No Need for Males

September 23, 2017

I probably read the novels At the Earth’s Core and Pellucidar about 20 times when I was between the ages of 10 and 15.  They were written by Edgar Rice Burroughs, creator of Tarzan, who also wrote a crossover novel entitled Tarzan at the Earth’s Core. The world Burroughs created fascinated me.  An old scientist, accompanied by a classic American hero, builds a drilling machine that takes them to the center of the earth where they find a land of dinosaurs, pre-historic mammals, friendly natives, and barbaric ape-like cavemen known as the Sagoths.  The novels are full of chivalrous nonsense.  After the hero, David Innes, saves a beautiful native woman from being ravaged by a Sagoth he makes a faux pas–according to the custom among the natives of this world, a saved woman was to be embraced and kissed and made a mate or freed.  Innes didn’t know he was supposed to place his hand over her head to symbolize her freedom, otherwise she was considered his slave.  It takes him a while to realize his mistake and right his wrong.  Later, he has to save her again from a race of intelligent dinosaurs that rule this world.  This race of all female dinosaurs, known as the Mahars, raise humans like livestock.  Whenever they want something to eat, they hypnotize, then eat their human chattel.

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Illustration of human being hypnotized by intelligent parthenogenetic dinosaur in Edgar Rice Burroughs’ At the Earth’s Core.  In this fantasy novel the intelligent all female dinosaurs enslaved and fed upon humans until they were routed by the hero from the earth’s surface.

In Burroughs’s novel the Mahars used science and technology to eliminate the need for males, but in the real world evolution has eliminated males in 80 species of reptiles, amphibians, and fish.  Organisms that produce viable eggs without mating are known as parthenogenetic.  Species that are all female have a couple of advantages over species that need to mate.  They can reproduce when their population is low, and energy is not wasted on individuals that produce no eggs.  Most species are not parthenogenetic because in most cases the disadvantages outweigh the advantages.  Parthenogenetic species can suffer low genetic variability leading to an increase in harmful mutations.

The New Mexican whiptail lizard (Cnemidophorus neomexicanus) is an example of an all female parthenogenetic species.  The New Mexican whiptail lizard is an hybridized cross between the little striped whiptail lizard (C. ornatus) and the western whiptail lizard (C. tigris).  The New Mexican whiptail lizard produces viable eggs that all hatch to become female clones.  New lineages are created and genetic variability is established every time a western whiptail mates with a little striped whiptail.  New Mexican whiptails engage in lesbian sex.  This, of course, doesn’t fertilize the eggs, but lesbian whiptails do produce more viable eggs, probably because the sex stimulates hormone production.

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New Mexican whiptail lizards are all female clones.

Some species of vertebrates are facultive parthenogenetic species.  They normally mate with individuals of the opposite sex, but when populations are low can produce viable eggs without mating.  Komodo dragons, boa constrictors, and some species of sharks are able to switch from sexual breeding to asexual reproduction.  The offspring can then mate normally when they come into contact with males.  Other species are considered accidental parthenogenetic species.  They produce viable eggs without mating on very rare occasions.  Parthenogenetic cases have been reported for chickens, turkeys, and pigeons.

Many species of plants and invertebrates are parthenogenetic.  Unlike vertebrate parthenogenetic species which produce all females, invertebrates and plants can produce offspring that are all female, all male, or female and male.

 

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Arizona Sky Islands–Another Ecological Analogue for Pleistocene Georgia

September 18, 2017

Rapid climate oscillations, megafauna foraging, fire, and wind throws shaped the landscapes of southeastern North America during the Pleistocene.  The resulting environment in the piedmont region consisted of open oak and pine woodlands but with significant patches of closed canopy forests, savannah, prairie, scrub, and wetland.  This variety of habitats in close proximity supported a great diversity of wildlife.  The Pleistocene ecosystem in this region was unlike any extant environment.  Nevertheless, I’ve previously considered some regions as relatively close ecological analogues, resembling the Pleistocene piedmont.  Russian’s Far East was until recently a vast untracked wilderness of mixed forests with abundant game and apex predators.  (See: https://markgelbart.wordpress.com/2011/06/06/russias-far-east-the-modern-worlds-closest-ecological-match-to-pleistocene-georgia/ )  The Cross Timbers region of Texas and Oklahoma where the eastern deciduous forest gradually gives way to prairie may also be a vaguely similar analogue.  (See: https://markgelbart.wordpress.com/2012/06/13/the-cross-timbers-ecoregion-an-analogue-for-georgia-environments-during-some-stages-of-the-pleistocene/ ) I’ve come across a 3rd region that in some ways may resemble Pleistocene piedmont Georgia–the Sky Islands of Arizona, New Mexico, and northern Mexico.

