Available online
Description
The programme examines some of the factors that influence the genetic polymorphism in the snails Cepaea nemoralis and Cepaea hortensis.
The programme examines some of the factors that influence the genetic polymorphism in the snails Cepaea nemoralis and Cepaea hortensis.
| Module code and title: | S299, Genetics |
|---|---|
| Item code: | S299; 09 |
| First transmission date: | 14-06-1976 |
| Published: | 1976 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:24:27 |
| + Show more... | |
| Producer: | Jean Nunn |
| Contributors: | Arthur Cain; David Jones |
| Publisher: | BBC Open University |
| Keyword(s): | Climate; Genetic polymorphism; Habitats; Shell banding; Shell colour |
| Footage description: | Arthur Cain, in a field near Oxford, introduces the programme. He shows several examples of Nemoralis and Hortensis shells. David Jones, with the aid of animations, demonstrates that the polymorphism found in these species of snails is genetic. Arthur Cain explains the importance of accurate habitat classification when researching the polymorphism of snails. Cain goes on to explain that his research showed a strong correlation between habitat and shell type. He speculates that this may be due to camouflage. Film shots of a thrush breaking open a snail. Cain, showing several different types of shell discusses the variability of shell type for Cepaea hortensis and compares this with nemoralis. David Jones compares the variability of the two species of snails in detail using scatter diagrams to illustrate his points. To test his hypothesis that habitat type correlates positively with shell type, Cain moves to a different part of the country. Panoramic views of downland. Cain collects snails from various points in this habitat. The characteristics appear to be in complete contrast to those found in the Oxford area. David Jones sums up these findings on scatter diagrams. Cain continues to collect snails in the downland habitat. He points out their characteristics as he goes along. David Jones, with fossil shells and diagrams, discusses the polymorphism of snails over the past several thousand years. He tries to correlate this with known climatic changes in the British Isles. Jones discusses research done on the continent which indicates that climatic factors do have an effect on the polymorphism of snails. Shots of the Valle de Aran and the Pyrenees. |
| Master spool number: | 6HT/72034 |
| Production number: | 00525_1177 |
| Videofinder number: | 998 |
| Available to public: | no |
