Urban ecologists have documented numerous biotic and abiotic consequences of urbanization, such as altered climate, species interactions, and community composition, but we lack an understanding of the mechanisms underlying organisms' responses to urbanization.
These studies are becoming increasingly important to understand the consequences of biotic homogenization, where rapid changes in climatic conditions, human alteration of natural habitats and species introductions make natural barriers to organism's distribution more permeable [12] [14].
Beyond these few examples, however, we still know relatively little about the evolutionary consequences of biotic invasions (Strauss et al. 2006), especially in freshwaters, which are among the most heavily invaded ecosystems (Strayer 2010).
Although the isolation of ST sequences in cDNA libraries does not necessarily mean that ST genes are expressed as a consequence of biotic or abiotic interactions, the high percentage (39%) (Table 3) of ST sequences found in plants under such stresses indicates that ST mRNAs are abundant in these growth conditions.
However, studies of such fitness consequences under natural biotic and abiotic conditions are uncommon, in part because so few of the currently grown transgenic crops can hybridize with feral, weedy, or wild relatives (exceptions include canola and squash).
Their last sentence read: "It is possible that increased debris influx had a net stimulating effect on biotic diversity, despite the occasional occurrence of large impacts with destructive consequences".
These observations make it difficult to determine whether behavioural specialisation by kleptoparasitic lineages on the domicile-building and gall-inducing thrips evolved as a consequence of either biotic or abiotic pressures.
They stated that particularly biotic interactions might explain the negative consequences of NP on ecosystem processes such as carbon dioxide emission, nitrogen or phosphorous fluxes [215] that could not be detected from short-term, single species tests [214].
The consequences of a persistent biotic crisis have been predicted to last for at least five million years.
