Genetic and environmental factors influencing clutch size in equatorial and temperate-zone stonechats (Saxicola torquata axillaris and S. t. rubicola): An experimental study.

摘要: ABsTRAcr.-European Stonechats (Saxicola torquata rubicola) from Austria usually lay 5.0 to 5.6 eggs per clutch, whereas their African conspecifics (S. t. axillaris) Kenya 3.0 3.1. To determine if this difference has a genetic basis we examined clutch size in both subspecies, as well F,-hybrids pairs that were held aviaries (either under changing European photoperiod, indoors or outdoors, constant 12.25-h indoors). Data (114 clutches 26 females, 254 34 and 41 6 F,-females) subjected residual maximum-likelihood analysis. The genotype of the female had highly significant effect on size: after adjustment for other effects, estimated means 5.09 3.44 birds. F,-females was intermediate (4.07 clutch) it significantly different subspecies. In contrast, male mate no (i.e. sizes females paired with males subspecies not those same subspecies). age holding conditions only marginal but there effects season year which laid. Our results suggest can be influenced limited extent by some environmental variables studied, between two is largely genetically determined. Received 4 October 1994, accepted 8 August 1995.