Page:The Gall Wasp Genus Cynips.pdf/82

Phylogenetic History

Epoch	Time estimate, millions of years	Geologic events	History of Cynips
Upper Cretaceous	80-60	Rise of flowering plants Origin of oak First rise of Rockies and Sierras	Ancestral Cynipidae
Eocene	60-35	Alaskan-Siberian connection maintained, climate mild, oak in the area	Differentiation of main groups in the family
Oligocene	35-20	Alaskan-Siberian connection maintained, climate mild, oak in the area Great Plains forming	Cynips and other modern genera in existence Eastern and western subgenera separated
Miocene	20-7	Alaskan-Siberian connection continuous, climate more severe Rockies elevating, deserts forming in the area Finally Alaskan land connections broken	Subgenus Cynips moves into Eurasia Antron and Besbicus species differentiate on Pacific Coast Acraspis, Atrusca and Philonix specific stocks arise in southern Rockies
Pliocene	7-1	Great Valley of Calif. in part an inland sea Rockies elevated and Great Plains become semi-arid Sierras elevated and Great Basin becomes more arid	Specific stocks of eastern subgenera move across Great Plains Modern species and varieties differentiated in all groups
Pleistocene	1 million to 20,000 years	Grand Canyon begun Extensive glaciation Cold climate south to Ohio River Moist climate in parts of Great Basin and north of Gulf of California	Northern varieties pushed south to hybridize with southern varieties Some Calif, species migrate back to so. Arizona