News summary produced by Claude AI
An international research team led by a University of São Paulo scientist has utilized citizen science contributions to advance understanding of how parental care behaviors evolved in harvestmen, a diverse group of arachnids. The study, published in the Zoological Journal of the Linnean Society, combined nearly three decades of traditional field observations with data submitted through iNaturalist, expanding the documented examples of parental guarding behavior in these creatures.
The analysis revealed that parental care did not follow a straightforward evolutionary trajectory. Rather, the behaviors appeared multiple times independently across different lineages, disappeared in some populations, and sometimes reemerged. Maternal care evolved only from species exhibiting no parental behavior, consistent with patterns observed in insects. Paternal care, however, demonstrated greater complexity, arising either directly from non-caring species or from lineages where females already provided egg care. The researchers propose that when paternal care evolved from maternal care, sexual selection mechanisms such as enhanced fecundity—where females favor males already caring for eggs—may have been driving factors.
Harvestmen represent an exceptional system for studying parental evolution, with over 6,900 identified species accounting for more than half of all independently evolved examples of paternal care known among arthropods, despite comprising only about 0.6% of arthropod diversity overall. The research team’s decision to leverage iNaturalist proved remarkably efficient, with the two-day search yielding 62 new records. Between 1936 and 2025, published literature documented parental guarding in 80 harvestman species; the iNaturalist data more than doubled this total.
The study underscores how citizen science platforms accelerate biological research by reducing costs associated with museum visits and extensive fieldwork, particularly benefiting scientists in the Global South. However, researchers emphasized that expert taxonomists remain essential for correctly identifying species, determining caregiver sex, and distinguishing genuine parental care from similar behaviors. The team acknowledged sampling bias as a limitation, since egg-guarding individuals are more readily observed than non-caring species, yet argued that such research helps address significant gaps in understanding parental care distribution across animal groups.