These results suggest that arable fields, other orchards and settlements might be more important sources of colonisation for natural enemies in orchards than certain semi-natural habitats.
A major source of microbial colonisation and infection of short term CVC is the patients' endogenous skin microorganisms located at the catheter insertion site.
The absence of fossil remains of southern species of aquatic Coleoptera among the abundant central and northern European Quaternary records [ 79] would support this view, as well as the recognition of the Mediterranean peninsulas as an area of endemism, not as a source of postglacial colonisation (e.g., [ 85]).
Kissing contacts have previously been suggested as a risk factor for carriage of F. necrophorum [ 20] and a partner could thus be an important source of re-colonisation.
Theory suggests that the sources and rates of colonisation relative to subsequent migration are critical determinants of the evolution of the genetic structure of meta-populations [ 18, 19, 23].
The difference in efficacy of SDD compared to SAP could possibly be explained by the fact that SDD reduces yeast load at the source of primary yeast colonisation (that is, the gastrointestinal tract).
It has been suggested that biofilm formation in the tracheal tubes is a source of persistent bacterial lung colonisation [ 47] because the film acts as a reservoir for infecting pathogens.
During the wet period, sedimentary seed banks prevailed, varying spatially at both broad and fine scales, presenting a source of propagules for re-colonisation following the unfavourable growing conditions of the monsoon.
According to Bilton et al. [ 9], such relic populations have preserved their genetic distinctiveness but have not been the source of major postglacial re-colonisations.
On the other hand, the presence of unique haplotypes in southern Italy concurs with the hypothesis that, contrary to common belief, most relic rear edge populations may not have been the source of major postglacial re-colonisations, thereby preserving their high genetic distinctiveness [ 7].
