Abstract
Hypotheses for divergence and speciation in rainforests generally fall into two categories: those emphasizing the role of geographic isolation and those emphasizing the role of divergent selection along gradients. While a majority of studies have attempted to infer mechanisms based on the pattern of species richness and congruence of geographic boundaries, relatively few have tried to simultaneously test alternative hypotheses for diversification. Here we discuss four examples, taken from our work on diversification of tropical rainforest vertebrates, in which we examine patterns of genetic and morphological variation within and between biogeographic regions to address two alternative hypotheses. By estimating morphological divergence between geographically contiguous and isolated populations under similar and different ecological conditions, we attempt to evaluate the relative roles of geographic isolation and natural selection in population divergence. Results suggest that natural selection, even in the presence of appreciable gene flow, can result in morphological divergence that is greater than that found between populations isolated for millions of years and, in some cases, even greater than that found between congeneric, but distinct, species. The relatively small phenotypic divergence that occurs among long-term geographic isolates in similar habitats suggests that morphological divergence via drift may be negligible and/or that selection is acting to produce similar phenotypes in populations occupying similar habitats. Our results demonstrate that significant phenotypic divergence: (1) is not necessarily coupled with divergence in neutral molecular markers; and (2) can occur without geographic isolation in the presence of gene flow.
Key words
- divergence with gene flow
- drift
- mtDNA
- natural selection
- speciation
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References
Benkman, C.W., 1991. Predation, seed size partitioning and the evolution of body size in seed-eating finches. Evol. Ecol. 5: 118–127.
Boag, P.T. & A. van Noordwijk, 1987. Quantitative genetics, pp. 45–78 in Avian Genetics: A Population and Ecological Approach, edited by F. Cooke & P.A. Buckley. Academic Press, New York.
Chapin, J.P., 1924. Size-variation in Pyrenestes, a genus of weaver-finch. Am. Mus. Nat. Hist. Bull. 49: 415–441 Size-variation in Pyrenestes, a genus of weaver-finch. Am. Mus. Nat. Hist. Bull. 49: 415–441.
Chapin, J.P., 1954. The birds of the Belgian Congo. Am. Mus. Nat. Hist. 75, New York.
Charlesworth, B., 1994. Evolution in Age-Structured Populations. Cambridge University Press, Cambridge.
Dieckmann, U. & M. Doebeli, 1999. On the origin of species by sympatric speciation. Nature 400: 354–357.
Edwards, S.V. & P. Beerli, 2000. Gene divergence, population divergence, and the variance in coalescence time in phylogeographic studies. Evolution 54: 1839–1854.
Endler, J.A., 1982a. Problems in distinguishing historical from ecological factors in biogeography. Am. Zool. 22: 441–452.
Endler, J.A., 1982b. Pleistocene forest refuges: fact or fancy, in Biological Diversification in the Tropics, edited by G.T. Prance. Columbia University Press, New York.
Fjeldså, J. & J.C. Lovett. 1997. Geographical patterns of old and young species in African forest biota: the significance of specific montane areas as evolutionary centres. Biodiv. Cons. 6: 325–346.
Fridolfsson, A.K. & H. Ellegren, 1999. A simple and universal method for molecular sexing of non-ratite birds. J. Avian Biol. 30: 116–121.
Funk, D.J., 1998. Isolating a role for natural selection in speciation: host adaptation and sexual isolation in Neochlamisus bebbianae leaf beetles. Evolution 52: 1744 1744–1759.
Gans, C., 1975. Tetrapod limblessness: evolution and functional corollaries. Am. Zool. 15: 455–467.
Garcia-Moreno, J. & J. Fjeldså, 2000. Chronology and mode of speciation in the Andean avifauna. Bonn. Zool. Monogr. 46: 25–46.
Garcia-Paris, M., D.A. Good, G. Parra-Olea & D.B. Wake, 2000. Biodiversity of Costa Rican salamanders: implications of high levels of genetic differentiation and phylogeographic structure for species formation. Proc. Natl. Acad. Sci. 97: 1640–1647.
Gavrilets, S., 2000. Waiting time to parapatric speciation. Proc. R. Soc. Lond. B 267: 2483–2492.
Gavrilets, S., H. Li & M.D. Vose, 2000. Patterns of parapatric speciation. Evolution 54: 1126–1134.
Grant, P.R., 1986. Ecology and Evolution of Darwin’s Finches. Princeton University Press, Princeton.
Haffer, J., 1969. Speciation in Amazonian forest birds. Science 165: 131–137.
Haffer, J., 1974. Avian speciation in tropical South America. Publ. Nutt. Ornithol. Club 14, Cambridge MA.
Haffer, J., 1993. Time’s cycle and time’s arrow in the history of Amazonia. Biogeographica 69: 15–45.
Haffer, J., 1997. Alternative models of vertebrate speciation in Amazonia: an overview. Biodiv. Cons. 6: 451–477.