Sky Islands are mountains that stand in the middle of the desert.  They host a variety of environments that change according to elevation.  A change of a few thousand feet in elevation equals the climatic difference of hundreds of miles in latitude.  In a day a man can ascend from an hot desert to temperate oak/pine woodland to boreal spruce/fir forests.  During Ice Ages the lowlands surrounding Sky Islands hosted continuous temperate forests, but now these forested environments are isolated on the mountains, surrounded by desert, hence the name Sky Island.

Mountains rise from the desert floor in Arizona, New Mexico, and northern Mexico.  They host diverse flora and fauna because the change in elevation supports a variety of environments adjacent to each other.

Sky Islands are rich in floral and faunal diversity because so many different natural communities are in such close proximity.  Sky Islands are home to 500 species of birds (over half of the species found in North America), 104 species of mammals, and 120 species of reptiles and amphibians.  Tree squirrels including Mexican fox squirrels, Arizona gray squirrels, and Mt. Graham red squirrels co-exist with rock squirrels (Spermophilus variegatus).  Rock squirrels live and nest in the ground, not trees.  13-lined ground squirrels, another species in the Spermophilus genus, also co-existed with tree squirrels in southeastern North America during the Pleistocene.  13-lined ground squirrels no longer occur in the region because they prefer open environments.  Their presence along with tree squirrels at some fossil sites suggest a more varied environment existed here during the Pleistocene.

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Rock squirrel (Spermophilus variegatus).  Sky islands are home to 7 species of squirrels.  During the Pleistocene a squirrel in the spermophilus genus also co-existed with tree squirrels in southeastern North America, suggesting a more diverse variety of habitats within the region.

Arizona Sky Islands are also famous for a small subspecies of white tailed deer known as the Coues.  For some reason the Coues deer is a popular trophy among deer hunters.  Jaguars and coati-mundi roam the Sky Islands as well.

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Coues deer–A small subspecies of white tail that lives on the Sky Islands of Arizona.

The oak savannahs and oak/pine woodlands of Sky Islands likely resemble natural communities that occurred in the piedmont region of Georgia during the Pleistocene, though they are composed of different species of trees.  Emory oak, Arizona white oak, Gambel’s oak, Canyon live oak, and blue oak grow with Arizona juniper, pinyon pine, yucca, bull grass, and bear grass.  Higher in elevation, silverleaf oak grows with ponderosa pine and Arizona pine.  Higher still, the forest may consist of ponderosa pine, Englemann Spruce, and Douglas Fir–trees of the northern Rocky Mountains.

Acorn Woodpecker Photo

Acorn woodpeckers are a communal species that hoards acorns.  They are a common species on Sky Islands.

The different types of forest attract many different species of birds.  Birds that prefer coniferous forests can be found with those that like oak forests. Tropical species including trogons, thick-billed parrots, buff-colored nightjars, and Arizona woodpeckers inhabit Sky Islands.  These species are found at few other sites north of the Rio Grande River.

 

New Species of Late Pleistocene Ground Sloth and Peccary Discovered on Yucatan Peninsula

September 13, 2017

My ongoing mission to catalogue the faunal composition of piedmont Georgia as it was during the late Pleistocene is but an educated guess.  I base my guess on the lone fossil site in the region plus fossil sites located to the north, south, and west of the piedmont.  (See for my list: https://markgelbart.wordpress.com/2013/12/27/if-i-could-live-during-the-pleistocene-part-xii-my-mammal-checklist/ ) I think I know most of the mammal species that occurred here during the Pleistocene, but there were probably species living in the region I never would have guessed.  Even in regions with many Pleistocene-aged fossil sites, scientists are still discovering the presence of new species.  Within the last 5 years paleontologists identified giant short-faced bear (Arctodus simus) and collared peccary (Tayassu tajacu) specimens in Florida where these species were not formerly known.  The dhole (Cuon alpinus) crossed the Bering land bridge sometime during the Pleistocene, yet the only fossil specimens of this species in North America were found at 1 site in Mexico.  This means all the dholes that lived between Alaska and Mexico left zero fossil evidence, or at least none that has been found to date.  And now, just within the last 2 years, scientists have identified 2 new species of large mammals that lived on the Yucatan peninsula during the late Pleistocene.

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Map of the Quintana Roo province on the Yucatan Peninsula.  Evidence excavated from sinkhole caves indicates an unique fauna resided here during the late Pleistocene.

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Skull of Xibalbaonyx oviceps found in Yucatan sinkhole.

