Pleistocene Pine Voles (Pitymys pinetorum)

October 16, 2018

Evolutionary biologists like to study rodent fossils.  Rodents occur in high population numbers, and their rapid generational turnover means evolutionary change occurs faster than with larger slower breeding animals.  Scientists recently studied pine vole teeth from 2 caves in Kentucky and 1 cave in Georgia that date to the last Ice Age and compared them with modern day pine vole teeth.  Pine vole teeth from Hilltop and Cutoff Caves in Kentucky date to about 30,000 years ago, and the pine vole teeth from Yarbrough Cave in Georgia date to about 23,000 years ago.  Pine voles are still a common species, occurring all across eastern North America.  Despite their name, they prefer living in moist deciduous forests where they tunnel under tree roots and feed on roots, seeds, fruit, fungus, and insects.  Their fossorial existence keeps them safe from owls and hawks, though snakes can enter their burrows.  Pine voles are considered arvicolid rodents because their teeth cusps are in the shape of alternating triangles.  Other common arvicolid rodents include meadow voles, lemmings, muskrats, and cotton rats.

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Pine voles weigh just an ounce.  They mostly live underground but occasionally venture to the surface.

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Pine vole range.  Pine vole is a misnomer.  They prefer moist deciduous woods, not pine forests.  Nobody knows why the common name is pine vole.

The pine vole teeth from the Kentucky Caves show the pine voles living then were the same size as modern day pine voles living in the region.  However, pine voles living in north Georgia during the Ice Age were larger than modern day Georgia pine voles and about the same size as northern pine voles.  Scientists believe this was in response to colder temperatures.  Bergmann’s rule states that animals living in colder climates generally grow to a larger size because they are better able to retain body heat.  The authors of this study can’t determine whether this large size was the result of inbreeding with northern populations of larger pine voles that colonized the region or natural selection of the local population.

Reference:

Martin, Robert; and K. O’Bryan

“Size and Shape Variation in the Late Pleistocene Pine Vole (Mammalia: Arvicolidae: Pitymys Pinetorum) First Lower Molars from 3 Caves in Kentucky and Georgia”

Paludicola September 2014

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A New Study of the Looper Collection

October 9, 2018

Between 1989-1995 Lonnie and Freida Looper hunted for fossils on 19 different gravel bars along the Mississippi River during droughts when the bars became exposed.  These gravel bars are located between Helena, Arkansas and Greenville, Mississippi.  Thousands of years ago, the bones were quickly buried when glacial meltwater pulses flooded the Mississippi River Valley.  The Mississippi River erodes this Pleistocene-aged sediment and deposits the soil and bones on the gravel bars.  For years the Looper family sold replicas of their specimens, but they donated most of the actual specimens to Delta State University.  I don’t think they still sell the replicas, though the Looper’s website remains on the internet.  The Looper family discovered over 550 specimens including 27 species.  A comprehensive study of their collection wasn’t published until 2017.

 

 

 

 

 

 

The Looper family found this Jefferson’s ground sloth claw on a Mississippi River gravel bar exposed during a drought.

During most of the late Pleistocene the Mississippi River entered the Mississippi River Valley through 3 gaps, but all of these flooded following the collapse of the ice dam that unleashed the waters of Lake Agassiz about 12,900 years ago.  Before this the Mississippi River didn’t meander broadly like it does today.  Instead, it was a series of braided channels clogged with sandbars because the water table was much lower then.  Cold glacial meltwater pulses caused cool microclimates within the valley that favored mixed Ice Age woodlands of pine, spruce, ash, aspen, oak, hickory, willow, tamarack, herbs, and grass.  Frequently flooded bottomlands and abandoned dried-out channels hosted alder thickets with beech, walnut, tulip, willow, and grass.  Spruce and jack pine dominated drier upland sites.  These were the types of habitats that supported the animal life represented in the Looper collection.  Some of the species they found were not known to have occurred within the Mississippi River Valley including paleolama, stag-moose, helmeted musk-ox, giant short-faced bear, and manatee.

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Map of the Mississippi River Valley in relation to the ice sheet during the Last Glacial Maximum. This map doesn’t represent the land area that occupied the continental shelf then.

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The Mississippi River resembled this modern day braided river during the Ice Age.

