Trade‐offs and bet‐hedging in clonal offspring allocation

Reproduction is vital to maintain populations and species, yet because of finite resources, organisms often specialise in their reproductive allocation strategies, such as with many plants prioritising seed size or number (i.e. size/number trade‐off). Alternatively, plants may make multiple types of seeds, as seed heteromorphism, a form of bet‐hedging to increase offspring survival under variable environmental conditions. Those strategies are well described for seeds, but many plants also reproduce clonally, and such reproductive allocation strategies remain unknown for clonal offspring because of difficulties in measuring and standardising allocation to individual offspring across a large number of species. To better understand potential trends in clonal offspring allocation, we studied the southern African clade of the genus Oxalis , where mature offspring bulbs are physiologically distinct from the mother plant. We assessed number, size, protection and placement of clonal offspring for 104 species grown from individual bulbs in pots in a greenhouse. We also measured investment (as dry mass) in below‐ground support structures: spacer stems and roots, tunics and contractile roots. We found a trade‐off between size and number of clonal offspring, where plants produce fewer large bulbs and more small bulbs, similar to the well‐known trade‐off between seed size and number. We also identified a trade‐off in distribution versus protection of offspring bulbs, as indicated by greater offspring bulb production correlated with investment in below‐ground spacers. For two thirds of the species, individual parental bulbs placed offspring in multiple locations simultaneously, here identified as clonal offspring heteromorphism. Offspring bulb size also varied with depth, with individual plants producing relatively larger bulbs deeper in the soil and smaller bulbs closer to or above the soil surface. Synthesis . This is the first study assessing trends in offspring allocation and protection across a large set of species. These trends indicate multiple coordinated trade‐offs and potential bet‐hedging, implying that investment in clonal reproduction is resource‐limited and adapted for unpredictable environmental conditions.