Guppy
Maturity

Guppies' body sizes are positively correlated with age, and their size at maturation varies highly depending on the predation risk of the occupied environments. Male and female guppies from high-predation regions mature faster and start reproducing earlier, and they devote more resources to reproduction than those from low-predation regions. Females from high-predation regions reproduce more frequently and produce more offspring per litter, indicating that they are more fecund than low-predation females. Female guppies' reproductive success is also related to age. Older females produce offspring with reduced size and at increased interbrood intervals.
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