Range-wide analysis of the spatial distribution and genetic diversity of Delonix s.l. (Leguminosae) in Madagascar : enhancing herbarium-based conservation assessments
Despite their ecological and economic importance, the majority of plant species and
their conservation status are poorly known. Only 4% of plants have been assessed
globally and listed on the IUCN Red List of Threatened Species; and without plant
conservation assessments, many plant species will not feature in conservation
planning.
Herbarium collection information can significantly increase the number of plant
conservation assessments. Thus, the aims of this thesis were: (1) to investigate how
the quality of herbarium-based conservation assessments can be optimised; (2) to
assess the extent to which herbarium-based conservation assessments reflect the
reality on the ground; and (3) to scientifically validate genetic and spatial underpinning
of IUCN criteria.
Preliminary range-based assessments of the Leguminosae of Madagascar achieved a
result consistent with the final conservation rating for over 95% of species when using
up to fifteen herbarium specimens. Bioclimatic modelling of range shifts based on
future climate change predicted that, in the worst case scenario, up to one third of
endemic Leguminosae in Madagascar will be threatened with extinction over the next
100 years. An analysis of the population structure of species of Delonix s.l.
(Leguminosae) showed that combining spatial analysis with population genetic data
provides a more complete picture of landscape-level population dynamics and the
impacts on conservation status.
Moreover, range-wide genetic analysis of AFLP markers for four species of Delonix
demonstrated a genetic basis for IUCN categories distinguishing between threatened
and non-threatened species. Although genetic data are currently not often
incorporated in conservation assessments, they are crucial in making accurate
management decisions and creating effective action plans for conservation. Only by
using all available scientific resources can informed conservation decisions be made
and the survival of plants and their associated ecosystems be ensured