Abstract Detail

Conservation Biology

Li, Bing [1], Vitt Gorra, Darwyn [1], Levy, Ben [1], Holloway, Jalen [2], Lamb, Nathan [1], Havens, Kayri [1].

Changes to floral morphology and phenology of an endangered species, Oenothera organensis, during ex situ conservation.

With increasing threats to biodiversity, ex situ conservation is an important approach to backup endangered species, and the preserved germplasm can be used for reintroduction and conservation purposes. However, ex situ collections may experience changes in morphology and phenology, which could cause fitness declines and maladaptation when the plants are reintroduced. Oenothera organensis (Onagraceae) is a rare species endemic to the Organ Mountains, New Mexico. The species has approximately 2000 individuals left in the wild, and it was historically threatened by overgrazing and water deficit. Indiana University has cultivated O. organensis since 1930s, which is one of the oldest ex situ collections of an herbaceous species. O. organensis is strictly self-incompatible and pollinated by three species of hawkmoths, but the ex situ plants were grown indoors and hand pollinated for more than 80 years. This study tests whether the ex situ collection of O. organensis has experienced changes to floral morphology and phenology, possibly because of genetic drift or relaxation of pollinator-mediated selection during cultivation. Information on the responses of floral morphology to long-term cultivation is scarce, and current ex situ practices have not focused on the potential problems caused by the absence of pollinator-mediated selection.
The Chicago Botanic Garden grew O. organensis from seed collected in the wild population and the Indiana University ex situ collection. We measured floral phenology and morphology of all O. organensis grown at the Chicago Botanic Garden during the growing seasons of 2017 and 2019. In both years, ex situ plants flowered on average 10 days later than the wild plants. Compared with the wild plants, the ex situ O. organensis exhibited significantly longer hypanthium length in 2019 and less nectar volume in 2017, but neither result was significant in both years. We did not detect significant differences in either year for other floral measurements, including nectar sucrose percentages, corolla size, and floral tube diameter. If the ex situ plants are reintroduced into the wild, these changes could potentially affect pollination success, but this remains to be tested. The absence of pollinator-mediated selection might be a potential drawback for ex situ collections maintained for multiple generations outside the range of native pollinators or in glasshouses. These results underscore the importance of maintaining ex situ living collections in conditions as close to those experienced by wild populations as possible.

1 - Chicago Botanic Garden, CONS SCI DEPT, 1000 Lake Cook Road, Glencoe, IL, 60022, United States
2 - The University of Mississippi, Department of Biology, P.O. Box 1848, Oxford, MS, 38677, USA

Keywords:
ex situ conservation
relaxation of selection
Oenothera
floral morphology
phenology
botanical gardens.

Presentation Type: Poster
Session: P, Conservation Biology Posters
Location: Virtual/Virtual
Date: Monday, July 27th, 2020
Time: 5:00 PM Time and date to be determined
Number: PCB005
Abstract ID:812
Candidate for Awards:None