Macroalgal domestication and farming can induce significant ecological and biological changes in exploited species. In the red macroalga, Agarophyton chilense, marine farming is based on clonal propagation by cuttings of the largest plants. This type of mass selection by farmers can have a considerable impact on the life history characteristics of cultivated strains. In this study, we investigated the potential effect of this type of selection on the reproduction in A. chilense, comparing female gametophytes from the natural and farmed populations. Our results showed strong differences between these two types of populations. As expected, individuals were larger in the farm than in the wild population. On the other hand, the number of cystocarps per centimeters of fronds was ten times lower in the farm than in the natural population. These differences suggest that artificial selection and cultivation environment significantly modify life-history traits in this macroalga. Moreover, the positive relationship between female size and number of cystocarps per centimeters of fronds observed in Dichato point out to the possible existence of cost of reproduction in A. chilense, with bigger females allocating more resources or energy to reproductive structures in natural populations.