The Yucatan peninsula is dotted with numerous sinkholes and caves because rain water unevenly dissolves underlying limestone bedrock.  The sinkholes and caves preserve remains of animals for tens of thousands of years.  Cave divers have discovered the bones of gompotheres, glyptodonts, ground sloths, llamas, horses, tapirs, peccaries, spectacled bears, saber-tooths, bobcats, rabbits, fruit bats, and humans in these subterranean spaces.  (I’m aware of 4 mostly complete human skeletons found in Yucatan sinkholes and caves–1 dating to the incredibly early date of 14,350 calendar years BP.)  Bones of Shasta ground sloths and collared peccaries are among the specimens recovered here, but relatives of each, previously unknown to science, have recently been described in the scientific literature.  The new ground sloth species was identified from a specimen found in the Zapote sinkhole.  It was a mostly complete skeleton of a sub-adult that weighed at least 500 pounds when it was alive.  It is thought to have been adapted to a desert grassland environment.  Scientists gave it the unpronounceable scientific name–Xibalbaonyx oviceps.  It was closely related to Jefferson’s ground sloth (Megalonyx jeffersonii), a species that occurred all across North America from Florida to Alaska.  Perhaps X. oviceps was a desert offshoot of Jefferson’s ground sloth.  The new species of peccary was given the more pronounceable scientific name of Mucknalia minimas. I haven’t been able to obtain a copy of either paper describing the new species.  When I do I may write an addendum to this blog entry.

The presence of 2 species seemingly endemic to the Yucatan peninsula indicates the region was ecologically unique.  The area around the Hoyo del Negro fossil site (See: https://markgelbart.wordpress.com/2015/08/08/the-hoyo-negro-fossil-site-in-yucatan-mexico/ ) was a mix of tropical forest, thorny scrub, and wetland; but further inland desert grassland predominated.  I think small sinkhole lakes, like oases, probably existed in drier areas.

Who knows?  Maybe the piedmont region of southeastern North America hosted endemic large mammal species during the Pleistocene that are currently unknown to science.  Unfortunately, the lack of sites suitable for fossil preservation in the region could keep them cloaked in mystery for eternity.

On an unrelated note: While researching this blog entry, I learned about a llama specimen (the extinct  Hemiauchenia macrocephela) found in a Yucatan cave that was apparently butchered, cooked, and eaten by humans.  This information doesn’t seem to be generally known in the archaeological literature.

References:

Gonzalez, Arturo: et. al.

“The Arrival of Humans on the Yucatan Peninsula. Evidence from Submerged Caves in the State of Quintana Roo, Mexico”

Current Research in the Pleistocene January 2008

Stinnesbeck, S.; et. al.

“A New Fossil Peccary from the Pleistocene-Holocene Boundary of the Eastern Yucatan Peninsula, Mexico”

Journal of South American Earth Science 2016

Stinnesbeck, S. et. al.

“Xibalbaonyx oviceps, a New Megalonychid Ground Sloth (Folivora: Xenarthan) from the Late Pleistocene of the Yucatan Peninsula, Mexico and its Paleogeographic Significance”

Palz 91 June 2017

 

How Far South did the Wolverine (Gulo gulo) Range during Ice Ages?

September 7, 2017

The voracious wolverine preys upon deer, caribou, and even moose when these much larger mammals flounder in deep snow.  The padded paws of the wolverine allow them to stay on top of the snow while the heavy hooved deer sink, making it easy for the wolverine to lock their jaws on a throat. The wolverine also preys on smaller animals and will eat insects and berries.  They live in remote wilderness areas, preferring high elevations with deep snow and plenty of tree or shrub cover.   Wolverines benefit from the presence of other large predators because they are just as much scavenger as predator.  During summer and fall wolverines are too clumsy to actively chase deer but will drive off much larger predators from their kills.  After they consume as much as they can eat, they spray musk on the remains, and it become unpalatable for other carnivores.  Wolverines store caches of dead meat during winter and are ideally suited to survive in cold unproductive natural communities.

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Historical range of the wolverine.  Camera traps suggest they have recently recolonized northern California. They also live in Eurasia.  During Ice Ages, wolverines probably ranged along the southern Appalachians perhaps as far south as north Georgia and Alabama.

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Male wolverines reach weights of 60 lbs but can drive away bears, cougars, and wolf packs. Wolverine cubs sometimes fall victim to the latter 2.

Wolverines occupy very large territories.  Males in Montana patrol 162 square miles on average, while male Yellowstone wolverines average a territory of an astounding 307 square miles.  Wolverines  live in low densities in boreal forests, and this makes their remains rare in the fossil record.  Nevertheless, subfossil remains of wolverines, dating to the Pleistocene, have been excavated from Maryland, Pennsylvania, Wyoming, Colorado, Nevada, Romania, Italy, Germany, France, and the United Kingdom.  (The wolverine is an Holarctic animal, living on both sides of the Arctic Circle.)  The specimen from Cumberland, Cave, Maryland is the southernmost known record of the wolverine in eastern North America and this is south of their known historical range during colonial times.  I hypothesize wolverines ranged into the southern Appalachians as far south as north Alabama and north Georgia during Ice Ages.  The key is deep snow–any climatic phase when deep snow regularly occurred at high elevations in the southern Appalachians would have been an invitation for wolverine range expansion south.  Other boreal species of mammals are found in the fossil record this far south including caribou, fisher, pine marten, porcupine, bog lemming, and red-backed vole.  Wolverine skeletal evidence is probably absent because they lived in low population densities at high elevations in forested environments where fossil preservation is rare.  Historical wolverine range is closely correlated with regions where snow stays on the ground through a good portion of spring.  Undoubtedly, spring snow cover existed in the southern Appalachians during the coldest stages of Ice Ages.