Paleolama mirifica was a species known from the coastal plains of South Carolina and Georgia, and throughout Florida; so the specimen found by the Looper family was a first for the region and evidence for a greater range than was previously known. The manatee was likely an accidental migrant that may have perished because it failed to go south during cool weather.  Manatees can’t survive in water temperatures below 68 degrees F.  The Looper family also collected bones of mammoth, mastodon, bison, white-tailed deer, long-nosed peccary, 2 species of extinct tapir, horse, beaver, giant beaver, Jefferson’s ground sloth, dire wolf, raccoon, black bear, giant tortoise, snapping turtle, soft-shelled turtle, unidentified bird, small-mouth buffalo fish, and flat-headed catfish.  Bones of bison and deer were the most common.

Nina Baghai-Riding, the lead author of this new study, thinks the Mississippi River Valley may have been a migratory corridor for some species.  Cool microclimates along the river may have attracted fauna of northern affinities.  Rivers are also rich in food resources as well because a greater quantity and quality of vegetation can grow in more irrigated environments.  The superior feeding opportunity attracted megafauna as well.

Reference:

Baghai-Riding, Nina; and D. Hunley, C. Beck, and E. Blackwell

“Late Pleistocene Megafauna from Mississippi Alluvium Plain Gravel Bars”

Paludicola December 2017

file:///C:/Users/Owner/AppData/Local/Packages/Microsoft.MicrosoftEdge_8wekyb3d8bbwe/TempState/Downloads/Baghai-RidingLatePleistocenegravelbarpaper%20(3).pdf

 

How far South did the Extinct Stag-Moose (Cervalces scotti) Range During the Late Pleistocene?

October 2, 2018

A species of extinct deer, slightly larger than a modern day moose (Alces alces), occurred south of the ice sheets during the late Pleistocene.  It is alternatively known as stag-moose or elk-moose, but its scientific name is Cervalces scotti. This giant deer had the long nose of a moose, though its antlers were more like those of an elk.  However, it shared a closer common ancestor with the former.  They inhabited wetlands surrounded by mixed forests dominated by spruce but with significant elements of pine and hardwoods.  Like modern day moose, they fed upon aquatic plants during summer and twigs during winter.  Mastodons occupied a similar habitat and fed on the same foods, so the 2 species often co-occurred together.

Evidence from the fossil record suggests stag-moose were particularly abundant in midwestern bogs left by retreating glaciers.  Stag-moose bones are quite commonly found in Ohio, Indiana, Illinois, and New York.  Surprisingly, they occurred even farther south with isolated fossil remains having been discovered in Virginia, Arkansas, Mississippi, and South Carolina.  The stag-moose remains found in Desha and Philips County, Arkansas and Rosedale, Mississippi are at 34 degrees latitude.  These consist of antler fragments and a jawbone with a tooth.  The stag-moose specimen from Charleston, South Carolina (just a tooth) occurred at 32 degrees latitude.  This is probably close to the southern limits of its former range because stag-moose remains are completely absent from sites in fossil rich Florida.

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Artist’s depiction of the stag-moose.  They were huge. That is a lot of venison.

A stag-moose skeleton found in Chippewa Lake, Medina, Ohio had 1 bone that had attached sediment filled with pollen representing the type of environment it lived in.  The pollen included fir, maple, alder, aspen, birch, hickory, hackberry, hazelnut, ironwood, pine, oak, basswood, elm, spruce, cedar, ragweed, grass, and cattail.  Spruce pollen made up 60% of the total.  It seems likely the type of environment favored by the stag-moose, as far south as Charleston, South Carolina, included various compositional ratios of these species.  I hypothesize stag-moose occurred in the mid-south during cool moist interstadials rather than the coldest driest stages of Ice Ages.  Wetlands would’ve been more common during these climatic phases.  Full blown glacial maximums restricted stag-moose habitat because desert scrub and grassland habitat expanded then.

Although there is no supporting archaeological evidence, I think overhunting by humans caused the extinction of the stag-moose.  Man colonized North America when ice sheets covered most of Canada, thus restricting stag-moose to more temperate regions where humans became common enough to impact their populations.  When the glaciers began to recede, optimal stag-moose habitat increased, but humans had already decimated their populations into extinction.  Modern day moose crossed the Bering land bridge, and ecologically replaced the stag-moose and were able to survive in northern latitudes where human populations remained too scarce to overhunt them.

Reference:

Mcdonald, Greg; R. Glotchober

“Partial Skeleton of an Elk-Moose, Cervalces scotti, from Chippewa Lake, Medina County Ohio”

Research Paper 2017

Were Beringian Wolves Blonde?

