Abstract Detail

Hybrids and Hybridization

Zizis, Diamanda [1], Martine, Chris [2], Williams, Tanisha [2].

Heading for a breakdown: Assessing evolution through the hybridization of two sexual systems.

Hybridization is an important evolutionary pathway that has contributed to the world’s vast biodiversity. In plants, especially angiosperms, hybridization is known to be an important mechanism for speciation, phenotypic divergence, and changes in reproductive systems. Solanum species present an ideal system to investigate how hybridization between two different sexual systems impacts the reproductive and phenotypic biology of the hybrid progeny. Hybrids were acquired from crosses between Australian Solanum species Solanum dioicum (dioecious) and S. ultraspinosum (andromonoecious). The only successful hybrids from the original crosses were those derived from S. dioicum as the pollen donor and S. ultraspinosum as the pollen recipient. Due to strong maternal effects, all F1 hybrids resembled S. ultraspinosum, thus all F1 plants were andromonoecious. To assess phenotypic differences between the hybrids and their parents, I collected morphometric data using calipers and ImageJ software. A series of statistical analyses were done using R. A principal component analysis confirmed that the hybrids were distinct from both parents, but were most similar to S. ultraspinosum, the pollen recipient. The F2 hybrids appear to demonstrate variability in inflorescence architecture, which may be suggestive of a change in sexual system, although further analysis is needed. In attempts to create an F3 hybrid generation (crosses among F2 plants), nearly all of our crosses have failed—suggesting that a hybrid breakdown is occurring. To determine where the breakdown is occurring, I am employing a new technique using fluorescent microscopy. This may explain what mechanisms are present in nature that prevent hybridization of species with two different sexual systems. This study should promote a better understanding of hybridization—a driving force in plant diversification—among Australian Solanum, a group in which hybridization is known to be widely possible but rarely confirmed in nature. Likewise, hybridization between taxa with two distinct sexual forms may shed light on the evolution of reproductive strategies in this clade.

1 - Bucknell University, 701 Moore Avenue, Lewisburg, PA, 17837, United States
2 - Bucknell University, Biology, 1 Dent Drive, Lewisburg, PA, 17837, United States

Keywords:
Solanum
Solanaceae
hybrids
hybridization
Australia
Dioecious
andromonoecious
morphometrics
reproductive biology.

Presentation Type: Poster
Number: PHH004
Abstract ID:662
Candidate for Awards:None