation. We will utilize
data from a variety of experimental systems, including Drosophila, Rhagoletis, birds, fishes and plants and
will give special attention to speciation in species flocks, since they provide a wonderful range of examples
on mechanisms of speciation, in particular on ecology of speciation. A significant component of the course
will be reading and discussion of original research papers on speciation, both classical and recent.
Below is the approximate list of lectures/topics roughly corresponding to 2-3 hours long classes;
in many cases the second half of each class will be a discussion of original paper(s). Ideally each student
will be asked to lead at least one discussion section and participate in many.
Some of the lecture descriptions contain “Tangential topics”. These are interesting issues not
directly related to speciation, but worth mentioning because they share either theoretical or empirical
concepts with speciation.
Text: J. A. Coyne and H. A. Orr. Speciation. Sinauer, 2004. (C&O)
#
Date
Topic
1
2
Aug 31
Sept 13
3
Sept 20
4
Sept 27
5
Oct 4
Organizational meeting
Introduction. Branching pattern of evolution – a
fundamental feature of living systems. “Evolution” of stars.
Evolution of species, languages and cultures. Speciation as
the only source of biodiversity. Specious and species-poor
clades and biotas. Adaptive radiations. Cambrian explosion
– did it happen and why. Vicariance and morphospace
saturation.
Polymorphism and population differentiation – necessary
first steps towards speciation. Mechanisms maintaining
genetic variation. Mutation-selection balance, drift,
balancing selection, frequency-dependent selection and GxE
interactions. Factors affecting differentiation. Tangental
topic: factors affecting species coexistence.
Speciation, extinction and phylogenies. Fossil record,
gradualism and punctuated equilibrium. How fast is
speciation? How often does it occur? What influences
species richness in a clade?
Genetics of reproductive isolation. Shifting balance.
Prezygotic and postzygotic isolation. Chromosomal
incompatibilities and why they are unlikely to be the cause
of speciation, at least in animals. Dobzhansky-Muller model.
Selection or drift? Reading: Tangental topic: Other types of
incompatibilities: cytoplasmic, parasite-induced, gamete
recognition.
Genetics of reproductive isolation 2. Causes of hybrid
Chapters and other
assignments
C&O: Introduction,
Chapter 1
C&O Chapter 12;
Godfrey and Lawton,
2001; Benton and
Pearson, 2001.
C&O Chapters 2, 5, 6;
Orr 1995;
Presgraves et al., 2003.
C&O Chapters 7-9;
sterility: chromosomal rearrangements and point mutations.
Haldane’s rule. Reading: Tangental topic: evolution of sex
chromosomes.
Allopatric speciation. Nature of barriers to migration.
Biogeorgaphy. Ring species.
6
Oct 11
7
8
Oct 18
Oct 25
Nov 1
9
Nov 8
10
Nov 15
11
Nov 22
12
Nov 29
Sexual selection, sexual conflict and speciation. Reading:
13
14
Dec 6
Dec 13
Review and discussion
Final exam
Break
Midterm exam
Parapatric speciation and hybrid zones. Models of
migration and genetic differentiation of populations. What
migration rate is sufficient to keep a species contiguous?
Primary and secondary hybrid zones. Tangential topic:
human evolution – why are we one species?
Reinforcement. Reproductive character displacement.
Theoretical validity and examples from nature.
Sympatric speciation. Selection required for speciation.
Single locus cases: Hori’s cichlid; lacewings. More loci –
does it make things harder? Mate choice and habitat choice.
Pleiotropy and “magic trait”. Sticklebacks.
Sympatric speciation 2. Modeling. How can we adequately
represent life cycle, genotype architecture and ecology in a
model? What can we learn from models of speciation?
Turelli & Orr, 1995.
C&O Chapter 3
C&O Chapter 3
Gavrilets et al., 2000;
Nurnberger et al., 1995.
C&O Chapter 10; Kelly
and Noor, 1996.
Marshall et al. 2000.
C&O Chapters 4, 5;
Schluter, 2001; Via,
2001.
Gavrilets, 2003.
Maynard Smith, 1966.
Doebeli and
Dieckmann, 2003.
C&O Chapters 4, 6;
Panhuis et al., 2001;
Parker and Partridge.
1998.
Papers:
Benton MJ and PN Pearson. 2001. Speciation in the fossil record. Trends in Ecology and Evolution. 16: 7 405-411.
Doebeli M and Dieckmann U. 2003. Speciation along environmental gradients. Nature 421 (6920): 259-264.
Gavrilets S. 2003. Perspective: models of speciation: what have we learned in 40 years? Evolution 57(10):2197-215.
Gavrilets S, Li H and Vose MD. 2000. Patterns of parapatric speciation. Evolution 54 (4): 1126-1134.
Godfrey SCJ, Lawton JH, 2001. Scale and species numbers. Trends in Ecology and Evolution 16: 7 400-404.
Kelly JK, Noor MA. 1996. Speciation by reinforcement: a model derived from studies of Drosophila. Genetics
143(3):1485-97.
Marshall JL, Arnold ML and Howard DJ. 2000. Reinforcement: The Road Not Taken. Trends in Ecology and
Evolution. 17 (12): 558-563.
Nurnberger B, Barton N Macallum C et al., 1995. Natural selection on quantitative traits in the Bombina hybrid
zone. Evolution. 49 (6) 1224-1238.
Orr HA. 1995. The population genetics of speciation: the evolution of hybrid incompatibilities. Genetics
139(4):1805-13.
Panhuis et al., 2001. Sexual selection and speciation. . Trends in Ecology and Evolution. 16: 7 364-371.
Parker GA and Partridge L 1998. Sexual conflict and speciation. Philosophical-Trans. Royal-Soc. B 353 (1366) 261274.
Presgraves DC, Balagopalan L, Abmayr SM, Orr HA. 2003. Adaptive evolution drives divergence of a hybrid
inviability gene between two species of Drosophila. Nature. 423(6941):715-9.
Schluter D. 2001. Ecology and the origin of species. Trends in Ecology and Evolution. 16: 7 372-380.
Turelli M, Orr HA. 1995. The dominance theory of Haldane's rule. Genetics 140(1):389-402.
Via S. 2001. Sympatric speciation in animals: the ugly duckling grows up. Trends Ecol Evol. 16(7):381-390.
Wu CI, Ting CT. 2004. Genes and speciation. Nat Rev Genet. 5(2):114-22