Welcome to the homepage of the aDiv project, a four-year (2013-17) initiative aiming to understand patterns of lineage diversification in the Agaricales. On this site, you will find useful information about the aDiv, publications arising from the project, the taxa included in the taxon sampling as well as datasets and new results as the project progresses.


Background
The Agaricales is the most diverse group of mushroom forming fungi. There is great variation in species richness across clades with some ancient clades having a single taxon, while others (e.g. Cortinarius) having thousands. However, the evolutionary forces generating this pattern are virtually unknown. The aDiv is part of a four-year collaborative project aiming to understand patterns of rate variation during fungal evolution. The project focuses on two groups, the Agaricales and zygomycete fungi (click here for the zygomycete part). Preliminary results indicate that rates of morphological and lineage diversification in these groups have not been constant through time, but the overall contribution of periods of rapid diversification to extant diversity is hardly understood. We are interested in

    - what drives lineage diversification in the Agaricales?
    - what is the contribution of adaptive radiations to extant diversity?
    - how morphological innovations relate to diversification rate variation?


In particular, we test whether ecological opportunity or key innovations contributed more to the generation of taxonomic diversity. Based on evidence from plants and animals, we  expect that episodes of explosive diversification contributed significantly fungal diversity, however, general evidence for this is lacking.


Preliminary evidence and working hypothesis
Previously, we reported on the first fungal adaptive radiation in the genus Coprinellus (Psathyrellaceae, Nagy et al 2012), which coincided with two major transitions in the life history of the group. This provides us with two alternative hypotheses as the trigger of the radiation, being either ecological opportunity or a key innovation. Ecological opportunity might have been provided by the global radiation
of large grazing mammals, which provided substrate for this predominantly coprophilous group of fungi. Large grazing mammals radiated following the expansion of dry open grasslands in the Miocene, with which the radiation of Coprinellus coincided. On the other hand, comparative analyses suggest an alternative hypothesis,  a key innovation that relaxed constraints on diversification in Coprinellus. At the most recent common ancestor of the radiation protective velar structures were lost and replaced by pileocystidia, a much simpler structure with the same function, defense of the fruiting body. The transition to a simpler defense mechanism might have reduced the nutritional investment in defense, which, in turn relaxed constraints on species diversification. To test if either of these, or other factors have a general role in shaping lineage diversification in the Agaricales, the aDiv project aims to infer broad patterns of diversification in the Agaricales.


Approach

In recent years, there have been an explosion in the methodological repertoire for examining rate variation using phylogenies. However, all of these methods have a common component: they require the phylogenetic trees to have a balanced, representative taxon sampling. Biased sampling or missing clades can yield misleading results, therefore, it is extremely important to produce a well sampled phylogenetic tree before we can address questions about diversification. In the aDiv Project we set out to generate nrLSU and RPB2 sequence data for ca. 30% of accepted Agaricales species (ca. 3000 taxa). 

While Genbank sequences form a valuable resource for inferring large trees, the taxonomic coverage is very patchy, so we need an independent plan to guide taxon sampling. We gather species richness information from multiple taxonomic databases and sample species in proportion to these data, to keep sampling proportional to the actual diversities of genera. At the same time, input from experts of specific genera help us fine-tune the taxon sampling, which is probably the biggest challenge of the aDiv.

The project started in January 2013, right now we are busy with gathering specimens, DNA extractions and sequencing the nrLSU and RPB2 genes to reach the goal of 3000 agaric species. You can check the progress of the project at the species list page, which lists the taxa which have been entered into the project pipeline.