Most of the wolverine’s present day range was covered by glacial ice during Ice Ages, so it seems likely their range shifted south, like that of so many other species then.  How far south did this range shift?  We can only speculate.  But this is an animal that requires deep wilderness, and North America was nothing but deep wilderness before man.  Wolverines won’t cross clear-cuts or burned over land.  The main factor restricting wolverine range before man were the extensive grasslands that likely formed an ecological barrier to their expansion below the southern Appalachians.

References:

Hornocker, M; and H. Hash

“Ecology of the Wolverine in Northwestern Montana”

Canadian Journal of Zoology 59 (7) 1981

Inman, R.

“Wolverine Ecology and Conservation in the Western U.S.”

Swedish University Doctoral Thesis 2013

http://www.paleobiologydatabase.com

 

 

Disjunct Populations of Western Insects Occur on Black Belt Prairies of Southeastern North America

September 4, 2017

The Black Belt Prairie region extends through Alabama and Mississippi with additional isolated patches in Georgia and Tennessee.  There is a different Black Prairie region in east Texas.  The chalky soils of Black Prairies favor grass over trees, and in the southeast they produce a mosaic of forest and prairie.  Western species of plants such as little bluestem grass grow on Black Prairie landscapes, and they attract species of insects not normally found in southeastern North America.  At least 15 species of insects that occur on western grasslands exist as disjunct populations on the Black Prairies located in southeastern North America.  This includes the white bee (Tetralonella albata)–a pollinator of prairie clover–as well as 4 species of long-horned beetles and 10 species of moths.  The red-femured long-horned beetle (Tetraodes femorataand the Texas long-horned beetle (T. texanus) feed upon milkweed.  Most of the moths are hosts on flowers in the aster family.

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Map of Black Belt prairie region in southeastern North America.  (Shaded orange.)  Although the map doesn’t show it, some isolated pockets of Black prairie occur in Georgia as well.

Bee on Dalea - Tetraloniella albata

The white bee occurs in disjunct populations in Mississippi and Arkansas.  The main population occurs from Colorado and Illinois to California.

Milkweed Longhorn Beetle (Tetraopes sp.) - Tetraopes femoratus

The red-femured long-horned beetle ranges from the Great Basin to Mexico.  Disjunct populations occur in the Blackland Prairie Region.

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Epiblema iowana–another western species found in the Black Belt prairie region plus 1 site in Florida.

A grassland corridor formerly must have connected the Great Plains grasslands with the Black Belt prairies of the southeast.  Some scientists speculate that before the last Ice Age this corridor may have existed along the Grand Prairie of Arkansas or through the Arkansas River Valley.  The Mississippi River was lower then and interspersed with lightly vegetated sandbars that allowed for insect passage between the 2 regions.  After the last Ice Age glacial meltwater expanded the Mississippi River, blocking insect passage, but a grassland corridor between the Great Plains and the southern Black Belt Prairie may have existed through cedar glades in Tennessee to Kentucky to Illinois where the Mississippi River was more narrow. Currently, the Mississippi River and forested habitat separate the 2 grassy regions.

During Ice Ages the Black Belt prairies may have served as a refuge for many species of grassland insects found in the Great Plains today.  Forests of jack pine and spruce replaced Great Plains grasslands during glacial phases.  Summers were cooler and shorter.  Species of insects that preferred grassland communities and long warm summers retreated to the Black Belt prairies and Gulf Coast grasslands of southeastern North America.  Populations considered disjunct today may actually be seed populations that replenish Great Plains insect fauna following the end of Ice Ages.

Reference:

Peacock, Evan; and Timothy Schauwecker

“Blackland Prairies of the Gulf Coastal Plain”

University of Alabama Press 2003

 

Pleistocene Saiga Antelopes

August 31, 2017

The saiga antelope (Saiga tatarica) ranged from western Europe to Alaska and the Yukon during some climate phases of the late Pleistocene.  This range closely corresponds with an environment known as the mammoth steppe.  This paleoenvironment was similar to the present day central Asian steppe but was more productive, hosting a greater variety of plants and microhabitats that included scrub, woodland, and wetland embedded in a sea of grass.  Summers were cool, winters were long, wind was constant, and precipitation was infrequent.  The bulbous nose of the saiga antelope is an adaptation for living in this kind of environment.  It helps warm frigid air and filter the dust in a dry windy climate.  The range of the saiga antelope has been greatly reduced since the late Pleistocene due to changes in the environment and overhunting by man.  Nevertheless, saiga antelope occurred in eastern Europe as late as the 17th century, indicating they are not a relict species confined to steppe grasslands.  A recent scientific study examining the bone chemistry of subfossil and extant saiga antelope specimens concluded this species can survive on a greater variety of plant foods than present day populations consume.

