An irreversible division of labor through a sexually dependent system in the clonal plant Iris laevigata (Iridaceae)

Abstract

Abstract. Scientists were concerned with the division of labor research early, and much current research in clonal plant ecology has proved environmentally induced or a developmentally programmed division of labor. However, the sexually dependent division of labor in clonal plants has received little attention, and few experimental tests have been conducted to date. Here, using reproductive ramets and non-reproductive ramets in the clonal plant Iris laevigata, we test this hypothesis on morphology and physiology through field and manipulative experiments, including an isotope ( 15 N) labeling method. With regard to morphology, under natural conditions, non-reproductive ramets of I. laevigata were more abundant, taller, and consisted exclusively of leaves, while the relatively rare, smaller reproductive ramets consisted of leaves, flowers, or seeds. However, the mean biomass of non-reproductive ramets was nearly half that of reproductive ramets. With regard to physiology, non-reproductive ramets had a significantly higher net photosynthetic rate over a 24-h period than reproductive ramets. Furthermore, the reproductive ramets stopped leaf growth when flower buds appeared in late May and lost photosynthetic capacity before late June, while its growing fruits still required a constant supply of many nutrients. Manipulative experiments showed that the non-reproductive ramets supplied the nutrient demands for reproduction of the reproductive ramets through clonal integration as high as d 15 N of the value (196.1 AE 73.39) of the seed. Thereby providing the first clear evidence of sexually dependent division of labor in clonal plants: Certain individuals constitute a very small amount of reproductive castes (reproductive ramets), whereas a large amount of other individuals (non-reproductive ramets) are "workers" as in social insect societies whose role is primarily as producers. The rapid withering of reproductive ramets that failed to be pollinated highlights their role as irreversibly focused on reproduction, and those unable to reproduce do not contribute to the colony. Additionally, "producer" ramets positively influenced reproductive castes growth, and the division of labor was assumed to underlie the resource allocation pattern among ramets.

Physiological Integration Increases Sexual Reproductive Performance of the Rhizomatous Grass Hierochloe glabra

“…Compared with vegetative propagation, sexual reproduction is considered to consume more resources and thus to be more nutrient demanding [ 38 ]. For example, the mean biomass of reproductive ramets was nearly twice that of vegetative ramets in Iris laevigata [ 39 ]. However, we found that the mean biomass of reproductive ramets was 27.2% that of vegetative ramets in H. glabra ( Table 2 ).…”

Slow stamen movement in a perennial herb decreases male–male and male–female interference

“…The annual precipitation in this region averages 704.2 mm and the mean temperatures in January and July are–15.7 and 22.5 °C, respectively. The vegetation type is classified as Changbai Mountain flora; the original vegetation, which mainly comprised Pinus koraiensis and broad-leaved mixed forests, has degraded into a secondary broad-leaved forest ( Wang et al 2017 ).…”

Phenotypic Plasticity in Sexual Reproduction Based on Nutrients Supplied From Vegetative Ramets in a Leymus chinensis Population

“…The translocation of resources to emerging ramets and the significant role of physiological integration in the early development of new ramets (e.g., Hartnett and Bazzaz, 1983;Alpert, 1996;Xu et al, 2012), as well as marked changes in patterns of resource translocation from maternal ramets to daughter ramets across ramet ontogeny, are well documented in the literature (Duchoslavová and Jansa, 2018), but studies on the translocation of resources between vegetative ramets and reproductive ramets are lacking. Although only one study found that vegetative ramets could transfer their nutrients to adjacent reproductive ramets through the rhizome at the flowering stage in an ornamental clonal plant Iris laevigata (Wang et al, 2017b), the research focused on a single point in reproductive development. It is unclear how translocation of nutrients changes with the process of reproductive development.…”

“…In fact, clonal fragments often contain ramets that are at different developmental stages or belong to different types, such as parental ramets and daughter ramets or vegetative ramets and reproductive ramets. For example, some studies found that the benefits of physiological integration in a homogeneous environment existed both between ramets of different ages with developmental differences (Stuefer, 1998;Yu et al, 2002;Dong et al, 2015;Zhang et al, 2016) and between ramets of different types with production differences (Wang et al, 2017b). Therefore, even under the same levels of external resource supply, resource sharing between interconnected ramets might improve clonal performance owing to differences in the amounts of absorbed or assimilated resources.…”