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Roca et al 2001 Vilgalys 1994

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Presentation on theme: "Roca et al 2001 Vilgalys 1994"— Presentation transcript:

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2 Roca et al 2001

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5 Vilgalys 1994 http://botit.botany.wisc.edu/toms_fungi/oct98.html

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7 Brown et al. 1999

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11 http://atlas.geo.cornell.edu/education/instructor/topography/hawaii_seamounts.html Decrease in Age of Island Movement of Pacific plate

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15 Mendelson and Shaw 2005

16 Distinquishing within- vs. between-island speciation using evolutionary trees Within-island speciation

17 Distinquishing within- vs. between-island speciation using evolutionary trees Between-island speciation

18 Geographic (island) distribution Parsimony reconstruction

19 http://commons.wikimedia.org/wiki/Commons:Featured_picture_candidates/Image:Hawaii_Island_topographic_map-fr.svg Host association in Trupanea arboreae Dubautia arborea Dubautia scabra Dubautia ciliolata Dubautia linearis Argyroxiphium kauense

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22 Darwin: geographic separation followed by gradual (slow) adaptation to different ecological circumstances eventually leads to reproductive isolation Two alternatives allow rapid speciation: –FOOD: Speciation due to shifts in host -- without geographic isolation –SEX: Speciation due to divergent sexual selection - with brief geographic isolation Mechanisms of species formation

23 Model of sympatric speciation via shifts to new host (FOOD) 1 Population uses ancestral host 1 1 2 Host shift New population founded via shift to derived host 2 Populations on two hosts become reproductively isolated 1 2 2 2 1

24 Signatures of sympatric speciation via host/habitat shift (after Via 2001) Sympatric overlap of host patches Mating on the host causes reproductive isolation between races Host phenology differs Divergent selection on different hosts/habitats

25 Illustration from Abrahamson and Weis (1997) Goldenrod gallmaker -- Eurosta solidaginis – an example of speciation via host-plant shift Photo:Warren Abrahamson

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31 Speciation via SEXual selection Females in ancestral populations prefer blue males Geographic barrier divides populations Female preference for male trait diverges due to genetic drift Upon recontact, populations reproductively isolated due ONLY to female preference

32 Signatures of speciation via sexual selection (after Panhuis et al. 2001) Populations within species vary in sexually selected traits and associated preferences, resulting in partial pre-mating isolation Closely related species differ markedly in mating signals and preferences, which constitute the primary barrier to gene exchange Species differ in few other traits besides those involved in mate choice

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35 from Turgeon et al. 2005 North American Enallagma

36 Turgeon et al. 2005

37 Damselfly Mating Practices Photo: Denise Steele, Dartmouth College

38 McPeek et al. (in press)

39 Robertson and Paterson, 1982. Evolution.

40 McPeek et al. (in press)

41 Shape evolution NS different from “punctuated evolution”

42 McPeek et al. 2009 Change in female shape correlated to change in male shape

43 Brown, McPeek and May.2000 Syst. Biol. 49:697-712.

44 Selection and the Enallagma radiation Four damselfly-lake species generated by habitat shifts and adaptive evolution (morphological, behavioral and physiological) Many fish-lake species generated during recent radiations (associated with glacial retreat?), possibly via founder effects on mechanical mate recognition system

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60 Shaw and Lesnick 2009

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