Conference Agenda

The global homogenisation of floral communities is a characteristic of the Anthropocene. Oceanic islands are especially prone to homogenisation due to their high invasibility and anthropogenically-caused extinctions and extirpations of unique native, and often endemic, species. In existing studies, the time horizon in which homogenisation is analysed rarely exceeds 500 years and pre-human times are often considered as a single point in time. Thereby, the temporal contextualisation of this process is disregarded. We analyse the similarity of island floras across the globe during the past 5000 years using fossil pollen data from sedimentary sequences. We track changes from a global, cross-ocean to a regional scale. While globally a clear harmonization trend can be detected, magnitudes of change in floral similarity differ at regional scales. This study underlines the usefulness of palynological data to support the analysis and contextualisation of biodiversity changes in the Anthropocene.

Global changes in biodiversity and their drivers are a major focus of scientific research. Recent studies have shown that taxonomic, phylogenetic and functional diversity can be combined to disentangle the drivers of community assembly. Due to their nature, islands are ideal biological model systems to study the effects of filters on diversity patterns. Although bird community assembly on islands are a popular subject of study, studies have been limited to single archipelagos or a few islands.

We used a comprehensive global dataset of 2719 islands and analysed the diversity of 4624 terrestrial breeding bird species. We calculated functional diversity as well as phylogenetic diversity and corrected both for species richness using null models. To analyse diversity patterns we used multivariate models.

We found a correlation between functional and phylogenetic diversity across biogeographic realms. However, functional diversity values were more clustered than expected based on species richness, while phylogenetic diversity was generally lower than expected. Correspondingly, dispersal and biotic and abiotic filters show strong effects that vary considerably between biogeographical realms.

Our results show strong regional effects on community assembly and highlight the importance of the interplay between different filters which a combined analysis of phylogenetic and functional diversity can disentangle.

How does marine biodiversity flourish on islands? Our understanding of island biodiversity is predominantly based on terrestrial examples, while processes governing marine biodiversity might differ completely. Here, we tested the effects of island size, isolation and age on fish taxonomic, functional and phylogenetic diversity in a unique island-like marine system - Indonesian tropical marine lakes. Marine lakes are bodies of seawater surrounded by land connected at different levels to the sea. Because of their high degree of natural replication combined with small and manageable sizes, they offer an unprecedented opportunity to investigate the processes shaping biodiversity. Additionally, we investigated whether fish communities in marine lakes are randomly assembled (a random subset from the regional species pool) or whether environmental or dispersal filters are at work (composed of species with similar traits such as high dispersal ability or environmental tolerance). This study is the first attempt to describe marine lake fish communities and to investigate how biodiversity arises and thrives in these isolated ecosystems, relevant in a world where nature is becoming increasingly fragmented.

Edaphic islands commonly host high numbers of habitat-specialized or endemic plant species. In the case of quartz islands in South Africa, many of these species are additionally characterized as dwarf succulent shrubs with unusual growth forms. The functional traits of these plants are poorly represented in trait databases and the distinctive succulent growth forms necessitate innovative approaches to trait measurement in addition to conventional protocols. In this study, we investigate whether and how the plant functional and biogeographic traits correspond to the specific soil abiotic and spatial characteristics of the edaphic islands, in comparison to the surrounding matrix. We use quantitative data on various traits of the most abundant perennial plant species (n = 195) found on a quartz island archipelago in the Knersvlakte nature reserve. We explore how a functional approach can enhance the comparison of different types of edaphic islands, enabling us to gain further insights into their unique or shared characteristics. Furthermore, we discuss where deviating from common standardized protocols for trait measurement in succulent plant species is unavoidable and which additional traits provide important information about the strategies of the studied edaphic specialists.