Hendry, A.P., 2001. Adaptive divergence and the evolution of reproductive isolation in the wild: an empirical demonstration using introduced sockeye salmon. Genetica 112-113: 515–534.
Hendry, A.P., J.K. Wenburg, P. Bentzen, E.C. Volk & T.P. Quinn, 2000. Rapid evolution of reproductive isolation in the wild: evidence from introduced salmon. Science 290: 516–518.
Johnson, K.P. & M.D. Sorenson, 1998. Comparing molecular evolution in two mitochondrial protein coding genes (cytochrome b and ND2) in the dabbling ducks (Tribe: Anatini). Mol. Phylogen. Evol. 10: 82–94.
Keith, S., E.K. Urban & C.H. Fry, 1992. The Birds of Africa. Academic Press, New York.
Kondrashov, A.S. & FA. Kondrashov, 1999. Interactions among quantitative traits in the course of sympatric speciation. Nature 400: 351–354.
Korol, A., E. Rashkovetsky, K. Iliadi, P. Michalak, Y. Ronin & E. Nevo, 2000. Nonrandom mating in Drosophila melanogaster laboratory populations derived from closely adjacent ecologically contrasting slopes at ‘Evolution Canyon’. Proc. Natl. Acad. Sci. 97: 12637–12642.
Longman, K.A. & J. Jenik, 1992. Forest-savanna boundaries: general considerations, pp. 3–20 in Nature and Dynamics of Forest-Savanna Boundaries, edited by P.A. Furley, J. Proctor & J.A. Ratter. Chapman and Hall, New York.
Losos, J.B., T.W. Schoener, K.I. Warheit & D. Creer, 2001. Experimental studies of adaptive differentiation in Bahamian Anolis lizards. Genetica 112-113: 399–415.
Louette, M., 1981. The birds of Cameroon. An annotated checklist. Verhandelingen van de Koninklijke Academie voor Wetenschap-pen, Letteren en Schone Kunsten van Belgie. Klasse der Weten-schappen, Brussels.
Lovette, I.J. & E. Bermingham, 1999. Explosive speciation in the New World Dendroica warblers. Proc. R. Soc. Lond. B 266: 1629–1636.
Lu, G. & L. Bernatchez, 1999. Correlated trophic specialization and genetic divergence in sympatric lake whitefish ecotypes (Coregonus clupeaformis): support for the ecological speciation hypothesis. Evolution 53: 1491–1505.
Lynch, M. & K. Ritland, 1999. Estimation of pairwise relatedness with molecular markers. Genetics 152: 1753–1766.
Maynard Smith, J., 1966. Sympatric speciation. Am. Nat. 100: 637–650.
Mayr, E., 1963. Animal Species and Evolution. Harvard University Press, Cambridge.
Mayr, E. & R.J. O’Hara, 1986. The biogeographical evidence supporting the Pleistocene forest refuge hypothesis. Evolution 40: 55–67.
McMillan, W.O., C.D. Jiggins & J. Mallet, 1997. What initiates speciation in passion-vine butterflies? Proc. Natl. Acad. Sci. 94: 8628–8633.
Moritz, C., L. Joseph, C. Cunningham & C.J. Schneider, 1997. Molecular perspectives on historical fragmentation of Australian tropical and subtropical rainforest: implications for conservation, pp. 442–454 in Tropical Forest Remnants, edited by W. Laurance & R. Bierregard. University of Chicago Press, Chicago.
Moritz, C., J.L. Patton, C.J. Schneider & T.B. Smith, 2000. Diversification of rainforest faunas: an integrated molecular approach. Ann. Rev. Ecol. Syst. 31: 533–563.
Orr, M.R. & T.B. Smith, 1998. Ecology and speciation. TREE 13: 502–506.
Peterson, A.T., J. Soberon & V. Sanchez-Cordero, 1999. Conservatism of ecological niches in evolutionary time. Science 285: 1265–1267.
Podos, J., 2001. Correlated evolution of morphology and vocal signal structure in Darwin’s finches. Nature 409: 185–188.
Prance, G.T. (ed.), 1982. Biological Diversification in the Tropics. Columbia University Press, New York.
Price, T., 1998. Sexual selection and natural selection in bird speciation. Phil. Trans. R. Soc. Lond. B 353: 251–260.
Reznick, D.N. & C.K. Ghalambor, 2001. The population ecology of contemporary adaptations: what empirical studies reveal about the conditions that promote adaptive evolution. Genetica 112-113: 183–198.
Reznick, D.N., F.H. Shaw, F.H. Rodd & R.G. Shaw, 1997. Evaluation of the rate of evolution in natural populations of guppies (Poecilia reticulata). Science 275: 1934–1937.
Rice, R.R. & E.E. Hostert, 1993. Laboratory experiments on speciation: what have we learned in 40 years? Evolution 47: 1637–1653.
Roy, M., 1997. Recent diversification in African greenbuls (Pycnonotidae: Andropadus) supports a montane speciation model. Proc. R. Soc. Lond. B 264: 1337–1344.
