Synthesis
Fig. 8.2. peA ordination of T, K, A, and M (Mediterranean) life history strategies (Asikidis 1989)
~\
!2
0
~ :2
~.
~
(
(
.. ( , ! .
,. M~$'r!ltegy.
i- ··t'
.. !
;
l
, . . j"
f
123
! . .
. ~
i-··. :
-.1
For a rough classification of adaptive strategies shown by Mediterranean
arthropods, the scheme suggested by Siepel (1994, 1995) can be used. Aiming
to tackle applied problems such as the analysis of the effect of management
practices and pollution, Siepel (1994) developed ideas concerning the development of a classification key to life history tactics. According to the key proposed in 1995, the characteristics exhibited by most Mediterranean arthropods fit either tactic V (non-phoretic arthropods with obligate diapause or
aestivation in their life cycle or synchronisation of their life cycle by quiescence) or tactic XI (non-phoretic arthropods with continuous generation in
which development can be slow in some periods, sexual reproduction, and
iteroparity) well or even both.
A different classification scheme was developed by Asikidis (1989). To
compare life history traits shown by Mediterranean oribatids (considered as
M-strategists) with those characterising r-, K- and A-strategists, the author
depicted the ordination of life history strategies on the three first axes of a
peA (Fig. 8.2). The first axis represents habitat predictability, the second axis
stands for the values of the ratio HIT (H=favourable oviposition time,
T=generation time), while the third one relates to the heterogeneity of habitat. Higher predictability, moderate values of the HIT ratio and higher heterogeneity are selective forces driving life history patterns of Mediterranean oribatids.
Even more convenient for classification of the life histories of Mediterranean arthropods is the scheme involving conservatism and conformism. As
shown in this section most physiological, behavioural and demographic characters of Mediterranean arthropods fall into either the conservative or the
conformist category, and life history strategies imply compromising configurations of conservative and conformist elements. According to Norton (1994),
it can be stated that conservatism involving both metabolic compensation
and plasticity is resulted from low metabolic rate. In fact, constrained physio-
Fig. 8.2. peA ordination of T, K, A, and M (Mediterranean) life history strategies (Asikidis 1989)
~\
!2
0
~ :2
~.
~
(
(
.. ( , ! .
,. M~$'r!ltegy.
i- ··t'
.. !
;
l
, . . j"
f
123
! . .
. ~
i-··. :
-.1
For a rough classification of adaptive strategies shown by Mediterranean
arthropods, the scheme suggested by Siepel (1994, 1995) can be used. Aiming
to tackle applied problems such as the analysis of the effect of management
practices and pollution, Siepel (1994) developed ideas concerning the development of a classification key to life history tactics. According to the key proposed in 1995, the characteristics exhibited by most Mediterranean arthropods fit either tactic V (non-phoretic arthropods with obligate diapause or
aestivation in their life cycle or synchronisation of their life cycle by quiescence) or tactic XI (non-phoretic arthropods with continuous generation in
which development can be slow in some periods, sexual reproduction, and
iteroparity) well or even both.
A different classification scheme was developed by Asikidis (1989). To
compare life history traits shown by Mediterranean oribatids (considered as
M-strategists) with those characterising r-, K- and A-strategists, the author
depicted the ordination of life history strategies on the three first axes of a
peA (Fig. 8.2). The first axis represents habitat predictability, the second axis
stands for the values of the ratio HIT (H=favourable oviposition time,
T=generation time), while the third one relates to the heterogeneity of habitat. Higher predictability, moderate values of the HIT ratio and higher heterogeneity are selective forces driving life history patterns of Mediterranean oribatids.
Even more convenient for classification of the life histories of Mediterranean arthropods is the scheme involving conservatism and conformism. As
shown in this section most physiological, behavioural and demographic characters of Mediterranean arthropods fall into either the conservative or the
conformist category, and life history strategies imply compromising configurations of conservative and conformist elements. According to Norton (1994),
it can be stated that conservatism involving both metabolic compensation
and plasticity is resulted from low metabolic rate. In fact, constrained physio-