122
Synthesis
The consideration of a phase difference continuum from -6 to 6 months is
more appropriate for populations living in regularly fluctuating environments allowing focus on strategies relating to synchronisation with the
seasonal environment. In fact, most characteristics of populations showing
positive phase difference refer to rapid recovery after adversity, while most
characteristics of populations with negative phase difference relate to rapid
decline in activity before the onset of the adverse period. In any case, synchronisation capabilities prerequisite the existence of thresholds and narrow
selection of crucial demographic parameters and refer to an organism's conformism.
Selection of habitat type is generally conditioned by vectorial environmental factors such as mean, minimum and maximum temperature, relative
air humidity, soil properties etc. However, conservative characteristics such
as relatively low water budgets are of decisive importance for the dispersal of
arthropods within favourable microsites of the subhumid to xeric, but finegrained Mediterranean habitats. Moreover, the need to avoid a large array of
predators as well as possible competitors increasing spatial uncertainty also
determines the spatial distribution of Mediterranean arthropods. In contrast,
moderate transpiration rates enable them to survive in even temporarily
flooded micro sites.
As shown in Chapter 7, most Mediterranean arthropods exhibit narrow
capabilities for food utilization. Besides, like the majority of worldwide
arthropods (e.g. Norton 1994), Mediterranean ones are not able to exploit
short-term changes in food resources. However, due to low metabolism they
can survive during periods of food shortage. In any case, narrow food selection restricts the spatial distribution of Mediterranean arthropods. Again,
conformist water relations such as fluctuations of blood osmolality, integumentary transpiration and differential allocation of water reserves during
ontogenesis, as well as the need for behavioural thermoregulation, deposition
of eggs and cocoons in favourable micro sites and the necessity for taking
refuge during summer drought stimulate animals. Thus animals are also forced
to conform with the structural adversity of their habitat as well as to undertake the risk of recolonisation of different microsites after man-induced disasters.
Again, strategies driving habitat selection compromise between conservatism and conformism. Conservative demographic features such as sexual
reproduction, precocity, dispersal of reproductive effort over time, and density dependence are principal characteristics related to the spatial heterogeneity of habitats. Mainly Allee-type density dependence resulting in aggregative spatial distribution is of primordial importance for understanding of
the ecology of Mediterranean arthropods. Indeed, as shown in Chapter 7
Allee-type density dependence accompanied by conformist traits such as
narrow food selection, broad weather selection and rapid response to external
signals allows arthropods to achieve optimal population size locally.
Synthesis
The consideration of a phase difference continuum from -6 to 6 months is
more appropriate for populations living in regularly fluctuating environments allowing focus on strategies relating to synchronisation with the
seasonal environment. In fact, most characteristics of populations showing
positive phase difference refer to rapid recovery after adversity, while most
characteristics of populations with negative phase difference relate to rapid
decline in activity before the onset of the adverse period. In any case, synchronisation capabilities prerequisite the existence of thresholds and narrow
selection of crucial demographic parameters and refer to an organism's conformism.
Selection of habitat type is generally conditioned by vectorial environmental factors such as mean, minimum and maximum temperature, relative
air humidity, soil properties etc. However, conservative characteristics such
as relatively low water budgets are of decisive importance for the dispersal of
arthropods within favourable microsites of the subhumid to xeric, but finegrained Mediterranean habitats. Moreover, the need to avoid a large array of
predators as well as possible competitors increasing spatial uncertainty also
determines the spatial distribution of Mediterranean arthropods. In contrast,
moderate transpiration rates enable them to survive in even temporarily
flooded micro sites.
As shown in Chapter 7, most Mediterranean arthropods exhibit narrow
capabilities for food utilization. Besides, like the majority of worldwide
arthropods (e.g. Norton 1994), Mediterranean ones are not able to exploit
short-term changes in food resources. However, due to low metabolism they
can survive during periods of food shortage. In any case, narrow food selection restricts the spatial distribution of Mediterranean arthropods. Again,
conformist water relations such as fluctuations of blood osmolality, integumentary transpiration and differential allocation of water reserves during
ontogenesis, as well as the need for behavioural thermoregulation, deposition
of eggs and cocoons in favourable micro sites and the necessity for taking
refuge during summer drought stimulate animals. Thus animals are also forced
to conform with the structural adversity of their habitat as well as to undertake the risk of recolonisation of different microsites after man-induced disasters.
Again, strategies driving habitat selection compromise between conservatism and conformism. Conservative demographic features such as sexual
reproduction, precocity, dispersal of reproductive effort over time, and density dependence are principal characteristics related to the spatial heterogeneity of habitats. Mainly Allee-type density dependence resulting in aggregative spatial distribution is of primordial importance for understanding of
the ecology of Mediterranean arthropods. Indeed, as shown in Chapter 7
Allee-type density dependence accompanied by conformist traits such as
narrow food selection, broad weather selection and rapid response to external
signals allows arthropods to achieve optimal population size locally.