Geographical variation of aquatic macrophyte biodiversity: Towards an integration of scale and ecological organisation = Variación geográfica en la biodiversidad de los macrófitos acuáticos: hacia una integración de la escala y la organización ecológica

Abstract

Eutrophication, pollution, habitat fragmentation, intense cultivation and global warming are increasingly causing deterioration of continental waters, and lentic ecosystems (here, lakes and ponds) are especially vulnerable to these changes, resulting in a critical situation that threatens their biodiversity in unparalleled rate. Aquatic macrophytes are the dominant element of most lentic ecosystems, and therefore, better understanding the patterns and mechanisms that structure their distributions would be valuable from basic and applied perspectives. Since the assessment of structures emerging from spatial organisation is now widely recognised as a cornerstone paradigm to interpret ecological phenomena, research has notably steered towards multi-scale perspectives on the assembly of biological diversity. This progress has been closely intertwined with recent developments in population genetics, metacommunity ecology and macroecology. However, their most recent conceptual advances are usually not fully operational because these empirical areas of research are usually considered independent of each other.The main aim of this thesis was to examine patterns and mechanisms of aquatic macrophyte diversity at regional and global scales using distinct organisation levels, from genes to species. Specifically, we (i) established a novel combination of robust mathematical methods capable of identifying the processes -including biotic interactions-and most important spatial scales involved in community assembly; (ii) built several phylogenies comprising most aquatic plant lineages and exploited a wide array of functional traits to determine whether different diversity facets (i.e. taxonomic, functional and phylogenetic) explain idiosyncratic patterns of macrophyte species distributions that would otherwise be missed in a traditional analysis of community turnover; (iii) used microsatellite loci to explore the spatial genetic variation of the aquatic macrophyte Myriophyllum alterniflorum DC. and examine if the results obtained through molecular estimates match modern perspectives of metacommunity theory at regional scales; and (iv) retrieved regional data from six continents to untangle if macroecological processes have left a footprint in the current patterns of compositional variation and community-environment relationships of aquatic macrophytes at global scales.