September 25, 2018

An extinct ecomorph of the gray wolf (Canis lupus) roamed North America from Beringia to at least as far south as Wyoming during the Late Pleistocene. (See: https://markgelbart.wordpress.com/2016/05/30/beringian-wolves-an-extinct-ecomorph-of-canis-lupus-lived-as-far-south-as-wyoming/ ) Beringia included the unglaciated region of Alaska, the Yukon, and the Bering Strait located north of the Ice Sheet that covered most of Canada then.  The Bering Strait emerged above sea level during Ice Ages.  An ecomorph is the regional variation of a species that differs morphologically from other populations of the same species.  Beringian wolves had bodies closely resembling those of gray wolves, but their teeth and jaws were larger and more robust like those of the extinct dire wolf (C. dirus).  Paleontologists interpret the larger teeth and jaws as an adaptation for preying and scavenging on megafauna.  Isotopic evidence of Beringian wolf bones does suggest they fed upon mammoths, horse, bison, musk-ox, and caribou.  Beringian wolves were not ancestral to modern day Alaskan gray wolves, but they do share a common ancestor.  Genetic evidence suggests Beringian wolves diverged from wolves found in northern China and Mongolia today about 28,000 years ago.  Present day Alaskan wolves descend from a different population of wolves than the Beringian wolves which became extinct about 7500 years ago.

Map showing location of sites where Beringian wolf bones have been discovered and the proposed route from Beringia to Wyoming.  I hypothesize they occurred as far south as the southern Appalachians.

I hypothesize Beringian wolves were an hybrid species originated when gray wolves interbred with dire wolves.  This hypothesis will be possible to test when scientists are able to extract DNA from a dire wolf fossil.  There are thousands of dire wolf specimens from the La Brae Tar Pits, but the tar in the bones prevents DNA extraction.  Many specimens of dire wolf have been found in Florida as well, but humid conditions here cause DNA to deteriorate.  I also hypothesize Beringian wolves were more widespread than the fossil record indicates.  Over much of the continent fossil evidence of canids consists of isolated teeth and bones difficult for scientists to differentiate between gray wolf, Beringian wolf, dire wolf, and even large Pleistocene coyote.  For example 1 wolf tooth found at Ladds Cave in north Georgia was identified as belonging to a gray wolf by 1 paleontologist, but another scientist ruled it fell within the size range of a dire wolf.  Maybe this specimen came from a Beringian wolf.

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80,000 year old mummified wolf pup found in a Yukon gold mine.  Note the coat color.  It’s is a brownish blonde.

During June of 2016 gold miners discovered the mummified remains of a wolf pup.  As the photo shows, it was perfectly preserved.  Carbon dating of the specimen indicated it was older than 50,000 years–the upper limit of carbon dating.  However, the specimen was associated with volcanic ash dated to about 80,000 years BP.  This predates the 28,000 year old divergence between Mongolian wolves and Beringian wolves, so it will be interesting to learn how this specimen relates to later populations of wolves.  Julie Meachen of Des Moines University will lead a study of the pup.

The coat color of this specimen surprises me.  Of all the speculative illustrations of Pleistocene wolves none depict a golden, blonde, or tawny colored coat.  This specimen appears to have a coat color similar to a lion but a little darker.  Perhaps preservation in permafrost for so long changed the original color of the coat but suppose this was the color.  The coat color likely resembled the landscape background of its habitat.  Patches of yellow grass interspersed with bare dirt predominated in Beringia and much of North America during Ice Age stadials when precipitation was scarce and temperatures dropped.  It’s possible packs of yellow dire wolf/gray wolf hybrids lived throughout parts of North America for thousands of years.

In Defense of House Sparrows

September 18, 2018

Jessica Neal and Virginie Rolland, scientists from Arkansas State, published a paper in Southeastern Naturalist about their research of bluebird nesting boxes, and they mentioned “euthanizing” non-native house sparrow nestlings that they found occupying the nest boxes intended for bluebirds.  This irritates me for several reasons.  I hate the use of the word, euthanize, because it was used to sanitize what they actually did.  They killed helpless baby birds.  Many people kill house sparrows because this species outcompetes native birds such as bluebirds, swallows, woodpeckers, and unestablished purple martins.  It is too bad these species may be in decline, but when she killed the house sparrows that were occupying that site there were then fewer  birds occupying that area.  Bluebirds probably weren’t going to return to that site during that nesting season, and there is no guarantee they ever will.  Without the house sparrows there was less avifauna for bird watchers to enjoy.  I also don’t like the way they played God by deciding which species they wanted to live there.  Some may say humans already decided to play God by introducing house sparrows to North America in 1852 when ironically they were brought to New York to control native linden moths.  I reject this argument.  Humans shouldn’t pick an animal to introduce, then decide they don’t want it any more and try to eradicate it.  Not only are humans playing God, they are playing a fickle God in this case.  Not even the worst Old Testament version of God was this monstrous.

