Glaciation, Land Bridges, and their relation with the spread

ChrisRezendes · #1 (**permalink**) 10-31-2002, 01:31 AM

Snakes and the Ice Ages

Sometimes physical and environmental barriers team up to influence the distribution of snakes. In his book "The Snakes of Europe", British herpetologist J.W. Steward offers a concise explanation that Europe's paucity of snake species- less than three dozen, compared to more than 100 in the United States and 300 in Mexico- is largely a result of Pleistocene glaciation. He also explains how glaciation may have caused many species of European snakes- vipers, for instance- to split up into several subspecies.
At it's maximum, the ice extended as far south as northern Germany, European Russia, and England. South of the glacial margin tundra, cold grasslands and taiga, too chilly for snakes, stretched across Central Europe. Glaciers also expanded on the Alps and Pyrenees, sealing off southern Italy and Spain. Only in these two areas along with the Balkans did the climate remain moderate enough, because of Mediterranean's influence, to support deciduous forest- and snakes.
Glaciation decimated Europe's reptile species. Some species of snakes, although not many, found refuge in the Mediterranean enclaves. Cut off from each other in these refuges, members of the same species well may have differentiated into subspecies. After the last glaciation, some, although by no means all, of the refugees left their enclaves and spread out across Europe. The climate was warmer then than it is today so some species, such as the Aesculapian snake, penetrated far into the north. As temperatures dropped to a more typical level, this species retreated to Central and Southern Europe, where it lives today. Meanwhile, species more tolerant of cold, such as the adder, expanded their ranged due to limited competition.

Taken from the book "The Snake Almanac" by Edward R. Ricciuti

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ChrisRezendes · #2 (**permalink**) 10-31-2002, 01:32 AM

Glaciation, Land Bridges, and their relation with the spread of snakes

WHY THERE ARE NO SNAKES IN IRELAND
Saint Patrick did not have a difficult job chasing snakes from Ireland. There were not any there. Ireland and Britain were almost completely glaciated. The low sea level allowed land bridges to connect them and link Britain with the continent. After the ice melted, some 12,000 years ago, the bridge to Ireland was quickly inundated. But the English Channel was not flooded until almost 8,000 years ago. A few snakes managed to get from Europe to Britain before the breach; Britain has three species. None made it to Ireland.

Taken from the book "The Snake Almanac" by Edward R. Ricciuti
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telefrag · #3 (**permalink**) 10-31-2002, 01:39 AM

I thought they were absent from those areas cause they went on vacation to the Rivera and decided not to go back. [img]modules/Forum/images/smiles/icon_biggrin.gif[/img]

Ok silly mode: OFF
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ChrisRezendes · #4 (**permalink**) 10-31-2002, 02:01 AM

Actually, before reading this, I was of the opinion that there were some serious political problems in ancient Europe that drove the snakes away. A band of young and rebel snakes decided to revolt against King Brown of the Serpents' empire. Most snakes tired of the political upheaval and the loss of reptilian life involved, and moved into Africa, the Middle East, or simple swam to the Americas. But now I know better.

_________________
You know she's a winner.
She couldn't be thinner.
Now she goes to the bathroom
to vomit up dinner.

Kohm · #5 (**permalink**) 10-31-2002, 04:09 AM

Chris, you have been really challenging all of us with your fantastically fascinating and intricate posts recently... [img]modules/Forum/images/smiles/icon_eek.gif[/img]

I am inclined to believe that glaciation and the high latitudes reduced Europe's snake species, but I don't think that all this happened so long ago, though.

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XzyluM · #6 (**permalink**) 10-31-2002, 04:16 AM

Very interesting Chris. Might have to see if I can pick up this book and give it a read.
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ChrisRezendes · #7 (**permalink**) 10-31-2002, 05:05 AM

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font class="pn-sub">Quote:</font><HR></TD></TR><TR><TD><FONT class="pn-sub"><BLOCKQUOTE> Chris, you have been really challenging all of us with your fantastically fascinating and intricate posts recently... [img]modules/Forum/images/smiles/icon_eek.gif[/img]

I am inclined to believe that glaciation and the high latitudes reduced Europe's snake species, but I don't think that all this happened so long ago, though. </BLOCKQUOTE></FONT></TD></TR><TR><TD><HR></TD></TR></TABLE>

As much as I would LOVE to take credit for this most excellent research, I lifted it straight from my all time favorite snake book, The Snake Almanac by Ed Ricciuti. I swear I would jump at the chance to read anything else this guy ever puts out. That book was simply amazing [img]modules/Forum/images/smiles/icon_eek.gif[/img]
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