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There is a lot of information on the factors limiting the distributions of species in their native areas, but much less on those limiting potential changes in distributions of species that are currently spreading outside their present range, especially invasive species. However, this information is often quite essential, as it enables the prediction of future spatial distributions and local abundances of invasive species and the potential effect they may have on people and crops. Arising from glasshouse escapes in North America and the Netherlands, the invasive ladybird, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), originally from the east Palearctic, has now spread across the whole of North America and most of Europe, both of which caused serious concern. Recent observations show that the spread of H. axyridis towards the equator is limited. For example, it is quite rare in the Mediterranean area and its northward spread in South America is also quite slow, as if there was something limiting its spread towards the equator. European literature indicates it is neither climate, nor the distance of the Mediterranean from the original release location in the Netherlands. Therefore, we hypothesized that it may be biotic factors. In particular, the duration of colonies of prey (colony is the set of individuals in one patch, usually on one plant) that becomes shorter as one approaches the equator. This may lower the fitness of the predator and subsequently lead to low population densities. We test here, whether the duration of aphid colonies is shorter in the Mediterranean area than in Central Europe. Unfortunately, our data does not support this hypothesis. Therefore, the question of what limits the distribution of H. axyridis towards the equator remains to be resolved.

We are experiencing climate warming that is likely to affect all regions worldwide, although in a different manner, when its consequences (e.g. increase of temperature, lower seasonality, lower environmental stochasticity) are considered. Thus, our prediction of how global change will affect distribution and survival of species can be estimated by using our knowledge, how species richness and distribution is related with latitude and elevation. We used 193 terrestrial orchid species and subspecies as an example and we classified them according to their root system. This trait represents the evolution of strategies for underground storage of resources and resource acquisition as well as a characteristics that can be described as a life history trait. Classification of orchid life history traits that focus on belowground strategies has never been examined in a macroecological study. We then explored the associations between species richness, mean niche breadth and mean distribution on one hand and selected predictors on the other hand, using regression techniques for all orchids, and then for their subsets with different root systems. The predictive power, as well as the significance of the predictors, was also tested using polynomial second order generalized linear models. Species richness for the three belowground strategies was significantly affected by the predictors, whereas their mean niche breadth and mean distribution were largely dependent on their evolutionary history. The correlations of mean niche breadth and mean distribution with maximum elevation, latitude and longitude were significant for all orchid taxa and their subsets. All the variables together accounted for almost 50% or more of the variance in each of the subsets. The maximum elevation was the most significant factor for rhizomatous and intermediate orchids, whereas minimum temperature in the coldest month was highly significant for the tuberous orchids. Spatial distribution of Greek orchids is associated with a combination of elevation, latitude and climate. The distributions of rhizomatous and intermediate orchids are mainly associated with the orographic configuration of Greece, whereas the tuberous orchids are widely distributed in the southern, central and north-western areas of Greece, where most of them are limited by the harsh winter climate.