Ecology and Genetics of Speciation

BIOL5300-201 Topics in Ecology and Evolution: Speciation Fall 2004 Dr. Lev Yampolsky [email protected] Phone 423-439-4359 http://faculty.etsu.edu/yampolsk/ 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 Chapters and other assignments 1 Aug 31 Organizational meeting 2 Sept 13 Introduction . Branching pattern of evolution – a C&O: Introduction, fundamental feature of living systems. “Evolution” of stars. Chapter 1 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. 3 Sept 20 Polymorphism and population differentiation – necessary C&O Chapter 12; first steps towards speciation. Mechanisms maintaining Godfrey and Lawton, genetic variation. Mutation-selection balance, drift, 2001; Benton and balancing selection, frequency-dependent selection and GxE Pearson, 2001. 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? 4 Sept 27 Genetics of reproductive isolation . Shifting balance. C&O Chapters 2, 5, 6; Prezygotic and postzygotic isolation. Chromosomal Orr 1995; incompatibilities and why they are unlikely to be the cause Presgraves et al., 2003. of speciation, at least in animals. Dobzhansky-Muller model. Selection or drift? Reading: Tangental topic: Other types of incompatibilities: cytoplasmic, parasite-induced, gamete recognition. 5 Oct 4 Genetics of reproductive isolation 2. Causes of hybrid C&O Chapters 7-9; sterility: chromosomal rearrangements and point mutations. Turelli & Orr, 1995. Haldane’s rule. Reading: Tangental topic: evolution of sex chromosomes. 6 Oct 11 Allopatric speciation . Nature of barriers to migration. C&O Chapter 3 Biogeorgaphy. Ring species.

Oct 18 Break 7 Oct 25 Midterm exam 8 Nov 1 Parapatric speciation and hybrid zones . Models of C&O Chapter 3 migration and genetic differentiation of populations. What Gavrilets et al., 2000; migration rate is sufficient to keep a species contiguous? Nurnberger et al., 1995. Primary and secondary hybrid zones. Tangential topic: human evolution – why are we one species? 9 Nov 8 Reinforcement. Reproductive character displacement. C&O Chapter 10; Kelly Theoretical validity and examples from nature. and Noor, 1996. Marshall et al. 2000. 10 Nov 15 Sympatric speciation. Selection required for speciation. C&O Chapters 4, 5; Single locus cases: Hori’s cichlid; lacewings. More loci – Schluter, 2001; Via, does it make things harder? Mate choice and habitat choice. 2001. Pleiotropy and “magic trait”. Sticklebacks. 11 Nov 22 Sympatric speciation 2. Modeling. How can we adequately Gavrilets, 2003. represent life cycle, genotype architecture and ecology in a Maynard Smith, 1966. model? What can we learn from models of speciation? Doebeli and Dieckmann, 2003. 12 Nov 29 Sexual selection, sexual conflict and speciation. Reading: C&O Chapters 4, 6; Panhuis et al., 2001; Parker and Partridge. 1998. 13 Dec 6 Review and discussion 14 Dec 13 Final exam

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) 261- 274. 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