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House sparrows are a commensal species with humans.

I love house sparrows because they thrive where few other birds can.  Every grocery store shopping center hosts a colony of house sparrows, and they often live in the patio section of big chain lawn and garden centers.  This habitat is completely unsuitable for native songbirds.  The only other bird species I see in suburban parking lots are city pigeons (also non-native) and ring-billed gulls during winter.  But house sparrows are abundant in these otherwise barren urban environments where they feast on discarded junk foods and fill the atmosphere with their delightful singing.

The house sparrow (Passer domesticus) originated in the Middle East having evolved from P. predomesticus following the development of agriculture.  Fossil remains of P. predomesticus have been unearthed from Qumm-Quatufa Cave in Israel that date to the mid-Pleistocene.  House sparrows may have already been a commensal species with archaic humans, hanging around their garbage middens.  Late Pleistocene remains have also been discovered from Kebara Cave in Israel.  Genetic evidence suggests P. predomestica diverged from the Spanish sparrow (P. hispaniolensis) about 100,000 years ago.  Another genetic study suggests P. domesticus evolved larger skulls and an improved ability to digest starch 11,000 years ago–the dawn of the agricultural era.  The larger skulls helped them crack human-grown grains, and the improved ability to digest starch let them survive on an heavy diet of wheat, rye, and oats.  They became less dependent upon insects than their wildest remaining subspecies P. domesticus bactranius. Unfortunately for other songbirds, their larger skulls gave them greater biting and piercing force, and this allows house sparrows to outcompete them.

House sparrows followed humans throughout Europe and Asia where they continued to feast on grain spillage and nest on housing structures.  This close association with humans let house sparrows conquer the world wherever humans became established.  House sparrows were formerly even more abundant when the horse and buggy were the most common mode of transportation.  In addition to excess grain spillage house sparrows ate the undigested grains in horse manure.  But the introduction of the automobile dealt a little setback to house sparrow populations, reducing the amount of grain and manure in the environment.  Nevertheless, a trip to the local grocery store is all it takes to see them.

References:

Schans, Franke

“How the Sparrow Made Its Home with Humans”

Science August 24, 2018

Neal, Jessica; and Virginie Rolland

“A Potential Case of Brood Parasitism by Eastern Bluebirds on House Sparrows”

Southeastern Naturalist (14) 2 2015

Ice Age Rhythm Shifts

September 10, 2018

For millions of years mild climate allowed soil to build in Canada and the northern regions of Eurasia.  Plants and animals lived and died and their remains turned into thick layers of top soil.  The uplift of the Himalayan Mountains and the Rocky Mountains and the emergence of a land bridge between the Americas changed climate patterns that then became triggered by the Milankovitch Cycles.  (See: https://en.wikipedia.org/wiki/Milankovitch_cycles)  Ice Ages began to occur during the Pliocene over 3 million years ago.  At first Ice Ages lasted for 40,000 years before cycling into interglacial periods.  But about 950,000 years ago Ice Ages began to last for 100,000 years, and they became more severe.  Scientists found evidence suggesting this is when glaciers began to scrape into bedrock instead of the deep soil built up during the Miocene and early Pliocene.  Whereas glaciers slid over soil during earlier Ice Ages, they instead became stuck in bedrock and grew thicker.  Earlier Ice Sheets repeatedly drove into soil and with each Ice Age stripped the soil until 950,000 years ago it finally reached the bedrock.  The increased size of the glaciers caused an increase in the length and severity of Ice Ages.

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Graph showing increased length of Ice Ages.

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Glaciers reached bedrock about 950,000 years ago.  Repeated glacial advances eventually stripped away deep layers of top soil.  Later Ice Ages produced glaciers that got stuck in bedrock and grew thicker.

