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Energetics of Reproduction in Peromyscus Leucopus: The Cost of Lactation
Author(s) -
Millar John S.
Publication year - 1978
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1938558
Subject(s) - peromyscus , offspring , litter , reproduction , energetics , biology , ecology , lactation , energy requirement , zoology , muridae , pregnancy , genetics , psychology , regression , psychoanalysis
Captive Peromyscus leucopus exhibited a positive relationship between weight of @V and number and size of nestlings. Size of neonates, but not size of post—neonatal young was negatively related to litter size. Ingested energy related to offspring was linearly related to litter size and varied from 899 kJ (74% of nonbreeding requirements) for 2 offspring to 2100 kJ (146% of nonbreeding requirements) for 6 offspring. Despite these differences between litter sizes, mean litter size was not different (° = 4.60 and 4.94) respectively between captive and wild females, and varied little seasonally and geographically. The relatively constant commitment to offspring may be related to the fact that conception occurs long before the period of peak energy demand.