On r- And K- Selection Theory: Life History Strategy of Emilia Coccinea (Sims) G. Don and Emilia Sonchifolia (Linn.) Dc

Abstract

Roots , stems, leaves and flowers of Emilia coccinea (Sims)G. Don and Emilia sonchifolia were harvested, separated and oven-dried at 110⁰ C for 48 hours  and then weighed to determine what proportion of their total biomass was allocated to each of the tissues. E. coccinea allocated 42.65% and E. sonchifolia allocated 36% of their total biomasses to stems respectively.  These represent the greatest allocation of their total biomasses allocation. However, E. sonchifolia allocated a relatively greater proportion of its biomass to reproductive structures than E. coccinea. E. coccinea allocated 93.4% of its biomass to vegetative tissues while E. sonchifolia allocated 70.1% to vegetative tissues. The two species allocated about the same percentage of biomass to roots. On the basis of their allocations to vegetative and reproductive tissues E. coccinea can be said to be K- selected with respect to E. sonchifolia which is r- selected. The result of this study supports the r- and K- selection theory.

Keywords: life-history strategy, Emilia coccinea, Emilia sonchifolia. r-and K. selection