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Saiga antelopes are critically endangered today but lived from the British Isles to the Yukon, Canada during the late Pleistocene.

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Present day saiga antelope range.  During the Pleistocene they occurred from western Europe to Alaska.

This study found the diet of the saiga antelope overlapped with that of the caribou (Rangifer sp.) in southwestern Europe between 20,000 years BP-15,000 years BP.  It seems likely both species were subsisting upon lichen during winters when other plant foods were scarce.  Pleistocene saiga antelope apparently had a greater flexibility in their diet than present day populations.  The authors of this study suggest saiga antelope could potentially be introduced outside their present day range.  Poaching and disease outbreaks are endangering the surviving remnants of saiga antelope populations, so it could prove beneficial to establish new populations outside their present day range.  However, it’s possible some Pleistocene populations of saiga antelope may have been a distinct now extinct species with different dietary tolerances.  Some Russian paleontologist noted some morphological differences in saiga antelope specimens found outside their present day range, and they proposed a new species–Saiga borealis. Other paleontologists don’t accept this designation.  So far, no genetic studies have solved this difference of opinion.

The saiga antelope is considered a distant sister clade to the springbok-gerenuk clade.  They are the sole survivors of antelopes that roamed Europe before Ice Ages began to occur.  None of their closest relatives were able to evolve fast enough to survive deteriorating climatic conditions.

Reference:

Jurgensen, J.; at. al.

“Diet and Habitat of the Saiga Antelope during the Late Quaternary Using Stable Carbon and Nitrogene Isotope Ratios”

Quaternary Science Review March 2017

The Korean Demilitarized Zone is an Amazing Wilderness

August 26, 2017

North Korea is not going to attack the U.S., no matter what Donald Trump says or doesn’t say.  The little fat turd who controls North Korea knows it would mean the end for him because even China wouldn’t back him, if he was the aggressor.  And the U.S. isn’t going to attack North Korea.  Trump will listen to his generals when they tell him an attack on North Korea would draw China into the war, and China has hundreds of nuclear weapons and enough surface-to-surface missiles to sink our entire Pacific fleet.

I feel sorry for the North Korean people because they are forced to live under the little fat turd’s rule.  But the U.S. voluntarily elected a giant fat turd as president.  Actually, referring to Donald Trump as a turd is an insult to turds.  A turd in a punchbowl would make a better president than Trump.

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A turd in a punch bowl would make a better president than Donald Trump.

Trump opened up his presidential campaign by calling Mexicans “drug dealers and rapists”–words that sounded like they came straight out of Archie Bunker’s mouth.  Ironically, Trump must think rape is only bad if a Mexican is the rapist because Trump brags about how he can rape women and get away with it. Trump is so dumb he equates peaceful protestors with neo-Nazis, and he thinks Jefferson Davis and other Confederate figures are comparable to George Washington and Thomas Jefferson.  They are not the same–they are the opposite.  George Washington helped found this country, while the Confederacy tried to tear it apart.  The Confederacy was an enemy of the U.S..  Enemies of the U.S. should not be venerated.  Trump has no credibility because he rarely tells the truth about anything.  He makes up absurd conspiracies and tweets them out in the middle of the night.  This is the symptom of a man who doesn’t have all his marbles.  Trump is also highly unethical, but I’m not going  to delve into this here because just the details of his crooked business interests could fill volumes.

Trump disgusts me, but I am even more disgusted with the stupid uneducated fools who voted for him.  They all look like a bunch of angry, shriveled-up losers.  They are so dumb they actually think this billionaire prick gives a shit about them.  Trump’s economic policies, if he ever is able to enact them, would greatly aid ultra rich plutocrats, like himself, while steamrolling the working class chumps who voted for him.  Trump proved this when he said he would actively work to make Obamacare fail.  This means he cares more about a legislative victory than the well being of the American people.  The election of Trump is an insult to the intelligence and integrity of the American people.  I think many people voted for him because of name recognition.  They were familiar with this dumb bigoted celebrity from his brainless TV show.  Other people are attracted to his xenophobic racism.  It is disturbing to realize there are millions of pro-rape racists living in this country.  I hate Trump voters.

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Trump supporters are shriveled up old losers.  His rallies are a sea of white faces, though occasionally there will be a token black guy carrying an awkward sign saying “Blacks for Trump.”  The Trump campaign undoubtedly paid for the token black guy to stand there.  Trump was elected by pissed off racists.  It is alarming to realize there are tens of millions of brain dead racists in this country.

