Recent Topics Posters
Hermsen, Elizabeth J. .
The Historical Biogeography of Itea—an eastern North American-eastern Asian-eastern African disjunct taxon—Based on its Fossil Record.
Itea has traditionally been considered a northern hemisphere Tertiary relict with a classic eastern North American-eastern Asian disjunct distribution. Recent expansion of the generic limits of Itea to include the eastern African species Itea (formerly Choristylis) rhamnoides has modified this perception and rendered the disjunct range of Itea more unique. In this poster, I will explore the development of the current range of Itea from the perspective of its fossil record using a comprehensive compilation of over 100 fossil occurrences attributed to Itea from Europe, North America, and Asia. I have sorted the occurrences into discrete age intervals and plotted them using published locality information as a guide. The compilation and plotting reveal that Itea has a fossil record spanning the early Eocene-early Miocene in western North America, early Miocene-recent in eastern North America, late Eocene-Pliocene in Europe and adjacent Asia Minor, and only one (early Miocene) occurrence in eastern Asia. These results suggest that the most logical route of Itea to Africa would have been from Europe. The precise relationships among populations that inhabit or once inhabited western North America, eastern North America, eastern Asia, and Europe are obscure. Itea is first documented in western North America in the early Eocene (ca. 49.4-52 Ma), with the next occurrences in northern Europe over 10 million years later. Given the robust temporal and geographic density of occurrences (and sampling) in Europe, the arrival of Itea over the North American Land Bridge from North America is likely. Occurrences of Itea pollen in Alaska also suggest that the genus crossed the Bering Land Bridge. A literal interpretation of these data suggests that the genus spread from western North America to eastern Asia, but the poor record in these regions makes this conclusion unreliable. Additional sampling of sediments in Asia and North America and a robust infrageneric phylogeny of the extant species are needed to better understand how Itea has achieved its current distribution.
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1 - Cornell University, Department of Plant Biology, 412 Mann Library Building, Ithaca, New York, 14853-5908, USA
Presentation Type: Recent Topics Poster
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM