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Directional climate change can potentially cause a nested pattern of species occurrences as species move or go extinct. That is, species-poor communities may become a nested subset of species-rich communities. There is a precedent for understanding these patterns in the context of historical climate change but few researchers have studied these patterns in the context of recent changes to climate. Here we show the value of nestedness analyses for understanding plant community responses to reduced annual rainfall using data on seedling establishment in restored jarrah forest between the years of 1992 and 2010. Specifically, we recorded the annual seedling establishment of species assemblages in plots 15 months after restoration. We tested to what extent jarrah-forest assemblages that established in low (<1000 mm) rainfall years were nested within assemblages that established in years of moderate (1000–1200 mm) and high (>1200 mm) rainfall, and whether assemblages established following lower standard restoration practice were nested subsets of those following higher standard practices. We also tested how both types of nestedness patterns varied among trait groups defined by status (i.e., native or non-native), life-form and seed size. We found high support for species and trait assemblages that established in dry years being a nested subset of assemblages that established in years of moderate rainfall, and consistently low support for nestedness of high in low, and moderate in low, rainfall years. Nestedness patterns associated with restoration practice were as we predicted. Recruitment failure in low rainfall years was the most parsimonious explanation for nestedness patterns associated with rainfall (i.e., selective environmental tolerance). Nestedness patterns associated with restoration practice were explained by differential seed dispersal of species via topsoil and their tolerance of inferior restoration practice. Taken together, we demonstrate the application of the nestedness approach for understanding community responses to climate change in a restoration context. Indeed, generalising species responses to climate change by linking these to ecological processes and traits will help to meet the current global demand for forest restoration. Therefore, we anticipate our findings will interest practitioners working to restore the world’s forests under climate change. [ABSTRACT FROM AUTHOR]

Abstract: Seed dispersal is a fundamental life history trait in plants. Although the recent surge of interest in seed dispersal by ants (myrmecochory) has added greatly to knowledge on the ecology of seed dispersal and ant–plant mutualisms, myrmecochory also represents a unique opportunity to examine the links between seed dispersal and evolution in flowering plants. Here we review the taxonomic, phylogenetic and biogeographic distribution of myrmecochory in flowering plants. Myrmecochory is mediated by elaiosomes, i.e., lipid-rich seed appendages that attract ants and serve as rewards for dispersal. We surveyed the literature for evidence of elaiosomes in angiosperm plants to estimate the global prevalence of myrmecochory. We then searched the literature for phylogenetic reconstructions to identify myrmecochorous lineages and to estimate the minimum number of independent evolutionary origins of myrmecochory. We found that myrmecochory is present in at least 11000 species or 4.5% of all species, in 334 genera or 2.5% of all genera and in 77 families or 17% of all families of angiosperm plants. We identified at least 101, but possibly up to 147, independent origins of myrmecochory. We estimated three or more origins in 13 families and found that at least half the genera are myrmecochorous in 10 families. Most myrmecochorous lineages were Australian, South African or northern temperate (Holarctic). A mapping of families containing myrmecochorous genera on a dated angiosperm supertree showed that myrmecochory has evolved in most of the major angiosperm lineages and that it is more frequent in younger families (crown group age <80 million years) than in older ones. We suggest that the relatively low physiological and energetic costs of producing an elaiosome and the consistent selective benefits of myrmecochory (dispersal, protection from seed predators and fire, safe and nutrient-rich microsites) explain the numerous evolutionary and developmental origins of myrmecochory in angiosperm plants, and we propose that elaiosomes thus provide one of the most dramatic examples of convergent evolution in biology. [Copyright &y& Elsevier]

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Abstract: Like most ecosystems of the world, tropical dry forests of the central coast of the Gulf of Mexico are inadequately preserved. Given that reserve expansion is unlikely, it is imperative that the conservation capacity of the matrix surrounding reserves is enhanced. Here, we examine the habitat value of isolated pasture trees and patches of secondary regrowth in terms of their terrestrial and arboreal ant assemblages in both a wet and dry season. These simplified wooded systems increase species densities within the agricultural matrix and provide habitat for some forest ant species. Estimated species richness of arboreal ants was particularly low on isolated trees, highlighting an important limitation. This was not the case for terrestrial ants, which were particularly species rich under isolated trees. We also found that the inter-site variations in species densities and similarity to the forest ant assemblage for terrestrial and arboreal strata were not correlated, suggesting that responses to restoration may not be as uniform as often thought. This has important implications for the use of indicator taxa in suggesting the response of other taxa. In terms of species composition, neither secondary regrowth nor isolated trees were appropriate replacements for forest fragments, even though the studied forest fragments were small (13–32ha). The ant assemblages did not exhibit a seasonal change in composition. However, season influenced the contrast between habitats, with isolated trees being more distinct from pasture, and regrowth more closely resembling forests, during the wet season. Microclimatic variables indicate that the forests were least affected by the tropical dry season, and this may contribute to their characteristic fauna. We conclude that even small forest patches make a unique contribution to landscape conservation and that, where reserves are limited, conscientious management of the landscape matrix may provide some species with sufficient new habitat to survive outside of reserve systems. These conclusions are influenced by both season and strata studied. [Copyright &y& Elsevier]