The Korean Demilitarized Zone divides North and South Korea.  People haven’t lived in this zone for 64 years, and the land has reverted to wilderness.  The KDZ is 400 square miles of mountains, forests, prairies, wetlands, and tidal marshes.  At least 52 species of mammals live in the KDZ including 5 kinds of deer, wild boar, Asiatic black bears, leopards, leopard cats, and raccoon dogs.  Many of the species that live here are rare or extinct in the rest of Asia.  Critically endangered long-tailed gorals (a kind of goat), musk deer, red-crowned cranes, white-naped cranes, and black-faced spoonbills make the KDZ their home.  There are even rumors of Siberian tigers roaming the KDZ.  It seems impossible that so much wildlife can exist here.  Reportedly, there are 2500 landmines per square mile, and animals occasionally do trigger them.  Animals can thrive in minefields but can’t tolerate the presence of man–another example of how detrimental people are for wildlife.  Maybe some day, if Korea is ever unified, the KDZ will become a park.  In the rest of China and Korea wildlife has been obliterated, and pollution is a disaster.  Asia badly needs a park like this.

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The critically endangered red-crowned crane finds refuge in the KDZ.

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Ruddy kingfisher.

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Korean water deer.

Naemorhedus caudatus

Long-tailed goral.

 

Rapid Anole (Anolis carolinensis) Evolution

August 21, 2017

Misinformed creationists some times ask, if evolution is true, why isn’t it happening now?  There is a simple answer to that question.  Evolution is an ongoing process, and it IS happening now.  Evidence of continuing evolution isn’t readily apparent to the non-observant eye because usually it is a slow process–evolution often requires generations of natural selection to influence the phenotypical changes that demonstrate it.  However,  scientists discovered an example of evolution that occurred within 1 generation of an anole population in south Texas.  A team of scientists had recently studied the differences in cold tolerance between the population of anoles that live in south Texas with those that live near the northern limits of their range.  The south Texas anoles lose muscular coordination when temperatures drop to about 51 degrees F, while anoles near the northern limits of their range lose coordination when temperatures reach 43 degrees F.  An unusual cold snap struck south Texas shortly after scientists gathered this data, and they took another look at this anole population.  They discovered that exposure to cold temperatures changed the DNA of south Texas anoles.  4 genomic regions, especially those related to nervous system function, changed.  The lizards had rapidly evolved the ability to retain muscle coordination at lower temperatures, and they will pass these genetic changes on to the next generation.  This is a perfect example of evolution, defined as the change over time in the genetic characteristics of a population.  Most creationists can’t even define evolution.  They reject the fundamental basis of all biological science because it interferes with their belief in the supernatural.  Let’s see them try to deny this case study.

Anole characteristic threat display.

Anoles are a successful and rapidly evolving species. Some populations have adapted to city living, having evolved stickier toe pads that enable them to climb window glass.  In Florida the brown Cuban anole was accidentally introduced.  They occupy the same niche as the American anole.  In areas colonized by this alien anole, native anoles evolved larger toes that allow them to climb thinner branches.  This occurred in less than 15 years (20 generations for anoles living in Florida).  So now, areas with both species of anoles have a niche partition–Cuban anoles occupy lower branches, while native anoles live in the tree tops.

Worldwide, there are 391 species of anoles, but 9 are closely related to the species (A. carolinensis) that is widespread in the southeastern U.S.  Genetic studies suggests all 9 of these species descend from a founder population originating on Cuba.  A. carolinensis diverged from western Cuban anoles about 6 million years ago.  This occurred as a rafting event when a tropical storm washed debris from Cuba to the Gulf Coast of North America.  At least 1 male and 1 female were clinging to the debris when it made landfall.  All Caribbean islands were populated by anoles originating on Cuba from similar rafting events.

Fossil evidence of anoles has been excavated from 1 site in Georgia (Ladds), 1 site in Alabama (Bell Cave), and 10 sites in Florida.  None date to older than the mid-Pleistocene, but genetic evidence indicates they’ve occurred in southeastern North America since the late Miocene.

References:

Campbell-Staten, Shane; et. al.

“Winter Storms Drive Rapid Phenotype, Regulation, and Genome Shift in the Green Anole Lizard”

Science August 4, 2017

Glor, Richard; J. Losos, A. Larso

“Out of Cuba: Overwater Dispersal and Speciation Among Lizards in the Anolis subgroup”

Molecular Ecology 14 2005

Extant South American Canids are Ancient Relics

August 16, 2017

Several species of medium-sized canids native to South America descend from species that formerly occupied North America.  The extant bush dog (Speothos vunaticus), maned wolf (Chrisocyon brachyuras), and the recently extinct Falkland Islands wolf (Dusicyon australis) are (or were) similar to primitive dogs that occurred across North America during the late Miocene and Pliocene.  The emergence of the Canis genus (wolves and coyotes) early during the Pleistocene competitively excluded these primitive dogs from North America, but their ancestors pushed through the jungles of Central America, and they colonized South America where they still thrive today when not persecuted by man. The tropical rain forests of Central America served as a geographical barrier that prevented Canis species from following their primitive relatives.  Though Canis species may be more adaptable overall, their primitive relatives were better able to withstand tropical conditions, a factor that saved them from extinction.

