Abstract Detail

Reproductive Processes

Moreira Hernandez, Juan [1], Terzich, Nicholas [1], Zambrano-Cevallos, Ricardo [2], Oleas, Nora [3], Muchhala, Nathan [1].

Differential tolerance to increasing heterospecific pollen deposition in two sympatric species of Burmeistera H. Karst. & Triana (Campanulaceae: Lobelioideae).

Heterospecific pollen deposition (HPD) on stigmas can impact plant reproduction by inducing fruit abortion or decreasing seed production. Nectar-feeding bats often carry pollen from many species on their fur and thus some bat-pollinated flowers commonly experience HPD. It is possible that these species might show tolerance to the negative effects of HPD but to our knowledge, this has never been studied. We investigated the relative impact of increasing HPD on female reproduction of two sympatric species of Burmeistera H. Karst. & Triana (Campanulaceae: Lobelioideae) that experience pollen transfer between them by their shared bat pollinators. We simulated HPD by applying pollen mixtures that differed in the ratio of conspecific to heterospecific flowers used to make them (4:0, 3∶1; 2∶2, 1∶3, and 0:4) and measured female reproduction by quantifying fruit abortion, seed number, and seed mass. For Burmeistera borjensis, applying a higher relative amount of heterospecific pollen led to decreased seed production and lighter seed mass, whereas no significant effect of increasing heterospecific pollen was detected in Burmeistera ceratocarpa. Burmeistera borjensis aborted more fruits than B. ceratocarpa (44.1% vs. 18.8%); however, in both species the probability of fruit abortion was not affected by pollination treatment. We found asymmetric impacts on female reproduction between this pair of sympatric Burmeistera: while increasing HPD decreased seed production and seed mass for B. borjensis, it had no detectable effect on B. ceratocarpa. Prior work showed that in nature B. borjensis receives much lower amounts of heterospecific pollen than B. ceratocarpa, thus our results suggest that B. ceratocarpa may have stronger gametic isolating barriers to be able to tolerate HPD. Future work should explore how different isolation mechanisms contribute to the asymmetric effects on female reproduction that we report here. In addition, we hypothesize that tolerance to heterospecific pollen deposition may be a common response among bat-pollinated plants and other plant taxa relying similarly on low-fidelity pollinators.

1 - University of Missouri-St. Louis, Department of Biology, One University Blvd, 223 Research Building, St. Louis, MO, 63121, United States
2 - Pontificia Universidad Católica del Ecuador, Escuela de Ciencias Biológicas, Avenida 12 de Octubre 1076 y Roca, Quito, Pichincha, Ecuador
3 - Universidad Tecnologica Indoamerica, Machala Y Sabanilla, Quito, 170301, Ecuador

Keywords:
bat pollination
heterospecific pollen transfer
reproductive success
reproductive interference
reproductive isolation
post-pollination processes
pollination competition.

Presentation Type: Oral Paper
Session: REP4, Reproductive Processes 4
Location: Virtual/Virtual
Date: Thursday, July 30th, 2020
Time: 3:45 PM
Number: REP4004
Abstract ID:766
Candidate for Awards:None