The Claim That Contrasts Between Lexical Items Construct Classifying Taxonomies

Martin & Rose (2007: 87):

Contrasts are an important resource in many genres for constructing classifying taxonomies in which one class of phenomenon is distinguished from another. The following biology report first contrasts the converse roles of producers and consumers. Sub-types of consumers are then contrasted in a series as primary, secondary and tertiary:

We have seen that organisms in an ecosystem are first classified as producers or as consumers of chemical energy. Producers in ecosystems are typically photosynthetic organisms, such as plants, algae and cyanobacteria. These organisms build organic matter (food from simple inorganic substances by photosynthesis). Consumers in an ecosystem obtain their energy in the form of chemical energy present in their 'food'. All consumers [sic] depend directly or indirectly on producers for their supply of chemical energy. 

Organisms that eat the organic matter of producers or their products (seeds, fruits) are called primary consumers, for example, leaf-eating koalas (Phascoiarctos cinereus), and nectar-eating honey possums (Tarsipes rostratus). Organisms that eat primary consumers are known as secondary consumers. Wedge-tailed eagles that prey on wallabies are secondary consumers. Some organisms consume the organic matter of secondary consumers and are labelled tertiary consumers. Ghost bats (Macroderma gigas) capture a variety of prey, including small mammals. (Kinnear and Martin 2004: 38)

Blogger Comments:

[1] To be clear, it is the grammar, not contrastive relations between lexical items, that constructs classifying taxonomies.  The reader can verify this by considering only the highlighted text in the absence of the grammatical structures in which they function.

In SFL theory, the inherent relation in lexis between the complementary antonyms producer and consumer is a resource of the textual metafunction, lexical cohesion, in creating the texture of a text.

[2] To be clear, the wordings primary consumers, secondary consumers and tertiary consumers are not lexical items, so the relations between them are not lexical relations.  Moreover, the sub-types of consumers — primary, secondary and tertiary — are construed grammatically through the Classifier function of the nominal group, and the identities of each are construed grammatically through the Token-Value relations of identifying clauses.

[3] To be clear, as sub-types, the Classifiers primary, secondary and tertiary constitute co-hyponyms of the Thing consumers.  See also the previous post on the notion of series (scales and cycles) as sub-types of "contrast".