Abstract Detail

Hybrids and Hybridization

Zweck, Justin [1], Moreno, Mauro [2], Peña, Paola [2], Oleas, Nora [2].

Intergeneric hybridization has a complex effect on reproductive fitness in an Andean hotspot.

Hybridization has long been recognized as an important evolutionary process due to the broad range of outcomes possible when combining the genomes of different species. For example, hybrid offspring may have higher (heterosis) or lower (reproductive interference) fitness compared to conspecific offspring. Furthermore, hybrid phenotypes may exhibit stronger influence from either the maternal or paternal species, or be a unique phenotype unto themselves. In this study, we examined the consequences of hybrid pollination between Phaedranassa dubia and Stenomesson aurantiacum, two bulbous species in the Amaryllidaceae that are native to the Andes. Despite being in different genera, these species have been suspected to hybridize because they co-occur, overlap in blooming period, and putative hybrids have been observed within their range. We conducted hand-pollinations in 2017 at a nursery within the Pululahua Geobotanical Reserve, Ecuador using ~30 plants of each species. Our hand pollinations consisted of 4 treatments: 1. Intraspecies cross pollination, 2. Interspecies cross pollination, 3. Unmanipulated, and 4. Emasculated. We found that both species set fruit when crossed with the other’s pollen, suggesting that taxonomically uncertain wild individuals are in fact hybrids between these two species. Interestingly, the effect of hybrid pollination between these species differed depending on the measure of reproductive success used. Relative to intraspecies cross pollination, both seed number and seed germination percentage decreased when P. dubia was the maternal parent in a hybrid cross, but not when S. aurantiacum was the maternal parent. In contrast, seed mass and days to germination decreased when S. aurantiacum was the maternal parent in a hybrid cross, but not when P. dubia was the maternal parent. Together, these results indicate a complex relationship between hybridization, phenotype, and reproductive fitness for P. dubia and and S. aurantiacum, and demonstrate that hybridization is an important and ongoing force in the evolution of these distantly related species.

1 - UM Duluth, Biology, 207 SSB, 1035 Kirby Dr, Duluth, MN, 55805, United States
2 - Universidad Tecnologica Indoamerica, Machala y Sabanilla, Quito, Pichi
3 - Universidad Tecnologica Indoamerica, Machala y Sabanilla, Quito, Pichi
4 - Universidad Tecnologica Indoamerica, Machala y Sabanilla, Quito, Pichi

Keywords:
hybrid
Amaryllidaceae
Reproduction
speciation.

Presentation Type: Oral Paper
Session: HYHY1, Hybrids and Hybridization
Location: Tucson H/Starr Pass
Date: Wednesday, July 31st, 2019
Time: 11:15 AM
Number: HYHY1011
Abstract ID:695
Candidate for Awards:Margaret Menzel Award