The South American bush dog is a widespread but uncommon pack-hunter that preys on large rodents, peccaries, and rheas.  One genetic study suggests they are most closely related to maned wolves, but another more recent genetic study determined they are most closely related to African hunting dogs.  A species similar to the African hunting dog lived in North America as late as the mid-Pleistocene, so the bush dog may very well be an offshoot of this canid line.  The maned wolf is a solitary species, not a pack-hunter–additional evidence supporting a closer evolutionary link between bush dogs and pack-hunting African dogs, rather than the maned wolf.  The bush dog was known from fossil evidence found in a Brazilian cave before it was recognized as an extant species.

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South American bush dogs.  They are descended from primitive dogs that roamed North America before the Canis genus dominated that continent.

The Falkland Islands wolf was the only mammal species native to the Falkland Islands.  It was a completely naïve species, unafraid of man, and was hunted to extinction by the late 19th century.  Settlers coveted its furry coat and were afraid it would kill their sheep.  Actually, the diet of this species is unknown, but it probably subsisted on penguins, geese, and sea shore scavenging.  How this species colonized the Falkland Islands, located 285 miles from the mainland of South America, was a mystery until recently.  Geologists discovered underwater ridges connected to the mainland that were above sea level during Ice Ages.  A narrow 20 mile straight between the ridges and the Falkland Islands froze into solid ice during winters of the Last Glacial Maximum (~16,000 years ago), allowing the canids to cross.  They may have been hunting penguins on the ice, leading them to the islands.  No other mammal found motivation to cross the ice bridge.

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Extinct Falkland Islands Wolf.  Unfortunately, they had no fear of people.

Genetic evidence suggests the Falkland Island and maned wolves are most closely related to false foxes (Lycalopex sp.), 6 species of which are found in South America today.  However, the Tibetan fox is the maned wolf’s closest living relative.  The Tibetan fox is likely related to the ancestors of all false foxes.  An extinct species of maned wolf (C. nearctus) lived in North America during the Pliocene.  Fossil evidence of this species has been found at sites in Arizona, California, and northern Mexico.  The maned wolf has long legs that help it look over tall grass for rodents–its main prey item.  Genetic evidence shows maned wolf populations increased during Ice Ages when grasslands expanded and contracted during interglacials.  Pliocene environments were often dry and included an expansion of prairie habitat, so it’s likely the North American maned wolf also had long legs.  The fossil evidence of C. nearctus is limited to lower jaws and teeth, so it’s not known how long its legs were.  Maned wolves are omnivorous, and they are important dispersers of seeds.  They often defecate on leafcutter ant nests, and the ants move the viable seeds, helping them germinate.

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Maned wolf.  Maned wolves lived in North America during the Pliocene.

The maned wolf grows to about 50 pounds, but a larger genus of primitive dogs lived in North America until the early Pleistocene.  Theriodictis hunted megafauna in Florida.  Species from the Canis genus outcompeted them in North America, but they continued to thrive in South America until the late Pleistocene extinctions of the megafauna.

Reference:

Nyakatura, K.; et. al.

“Updating the Evolutionary History of Carnivora (Mammalia): A New Species Level Super Tree Complete with Divergence Time Estimates”

BMC Biology 10 (12) 2017

Tedford, Richard; X. Wang, B. Taylor

“Phylogenetic Systematics of the North America Fossil Caninae”

Bulletin of the American Museum of Natural History 2009

 

Hurricane Ivan Uncovered a 60,000 year old Cypress Forest in the Gulf of Mexico

August 9, 2017

In 2004 Hurricane Ivan spawned 140 mph winds, 90 foot waves, and the fastest sea floor current ever recorded.  That incredible sea floor current removed a sediment layer covering a 60,000 year old cypress forest in the Gulf of Mexico.  The exposed trees formed a natural reef, attracting a concentration of fish and other sea life 60 feet below the ocean surface and 15 miles offshore.  Fishermen noticed the unusual concentration of fish and asked scuba divers to investigate.  The scuba divers discovered the uncovered ancient forest, and scientists are now studying this rare site.