The evidence for changing Ice Age rhythms comes from deep ocean cores taken from the South Atlantic.  Scientists noticed the sudden influx of isotopes that are more common in the Pacific Ocean in the section of cores dating to 950,000 years ago.  These isotopes of neodymium originate from young volcanic islands located in the Pacific Ocean, and the rock sediment erodes into the ocean and gets carried by currents into the South Atlantic.  Normally, older rocks from coastlines surrounding the North Atlantic Ocean with a different ratio of neodymium isotopes erode and wash into the sea, and they predominate.  But normal ocean circulation shuts down during Ice Ages, and more water from the Pacific Ocean makes its way into the North Atlantic.

Reference:

Vougen, Paul

“Sea Floor Cores Suggest Sticky, Thick Glaciers Caused Mysterious Shift in Ice Age Rhythms”

Science Augusts 22, 2018

 

The Vice-Versa Climate Phases of South Florida during the Late Pleistocene

September 3, 2018

Drastic climatic fluctuations occurred during Ice Ages.  Sudden warm spikes in average annual temperatures followed by rapid onsets of much colder climate phases altered the quantitative composition of plant species in the environment.  In most of North America oaks and other broad-leafed trees increased in abundance during warm wet interstadials but waned during arid cold stadials when coniferous parkland forests consisting of pine and spruce expanded in response to the changing climate.  These fluctuations were part of a feedback loop.  The warmer temperature phases gradually caused giant ice dams to weaken and break.  Torrents of cold freshwater from glacial lakes with floating icebergs flooded the North Atlantic, shutting down the Gulf Stream which during present day conditions moderate temperatures.  These deluges of iceberg studded meltwater are known as Heinrich Events, and they caused average annual temperatures to drop by 15-20 degrees F within decades.  In response to the drop in temperatures the Ice Sheets expanded for thousands of years until the next warm phase.  Climate also became drier because moisture for potential precipitation became locked in glacial ice.  However, evidence from a lake in south Florida suggest climate there was out of sync with the rest of North America north of the Rio Grande.

Graph depicting Heinrich Events and the subsequent fall in temperature.  Pollen evidence from sediment in Lake Tulane, Florida reveals the floral response to these climatic shifts, including the most recent 6 Heinrich Events.

Location of Avon Park in Highlands County, Florida.

Lake Tulane is located near Avon Park, Florida.

Scientists have taken numerous cores of sediment from Lake Tulane, located in south central Florida.  Lake Tulane is a very old body of water and has probably existed for almost 5 million years since this region emerged above sea level.  The sedimentary record goes beyond the limits of radio-carbon dating (50,000 years). The pollen composition in these cores shows the local environment’s response to Heinrich Events, but curiously it is the opposite from that of the rest of North America.  When the rest of North America experienced a warm wet interstadial, south Florida became cooler and drier (though mostly not sub-freezing).  The landscape transformed into an environment dominated by scrub oak, Florida hickory, red cedar, ragweed, grass, asters, staggerbush (Lyonia sp.), and rosemary (Ceratiola).  Scrub oak thickets surrounded by open spaces prevailed.  These are all drought-tolerant but shade-intolerant species, and red cedar is fire-intolerant, indicating the rarity of lightning-induced fires.  Conversely, when the rest of North America suffered cold dry stadials south Florida was warmer and wetter and pine forests spread across the land because lightning-induced fire frequency increased, and pine is fire tolerant.  Scientists find macrofossils of aquatic plants in the sediment representing dry phases because the lake was shallow enough to support emergent marsh vegetation, but these are absent during the wetter phases.

A brand new study introduced a new line of evidence that supports assumptions based on the earlier pollen evidence.  The authors of this study looked at variations in carbon and oxygen isotopes from Lake Tulane plant leaf waxes.  Scientists can understand the historical precipitation characteristics by studying the isotopic composition of plant leaf waxes.  (Plants synthesize organic compounds by using hydrogen atoms they absorb from water molecules.  The isotopes vary depending upon their source.)  They discovered that during climatic phases when scrub oak and ragweed dominated, average annual precipitation dropped by 22%.  The source of precipitation was different too.  Oak phase precipitation mostly came from storm fronts, but pine phase precipitation originated from tropical oceanic storms.

