TY - JOUR
T1 - Natural history and population dynamics of the land snail Helix texta in Israel (pulmonata: Helicidae)
AU - Heller, Joseph
AU - Ittiel, Haya
PY - 1990/5
Y1 - 1990/5
N2 - Helix texta is endemic to the Mediterranean regions of Israel. It has a seasonal activity pattern which starts in the autumn, with the first rains, and dwindles towards the spring, when the snails dig into the ground for a six months long aestivation. A cold spell of 0°C will, however, terminate the active season of the adult snail, even in the middle of the rainy season. Survival of the young is very low and most of them (90%) do not survive their first year, because of the winter cold and the summer drought.Massive predation of adult snails by wild boar was observed in December 1986: within a few days, about 50% of the adults in the study in the area were eaten. A very rapid growth of young and subadults was observed immediately after this predation. These observations suggest that the extent of recruitment of new adults to the population may be partly controlled by existing adults, through a growth-inhibiting pheromone in the mucus. After predation this inhibiting factor disappears, enabling a subsequent rapid growth of the young. In this manner, massive, irregular predation of the adults by a large predator, and changes in juvenile survival, result in sharp fluctuations in the age structure of the population. The resulting pattern of unstable population dynamics is different from that described for the European species of Helix.
AB - Helix texta is endemic to the Mediterranean regions of Israel. It has a seasonal activity pattern which starts in the autumn, with the first rains, and dwindles towards the spring, when the snails dig into the ground for a six months long aestivation. A cold spell of 0°C will, however, terminate the active season of the adult snail, even in the middle of the rainy season. Survival of the young is very low and most of them (90%) do not survive their first year, because of the winter cold and the summer drought.Massive predation of adult snails by wild boar was observed in December 1986: within a few days, about 50% of the adults in the study in the area were eaten. A very rapid growth of young and subadults was observed immediately after this predation. These observations suggest that the extent of recruitment of new adults to the population may be partly controlled by existing adults, through a growth-inhibiting pheromone in the mucus. After predation this inhibiting factor disappears, enabling a subsequent rapid growth of the young. In this manner, massive, irregular predation of the adults by a large predator, and changes in juvenile survival, result in sharp fluctuations in the age structure of the population. The resulting pattern of unstable population dynamics is different from that described for the European species of Helix.
UR - http://www.scopus.com/inward/record.url?scp=0025598724&partnerID=8YFLogxK
U2 - 10.1093/mollus/56.2.189
DO - 10.1093/mollus/56.2.189
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AN - SCOPUS:0025598724
SN - 0260-1230
VL - 56
SP - 189
EP - 204
JO - Journal of Molluscan Studies
JF - Journal of Molluscan Studies
IS - 2
ER -