Citizen scientists have helped researchers better understand how parental care evolved in harvestmen, the spider-like arachnids, according to ScienceDaily. The study was published in the Zoological Journal of the Linnean Society.
An international team led by a University of São Paulo researcher used nearly 30 years of field observations along with records from iNaturalist. That effort more than doubled the number of known examples of parental care in harvestmen and, for the first time, helped scientists reconstruct the evolution of both maternal and paternal care in the superfamily Gonyleptoidea.
The researchers found that parental guarding did not develop in a straight line. Instead, it emerged multiple times, disappeared in some lineages, and later reappeared. Maternal care evolved only from species that previously showed no parental care, while paternal care followed two different routes: either directly from no care or from species where females already guarded eggs.
According to the researchers, that pattern suggests different evolutionary pressures may have shaped mother and father care. They also propose that when paternal care evolved from maternal care, it may have involved sexual selection, with females favoring males already caring for eggs.
The study also highlights how citizen science can speed up research. From 1936 through 2025, published studies had documented parental guarding in 80 harvestman species, but the iNaturalist search added 62 new records on its own, more than doubling that total.
