Ecological restoration is widely used to reverse the environmental degradation caused by human activities. However, the effectiveness of restoration actions in increasing provision of both biodiversity and ecosystem services has not been evaluated systematically. A meta-analysis of 89 restoration assessments in a wide range of ecosystem types across the globe indicates that ecological restoration increased provision of biodiversity and ecosystem services by 44 and 25%, respectively. However, values of both remained lower in restored versus intact reference ecosystems. Increases in biodiversity and ecosystem service measures after restoration were positively correlated. Results indicate that restoration actions focused on enhancing biodiversity should support increased provision of ecosystem services, particularly in tropical terrestrial biomes.

This paper considers the extent to which differences in pollen tube growth rates can provide prezygotic reproductive isolation between Mimulus nasutus and its presumed progenitor, Mimulus guttatus. Mimulus nasutus is partially cleistogamous, but its larger chasmogamous flowers offer appreciable opportunity for outcrossing. Mimulus nasutus was found to have smaller pollen grains and shorter styles than M. guttatus. No differences were observed in pollen grain germination on conspecific and heterospecific stigmas. However, pollen tube growth rates of M. nasutus were found to be much slower than those of M. guttatus in the styles of that species. Consequently, any M. nasutus pollen transferred to an M. guttatus stigma was found to be competitively disadvantaged in an M. gutattus style. By contrast, no difference in pollen tube growth rate was detected between the species when growing in M. nasutus styles, possibly because M. nasutus styles are unable to support fast pollen tube growth. We tested the prediction from the pollen tube studies that a 50 : 50 mix of M. guttatus and M. nasutus pollen would produce 50% hybrid seeds when M. nasutus was the maternal parent, and near to 0% hybrid seed when M. guttatus was the maternal parent. The results were found to support this prediction. We conclude that pollen-pistil interactions can effect strong reproductive isolation between these species, as M. guttatus pollen tubes have a competitive advantage over those of M. nasutus in an M. guttatus style, but not in an M. nasutus style.

We examined the quantitative genetics of 20 floral traits in Mimulus guttatus including flowering time, autofertility, flower size, the spatial arrangement of flower parts, pollen and ovule production and seed number and size. A six by six diallel crossing design including selfs was performed in the glasshouse between plants derived from one population of M. guttatus from California. All characters with the exception of pollen number showed significant amounts of additive genetic variance indicating a potential to respond to selection. A principal components analysis revealed that some variation in many characters could be explained by general flower size. However, most characters still displayed heritable variation after the flower size effect was removed by analysis of covariance. Families showed considerable variation in the ability to self in glasshouse conditions. Only a weak relationship between autofertility and herkogamy was detected, suggesting that an unidentified mechanism was responsible for differences in selfing ability. Pollen quality and ovule production were also strongly heritable, suggesting the potential for gender specialization of plants but no trade-off between male and female function could be detected. Inbreeding depression was evident in flower size and pollen and ovule production. It is postulated that the heritable variation observed is maintained in this population through disruptive selection on autofertility in response to seasonal variation in the onset of spring drought and pollinator availability.

No abstract

Summary 1.Calcareous grasslands are communities of high conservation value, often characterized by high plant species richness. These grasslands have experienced a major decline in area throughout Europe, principally resulting from agricultural intensification. Although they have been the focus of extensive previous research, few attempts have been made to examine the long-term dynamics of multiple communities at the landscape scale. 2. To assess long-term change in the structure and composition of a calcareous grassland metacommunity, 88 extant sites first surveyed by R. Good in the 1930s were resurveyed in 2009. Values of a-, b-and c-diversity were compared between the two surveys, using a one-way analysis of similarity (ANOSIM) and non-metric multidimensional scaling. Elements of metacommunity structure (EMS) analysis was used to identify metacommunity structure, and changes in metacommunity composition were related to plant traits. 3. Analyses indicated that a-diversity increased over time, with mean (±SD) species richness per site increasing from 29.31 ± 7.65 in the 1930s to 40.18 ± 16.41 in 2009. No change in b-diversity was recorded. However, c-diversity increased, with the total number of species rising from 219 in the 1930s to 280 in 2009. Species composition shifted over time, associated with a decline in 'stress-tolerant' species typical of species-rich calcareous grasslands, and an increase in species typical of mesotrophic grasslands. This was associated with an increase in mean Ellenberg N value, suggesting that eutrophication has been a driver of floristic change. 4. Elements of metacommunity structure analysis indicated that the structure of this grassland plant metacommunity was Clementsian at both survey times, indicating species sorting. Metacommunity structure was stable over time, despite changes in a-and c-diversity. Analysis of potential structuring mechanisms revealed a significant influence of elevation. 5. Synthesis. This investigation provides a rare example of the long-term dynamics of a plant metacommunity. Results indicate that substantial change has occurred in the composition of calcareous grasslands during this time, both at local and regional scales. The investigation provides evidence of the impact of environmental change on immigration and extinction processes operating in calcareous grasslands at different scales, and highlights challenges for their future conservation.