This data file contains five sheets. "Wild Data" and "Wild Data Individual Offspring" contains the lengths of offspring and their mothers after collecting pregnant females from the wild. "Lab Data" and "Lab Data Individual Offspring" contain data from a laboratory breeding experiment, whereby the daughters of wild-caught mothers were raised in different environments to produce four groups of females (Old/Large, Old/Small, Young/Large, Young/Small) to measure the effect of maternal size and age on offspring size and number. The final sheet - "Meta-data" - contains descriptions of the headers used in the four sheets of data.