Differences in maturity age can lead to skewed sex ratios on spawning grounds; if one sex matures later, fewer individuals survive the return migration. 4. Human Development and Invariance

Sexual maturation is a critical life-history trait with major fitness consequences.

Intense competition often leads to delayed maturation in the competing sex.

: In many species, intense competition for mates can lead to delayed maturation in the sex facing higher selection pressure. For example, in some bird populations, males mature later than females to reach a size or social status necessary for successful competition.

Males often mature at much younger ages and smaller sizes than females.

Maturation timing often creates (SSD), where one sex is significantly larger than the other. Maturation Observations Birds