The spiders in the genus Nephila are famous (or infamous) for  extreme sexual size dimorphism:  females are much larger than males.  Current phylogenetic analyses from Gustavo Hormiga's laboratory suggest that this size dimorphism is due primarily to female gigantism, and the data I've collected indicate that there is strong fecundity selection on females.  Both the number of eggs per clutch, and the number of clutches (egg sacs) increase as female size increases.  This holds true for both N. maculata and N. clavipes.

N. clavipesin copula;  the male is on the right.

 

In Madang, on the north east coast of Papua New Guinea,  N. maculata experience an environment with relatively little seasonality.  Although some females mature early (for unknown reasons),  others reach remarkable size.  This spider, sitting on my hand, I nicknamed "Big mac". She weighed in at 6.8 g (larger than many small rodents and birds).  The night after this photo was taken, she laid an egg sac with nearly 10,000 eggs and reduced her wieght by 50%.