The Balance Between Coherence and Variation in Evolution

Clausen, J.; Hiesey, Wm. M.

doi:10.1073/pnas.46.4.494

Cited by 63 publications

(32 citation statements)

References 5 publications

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“…Various entities that have become differentiated are thus preserved from generation to generation by this semi-stable genetic mechanism" (Nobs, 1963). The same system has been found in Potentilla (Clausen andHiesey, 1958, 1960).…”

Section: Genetic Coherencesupporting

confidence: 59%

THE EVOLUTIONARY SIGNIFICANCE OF THE SPECIATION OFEUPHRASIAIN EUROPE

Yeo

1968

Evolution

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Section: Genetic Coherencesupporting

confidence: 59%

THE EVOLUTIONARY SIGNIFICANCE OF THE SPECIATION OFEUPHRASIAIN EUROPE

Yeo

1968

Evolution

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“…However, when the bloom gets heavier in an area, pollinators may become limiting to ohia because their numbers are likely to lag behind the increase in flower numbers. At these times there is likely to be competition (Iversen 1940, Rocking 1965, and Docters van Leeuwen 1933, Clausen and Hiesey 1960 and in extreme deserts (Hagerup 1932). Second, pollinators may alternate between being limiting and being unlimited, as seems to be the situation in ohia.…”

Section: Pollinators As a Limiting Factor To Plantsmentioning

confidence: 99%

Plant-Pollinator Interactions in Hawaii: Pollination Energetics of Metrosideros Collina (Myrtaceae)

Carpenter¹

1976

Ecology

163

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The most abundant tree species in much of the undisturbed Hawaiian forests was the subject of a two year study on plant-pollinator interaction and energetics. The purposes of the study were 1) to determine the roles of insects and of some endemic Hawaiian birds in the pollination of the tree, Metrosideros collins, 2) to test the hypothesis that maximal outbreeding and seed set occur at intermediate levels of nectar availability, 3) to understand the adaptive significance of profuse flowering in this species, and 4) to compare the pollination ecology of this species and the degree of specialization in the plant-pollinator community with those of similar mainland systems.Endemic Hawaiian birds (Drepanididae) are essential for high levels of fruit set and outbreeding in M. collina. Fruit set was much higher in redflowered individuals when birds were allowed to use inflorescences than when only insects used them. This is apparently caused by partial self-incompatibility, such that maximal fruit set occurs only with outbreeding, the primary agents of which are the birds. The predominant flower color in the population, the dimensions of floral parts, and copious nectar secretion adapt this species to bird pollination. However, insects effect moderate amounts of pollination In comparison with mainland communities, the degree of specialization in the plant-pollinator relationship seems to be less in Hawaiian forests, although more information is needed on the Hawaiian lobelias and Sophora chrysophylla before such a statement should be made ~ith any certainty.-i i - ABSTRACT ••• LIST OF TABLES LIST OF FIGURES INTRODUCTION • • MATERIALS AND METHODSThe study subjects Nectar measurements -iv-

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“…The rate of production of adapted organisms will depend on the number of genes involved in the adaptive complex, the fewer being involved the greater the probability of their coming together. Whereas hundreds of genes have been assumed to be involved in given adaptive attributes (Mather, 1943), single gene differences may be sufficient to render organisms significantly better adapted (Daday, 1958) and, in fact, adaptive differences may be controlled by far fewer genes, from 3 to 20 pairs (Clausen and Hiesey, 1960). Thus, it would seem easier for a harmoniously adapted gene complex to arise than Huxley imagined.…”

Section: Local Variation and A!?aptationmentioning

confidence: 99%