Life history comparison of two terrestrial isopods in relation to habitat specialization

Balloniscus glaber (Crustacea, Isopoda, Balloniscidae), a habitat specialist species in a disturbed area of Brazil

“…Meinhardt et al (2007) described its species' growth curve and demonstrated that females reach a larger size, live longer, and have a slower growth rate compared to males. Quadros et al (2009) investigated two sympatric populations of Atlantoscia floridana (van Name, 1940) and B. glaber at PEI and found that females of the latter species became reproductive at approximately 7.5 months old and incubated 5-20 eggs for approximately 40 days. This study also demonstrated that B. glaber has a restricted spatial distribution and is mainly associated with Atlantic Forest fragments, a biome threatened by deforestation and monoculture replacement (Morellato & Haddad, 2000).…”

“…This is evidenced by its longer lifetime, later reproductive age, some degree of parental reproductive investment, slower development, and a lower growth rate when compared with A. floridana, a generalist species that exhibited r-strategist species patterns. The apparent local requirement for non-impacted habitat combined with the K-strategist characteristics of B. glaber (Sutton et al, 1984) may contribute to its threat of extinction (Quadros et al, 2009).…”

“…Following , the reproductive period was defined, as the monthly operational sex ratio (OSR), which is based on the rate of males and females that are apt to reproduce at a given time (Emlen & Oring, 1997), and the ovigerous females' categorization (females with eggs, EG; females with embryos, EM; females with manca, MA; and post-ovigerous females, PO). The adult's minimum CW (mm) size determination followed Quadros et al (2009). The potential reproductive females (PRF), the actual reproductive females (ARF), and the index of reproduction mobilization (IRM) were calculated following , as well as the index of maximum reproduction mobilization (IRM max ) assuming that all females were reproductive (i.e., PRF = 1 and ARF = 1).…”

“…The mean intra-marsupial development time used in the equation above was 40 days, as proposed by Quadros et al (2009). Multiple regression tests (p < 0.05) were used for correlation analyses between soil temperature (°C) and relative moisture (%); litter temperature (°C) and relative moisture (%); air temperature (°C) and relative humidity (%); and the individual density, after .…”

“…The results of Almerão et al (2006) showed that the highest abundance of Balloniscus glaber Araujo & Zardo, 1995 in Parque Estadual de Itapuã (PEI), referred as a nonurban area, in southern Brazil, occurred along a trail closed to visitors. Later, Quadros et al (2009), studying the same species from the same area, concluded that B. glaber is a habitat specialist species that shows K-selected traits. Recently, a population of B. glaber was found in a disturbed area within the limits of the city of Porto Alegre, RS, Brazil, close to PEI.…”