Abstract Detail

Macroevolution

Clement, Wendy [1], Howarth, Dianella [2], Landrein, Sven [3], Srivastav, Mansa [4], Donoghue, Michael [5].

Extrafloral organ fusion in the evolution of Lonicera and its relatives (Caprifoliaceae, Dipsacales).

We have embarked on a study of the repeated fusion of adjacent extrafloral organs in Lonicera and its relatives. Here we describe this phenomenon and its significance, and present preliminary phylogenetic, morphological, and developmental data supporting both convergent and parallel evolution. Perfoliate leaves are well known in several lineages Caprifoliaceae sensu lato, as are fused fruits. A less widely known phenomenon in these plants is the fusion of the bracts and/or bracteoles subtending the flowers. The “epicalyx” of the Dipsacaceae evolved through the fusion of several sets of bracts subtending a central flower, and it has largely taken over the function of ovary protection and fruit dispersal. In other lineages, the bracteoles associated with flowers have been variously modified, and in one major clade within Lonicera (Chamaecerasus) such fusions have occurred multiple times, in some cases resulting in the evolution of a specialized “cupule” that surrounds a pair of adjacent ovaries during their development. In some of these cases the fruits eventually mature out of the cupule, but in one case (L. caerulea and its immediate relatives) the cupule becomes a colorful fleshy structure that completely encloses the two separate ovaries throughout their maturation. Our preliminary analyses suggest that cupules evolved independently at least four times, and that in these cases the ovaries themselves have remained unfused. We hypothesize that the evolution of bracteole fusion and the production of a cupule was enabled by the loss of a central flower from an ancestral three-flowered inflorescence unit characteristic of the other major clade of Lonicera (Periclymenum) and related Caprifoliaceae. This loss had the effect of bringing the ovaries of the two lateral flowers and their bracteoles into direct contact, thereby facilitating their fusion. This provides a concrete example of the evolution of novelty (a new, individualized body part) that was facilitated by an enabling trait with only an indirect effect on the rate of diversification.

1 - The College Of New Jersery, Dept. Of Biology, 2000 Pennington Road, Ewing, NJ, 08628, United States
2 - St. John's University, Department Of Biological Sciences, St. Albert Hall Rm 257, 8000 Utopia Pkwy, Jamiaca, NY, 11439, United States
3 - Xishuangbanna Tropical Botanical Garden, Horticulture, Xishuangbanna Tropical Botanical Garden, Menglun, Xishuangbanna, Yunnan, 666303, China
4 - Yale University, Ecology And Evolutionary Biology, 21 Sachem Street, Room 364 New Haven, CT 06511, Environmental Science Center, Room Number 356, New Haven, CT, 06511, United States
5 - The College of New Jersey, Department of Biology, 2000 Pennington Road , United States, Ewing, NJ, 08628, USA

Keywords:
none specified

Presentation Type: Oral Paper
Session: MACRO2, Macroevolution II
Location: Tucson B/Starr Pass
Date: Tuesday, July 30th, 2019
Time: 2:15 PM
Number: MACRO2004
Abstract ID:1015
Candidate for Awards:None