<DIV id=RTEContent>Phil Nisbet <pcnisbet1@hotmail.com> wrote:<BR><BR>> The facts are that Darwin’s ideas of gradualism are simply not<BR>> shown to happen in real data.<BR><BR>> The trouble with this approach is that there is actually no data<BR>> for gradualism and no proof that it ever occurs<BR><BR>This is wrong. There is a lot of evidence for gradualism (as there is for punctuated equilibrium):<BR><BR>Alvaro, JJ; Vizcaino, D. Evolutionary trends in the ornamentation of Cambrian solenopleuropsine trilobites. Palaeontology. Vol. 44, no. 1, pp. 131-141. Feb 2001.<BR>"The transformation of the Pardailhania-Solenopleuropsis (Manublesia)-Solenopleuropsis (Solenopleuropsis) lineages occurred during the mid Caesaraugustian-early Languedocian interval, with all measured morphological variables exhibiting continuous and gradual changes."<BR><BR>Chaline, J; Brunet-Lecomte, P; Montuire, S; Viriot, L; Courant, F. Anatomy of the arvicoline radiation (Rodentia):
palaeogeographical, palaeoecological history and evolutionary data. Annales Zoologici Fennici. Vol. 36, no. 4, pp. 239-267. 1999.<BR>"Study of arvicolines reveals three modes of evolution: stasis, phenotypic plasticity and phyletic gradualism."<BR><BR>Kucera, M; Malmgren, BA. Differences between evolution of mean form and evolution of new morphotypes: an example from Late Cretaceous planktonic foraminifera. Paleobiology. Vol. 24, no. 1, pp. 49-63. 1998.<BR>"A gradual increase in mean shell conicity was observed over the last 3 million years of the Cretaceous."<BR><BR>Norris, RD; Corfield, RM; Cartlidge, J. What gradualism? Cryptic speciation in globorotaliid as foraminifera. Paleobiology. Vol. 22, no. 3, pp. 386-405. 1996.<BR>"Gradual morphological changes were associated with the main phase of shell growth of both the ancestor and descendant species in the near-surface ocean."<BR><BR>Wei, K-Y; Kennett, JP. Phyletic gradualism and punctuated equilibrium in the late Ne!
ogene
planktonic foraminiferal clade Globoconella. Paleobiology. Vol. 14, no. 4, pp. 345-363. 1988.<BR>"The evolution of the Globoconella clade shows both phyletic gradualism and punctuated equilibrium."<BR><BR>Malmgren, BA; Berggren, WA; Lohmann, GP. Species formation through punctuated gradualism in planktonic foraminifera. Science. Vol. 225, no. 4659, pp. 317-319. 1984.<BR>"The lineage was in stasis over a considerable part of its total duration but underwent relatively rapid, but not geologically instantaneous, gradual morphologic change that did not lead to lineage splitting."<BR><BR>Malmgren, BA; Berggren, WA; Lohmann, GP. Evidence for punctuated gradualism in the Late Neogene Globorotalia tumida lineage of planktonic foraminifera. Paleobiology. Vol. 9, no. 4, pp. 377-389. 1983.<BR><BR>Also:<BR><BR>Sheldon, PR. Plus ca change -- a model for stasis and evolution in different environments. Palaeogeography, Palaeoclimatology, Palaeoecology. Vol. 127, no. 1-4, pp. 209-227. Dec
1996.<BR>"Punctuated equilibrium could be being mistakenly perceived as the overwhelming pattern in the history of life because the environments in which gradualism predominates are rarely preserved in the fossil record."<BR><BR>As Webster and Pellmyr pointed out in their column, punctuated equilibrium and gradualism occur both and are complementary:<BR><BR>Gould, SJ; Eldredge, N. Punctuated equilibrium comes of age. Nature. Vol. 366, no. 6452, pp. 223-227. 1993.<BR>"The intense controversies that surrounded the youth of punctuated equilibrium have helped it mature to a useful extension of evolutionary theory. As a complement to phyletic gradualism, its most important implications remain the recognition of stasis as a meaningful and predominant pattern within the history of species, and in the recasting of macroevolution as the differential success of certain species (and their descendants) within clades."<BR><BR>Geiger, G. On the dynamics of evolutionary discontinuities.
Mathematical Biosciences. Vol. 67, no. 1, pp. 59-79. 1983.<BR>"It is argued that evolutionary gradualism and saltationism represent complementary modes of macroevolution corresponding respectively to the local and global topographical structure of adaptive surfaces."<BR><BR>Parsons, PA. The importance and consequences of stress in living and fossil populations: From life-history variation to evolutionary change. American Naturalist. Vol. 142, no. supplement. 1993.<BR>"In moderately stressed and narrowly fluctuating environments there should be sufficient genetic variability and metabolic energy to permit genetic adaptation. Phyletic gradualism is an expectation in these environments. In more stressed and widely fluctuating environments a punctuated evolutionary pattern is likely even though stasis may occur most of the time."<BR><BR>Bodnar, JW; Jones, GS; Ellis, CH Jr. The domain model for eukaryotic DNA organization 2: A molecular basis for constraints on development and e!
volution.
Journal of Theoretical Biology. Vol. 137, no. 3, pp. 281-320. 1989.<BR>"Additionally, these suggested developmental pathways are consistent with mechanisms of evolution in which gradualism and punctuated equilibrium are not exclusive of one another and are interrelated mechanisms of evolution that are both induced by specific chromosomal mutations."<BR><BR>Riccardi, AC. The Andean Eurycephalitinae (Ammonitina, Middle Jurassic): Evolutionary models and paleontological resolution. Boletin Genetico. no. 13, pp. 1-27. 1985.<BR>"Phyletic gradualism and punctuated equilibrium are part of neodarwinism and both are compatible with the theory of population genetics." <BR></DIV><p>
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