Abstract Detail

Reproductive Processes

Richardson, Lea [1], Beck, Jared [2], Wagenius, Stuart [3].

Spring fires improve summer mating opportunities and influence multiple components of reproductive fitness.

Outcomes of sexual reproduction depend on multiple components of fitness, including the investment of resources to flowering stems, flowers, fruits, and seeds, as well as pollination. When plants lack co-flowering mates, seed production declines, regardless of resource availability. Fire-stimulated flowering is hypothesized to improve reproductive outcomes, specifically seed set, when mates limit reproductive success, as has been demonstrated in two species from the tallgrass prairie of North America. But fire is also associated with greater reproductive effort by stimulating more plants to flower and potentially more flowers per plant. Therefore, fire and mate-availability may differentially influence components of reproductive fitness including counts of flowering stems, heads, fruits, and seeds; and these differences should yield insights into the mechanism by which fire affects reproductive fitness. We ask how fire and mate-availability affect several components of reproductive fitness in three prairie perennials, Echinacea angustifolia, Liatris aspera, and Solidago speciosa. We predict that fire influences stem, flower, and ovule counts, which are determined before flowering begins, while mate-availability influences seed production. Using an aster modeling approach and data from 383 E. angustifolia plants over seven years, and 223 L. aspera and 232 S. speciosa plants over three years, we examine how multiple components of reproductive fitness are related fire and mate-availability, and report annual fecundity per individual. Fire increased total seed production in E. angustifolia and L. aspera but not S. speciosa. E. angustifolia individuals with greater spatial and temporal mating potential produced more seeds regardless of fire. In L. aspera, fire mediated the relationships between seed production and both temporal and spatial mate availability. Burned L. aspera plants produced more seeds when they were closer in space to mates and showed no relationship between flowering synchrony and seed production. Meanwhile unburned L. aspera plants produced fewer seeds when they were closer to mates in space and time. In S. speciosa, mate-availability did not influence seed production, but temporal and spatial mate availability did vary with stem, head, and achene counts. In E. angustifolia and L. aspera, mate-availability varied with head and achene counts. The differential relationships between fire, mate-availability, and components of reproductive fitness suggest that fire influences reproductive outcomes by affecting both reproductive effort and the timing of flowering in prairie plant species that exhibit fire-stimulated flowering.

1 - Northwestern University, Plant Biology and Conservation, O.T. Hogan Hall, Room 6-140B, 2205 Tech Drive, Evanston, IL, 60208, USA
2 - Chicago Botanic Garden, Plant Science and Conservation, 1000 Lake Cook Road, Glencoe, IL, 60022, USA
3 - Chicago Botanic Garden, Conservation Science, 1000 Lake Cook Road, Glencoe, IL, 60022, United States

Keywords:
Fire
seed production
reproductive fitness
flowering phenology
mating potential
prairie
perennial
synchrony
mating opportunities.

Presentation Type: Oral Paper
Session: RP1, Reproductive Processes 1
Location: /
Date: Thursday, July 22nd, 2021
Time: 10:30 AM(EDT)
Number: RP1003
Abstract ID:475
Candidate for Awards:None