today
8:30 a.m. Audubon Field Trip: Arcata Marsh Klopp Lake, foot of I St.
read >9 a.m. Arcata Farmers' Market Arcata Farmers' Market (off the plaza)
read >9 a.m. Erik Stitt Stardough's Cafe
read >9:30 a.m. Fourth of July Run 5K Klopp Lake, foot of I St.
read >10 a.m. Arcata's 4th of July Jubilee Arcata Plaza
read >10 a.m. Friends of the Dunes Guided Walk: Family Fun Trek Pacific Union School
read >10 a.m. Used Book Sale See Event Description
read >10 a.m. Eureka's Annual 4th of July Festival See Event Description
read >10 a.m. Ferndale's 4th of July Celebration Various Locations
read >10:30 a.m. Ferndale Farmers' Market Ferndale Farmers' Market
read >noon 4th of July Hoedown Six Rivers Brewery
read >noon VFW Deep Pit BBQ Willow Creek VFW Hall
read >noon Garberville-Redway 4th of July Celebration Benbow Lake SRA
read >noon Orick's 4th of July Celebration BBQ Little Red Schoolhouse
read >12:30 p.m. Humboldt Crabs vs. Nevada Bighorns Arcata Ball Park
read >2 p.m. Friends of the Marsh Tour with Richard Vincent Arcata Marsh and Wildlife Sanctuary Interpretive Center
read >3 p.m. Celebrate America! Ferndale Repertory Theater
read >4 p.m. Acoustic and Open Mic Has Beans
read >6 p.m. Matthew Cook Cher-Ae-Heights Casino
read >6 p.m. The Tumbleweeds Chapala Cafe
read >6 p.m. Arts Alive! Various Locations
read >6 p.m. For the Good Times Accident Gallery
read >6:30 p.m. Guitar Stan Old Town Coffee & Chocolates
read >7 p.m. Karaoke at the Boiler Room The Boiler Room
read >8 p.m. G-Money Karaoke Cher-Ae-Heights Casino
read >8 p.m. The Ethniks Cafe Mokka
read >8 p.m. Diamonds Under Fire Muddy's Hot Cup
read >9 p.m. The Roadmasters Bear River Casino
read >9 p.m. Jsun Pearl Lounge
read >9 p.m. VJ Itchiefingaz Nocturnum
read >9 p.m. Back in the Daze WAVE @ blue lake casino
read >9:30 p.m. Live DJ Ragg's Rack Room
read >10 p.m. Music by DJ Sidelines
read >10 p.m. DJ Icy Hot Aunty Mo's Lounge
read >previous columns
July 17, 2008
Si, PV and LED
Silicon, PhotoVoltaics and Light Emitting Diodes are of growing importance. ...
read >July 10, 2008
Pupal Memories
I remember watching a chick emerge from an egg. It ...
read >July 3, 2008
Lagoons and Beaches
Lagoons Shelter Cove Much of our coastal topography is generated ...
read >Photos
Arms Race & Species
By Don Garlick
Herpetology, the study of amphibians and reptiles, sheds much light on the nature of evolution. Consider the range of body plans and lifestyles among salamanders (amphibians with tails). They commonly hatch from eggs in water or moist places, though a few species give birth to live young. Some are confined to water and use external gills. Some metamorphose into land crawlers and breathe with lungs. Surprisingly, most require neither gills nor lungs, but exchange gases through moist skin and mouth membranes. A local lungless species has such small legs that it resembles a tiny snake. The nine-inch Pacific Giant Salamander devours banana slugs. A Japanese salamander is almost six feet long.
Salamanders with drier skin are called newts. The Rough-skinned Newt (photo), ranging from Santa Cruz to Alaska, has a particularly toxic skin. If ingested, it can paralyze and kill several humans. That "tetrodotoxin" also occurs in Pufferfish and Blue-ringed Octopuses. In those marine animals, at least, the toxin is produced by symbiotic bacteria.
Garter Snakes have evolved an immunity to tetrodotoxin. It is clear that predation has driven newts to become increasingly toxic, and snakes to become increasingly immune. It's an example of co-evolution and a natural arms race. Moreover, after eating a newt, toxin resides in a snake's liver for weeks, undoubtedly affording it some protection from birds. On Vancouver Island, newts and snakes have avoided the chemical arms race. Canada is just more peace-loving.
An insight into speciation is provided by lungless Ensatina Salamanders, whose young, hatched from eggs under damp wood, resemble tiny adults. Several sub-species range southward on both sides of the Central Valley (map). Neighboring sub-species readily interbreed and blend, except those at the southern extreme of the range. These remain distinct because their hybrids have reduced vigor. Biologists consider the southern-end members to represent two different species.
Another example of a "ring species," demonstrating the gradual origin of species by increasing geographic separation, is provided by sea gulls: Gradual changes through 360 degrees around the Arctic Ocean culminate in two distinct species in northern Europe.
Be kind to salamanders -- our ancestors resembled them just 360 million years ago.
I thank Prof. Sharyn Marks of H.S.U. for correcting my errors.



















No comments for this entry
post a comment