Abstract Detail

Macroevolution

Fritsch, Peter W [1], Lu, Lu [2], Peng, Ju [3], Bush, Catherine M [4], Wang, Hong [2], Zhang, Ming-Ying [2], Kron, Kathleen A [5], Li, De-Zhu [2].

Fruit evolution, lineage diversification, and biogeographical patterns in the circum-Pacific tribe Gaultherieae (Ericaceae).

Fruit is a key innovation in flowering plants and fleshy fruit is generally thought to have evolved for effective seed dispersal by frugivores. However, the evolution of fleshy fruit colors and its adaptive significance have received little attention in a phylogenetic context. Here we investigate fruit evolution in the circum-Pacific tribe Gaultherieae (Ericaceae), a clade with a wide array of fruit types and colors. We found evidence for an acceleration in species diversification rate associated with the initial evolution of fleshy fruit in the Wintergreen Group (Diplycosia, Gaultheria, and Tepuia), followed by independent rate accelerations associated with the switch from red to violet (including blue, purple, or black) colors. We also observed significant correlations among red fruits, low elevations, and high latitudes, versus violet fruits, high elevations, and low latitudes. A biogeographic analysis recovered a pattern in which inferred oceanic dispersals involved red-fruited lineages, whereas in situ diversification involved predominantly violet-fruited lineages. Phytochemical tests on the fruits of several species of Gaultheria recovered a derivative of cyanidin in red fruits and a derivative of delphinidin, frequently also with the cyanidin derivative, in violet fruits. Delphinidin absorbs ultraviolet (UV) radiation more strongly than cyanidin and is thus thought be more effective in protecting against UV than other anthocyanidins. From the sum of morphological, phylogenetic, biogeographic, and chemical evidence, we postulate that fleshy red fruit initially evolved as a key innovation for animal dispersal, but that subsequent species diversification in the tribe was facilitated by the switch from red to violet fruits, at least in part for the protection of seeds against prolonged UV exposure in either tropical or montane environments, or both. This key innovation may have evolved specifically in the Gaultherieae because their fleshy fruits are generally non-preferred by animals and thus tend to remain on the plant for long periods of time, often for many months. Although conjectural with the current data, this situation may represent an evolutionary trade-off between capacity for frugivore dispersal versus UV protection of seeds, in line with recent investigations highlighting the variety of adaptations to UV exposure in terrestrial organisms.

1 - Botanical Research Institute of Texas, 1700 University Drive, Fort Worth, TX, 76107, USA
2 - Kunming Institute of Botany, Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming, Yunnan, 650201, China
3 - Kunming Institute of Botany, State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming, Yunnan, 650201, China
4 - Elon University, Department of Biology, Elon, NC, 27244, USA
5 - Wake Forest University, Department Of Biology, 1834 Wake Forest Road, WINSTON-SALEM, NC, 27106, USA

Keywords:
adaptation
anthocyanidin
fleshy fruit
Gaultherieae
UV protection
Ericaceae
Diplycosia
Gaultheria.

Presentation Type: Oral Paper
Session: 10, Macroevolution
Location: 202/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 1:30 PM
Number: 10001
Abstract ID:64
Candidate for Awards:None