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One of the major tasks in evolutionary ecology is to explain how interspecific interactions influence the dynamics of evolutionary processes and enable radiation and genesis of biological diversity. The bewildering diversity of dog roses is generated by a heterogamous reproductive system. Genetic distance between rose taxa was analysed as base line for the explanation of subsequent radiation of the two host-dependent parasite groups, rust fungi and insects. We investigated the interaction between each host–parasite system and between the parasite groups. We learned that the functional diploidy at the meiotic level is not reflected at the phenotypic level in dog roses. The phytophagous insect community shows only minor differences in composition on different rose species. These invertebrates seem not to be negatively affected by glandular trichomes, but for the rust fungi, Phragmidium glandular trichomes matter, because they are negatively correlated with the infection. The abundance of two rose specialists, the rose hip fly Rhagoletis alternata Fall. and the rose gall wasp Diplolepis rosae L., differed on rose species, but Rh. alternata showed neither any genetic differentiation on host species nor geographical differentiation. As a basic result, we detected that genetic diversity of dog roses is not translated into a host-specific radiation of the parasites. We assume that intensive reticulate evolution of dog roses prevents co-speciation.

Tropical rainforests are disappearing, causing irreversible species losses, especially of rare and specialised species (e.g. Owens and Bennett 2000, Acebey et al. 2003, Kessler et al. 2009, Maas et al. 2009). Despite an increasing recognition of the value of biodiversity and associated ecosystem services at national and international levels, rainforests continue to be seriously threatened by human-induced global change such as agricultural intensification and climate change.

In many plant communities, weeds are important drivers of ecosystem processes, but natural enemies may control their growth and population dynamics. These enemies may directly reduce plant growth by grazing or infection, or indirectly enhance plant susceptibility to other enemy species. The role of insects as vectors of plant pathogens has thereby often been underestimated but appears to be widespread and important. Crucial for the understanding of such plant–enemy interactions is the consideration of processes on local and regional scales. We analysed the effects of herbivore and pathogen attack and their interactions using the weed creeping thistle, Cirsium arvense, as a model system. Local thistle patches were limited by the thistles’ low competitive ability in secondary succession, by pathogens and insects and by the disturbance or management of habitats. The regional dynamics of C. arvense were mainly driven by human activities and showed a mosaic of increasing and decreasing local patches with low persistence. High patch turnover rates and subsequent small average patch sizes limited the success of herbivore populations.

The determination and evaluation of ecosystem services provides crucial information for a comprehensive strategy to preserve near natural habitats such as rainforest margins. We show results of an economic evaluation of coffee bee pollination services and pest control in two distinct tropical regions: a low human-impact area in Indonesia with continuous near natural forests neighboring agroforestry and a high-impact landscape in Ecuador with almost no forest fragments left. We evaluate bee pollination services comparing forest destruction scenarios, where coffee yields depend on forests providing nesting sites and foraging habitats for bees and present three novel approaches: first, we show how net coffee revenues depend on pollination services of adjacent forests considering berry weight in addition to fruit set, thereby providing a more comprehensive evaluation. Second, we combine our findings on pollination with an assessment of pest management affecting coffee production. Third, we determine net welfare effects of land-use changes including the fact that former forestland is normally used for alternative crops. In both regions, crop revenues exceed coffee pollination values, generating incentives to convert forest margins even if owners would be compensated for pollination services. The promotion of certified “biodiversity-friendly” coffee is a feasible option to maintain shade-coffee systems for conservation purposes. This is of special importance in high-impact areas where only small forest fragments remain. We conclude that a comprehensive economic analysis is necessary to adequately evaluate rainforest preservation for the enhancement of ecosystem services within a mosaic of competing land-use systems.

Tropical rainforests disappear at an alarming rate causing unprecedented losses in biodiversity and ecosystem services (Hughes et al. 1997, Noble & Dirzo 1997, Tilman et al. 2001, Achard et al. 2002) with Southeast Asia showing the highest rates of deforestation of any major tropical region (Sodhi et al. 2004). Despite an increased recognition of the value of these goods at national and international levels, rainforests continue to be seriously threatened by various forms of encroachments such as low-intensity harvesting of non-timber forest products by the rural poor, large-scale plantation forestry by the state or private actors, and the conversion of forested land by smallholder farmers. Transformation of ecosystems and changes in land use affect important ecosystem services and ultimatively human well-being (Robertson & Swinton 2005).

Many studies focus on the impact of forest disturbance on tropical diversity (e.g. Chung and Maryati 1996; Dahaban et al. 1996; Eggleton et al. 1997; Hamer et al. 1997; Intachat et al. 1997, 1999a; Johns 1992; Lambert 1992; Lawton et al. 1998; Liow et al. 2001; Watt et al. 1997; Willott 1999; Willott et al. 2000). In contrast, agricultural ecosystems and forest plantations have been taken into account only exceptionally (e.g. Chey et al. 1997; Davis et al. 2000; Holloway 1998; Holloway et al. 1992; Intachat et al. 1999b). Published studies of agroforests do not provide comparative data from pristine forests to evaluate the relative importance of agroforestry for maintaining tropical biodiversity (e.g. Klein et al. 2002a, 2002b; Perfecto and Snelling 1995; Perfecto and Vandermeer 1996). Secondary forests and certain land-use systems may be important in preserving at least a fraction of the tropical biodiversity (Hughes et al. 2002; Lugo 1992) of which insects are a major part (Hammond 1992; Stork 1988).