Genetic diversity, biogeography and the morpho-genetic relationship in extant planktonic foraminifera

Planktonic foraminifera are widely used as proxies for the reconstruction of past ocean conditions, a method that requires exact species classification and knowledge of their ecological adaptations. Species classification traditionally was conducted using morphological characteristics of the calcite shell. The application of genetic approaches on living planktonic foraminifera, however, challenged the classical species concept, by discovering a large number of cryptic species within the morphospecies. The present dissertation aims at establishing a connection between the fossil record and the genetic background of extant species by finding out to what degree morphologically defined species reflect real biological diversity. Molecular genetic techniques in combination with morphometric analyses were used to examine the extent of cryptic diversity in selected morphospecies and its relation to morphological traits. Furthermore, the biogeographic distribution patterns of extant species were analyzed in order to differentiate between species with local adaptations and endemism versus species with global dispersal and gene flow.