Rundle, H.D., L. Nagel. J.W. Boughman & D. Schlüter, 2000. Natural selection and parallel speciation in sticklebacks. Science 287: 306–308.
Schluter, D., 1998. Ecological causes of speciation, pp. 114–129 in Endless Forms: Species and Speciation, edited by D.J. Howard & S.H. Berlocher. Oxford University Press, Oxford.
Schluter, D., 2000. The Ecology of Adaptive Radiation. Oxford University Press, Oxford.
Schluter, D. & J.N.M. Smith, 1986a. Natural selection on beak and body size in the song sparrow. Evolution 40: 221–231.
Schluter, D. & J.N.M. Smith, 1986b. Genetic and phenotypic correlations in a natural population of song sparrows. Biol. J. Linn. Soc. 29: 23–36.
Schneider, C., 2000. Natural Selection and Speciation. Proc. Natl. Acad. Sci. 97: 12398–12399.
Schneider, C.J. & C. Moritz, 1999. Refugial isolation and evolution in Australia’s wet tropics rainforest. Proc. Roy. Soc. Lond. B 266: 191–196.
Schneider, C., T.B. Smith, B. Larison & C. Moritz, 1999. A test of alternative models of diversification in tropical rainforests: ecological gradients versus rainforest refugia. Proc. Natl. Acad. Sci. 94: 13869–13873.
Schneider, C.J., M. Cunningham & C. Moritz, 1998. Comparative phylogeography and the history of vertebrates endemic to the Wet Tropics rainforest of Australia. Mol. Ecol. 7: 487–498.
Shields, G.F. & A.C. Wilson. 1987. Calibration of mitochondrial DNA evolution in geese. J. Mol. Evol. 24: 212–217.
Slabbekoorn, H. & T.B. Smith, 2000. Does bill size polymorphism affect courtship song characteristics in the African finch Pyrenestes ostrinus? Biol. J. Linn. Soc. 71: 737–753.
Smith, T.B., 1987. Bill size polymorphism and intraspecific niche utilization in an African finch. Nature 329: 717–719.
Smith, T.B., 1990a. Natural selection on bill characters in the two bill morphs of the African finch Pyrenestes ostrinus. Evolution 44: 832–842.
Smith, T.B., 1990b. Patterns of morphological and geographic variation in trophic bill morphs of the African finch Pyrenestes. Biol. J. Linn. Soc. 41: 381–414.
Smith, T.B., 1990c. Resource use by bill morphs of an African finch: evidence for intraspecific competition. Ecology 71: 1246–1257.
Smith, T.B., 1991. Inter-and intra-specific diet overlap during lean times between Quelea erythrops and bill morphs of Pyrenestes ostrinus. Oikos 60: 76–82.
Smith, T.B., 1993. Disruptive selection and the genetic basis of bill size polymorphism in the African finch, Pyrenestes. Nature 363: 618–620.
Smith, T.B., 1997. Adaptive significance of the mega-billed form in the polymophic black-bellied seedcracker Pyrnestes ostrinus. Ibis 139: 382–387.
Smith, T.B. & S. Skulason, 1996. Evolutionary significance of resource polymorphisms in fish, amphibians and birds. Ann. Rev. Ecol. Syst. 27: 111–133.
Smith, T.B. & D. Girman, 2000. Reaching new adaptive peaks: evolution of bill size polymorphism in a African finch, pp. 139–156 in Adaptive Genetic Variation in the Wild, edited by T. Mousseau, B. Sinervo & J. Endler. Oxford University Press. Oxford.
Smith, T.B., R.K. Wayne, D.J. Girman & M.W. Bruford, 1997. A role for ecotones in generating rainforest biodiversity. Science 276: 1855–1857.
Stebbins, G.L., 1974. Flowering Plants, Evolution above the Species Level. Harvard University Press, Cambridge, MA.
Thiollay, J.M., 1971. L’avifaune de la region de Lamto. Annales De L’Universite D’Abidjan, Ser. E. Ecologie IV: 1–132.
Turton, S.M. & G. J. Sexton, 1996. Environmental gradients across four rainforest-open forest boundaries in northeastern Queensland. Aust. J. Ecol. 21: 245–254.
Wilson, A.C., R.L. Cann, S.M. Carr, M. George, U.B. Gyllensten, K.M. Helm-Bychowski, R.G. Higuchi, S.R. Palumbi, E.M. Prager, R.D. Sage & M. Stoneking, 1985. Mitochondrial DNA and two perspectives on evolutionary genetics. Biol. J. Linn. Soc. 26: 375–400.
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Smith, T.B., Schneider, C.J., Holder, K. (2001). Refugial isolation versus ecological gradients. In: Hendry, A.P., Kinnison, M.T. (eds) Microevolution Rate, Pattern, Process. Contemporary Issues in Genetics and Evolution, vol 8. Springer, Dordrecht. https://doi.org/10.1007/978-94-010-0585-2_23
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