**3. Reproductive traits comparison of** *Porcellio albinus* **and** *Porcellio buddelundi* **in pre-desert habitats**

In North Africa, only the xeric species *Armadillo officinalis* from Libya [71] and *Hemilepistus reaumurii* from Tunisia [72, 73] have been the subject of study on reproductive phenology. These studies confirmed seasonal reproduction of temperate region species. Considering this element and what has been reported for the xeric Oniscidea of the Middle East in the introduction, two *Porcellio* species from the arid regions (*P. buddelundi* and *P. albinus*) were chosen on the basis of their geographical distribution in Tunisia (quite large in the case of *P. buddelundi* and more restricted in *P. albinus*) and their burrow digging (non-burrow digging *P. buddelundi* and *P. albinus* burrowing species). Both species are expected to have seasonal breeding, based on studies of reproductive phenology performed on temperate oniscoids.

#### **3.1. Breeding phenology**

The two *Porcellio* we investigated on Tunisia area were studied in the field. To study the breeding pattern of both species, a sampling of almost 100 specimens of *P. buddelundi* and about 60 specimens of *P. albinus* took place during 12 consecutive months for the former and 17 months for the latter. See Medini-Bouaziz et al. [22, 23] for further details on material and methods.

Sexual maturity was reached at about 14 mm in size during the first year of life (9 months) in females *of P. albinus* and at 41.1 mg of body mass in those of *P. buddelundi*. Considering this and the mean ovigerous female size (17.38 ± 1.8 mm), females of *P. albinus* cannot reproduce until the second year of their life. Those of *P. buddelundi* reproduce when they reach or exceed 70 mg body mass.

For both species, breeding starts in March and two breeding activities are defined (**Figure 10**). The first and the most important one was in spring, from March to June in the Zarat population of *P. albinus* and from March to May in Matmata population of *P. buddelundi*. The second was in the fall during the month of September in the first population and from September to October in the second one.

them with food and defends them against predators. At the age of 2 months (size 8 mm), the

Behavioral and Reproductive Strategies of *Porcellio* Species (Oniscidea) in Tunisian Pre-Desert…

http://dx.doi.org/10.5772/intechopen.76191

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Besides these results, the digging of about 30 burrows during the spring breeding season, carried out during the day when the animals are inside their burrows, revealed that these burrows contain either adults over 14 mm in size (one or two males/burrow, one female/burrow, a couple/burrow) or an adult female with several mancae or juveniles less than 12.5 mm in size. The number of these young in the burrows ranges between 3 and 35 individuals with an average number of 15 ± 10 pulli or juveniles/burrow. This indicates that the young of *P. albinus*

The study of life history strategies integrates physiological, morphological, and behavioral traits to explain how organisms allocate finite resources to maintenance, growth, and reproduction, under predictable and unpredictable environments [74]. Thus life history patterns, evolved by natural selection, represent an optimization of tradeoffs between growth, survival, and reproduction. One major tradeoff could be between the number of offspring produced and the amount of energy allocated to each one. The timing of the first reproduction is another tradeoff; early reproduction reduces the chances of dying without offspring, but late reproduction can provide healthier offspring or better care. Members of some species breed only once (semelparity), while members of other species can breed several times (iteroparity). The choice of the appropriate strategy may be related to the degree of habitat specialization. Habitat specialists have often shown K-selected traits, while habitat generalists have shown r-selected traits. The xeric species *P. albinus* and *P. buddelundi* well adapted to arid environment differ considerably in their life history traits. These life history traits are summarized in **Table 3**.

To shelter from the extreme heat and dryness in arid environments, *P. albinus* digs burrows, while *P. buddelundi* performs a vertical migration. Both species are iteroparous and started their breeding activity in March with two breeding seasons. The length of the reproductive activity of *P. albinus* longer than 1 month in spring and less than 1 month in autumn than that of *P. buddelundi*. *P. albinus* has a longer development time, and sexual maturity is reached late, at 9 months old, which represents more than a third (37.5%) of its lifetime. *P. buddelundi* grows faster and reaches sexual maturity at 3–3.5 months old which corresponds to almost 20% of its lifetime. In *P. albinus*, there was no difference between ages of oldest female (largest female) and the largest reproductive females. This indicates that in this species, females were able to reproduce until their death, while in *P. buddelundi*, there is a difference between largest female (18 months) and largest reproductive female (12 months) because largest females in this species were not reproductive. *P. albinus* and *P. buddelundi* have a similar length of breeding period at the first brood: 28–35 and 28–33 days, respectively (**Table 3**). Although females of *P. albinus* were larger than those of *P. buddelundi*, they have a lower fecundity range (36.3 ± 13.8 egg) and fertility (19 ± 9 mancae). *P. albinus* also showed the lower mean reproductive allocation (9.94 ± 6.04) but the higher newborn body mass (1.44 ± 0.75 mg). Only *P. albinus* which has few offspring during each reproductive event often gives extensive parental care. This species with this type of high investment strategy uses much of its energy budget to care for its offspring.

remain in their natal burrow and do not disperse until they reach sexual maturity.

**3.4. Life history traits comparison of** *Porcellio albinus* **and** *Porcellio buddelundi*

young emerge for the first time from the burrow to forage.
