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Oceanic islands only comprise a small amount of the Earth’s land area but harbour a disproportionate amount of global biodiversity. This vast diversity is not only reflected in the taxonomic uniqueness of island biota but also in the remarkable evolution of functional traits. Functional traits, i.e. measurable characteristics that strongly influence the fitness of species, determine how a species responds to its environment and can help to gain more insights into the biogeographical, ecological and evolutionary processes that have shaped island biodiversity. However, research in island biogeography has primarily focused on species richness, and knowledge of functional trait patterns on oceanic islands is scarce. Hence, in this dissertation, I have explored how trait-based approaches can increase our understanding of how biodiversity on oceanic islands assembles and how it is driven by the environment. The Canary Islands (Spain) are a particularly suitable model system to investigate patterns and drivers of biodiversity. The archipelago is characterised by a high variation in environmental heterogeneity and inhabits a unique and well-described native flora. Therefore, I have investigated five principal research questions using the flora (Spermatophytes) of the Canary Islands as a study object. First, I have analysed how climate and biogeography shape the assembly of the Canary Islands flora using a novel trait-based approach. Second, the question of whether rare climates link to functional trait distinctiveness in the native Canary Islands flora was addressed. Third, I have examined how intraspecific trait variation is represented in the native flora of oceanic islands focusing on the succulent scrub of La Palma (Canary Islands). Fourth, this dissertation investigated whether scientific floras can be reliable sources for trait data of plants native to oceanic islands. Finally, I have explored how climate change may impact the native Canary Islands flora by analysing possible climate change-induced shifts in plant species distribution and plant traits.
The results of my dissertation expand the understanding of the importance of biogeography and the environment in determining the functional composition of island floras. I have assessed that traits of endemic plant species did not expand the functional trait space of the Canary Islands but were packed with the ones of non-endemic species. This result hints at a trait convergence in endemic species, possibly driven by non-adaptive speciation processes. Moreover, I have evidenced that humidity is a critical driver of functional diversity in native plant assemblages and particularly leads to a high trait convergence in arid environments via environmental filtering. In contrast, alien species have expanded the Canary Islands flora’s functional trait space. I further have shown that in contrast to native species assemblages, alien species assemblages are characterised by an increasing functional diversity with increasing aridity. This contrasting pattern of functional diversity could pose a potential risk to the native flora of the Canary Islands as a low functional diversity is expected to reduce the resilience of species assemblages to the establishment of more functionally diverse alien plant species. However, in this dissertation, I also have revealed that endemic plant species on the Canary Islands show a high intraspecific variation in arid environments, possibly as an adaptation to environmental stress. Intraspecific variation could help endemic plant species have a competitive advantage over alien species and be more resilient to environmental changes. Furthermore, in this dissertation, I have shown that scientific floras and taxonomic monographs could be used to gain information on quantitative functional traits of plants native to oceanic islands. This finding is particularly relevant for advances in trait-based research, as coverage of trait data for oceanic island floras is extremely poor in global trait databases. Hence, for some of the studies included in this dissertation, trait data were retrieved from scientific floras and taxonomic monographs and used to answer novel scientific research questions. Thus, I have used trait data from the literature to analyse the effect of climate change on the range size of plants native to the Canary Islands. Identifying plant species of particular conservation concern is critical on oceanic islands as many island species have limited distributions and small population sizes, and their niche tracking is impeded by insularity. I have revealed that single-island endemic plants gain less and lose more climatically suitable areas than archipelago endemic and non-endemic native plants due to a climate change-induced decrease in precipitation until 2100...
We present an overview of the morphological diversity and geographical distribution of the anostracan genus Dendrocephalus Daday, 1908, and describe two new species: D. aranai sp. nov. from Jequitinhonha in the state of Minas Gerais and D. xikrini sp. nov. from the Carajás Mountains (Serra dos Carajás) in the state of Pará. These species have important similarities to D. goiasensis Rabet & Thiéry, 1996 and D. thieryi Rabet, 2006, respectively, but differ from them and each other through a combination of characters that are essentially unique to the endopods, and frontal appendage branch 2A and branch 2D. We also partly redescribe D. carajaensis Rogers, Gomes & Vieira, 2012, which shows a particular intra-populational variability in branch 2A and 2D III of the frontal appendage, a type of polymorphism that was also recently observed in D. orientalis Rabet & Thiéry, 1996 and which must now be taken into account in taxonomy. In terms of the distribution of species of Dendrocephalus in Brazil, we suggest that several other species are probably present in the Amazonian, Cerrado and Pantanal Biomes, which remain largely unexplored. A new taxonomic key for the identification of males of the Brazilian species is provided.
The status of endemic liverworts in the Western Ghats ‘one of the major Hot spots’ of plant biodiversity have been discussed in the present paper. The study is based on the evaluation of type and authentic specimens available in Lucknow University Hepatic Herbarium (LWU) as well as those in several international herbaria including NICH, NY, JE, FH, G and excicatae of the world and published data. An overall assessment and evaluation revealed the presence of a total of 54 liverworts endemic to Western Ghats in India. The paper also discusses those species which were earlier known as endemic to the area but now show an extended range of distribution elsewhere and also the species earlier introduced from Western Ghats but now changed their status.