The vice-versa climate of south Florida was tied to the shifting Gulf Stream.  Under non-Ice Age conditions the Gulf Stream carries tropically-heated water to the North Atlantic as far as the coast of Canada, moderating temperatures.  When it shut down following Heinrich Events, the warm water stayed near the coast of south Florida, keeping it warm and wet while the rest of North America suffered dry cold conditions.  The Gulf Stream eventually restarted, bringing warmer wetter temperatures north, but this caused cooling and aridity in south Florida.

I hypothesize the Gulf Stream periodically began to restart within stadials, then shut down with new influxes of meltwater.  These partial changes likely influenced temperatures near the coasts of Georgia and South Carolina.  The climate may have temporarily been warmer in this region even during colder climate stages, and the composition of species here may have varied as well, though it involved different species than the Florida endemics.  Eventually, when the Gulf Stream restarted for longer periods, coastal Georgia may have experienced warmer climates centuries before northern latitudes of North America did.

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Common ragweed.  It was much more common in south Florida during the late Pleistocene than it is today.

There is no modern analogue for the abundance of ragweed (Ambrosia artemisifolia) in south Florida during the late Pleistocene.  Ragweed prefers cooler nights than occur in present day Florida for germination, and its abundant presence during the late Pleistocene indicates cooler nights prevailed, even during the out of phase warmer climate stages.  Ragweed is a tough plant that grows on disturbed sites such as abandoned agricultural fields and vacant lots.  It produces up to 32,000 seeds per plant, so it is able to survive heavy foraging by herbivores.  The seeds persist indefinitely and can wait for centuries before germinating when an environment transforms into a sunny one.  This means it can lay dormant through several stages of forest succession, and then colonize the habitat when conditions become favorable.  This may explain why it was so successful during the late Pleistocene when both sudden climatic fluctuations and megafauna foraging greatly disturbed and altered the landscape.  Many animals consume ragweed.  Rabbits and meadow voles eat the leaves while birds including juncos, cowbirds, quail, purple finch, mourning dove, goldfinch, and red-bellied woodpeckers eat the seeds.  Rabbits and meadow voles were common in south Florida during the Pleistocene, though the latter is presently restricted to 1 county in the state.  Farmers report livestock prefer giant ragweed (Ambrosia trifida) over clover.  It’s unclear if this species lived in south Florida during the late Pleistocene.  It is found in a couple counties, and this may represent relic populations, but they also may be invasive.  Livestock will also eat common ragweed, though they don’t like it as much.  Pleistocene megafauna such as horses, bison, and mammoth likely ate ragweed and grass, and they probably occurred in large herds during both climatic phases.  Other species probably common during the oak phase were Harlan’s ground sloth, northern pampathere, flat-headed peccary, and giant tortoise.  Flat-headed peccaries preferred thorny thickets, and the other 3 liked open environments.  Predators such as saber-tooths, lions, jaguars, and dire wolves fed upon the herbivores.  Ragweed survived megafauna foraging by producing large numbers of seeds, but 2 other plant species in this environment survived because their leaves were toxic–rosemary and staggerbush.  I think both climatic phases in Florida supported approximately similar populations of megafauna.

References:

Arnold, T. Elliott; et. al.

“Climate Response of the Florida Peninsula to Heinrich Events in the North Atlantic”

Quaternary Science Reviews 194 2018

Grimm, Eric; et. al.

“A 50,000 year old record of Climate Oscillation from Florida and its Temporal Correlation with Heinrich Events”

Science 9 July 1993

Grimm, Eric: et. al.

“Evidence for Warm Wet Heinrich Events in Florida”

Quaternary Science Review 25 Sept 2006

The Pinhotti Trail in North Georgia and Alabama

August 28, 2018

The Pinhotti Trail connects with the more famous Appalachian Trail and is 335 miles long.  I hiked the first half mile from the Georgia side a few days ago.  This section of the trail goes up a rocky steep mountain side, and the forest is dominated by mountain chestnut oak, hickory, and Virginia pine with an undergrowth of maple saplings, dogwood, and muscadine grape vines.  I also saw silver maple, red maple, black oak, and overcup oak.  It is excellent habitat for chipmunks, though I didn’t see any.  Chipmunks like to tunnel in the crevices under boulders, and the oak and hickory trees provide plenty of acorns and nuts for them.  Perhaps I didn’t see any chipmunks because they were hiding from a weasel or skunk.  The distinct odor of a mustelid was present near the entrance of an hollow log.  Weasels kill prey in bunches–far more than they usually consume–so maybe the local chipmunks had been recently decimated.  A camera trap could probably produce video of a weasel going in and out of the hollow log.  I didn’t see any birds, but I was only on the trail for about 25 minutes.  I did hear a chickadee and the partial call of a woodpecker, and this time of year there is the ever present mating sound of cicadas.

