Integrated Fossil and Molecular Data Reveal the Biogeographic Diversification of the Eastern Asian-Eastern North American Disjunct Hickory Genus (Carya Nutt.)

Abstract

The hickory genus (Carya) contains ca. 17 species distributed in subtropical and tropical regions of eastern Asia and subtropical to temperate regions of eastern North America. Previously, the phylogenetic relationships between eastern Asian and eastern North American species of Carya were not fully confirmed even with an extensive sampling, biogeographic and diversification patterns had thus never been investigated in a phylogenetic context. We sampled 17 species of Carya and 15 species representing all other genera of the Juglandaceae as outgroups, with eight nuclear and plastid loci to reconstruct the phylogeny of Carya. The phylogenetic positions of seven extinct genera of the Juglandaceae were inferred using morphological characters and the molecular phylogeny as a backbone constraint. Divergence times within Carya were estimated with relaxed Bayesian dating. Biogeographic analyses were performed in DIVA and LAGRANGE. Diversification rates were inferred by LASER and APE packages. Our results support two major clades within Carya, corresponding to the lineages of eastern Asia and eastern North America. The split between the two disjunct clades is estimated to be 21.58 (95% HPD 11.07-35.51) Ma. Genus-level DIVA and LAGRANGE analyses incorporating both extant and extinct genera of the Juglandaceae suggested that Carya originated in North America, and migrated to Eurasia during the early Tertiary via the North Atlantic land bridge. Fragmentation of the distribution caused by global cooling in the late Tertiary resulted in the current disjunction. The diversification rate of hickories in eastern North America appeared to be higher than that in eastern Asia, which is ascribed to greater ecological opportunities, key morphological innovations, and polyploidy.

Combined LM and SEM study of the middle Miocene (Sarmatian) palynoflora from the Lavanttal Basin, Austria: part IV. Magnoliophyta 2 – Fagales to Rosales

“…Annamocarya), Juglans and Pterocarya; and the monotypic Cyclocarya and Platycarya (e.g. Manchester 1987b; Manos & Stone 2001;Manos et al 2007;Zhang et al 2013). Pollen morphology (LM and SEM) and ultrastructure (TEM) of Carya has been presented in detail by Stone and Broome (1975).…”

“…-The subfamily Engelhardioideae includes four well-defined extant genera that are supported by both molecular and morphological data; Alfaroa, Alfaropsis, Engelhardia (often misspelled as 'Engelhardtia'; see Dilmy 1955) and Oreomunnea (e.g. Manchester 1987b;Manos & Stone 2001;Manos et al 2007;Zhang et al 2013). The most comprehensive work on Juglandaceae pollen including species representing every extant genera of the family is that of Broome (1971, 1975).…”

“…Carya is considered a monophyletic genus composing two well supported clades that correspond to the eastern Asian group and the eastern North American group (e.g. Zhang et al 2013). The species ranging in habitat from temperate mixed mesophytic forests to mountain rain forests (Stone 1997;.…”

New fossil fruits of Carya (Juglandaceae) from the latest Miocene to earliest Pliocene in Tennessee, eastern United States

“…This southward migration of the genus appears to support the global cooling trend during this period (Zachos et al, ; Mosbrugger et al, ). It represents a new potential migration route of Carya other than those proposed by Zhang et al (), and therefore helps better know the biogeographical framework of the genus in the past.…”

Plants in movement – Floristic and climatic characterization of the New Jersey hinterland during the Palaeogene–Neogene transition in relation to major glaciation events

“…In our record, the relative occurrences of this genus were as low as those of Fagus. Carya first appeared in the Palaeocene in North America (Manchester, 1987) and the first radiation began in the early Miocene (Zhang et al, 2013). Zhang et al (2013) suggest that the Appalachian uplift phases created new habitats, which led to a diversification of the genus.…”