RELATION BETWEEN BIRTH WEIGHT AND LITTER SIZE IN MULTIPAROUS MAMMALS

Area of Science:

• Reproductive biology
• Mammalian physiology
• Quantitative biology

Background:

• Multiparous mammals exhibit a relationship between litter size (N) and total litter weight (W).
• Understanding this relationship is crucial for assessing maternal investment and offspring development.

Purpose of the Study:

• To investigate the mathematical relationship between litter size and total litter weight in multiparous mammals.
• To determine if this relationship is influenced by the parturition process.
• To identify key factors governing litter weight in relation to litter size.

Main Methods:

• Analysis of existing data on litter size and weight across various mammalian species.
• Development of a mathematical model (W = N(K) + const) to describe the observed relationship.
• Statistical evaluation to confirm the significance and independence of the relationship from parturition mechanisms.

Main Results:

• A consistent mathematical relationship (W = N(K) + const) was found between litter size (N) and total litter weight (W).
• This relationship was demonstrated to be independent of the specific mechanism of parturition.
• The average increment in W per unit increase in N was found to be proportional to W and inversely proportional to N.

Conclusions:

• The established relationship signifies a direct proportionality between litter size and the nutritive drain on the mother.
• It also implies an equitable distribution of resources among litter members.
• The parameter K was identified as a non-specific 'partition index' reflecting resource allocation efficiency.