62
Life Cycle Tactics and Development
work (1982) described a short life span among woodlice of arid and semiarid regions, while populations of the same species may enjoy shorter lives in
xeric than in mesic habitats. An analogous observation was also reported by
Crawford et al. (1987) among millipede species. It seems that a short life span
agrees well with the strongly fluctuating Mediterranean environment.
Nonetheless, in accordance with Norton (1994) it can hardly be considered as
an apotypic trait of adaptive value. Presumably, under mild temperature conditions a short life span may originate from relatively high heat budgets that
allow for a relatively rapid life cycle.
5.1.2
Age at Maturity
Due to higher heat budgets than in temperate relatives and lower maintenance costs than in arid counterparts encountering harsher environments,
the age at maturity of Mediterranean arthropods is likely to be short. Evidence shows that this rule holds true in many cases, while many exceptions
have also been reported. For example, maturation lasts for less than one third
of the life span of different Mediterranean arthropods from Hortiatis (Iatrou
and Stamou 1990; Stamou et al. 1993a) and from south eastern Australia (estimates based on data by Baker 1978b) living in comparable environments. In
contrast, maturation takes up about two thirds of the life span of the millipede
A. t. judaicus and the coleopteron G. leucoloma (among many others) living in
more severe environments. Moreover, different times leading to maturity have
also been reported (e.g. Baker 1978a,b; Iatrou and Stamou 1991).
Notwithstanding interspecific discrepancies, the age at maturity of Mediterranean arthropods is to a large extent in tune with the predictable seasonal and interannual cycles. For example, Iatrou and Stamou (1990) concluded
that maturation in G. balcanica coincides with the approximate 3-year interannual cycle recorded on Hortiatis. Indeed, anamorphosis (up to the fourth
free-living stage) takes about a period of 9 months and epimorphosis (up to
the tenth free-living stage) about 18 months. Thus, the animals attain maturity after 2.5 years. As in other Mediterranean arthropods (e.g. David 1982),
the age at maturity of G. balcanica appears to depend on annual and seasonal cycles rather than on the number of moults.
5.1.3
Reproductive Strategies
Reproductive strategies have been discussed in detail in papers by Cole
(1954), Gadgil and Bossert (1970), and Charnov and Shaffer (1973) while a
critical review has been written by Sterns (1976). In summary, animals having
only a short time to maturity and experiencing low premature mortality are
semelparus, as would be expected. Semelparity is assumed in temporally pre-
Life Cycle Tactics and Development
work (1982) described a short life span among woodlice of arid and semiarid regions, while populations of the same species may enjoy shorter lives in
xeric than in mesic habitats. An analogous observation was also reported by
Crawford et al. (1987) among millipede species. It seems that a short life span
agrees well with the strongly fluctuating Mediterranean environment.
Nonetheless, in accordance with Norton (1994) it can hardly be considered as
an apotypic trait of adaptive value. Presumably, under mild temperature conditions a short life span may originate from relatively high heat budgets that
allow for a relatively rapid life cycle.
5.1.2
Age at Maturity
Due to higher heat budgets than in temperate relatives and lower maintenance costs than in arid counterparts encountering harsher environments,
the age at maturity of Mediterranean arthropods is likely to be short. Evidence shows that this rule holds true in many cases, while many exceptions
have also been reported. For example, maturation lasts for less than one third
of the life span of different Mediterranean arthropods from Hortiatis (Iatrou
and Stamou 1990; Stamou et al. 1993a) and from south eastern Australia (estimates based on data by Baker 1978b) living in comparable environments. In
contrast, maturation takes up about two thirds of the life span of the millipede
A. t. judaicus and the coleopteron G. leucoloma (among many others) living in
more severe environments. Moreover, different times leading to maturity have
also been reported (e.g. Baker 1978a,b; Iatrou and Stamou 1991).
Notwithstanding interspecific discrepancies, the age at maturity of Mediterranean arthropods is to a large extent in tune with the predictable seasonal and interannual cycles. For example, Iatrou and Stamou (1990) concluded
that maturation in G. balcanica coincides with the approximate 3-year interannual cycle recorded on Hortiatis. Indeed, anamorphosis (up to the fourth
free-living stage) takes about a period of 9 months and epimorphosis (up to
the tenth free-living stage) about 18 months. Thus, the animals attain maturity after 2.5 years. As in other Mediterranean arthropods (e.g. David 1982),
the age at maturity of G. balcanica appears to depend on annual and seasonal cycles rather than on the number of moults.
5.1.3
Reproductive Strategies
Reproductive strategies have been discussed in detail in papers by Cole
(1954), Gadgil and Bossert (1970), and Charnov and Shaffer (1973) while a
critical review has been written by Sterns (1976). In summary, animals having
only a short time to maturity and experiencing low premature mortality are
semelparus, as would be expected. Semelparity is assumed in temporally pre-