Presentation Detail

Life History Studies

Hughes, P. William [1], Simons, Andrew M. [2].

Empirical evidence for the continuity of degree of parity: phenotypically plastic semelparous reproduction in Lobelia inflata.

Semelparity is the life-history tactic characterized by a single reproductive episode, and has evolved independently many times. It is usually treated as a discrete, ‘single-event’ strategy rather than as a special case at one extreme along a continuum of potential reproductive patterns. However, wide variation in degree of parity (i.e. the "semelparousness" or "iteroparousness") exists in nature. Assuming consistent expression of reproductive traits in semelparous organisms ignores the potential for biologically relevant phenotypic plasticity to alter reproductive phenotype as organisms make strategic decisions to maximize realized reproductive effort.
In our study, we tested an "archetypically" semelparous annual, Lobelia inflata (Campanulaceae), for plasticity in degree of parity. Plants were induced to initiate reproduction at episode at early-, mid- and late-season. We followed reproduction in more than 1,500 plants across three replicate years and in two environments (field and lab). Results consistently showed that late initiation of reproduction severely constrains semelparous reproduction. Late-season plants reproduced more quickly and at a smaller size, realized smaller offspring sizes, and maximized flower number by creating new branches. Our work demonstrates that key reproductive traits exhibit substantial plasticity, and vary predictably along a semelparity-iteroparity continuum.

1 - Carleton University, Biology, NB 227, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
2 - Carleton University, Biology, NB317, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada

Keywords:
semelparity
iteroparity
phenotypic plasticity
life-history strategy.

Presentation Type: Regular Oral Presentation
Session: 126
Location: Alpine C/Snowbird Center
Date: Tuesday, June 25th, 2013
Time: 9:30 AM
Number: 126005
Abstract ID:46
Candidate for Awards:W.D. Hamilton Award for Outstanding Student Presentation