About the Book

It was in the 1960s that the scientific community first became aware of

the threat that disruption of natural environments posed to the

germplasm of numerous cultivated species. It began working to

collect that germplasm, and a multitude of collections were set up

worldwide. These collections are now so large that they are proving

difficult to maintain and characterize, and their management has

become a crucial issue. Germplasm conservation, evaluation, and use

all need to be rethought.

In response to those concerns, Frankel and Brown introduced the

idea of core collections in the 1980s : a sample of accessions from a

larger collection is taken to provide as accurate a picture as possible of

the existing range of diversity. However, what criteria and tools should

be used to put together the sample ?

Agronomic criteria are primordial for breeders but are sometimes

difficult to evaluate, and their genetic determinism is often complex.

Molecular genetic markers, which are of no direct use, reveal the

structure of the existing diversity, which can be used as the basis for

setting up a core collection. Little is known about the relationships

between these two levels of variability : Are the different types of

molecular markers equivalent ? Does a strong molecular structure

systematically mean a strong structure based on agronomic criteria as

well ? Do the two types of structure necessarily tally ?

Statistical tools, which can be used to analyse the resemblances

between individuals or populations, are essential in identifying the

structure of diversity, if indeed it is structured. But which method is

most appropriate for each type of marker ? How reliable is the picture

it gives of diversity and what biological significance can it be assumed

to have ?

This work goes some way towards answering those questions on

the basis of a study of the genetic diversity of eleven tropical plants.

Three methodological chapters-on biochemical and molecular

markers, data analysis, and setting up core collections-complement

the study.