Diversity Of Oceanic Island Floras A Functional And Taxonomic Approach Along Gradients Of Environmental Heterogeneity And Across Spatial Scales PDF Download

Biodiversity is one of the most fundamental aspects of the environment and is vital in preserving the stability of ecosystems. It is therefore important to understand and maintain factors that influence biodiversity. This thesis aims to explore foundation species as one of these influences. The two methods of quantifying biodiversity that will be used are taxonomic diversity (diversity based on taxonomic grouping) and functional diversity (diversity based on functional traits) which allows for a combined consideration of what taxa are in the studied communities and also how those taxa interact with each other and their environment. This thesis is comprised of two independent studies that are each given their own chapter. In the first study, I ask: "Do functionally distinct foundation species host taxonomically and functionally unique communities?" I hypothesized that the communities associated with each foundation species would differ both taxonomically and functionally and the functional composition of the associated communities would be related to the functional properties of the foundation species themselves. On the rocky shore of Nova Scotia near Duncan's Cove, I collected patches of Mytilus spp. and Chondrus crispus including their associated communities. These species are distinct in their form and function; one being a hard-shelled consumer and the other a flexible primary producer. However, they are both common foundation species that occur in dense stands in the mid-to-low intertidal zone in Nova Scotia. I identified 29 invertebrate taxa from 7 phyla and found a marked difference in species composition and taxonomic diversity between both community types. The communities also differ drastically in their functional trait composition, despite having similar values from functional diversity metrics. These findings indicate that the functional properties of foundation species occurring in the same environment may influence the functional properties of the associated communities. In my second study, I ask: "Do mussel beds across the globe provide habitat to similar invertebrate communities?". I hypothesized a striking difference in the taxonomic composition of the associated communities but a larger overlap in the functional traits that such communities exhibit due to the similarities in the functional properties of the mussels hosting them. I analyzed 10 datasets of invertebrate communities associated with mussel beds in temperate-rocky shores across the globe from the north-east, south-east, north-west and south-west Pacific as well as the north-east, south-east, north-west and south-west Atlantic. I compared coasts based on taxonomic and functional diversity (based on functional traits). The results reveal that, globally, mussel bed communities have many similarities. Firstly, they hold similar numbers of species per unit area. Moreover, multivariate comparisons based on coarse taxonomic groups and functional traits revealed a noticeable overlap in the communities that inhabit mussel beds on different coasts. Overall, the ability of these mussels to host similar communities despite local and regional environmental differences emphasizes their importance in maintaining both community functions and biodiversity of the rocky intertidal. Combined these two studies compare the effect of the foundation species and the effects of the environment on the faunal community. The results indicate that functionally different foundation species in the same environment hold very different communities but functionally similar foundation species in different environments have more overlap in their associated communities. It is therefore possible that in my studied systems, the functional properties of foundation species play a bigger role in determining the assembly of associated communities than environmental conditions. In this way, these studies highlight, from a novel perspective, the influence of foundation species on biodiversity within the environments they inhabit.