1Questions: (1) Which species dominate mid-successional old-fields in Hungary? How does 2 the identity of these species relate to local (patch-scale) diversity and to the progress of 3 succession? (2) Which species have the strongest negative impact on diversity in spontaneous 4 old-field succession and what generalizations are possible about the traits of these species? 5 (3) Are these species dominant or subordinate components in mature target communities? (4) 6 Do native or alien species have stronger effects on the diversity and progress of succession? 7Location: Abandoned agricultural fields (abandoned croplands, orchards and vineyards) at 8 various locations scattered throughout Hungary. 9Methods: Vegetation patterns on 112 old-fields, in 25 sites varying in soils and climatic 10 conditions, topography, landscape contexts and land use histories were sampled. Most old-11 fields had appropriate seed sources in the immediate vicinity, i.e. natural or semi-natural 12 grasslands (meadows steppes, closed and open sand steppes) as source and target habitats. 13The age of abandoned fields ranged from 1 to 69 years, but most sites were between 15 and 14 60 years. The cover of vascular plant species (in %) was estimated in 2 m x 2 m plots. 15Relationships between diversity, the progress of succession (similarity to target communities) 16 and the identity of dominants were tested. 17Results: A small portion of successional dominants (eight species) had strong negative 18 impacts on diversity. These species belonged to Poaceae, Asteraceae and Fabaceae families. 19Most of these species were wind pollinated, and capable of lateral vegetative spread. 20 Dominant species varied in size and had, on average, low requirements for nitrogen but a 21 high requirement for light. With one exception, Solidago gigantea, they were native to the 22
Fruiting body evolution is one of the central topics in fungal evolutionary biology. A number of hypotheses have been developed to explain the contemporary diversity of fruiting body forms, but their evaluation has been hampered by the lack of well-sampled data sets and suitable statistical methods. Phylogenetic evidence of the physiological changes that accompany switches in fruiting body type is lacking, and very little is known about the age of major events of fruiting body evolution. Based on a new multigene phylogeny, by using Bayesian methods, we demonstrate the existence of correlation between a number of morphological features and switches from nondeliquescent to deliquescent (autodigesting) fruiting bodies in the mushroom family Psathyrellaceae. Our results show that switches in the anatomy of two types of spacer cells (cystidia and pseudoparaphyses) and basidia (bimorphic or monomorphic) as well as the structure of the mushroom cap follow the evolution of deliquescent fruiting bodies, which suggests strong functional linkage between these traits. We performed Bayes factor-based tests, referred hereafter to as evolutionary pathway test (EPT), to decide which of the correlated characters were gained first during evolution. The EPTs strongly suggest that deliquescence was gained first, followed after short waiting times by the other morphological features. Bayesian relaxed molecular clock analyses suggest that the various events of switching between fruiting body types occurred independently at various ages during the history of the family. The utility of two mushroom fossils (Archaemarasmius and Protomycena), the only ones with unambiguous taxonomic positions, for the calibration of agaric trees were also examined. Based on our results, we suggest that the evolutionary benefit of deliquescence may be prevention against desiccation via accelerated ontogeny of the fruiting body. Hypotheses regarding the functional significance of the correlated evolution are presented and discussed. Further, we argue that the changes in fruiting body types in mushrooms in general can be attributed to independent events (e.g., dispersal and adaptation) and not to particular geologic ages.
Regeneration of seminatural grasslands are often threatened by the invasion of Calamagrostis epigejos, which can slow down or arrest secondary succession. Here we report the results of a 9-year mowing experiment designed to suppress the spread of C. epigejos in mid-successional grasslands in Hungary. The experimental design consisted of 16 permanent plots of 3 6 3 m. Half of the plots were mowed twice a year (in June and September), the other half was left as control. Vegetation was sampled in 2 6 2 m quadrates before mowing in each year between 2001 and 2009. The effects of mowing were tested using repeated-measure analyses of variance (ANOVA) and Tukey HSD for post hoc tests. Significant decrease of C. epigejos appeared after 2 years of mowing. Species richness increased after 4 years, while diversity after 8 years. By this time the target native species Brachypodium pinnatum become dominant. Similar trends appeared in the control plots during spontaneous succession but at much slower rates. Our results suggest that C. epigejos disappears spontaneously in secondary grassland succession after ca. 40-50 years. However, mowing twice a year can speed up this process by opening a ''colonization window'' to the valuable target species. For successful control, mowing should be maintained for approximately 8 years.
Bursts of diversification are known to have contributed significantly to the extant morphological and species diversity, but evidence for many of the theoretical predictions about adaptive radiations have remained contentious. Despite their tremendous diversity, patterns of evolutionary diversification and the contribution of explosive episodes in fungi are largely unknown. Here, using the genus Coprinellus (Psathyrellaceae, Agaricales) as a model, we report the first explosive fungal radiation and infer that the onset of the radiation correlates with a change from a multilayered to a much simpler defense structure on the fruiting bodies. We hypothesize that this change constitutes a key innovation, probably relaxing constraints on diversification imposed by nutritional investment into the development of protective tissues of fruiting bodies. Fossil calibration suggests that Coprinellus mushrooms radiated during the Miocene coinciding with global radiation of large grazing mammals following expansion of dry open grasslands. In addition to diversification rate-based methods, we test the hard polytomy hypothesis, by analyzing the resolvability of internal nodes of the backbone of the putative radiation using Reversible-Jump MCMC. We discuss potential applications and pitfalls of this approach as well as how biologically meaningful polytomies can be distinguished from alignment shortcomings. Our data provide insights into the nature of adaptive radiations in general by revealing a deceleration of morphological diversification through time. The dynamics of morphological diversification was approximated by obtaining the temporal distribution of state changes in discrete traits along the trees and comparing it with the tempo of lineage accumulation. We found that the number of state changes correlate with the number of lineages, even in parts of the tree with short internal branches, and peaks around the onset of the explosive radiation followed by a slowdown, most likely because of the decrease in available niches.
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