Harvesting large guppies favored earlier sexual maturity
A 10-year experiment in nine populations found earlier maturity and higher natural death rates when harvesting targeted large guppies.
Limit: Only three populations per harvest approach
Edited by Boris Djordjevic · AgingResearch.News
Guppies (Poecilia reticulata) in nine laboratory populations underwent a 10-year animal experiment comparing removal of large fish, small fish or fish regardless of size. Each approach had three populations, and the experiment included a recovery period. Populations where large fish were removed evolved toward earlier maturation. Population assessments found higher embryo counts under large-fish than small-fish harvesting, after accounting for body length. Large-fish harvest populations also had higher death rates from causes other than harvesting.
Researchers also raised second-generation offspring under standardized conditions without harvesting. At the end of the first harvest phase, male offspring from large-fish harvest populations had mean adult lifespans of 586 days, compared with 409 days for those from small-fish harvest populations. Female offspring from large-fish harvest populations also had longer adult lifespans than those from the other harvest regimes.
Why it matters
Size-dependent harvesting raises questions about how reproduction and survival evolve together. The authors emphasized allowing repeated breeding and changing population conditions when studying these trade-offs.
Caveats
These were laboratory populations, and lifespan differences came from one assessment at the end of the first harvest phase. Reproductive output differed between harvest regimes in the populations but not among second-generation offspring raised under standardized conditions.
The paper
Norwegian Institute of Marine Research; Okinawa Institute of Science and Technology Graduate University
Evolutionary Applications, May 18, 2026, Open access
