TY - JOUR
T1 - Sex allocation by a mite parasitic on insects
T2 - Local mate competition, host quality and operational sex ratio
AU - Izraylevich, Sergey
AU - Gerson, Uri
PY - 1996/12
Y1 - 1996/12
N2 - The aim of this study was to test the predictions of local mate competition (LMC), host quality (HQ) and operational sex ratio (OSR) models, using a non-arrhenotokous parasitic mite. Hemisarcoptes coccophagus (Astigmata: Hemisarcoptidae). The life-history pattern of this mite meets the assumptions of these sex allocation models. Mating group size (LMCm model), HQ and OSR affected the sex allocation of H. coccophagus females. Only young mite females adjusted the sex ratio of their progenies according to the predictions of LMC and HQ models: the sex allocation of old females was contrary to these predictions. We explain these patterns by the dynamic nature of the mite's population structure. When parents are young, their population distribution is patchy and progeny matings are local: hence sex allocation is in accordance with LMC theory. When parents become older, their populations shift towards panmixis; factors which had operated previously no longer exist. Consequently, females adjust the sex ratio of late progenies so that it can compensate for the earlier sex allocation, in order to make their total sex ratio unbiased, as expected in panmictic populations. Our data, expressed as the cumulative sex ratio, support this hypothesis.
AB - The aim of this study was to test the predictions of local mate competition (LMC), host quality (HQ) and operational sex ratio (OSR) models, using a non-arrhenotokous parasitic mite. Hemisarcoptes coccophagus (Astigmata: Hemisarcoptidae). The life-history pattern of this mite meets the assumptions of these sex allocation models. Mating group size (LMCm model), HQ and OSR affected the sex allocation of H. coccophagus females. Only young mite females adjusted the sex ratio of their progenies according to the predictions of LMC and HQ models: the sex allocation of old females was contrary to these predictions. We explain these patterns by the dynamic nature of the mite's population structure. When parents are young, their population distribution is patchy and progeny matings are local: hence sex allocation is in accordance with LMC theory. When parents become older, their populations shift towards panmixis; factors which had operated previously no longer exist. Consequently, females adjust the sex ratio of late progenies so that it can compensate for the earlier sex allocation, in order to make their total sex ratio unbiased, as expected in panmictic populations. Our data, expressed as the cumulative sex ratio, support this hypothesis.
KW - Host quality
KW - Local mate competition
KW - Operational sex ratio
KW - Population structure
KW - Sex allocation
UR - http://www.scopus.com/inward/record.url?scp=0030301675&partnerID=8YFLogxK
U2 - 10.1007/BF00329042
DO - 10.1007/BF00329042
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AN - SCOPUS:0030301675
SN - 0029-8549
VL - 108
SP - 676
EP - 682
JO - Oecologia
JF - Oecologia
IS - 4
ER -