Transference of Function

Abstract

The systematic comparison of plants, and probably of animals, shows that a property which occurs in an organ, tissue, or cell-layer in one case may occur in other parts of the body in other cases. The property is the same, but its site of development has shifted. These deviations are found a t all levels of classification ; the transference of function, therefore, as I have called the process (Corner, 1949a, p. 381 ; 19496, p. 360) is a method of evolution.A simple example is the presence of anthocyanin in the flowering-plant. At some stage in development, the colour appears. In one variety the underside of the leaf may be red, or merely the veins, or the petiole or node or internode, or the colour may appear only in young leaves or old leaves, or only on insolated surfaces. Such small differences are usually passed over, though of horticultural value ; yet, they raise the question why one part of the epidermis should be different from another. There is not just the property to be considered, but the site of its materialization. Presumably the property is inherent in all the cells, but only in certain parts of the body do the circumstances evoke it. A hereditary character consists of two parts, the property and, what must be more complex, the conditions which materialize it. Thus I understand the evolution of the property as anagenesis in the fist place, and the diversification or cladogenesis of its occurrence. Stasigenesis of Huxley (1957) is shown by the widespread pigmentation of petals rather than sepals. When, with the loss of petals, the calyx becomes pigmented, there is a profound modification of floral organization, as Miss Saunders (1033) has explained. A remarkable instance is Sairaca (Leguminosae-Caesalpinioideae-Amherstieae). Its petals are lost ; the tetramerous calyx takes their function and their vascular supply ; the inner whorl of stamens takes the place of the petals ; and the outer whorl of stamens is variously reduced (Text- fig. 1). S. thaipingensis Cantley ex King has the effective formula K4 CO A 0 + 4, but the full vascular supply K5 C5 A5 + 5, the petal-bundles lying in the

Is LEAFY a useful marker gene for the flower-inflorescence boundary in the Euphorbia cyathium?

“…Corner (1958) speculated that it could share homology with both flowers and inflorescences. Recent detailed comparative ontogenetic and morphological investigations (Prenner and Rudall, 2007; Prenner et al , 2008 a , 2009) highlighted the indistinct boundary between the inflorescence, flower, and floral organs.…”

Deep homology: A view from systematics

“…If homoplastic traits can be characterised as recurrent evolution, [53] then analogous traits can be considered as a type of replacement evolution, when a non-correspondent morphological trait replaces or transfers to another position to carry out a particular function. [93,94] In contrast to examples 1, 2 and 4, the interpretation of deep homology in example 3 [7] represents homoplastic genetic mechanism that regulates a homoplastic character (bipartite perianth) that evolved independently several times and did so in a variety of ways (various types of petals and lodicules, etc.). It is possible to interpret this example, of deep homology, as representing the inherited capacity or potential for the mechanism to regulate the inner perianth domain and, therefore, the deep homology would not necessarily be linked to any particular phylogenetic level or node on a tree.…”

Developmental causation and the problem of homology

“…While some biologists will find this implication distasteful, others have already come to terms with such conclusions (e.g., Sattler 1984Sattler , 1988Wake 1999). For example, the idea of mixed (or partial) homology has been found useful for exploring cases of developmental evolution through "transference of function" (Corner 1958;Baum and Donoghue 2002). Furthermore, we have a linguistic framework for handling situations of mixed homology.…”