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Map of Pinhotti Trail.

The forest here is dominated by mountain chestnut oak, hickory, and Virginia pine.

Mountain chestnut oak leaves.

Can anyone identify this species of mushroom?  I can’t find it in my field guide or on the internet.

Chipmunks like to tunnel in crevices under boulders like this.  This part of the trail is excellent habitat for chipmunks.

Boulder field.

I could smell the odor of a skunk or weasel near the entrance of this hollow log.

 

Gulf Fritillary and Passion Flower Vine

August 21, 2018

Butterfly migration is even more amazing than bird migration.  Bird migration includes the same generation, but butterflies that begin migrating north never live long enough to return south.  Instead, butterflies gradually expand their range north as the weather warms; breeding, laying eggs, and dying.  The next generation advances farther north.  Then, several generations later, they begin moving south, retreating before killing frosts.  The gulf fritillary (Augraulis valinae) is an example of a migratory butterfly.  They winter in Florida, south Texas, and Mexico, but generations of them migrate as far north as Pennsylvania.  Gulf fritillaries were named because they are some times seen fluttering over the Gulf of Mexico.  Their larva feed upon passion flower vine (Passiflora incarnata) foliage.  The adults obtain their energy from nectar in flowers , and as the below photo represents, they often find some nutrition in animal feces.  Gulf fritillaries are particularly fond of lantana, a non-native shrub that rapidly colonized Florida during early Spanish occupation.

Gulf fritillary snacking on dog feces.

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Passion flower.  Spanish conquistadors thought it symbolized the passion of Christ.

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The fruit of passion flower is edible.  The seeds are covered in a gelatinous substance with a sweet-sour flavor and a tropical aroma.  Brazil produces and consumes the most passion fruit.  Imported passion fruit is occasionally available in the grocery store.

There are between 520-700 species of passion flower vine–taxonomists disagree about the number of species.  96% of them occur in the Americas, indicating this is where they originated.  Other species live in southeast Asia, Australia, and Pacific islands.  They probably colonized these regions by rafting on clumps of debris ripped from the land by  tropical storms.  P. incarnata and the crinkled passion flower (P. gracilis) are the only species that evolved to live in temperate climates.  P. gracilis  is restricted to 1 county in South Carolina, while P. incarnata ranges throughout eastern North America.  During the Miocene when most of North America was sub-tropical there were probably many species of passion flower native to North America, but just 2 evolved the ability to survive frosty seasons.

Passion flower vines are shade intolerant but drought tolerant.  They prefer disturbed areas, and I’ve found them growing on vacant lots in my neighborhood.  This species was well adapted to live during the Pleistocene when rapid climate change and megafauna foraging often drastically altered local landscapes.  Mammoths and other large animals girdled and uprooted trees, opening up the canopy so shade intolerant passion flower vines could thrive.  Many vertebrates, perhaps peccaries, fed on the fruit and distributed the still viable seeds in their dung.  Long Ice Age droughts also killed trees and let passion flower vine spread in the available sunshine, climbing over grass and tree saplings and across bare sandy soils.

When the Spanish conquistadors conquered the Americas, they found passion flower vine growing everywhere.  The soldiers were super religious, though they ignored 1 of the 10 commandments when they were butchering the Indians.  They thought passion flowers symbolized the crucifixion of Christ, known as the passion by religious zealots.  Supposedly, the 5 petals and 5 sepals represent the 10 apostles.  The 72 filaments = the number of thorns in Jesus’s crown.  The 3 stigmas = the cross.  The 3 stamens = the wounds in Jesus’s hands.  The leaf lobes resemble the spear wounds.  The dark spots under the leaves represent the 33 pieces of silver given to Judas to betray Jesus.  The flowers die after just 1 day, just like Jesus died after a day on the cross.  And the petals reclose like the tomb enclosed Jesus.  Some superstitious priest sure had an overactive imagination.

Does a Clam Know it’s Alive?