The scientists who visited the flooded forest were impressed with the marine life they encountered–flounder, cardinal fish, red snapper, blennies, sea bass, moray eels, sandbar sharks, hawksbill turtles, octopus, boring worms, anemones, and sponges.  But they were even more impressed with the ancient cypress wood they brought with them to the surface.  They sawed through it in the laboratory and smelled fresh sap.  Nevertheless, they couldn’t use radiocarbon dating because they discovered the wood was over 50,000 years old–too old for that method.  Instead, they found the nearest organic material that could be dated and estimated a 60,000 year old date based on stratigraphic location and assumed rates of deposition.

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Map of weather stations in south Alabama.  During Ice Ages dry land extended for miles into the Gulf of Mexico.  Mobile Bay was a valley of forests and grasslands.  Dauphin Island and Fort Morgan were high hills “hundreds of feet above the surrounding landscape.”

When it was alive, this flooded forest stood during a time period classified as Marine Isotope Stage 3.  I am fascinated with MIS3 because the dramatically fluctuating climate cycles had a major impact on natural communities.  MIS3 occurred just before the Last Glacial Maximum (the coldest stage of the last Ice Age), but unlike the LGM, MIS3 experienced warm interstadials alternating with cold phases.  Many geographical regions hosted an admixture of northern flora and fauna with warm climate species of plants and animals because of this climatic instability.  Tree rings on the fossil cypress wood excavated from this locality demonstrate this instability.  The tree rings provide a 489 year record of climate from MIS3.  The cypress tree rings show climate varied with warm wet years and dry cold spells but for the most part they are narrower than tree rings found in modern day cypress trees.  This reflects a cooler drier climate with lower levels of carbon dioxide in the atmosphere.  The trees were especially stressed during the last 50 years of their existence, and they all died at the same time, though the trees were of different ages.  Saltwater intrusion killed the trees.

Sea level rose rapidly here, probably during a warm phase of climate when glaciers were melting.  Cypress wood is resistant to decay, an adaptation for living in aquatic environments, but when exposed to air will eventually rot away.  The dead stand of cypress wood likely stood for decades, perhaps a century, before becoming covered in sand and mud.  Thus sealed off from air, it was preserved for tens of thousands of years.  Now that it is exposed to oxygen again, it will decay into nothing in a few centuries.

Scientists cored into the mud around the trees and took samples of pollen to analyze the type of natural environment that existed here 60,000 years ago.  Cypress, oak, and alder pollen dominated.  The palynologist who analyzed the pollen composition (the data as far as I know is still unpublished) concluded the forest was a rare type that no longer occurs in the region.  The closest modern analogue is classified as an Atlantic Coastal Plain Blackwater Bar/Levee Forest.  This type of forest occurs in small areas near the coasts of North and South Carolina.  Bar/Levee forests grow on soil formed on the inside bend of a river.  Sediment accumulates here through deposition, and the area is seasonally flooded.  (Indeed, this particular forest occurred alongside a river, and the paleomeander scar is still visible at the bottom of the ocean adjacent to the flooded forest.)  Dominant trees in a Bar/Levee forest are cypress, river birch, laurel oak, overcup oak, willow oak, sweetgum, red maple, elm, and loblolly pine.  The understory consists of holly and hop hornbeam along with red maple and ash saplings.  The shrub layer is made up of blueberry, titi, sweetspire, grape, poison ivy, climbing hydrangea, Alabama supplejack, greenbrier, sweet pepperbush, violet, and sedge.  Spanish moss covers the trees.  Bar/levee forests are similar to bottomland hardwood forests but are distinguished by the abundant presence of river birch or water elm (Planara aquatica which is not a true elm).

Macrofossils of Atlantic white cedar and palm have also been found among the dead cypress.  There are small disjunct colonies of Atlantic white cedar scattered throughout the southeast, indicating it was more widespread in the region during the Ice Age.  (See: https://markgelbart.wordpress.com/2012/03/11/the-discontinuous-range-of-the-atlantic-white-cedar-chamaecyparis-thyoides/ ) The presence of palm shows that climate, though cooler than that of today, was still warm enough for that species.  I suspect this was a unique forest that doesn’t exactly match any classified natural community of the present day.

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60,000 years ago, a cypress and oak forest grew at a location 15 miles off the coast of Alabama.  It was rapidly inundated during a sudden rise in sea level, becoming covered in sediment before the cypress trees rotted away.

The pollen evidence suggests alder was a pioneer species here that probably became established when the point bar of the river began depositing sediment.  Cypress and oak became dominant for about 500 years.  Then, after salt water intrusion killed the cypress, grass pollen predominates, suggesting a salt marsh replaced the cypress forest.  Extinct megafauna such as mastodon, tapir, and capybara undoubtedly passed through this environment, but vertebrate fossils have yet to be found.

Below is a documentary about the flooded forest–the source of information for much of this blog entry.

Reference:

Schafale, M; and A. Weakley

“Classifications of the Natural Communities of North Carolina, third approximation”

North Carolina Natural Heritage Program 1990