Fossil nightshade berries reveal the global radiation of an Andean-centered family in the Eocene

DEANNA, ROCÍO; MARTINEZ, CAMILA; MANCHESTER, STEVEN; CAMPOS, ABEL; KNAPP, SANDRA; WILF, PETER; CHIARINI, FRANCO; BARBOZA, GLORIA E.; BERNARDELLO, GABRIEL; SAUQUET, HERVE; DEAN, ELLEN; OREJUELA, ANDRÉS; SMITH, STACEY D.

Cleveland

Congreso; Evolution 2022; 2022

The Andes of South America are the center of diversity for many cosmopolitan plant clades. Among these Andean-centered families, Solanaceae or the nightshade family stands out for the stark incongruences between molecular dating estimates and recent fossil discoveries. Divergence time estimates based on the few reliable fossils placed the stem age of the family around 49 Ma. However, the subsequent discovery of Eocene lantern fruit fossils (genus Physalis) from Patagonia suggests the family may have much earlier origins, in Gondwanan South America or Antarctica. Herein, we present a broader set of Solanaceae fruit fossils, including the first record from North America and a new record from Colombia. The taxonomic affinities of these fossils span additional lineages from the berry clade and are all confidently dated to the early to late Eocene. A clustering analysis (NMDS), based on 15 morphological characters from seven fossils and 291 extant species of Solanaceae, showed the strong morphological similarity of some fossils to the physaloids and others to the Lycianthes/Capsicum (pepper) clade. The geographic spread of these berry lineages, from southern South America to the Green River Basin of North America (present day Wyoming and Colorado), indicates that the tomato family diversified much earlier and may have spread northward through Late Cretaceous island-hopping, opening the possibility of spreading to Europe and Asia through land connections. In addition to providing insight into the deep history of the family, these new fossils hint at a previously rich solanaceous flora in northern North America that has now disappeared.