August 15, 2018

The late Carl Sagan guessed there might be 1 million civilizations in our galaxy, the Milky Way.  He based this guess on the Drake Equation–a formula that takes the number of stars in the galaxy and multiplies it by fractions of: sun-like stars, sun-like stars with planets, planets in inhabitable zones, planets where life evolved, planets with intelligent beings, and the percentage in the lifetime of a planet with a civilization.  However, the Rare Earth Hypothesis proposed by Peter Ward and Don Lee in 2000 posits microbial life may be widespread in the universe, but complex life must be extremely rare.  Since the Rare Earth Hypothesis was proposed, astronomers have discovered 3600 exoplanets in solar systems outside our own.  The evidence so far indicates the Rare Earth Hypothesis might be the more accurate guess.  Of the 3600 exoplanets discovered just 1 is a rocky earth-like planet that orbits in an inhabitable zone.  It is known as Proxima b. All other planets found in habitable zones are gas giants with no surface, similar to Jupiter and Saturn.  Though Proxima b is located in an habitable zone, it probably does not support life because it is tidally locked, meaning 1 side of the planet always faces its sun.  Half of the planet is too hot, and the other half is too cold.

Complex life evolved on earth thanks to numerous unique characteristics that apparently are extremely rare elsewhere in the galaxy and probably the universe.  Earth is just the right distance from the sun, and the sun is just the right kind of star.  Our sun is bigger than 95% of other stars.  The habitable zones of planets orbiting smaller stars would have to be much closer, but this would make the planets tidally locked like Proxima b or Mercury.  Moreover, most other solar systems are binary.  Solar systems with 2 or more suns force planets to have wild perturbations in their orbits, causing a great frequency of cosmic impacts that extinguish complex life.  Earth is the only known planet with abundant tectonic activity which helps control CO2 buildup.  Without tectonic activity CO2 concentrations in the atmosphere amplify heat and scorch complex life into extinction.  Venus is an example of this kind of uninhabitable world.  And earth is lucky to have a large moon that stabilizes earth’s tilt.  The earth’s tilt varies between 23.5-25 degrees, but planets without a large moon may vary in their tilt by up to 90 degrees.  The resulting climate instability would cause the complete extinction of complex life.

Microbial life first evolved on earth about 4 billion years ago, but complex plants and animals don’t appear in the fossil record until about 700 million years ago–a colossal gap in time.  Most earth-like planets in the universe probably resemble the early earth of 2.5 billion years ago.  The earth of that time was mostly ocean with a few volcanic islands.  The ocean was brown from cosmic-impacted debris, and the sky was red in an atmosphere of little free oxygen.  Eventually, plate tectonics formed continents, and shallow water environments supported greater populations of photo-synthesizing bacteria that produced enough oxygen to support complex life.

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Illustration of early earth’s atmosphere.  Land was restricted to a few volcanic islands and the sky was red in an atmosphere with little free oxygen.

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Early microbial life on earth resembled these primitive thermophilic Archaea.  They can survive in temperatures exceeding the boiling point.  This suggests microbial life may be widespread in the galaxy, though complex life is much more rare.  It took over 3 billion years for microbial life to evolve into complex life on earth.

Though complex life must be rare, there are between 1-2 billion galaxies in the universe, each with up to 1 billion stars that in turn have close to 10 planets in their systems.  The universe is so vast complex life likely evolved elsewhere besides earth.  But why?

I think the universe would not exist without complex life aware of its existence.  Suppose complex life never evolved anywhere.  Sure, there could be billions of galaxies, but if there was nothing aware of all that matter, it might as well not exist.  No sentient being would know it was there, so it would not be there.  This is why I think the universe produces worlds where complex life evolved.  It is an attempt by the universe to exist.  It becomes self aware through the minds of many individual sentient beings.  This complex life can’t be just a tree or a clam or a thermophilic micro-organism.  I doubt those living things are aware of their own existence let alone the existence of the universe.  Dogs and cats are aware of their existence, but I doubt they contemplate the existence of the universe.  Give them a smelly piece of meat and a caress and that’s as far as their in depth thought of the universe goes.  I believe the universe strives to produce life that recognizes it exists.  Otherwise, it will cease to exist or it may as well not exist because no sentient being would know of its existence.  Without complex life equivalent or above the intelligence of humans, the universe would have no knowledge of its existence, so it would not exist.

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I doubt a clam knows it is alive.  I believe the universe depends on life more complex than this for its existence.  The existence of complex life and the universe is an interdependent relationship.

Reference:

Ward, Peter; and Donald Brownlee

Rare Earth: Why Complex Life is Uncommon in the Universe

Copernicus 2000