An Overview of the Paleoclimatic Influences on the Genetic Variation of Chelydra

by Jack M. Corbo and H. Greg McDonald

Bulletin of the Chicago Herpetological Society, June/July 2016

“We must expect a compromise between the human need for pigeon-holing facts and the variety and fluidity of nature.” –J.S. Huxley

Chelonian Lineage Unclear

Odontochelys semitestacea

Ancestral Chelonians

Clypemys insculpta Maze Learning(N.A. Wood Turtle)

PETM and Origins of Protochelydra

Protochelydra zangerli56 Ma, Alaska

Protochelydra Comparison

Ohio Hopewell Culture (100BC-AD400) Snapping Turtle Platform Pipe

1900’s Seneca Vessel Rattle (kanyáhte’ ká’owá)

1808 American Political Cartoon of Jefferson Embargo Act

Children’s Literature

Scientific Literature

Chelydra Art(Marty Capron)

Reluctant Model Herps Alive Foundation

Road Mortality Anthropogenic Interactions

Non LethalAnthropogenic Interactions

Anthropogenic Effects (faux bicephalic C. serpentina)

Non Lethal Anthropogenic Effects

Taxonomy

Taxonomy of the Family Chelydridae

Macrochelys M. temminckii M. suwanniensis M. apachicolae

Chelydra C. serpentina C. rossignonii C. acutirostris

Macrochelys temminckii(Alligator Snapping Turtle)

Chelydra serpentina(North American Snapping Turtle)

Chelydra and Macrochelys

C. Serpentina Skeletal Features

Prior Chelydra Taxonomy

Prior Taxonomy Ranges

Current Chelydra Taxonomy

Arid Regions of North and South America

“this species furnishes a case of distribution unparalleled among reptiles, ranging as it does from the (nearctic) cold regions of Canada to

the torrid region of Ecuador” (Cope, 1868)

Extirpation of C. serpentinaWest of the Continental Divide

Great Basin Past and Present

Biochemistry Primer

DNA

Linear DNA

Bacterial and Animal Cell Structure

Animal CellStructure

Mitochondria

Mitochondria

Plasmid mtDNA• Circular• Haploid• Maternal

Population Genetics

Parapatric Speciation

Kinosternon baurii (Striped Mud Turtle)

Kinosternon subrubrum(Eastern Mud Turtle)

Sterntherus minor(Loggerhead Musk Turtle)

Sternotherus odoratus(Common Musk Turtle)

Trachemys scripta(Red-eared Slider)

Trachemys scripta Range

Dierchelys reticularia(Chicken Turtle)

Lepomis punctatus (Spoted Sunfish)

Gopherus polyphemus(Gopher Tortoise)

Macroclemys temminckii(Alligator Snapping Turtle)

M. temminckii(Alligator Snapping Turtle)

Chelydra serpentina(North American Snapping Turtle)

Chelydra serpentina CR mtDNA Sequence

Chelydra Phylogram

Panamanian Land Bridge 7 Ma

The Great American InterchangePanamanian Land Bridge

Plate Tectonics: Island Continents of

South America and Africa

Tertiary Ocean Currents

Chelydra Phylogram

Genetic Bottlenecks:Population Crash and Recovery

(population vs time)

Genetic Bottlenecks

Population Crashes of Chelydra

Possible CatastrophesImpact Event

Glacial Advances Marine Transgression

Arid Climate

Younger Dryas Impact Hypothesis

Carolina Bays(elliptical lakes aimed at Michigan)

Younger-Dryas Impact Event 12.9 ka

Suspected Crater in Southern Ohio(cryptoexplosion)

Megafaunal Extinctions

Comparison of Younger Dryas Ejecta Field and Range of

M. temminckii

Glaciations

Glaciations and Interglacials

Milankovich Cycle

Glaciation Worldwide

Ohio Glacial Maximum

Megafauna Sites Found in Ohio

Glacial Erratic BoulderSouth Euclid

Palynology of Soil Core Samples

Tree Ranges over 18,000 years(proxy ranges for C. serpentina)

Percidae Species Density(Darters)

Amphibian Species Density Map

Mammal Species Density Map

Terrapene carolina carolinaTransients

(Eastern Box Turtle)

Chelydra Hatchlings

Hatchling Freezing Mortality

Chrysemys picta Range(Painted Turtle)

C. picta Clade Ranges

C. Picta Ranges

Northern and Western Range Borders of C. serpentina

C. serpentina Range

C. serpentina Deformities

Comparison of Mean July Temperature Isotherm

and C. sepentina Range

18 ka Mean July Isotherms

Caribbean Marine Transgressions

Galapagos Islands

Temperature-dependant Sex Determination

(TSD)

C. SerpentinaTSD

Chelydra rossignonii(Mexican Snapping Turtle)

Refuge Theory

C. Rossignonii Range and Refugia

American Refugia and Flooding Areas

Chelydra acutirostris(Ecuadorian Snapping Turtle)

C. acutirostris Range and Refugia

Dehydration Study(7 days)

Kinosternon leucostomum(White-lipped Mud Turtle)

Distribution

Kinosternon leucostomum(White-lipped Mud Turtle)

K. Leucostomum Range

North Eastern South America

Kinosternon Scorpiodes(Scorpian Mud Turtle)

Kinosternon Scorpiodes(Scorpian Mud Turtle)

C. AcutirostrisColonization of Amazon Basin

Bonanza

“[Snapping turtles evoke impressions of a primitive nature

and time, because of their appearance and because they

shared the earth with the dinosaurs; they are] entitled to

regard the brontosaur and mastodon as brief zoological

fads.”-B. Gilbert

Chelydra Phylogram

Conclusions

• Alternating glacial and interglacial climatic changes caused a series of genetic bottlenecks in the North American C. serpentina population that resulted in one predominate CR mtDNA.

• Refugia embedded in the ranges of C. rossignonii and C. acutirostris preserved CR mtDNA polymorphism.

Recommendations • Total genomes of peninsular and continental populations

of C. serpentina made to determine if they too are identical.

• More genomes of C. rossignonii and C. acutirostris should be determine to confirm that the polymorphisms exists throughout the two populations.

• Investigate if Chelydra fossils can be found in the northeastern hiadus region between C. sepentina and C. rossignonii ranges.

AcknowledgementsReviewers:Dr. Ron Heyer, Smithsonian Institution Dr. Joe Hannibal, Cleveland Museum of Natural HistoryDr. Michael Hofreiter, Max Planck InstituteDr. John Iverson* (twice), Earlham CollegeDr. Chris Sheil, John Carroll UniversityDr. Harry van Keulen (emeritus), Cleveland State UniversityDr. George Zug* (emeritus), Smithsonian Institution Robert R. Perry*, Trebor Specialities, Inc.

Assistance:Dr. Brad Shaffer, University of California at Davis Dr. Don Moll, University of Southwestern MissouriDr. John Avise, University of California at Davis

Acknowledgment

The End