a pleistocene clone of palmers oak persisting in southern california帕默的更新世克隆橡树持久化在南加州.pdfVIP

A Pleistocene Clone of Palmer’s Oak Persisting in Southern California 1 2 2 3 4 Michael R. May , Mitchell C. Provance , Andrew C. Sanders , Norman C. Ellstrand , Jeffrey Ross-Ibarra * 1 Section of Ecology and Evolution, University of California Davis, Davis, California, United States of America, 2 Department of Botany and Plant Sciences, University of California Riverside, Riverside, California, United States of America, 3 Department of Botany and Plant Sciences and Center for Conservation Biology, University of California Riverside, Riverside, California, United States of America, 4 Department of Plant Sciences, University of California Davis, Davis, California, United States of America Abstract Background: The distribution of Palmer’s oak (Quercus palmeri Engelm.) includes numerous isolated populations that are presumably relicts of a formerly larger range that has contracted due to spreading aridity following the end of the Pleistocene. Principal Findings: We investigated a recently discovered disjunct population of Palmer’s oak in the Jurupa Mountains of Riverside County, California. Patterns of allozyme polymorphism, morphological homogeneity, widespread fruit abortion, and evidence of fire resprouting all strongly support the hypothesis that the population is a single clone. The size of the clone and estimates of annual growth from multiple populations lead us to conclude that the clone is in excess of 13,000 years old. Conclusions: The ancient age of the clone implies it originated during the Pleistocene and is a relict of a vanished vegetation community. Range contraction after climate change best explains the modern disjunct distribution of Q. palmeri and perhaps oth