Life Histories, Breeding Systems, and Life Cycles in Brood-Site Pollination Mutualisms

In brood-site pollination mutualisms (BSPMs), insect pollinators breed within the plants that they pollinate. Organisms involved in BSPMs show adaptations in life-history strategies and life cycles. BSPM plants are monoecious or dioecious, or have bisexual flowers; are monocot or dicot; and are angiosperms or gymnosperms. All plants are perennial, mostly iteroparous, while a few are semelparous. The highly specific pollinators are mostly small-sized wasps, micromoths, thrips, fungus gnats, flower weevils, beetles, and gall midges. Most BSPMs involve ovule/seed parasites, while larvae also consume pollen, other floral tissues, and fungi. Active pollination occurs only in ovule/seed parasites, accompanied by special pollen-deposition structures and reduced pollen:ovule ratios. Quiescent stages involving egg, larval, prepupal, and pupal diapause enable synchrony with plant reproduction. Prolonged flower longevity enables the completion of larval growth. Haplodiploidy via arrhenotoky or paternal genome elimination often occurs. Many brood sites constitute mating arenas and impose restriction of mating opportunities.