passed Fossils around in class: Horse teeth (Pliocene) 4-5 million years old Molluscs and sharks teeth from Calvert Cliffs, about 15 my old Dinosaur bone, 70 my old?? Trilobite, 230 my old (Permian-Triassic extinction
Pseudo-extinction
Cladogenesis Anagenesis
Cladogenesis = branching of lineages during phylogeny
Anagenesis = directional evolution of a feature over an arbitrarily short segment of a lineage
Feel it in your bones SUMMARY: Deciding whether our ancestors evolved as a single lineage may depend more on philosophy than fossils. Rex Dalton reports. Nature 440, 1100 - 1101 (27 Apr 2006) News http://www.nature.com/nature/journal/v440/n7088/f ull/4401100a.html
Scientific Description Can Imperil Species Scientists are racing to discover and describe new species in the face of a global biodiversity crisis. Ironically, in cases of commercially valuable taxa, publishing new species descriptions may inadvertently facilitate their extinctions. These descriptions advertise "novelties" for hobbyists and drive new markets. Most modern descriptions provide detailed information on the locality and habitat where the new species occurs, turning a scientific article into a treasure map for commercial collectors. Researchers in fields with application to bioterrorism are debating codes of conduct to ensure that their findings do not fall into the wrong hands, the so-called "dual-use dilemma". Taxonomists describing new species that have the potential to become commercially valuable are also faced with a dual-use dilemma.
Chinese gecko: $1500-2000 per lizard, now $40
Neurobiology: After the bomb
NATLNUCLEARSECURITYADMIN./NEVADASITEOFFICE Proc. Natl Acad. Sci. USA1031256412568(2006) Alegacyofnuclear-bombtestsishelpingtosettlecontroversyaboutwhether newneuronsareborninthebrain'sneocortexthroughoutourlives. Thelevelofcarbon-14intheatmosphere(andthusthehumanbody)wasmore orlessdoubledbyColdWarbombtests,thendroppedafterthe1963TestBan Treaty.AteamledbyPeterErikssonofGothenburgUniversityandJonasFrisn oftheKarolinskaInstitute,Stockholm,Sweden,measuredcarbon-14inautopsy tissueofpeoplebornbeforeandafterthebombtests.Levelsoftheisotopein neocortexneuronscorrespondedtoatmosphericlevelsatthetimeofthe person'sbirth,suggestingthatalmostallneuronsarebornatthattime.This supportsFrisn'searlierwork.
Raccoon dogs, indigenous to some Asian countries, supplied some coats' fur. It is illegal to import dog and cat hair to the United States. (Courtesy Of The Humane Society Of The United States)
Md. Bill Seeks to End Mislabeling of Fur Coats By Philip Rucker Washington Post Staff Writer Tuesday, February 5, 2008; Page B01 Imagine discovering that the trim on your designer coat, labeled as faux fur, actually was rabbit. Or raccoon. Or even dog hair. Some of the biggest names in retail -- Bloomingdale's, Saks Fifth Avenue and Burlington Coat Factory -- have acknowledged that they sold coats made with rabbit or dog hair but labeled or advertised as different species or as artificial. They say they were misled by the coatmakers and have corrected the labels in recent months, after the Humane Society reported its findings from a two-year investigation. The Humane Society said it had discovered those stores, and others, were selling coats that were trimmed with the hair of raccoon dog, a species of dog indigenous to China and other Asian countries that closely resembles raccoon. Although U.S. law prohibits the importing of dog and cat fur, federal regulations don't require manufacturers to label the type of fur if the piece is valued at less than $150. So a lawmaker from Montgomery County plans to introduce legislation today that would change the rules in Maryland by requiring all manufacturers and retailers selling fur coats in the state to identify the species and country of origin on their labels, regardless of value.
White House Went Too Far in Sonar Case, Judge Rules Tuesday, February 5, 2008; Page A02 The Bush administration overreached when it sought to limit the Navy's obligations under national environmental laws related to sonar training exercises off California, a federal judge ruled yesterday. In a sharply worded decision that will keep the Navy from continuing a series of 14 planned exercises, U.S. District Judge Florence-Marie Cooper wrote that the Navy and the administration had improperly declared that an emergency would be created if they had to accept court-mandated steps to minimize risk to whales and other sea mammals. Because no real emergency exists, she said, the White House cannot override her decisions and those of the U.S. Court of Appeals for the 9th Circuit. Accepting the Navy's arguments, she wrote, would produce "the absurd result of permitting agencies to avoid their [environmental] obligations by re-characterizing ordinary, planned activities as 'emergencies' in the interest of national security, economic stability or other long-term goals." White House spokesman Tony Fratto said, "We disagree with the judge's decision. We believe the orders are legal and appropriate." A Navy spokeswoman, Lt. Cmdr. Cindy Moore, said the military was studying the decision. Joel Reynolds, an official at the Natural Resources Defense Council, which obtained an earlier injunction against the Navy blocking the exercises, said in a statement that the court "has affirmed that we do not live under an imperial presidency."
Paid Summer Ecology Internships for Undergraduates NSF REU The Louis Calder Center - Biological Field Station of Fordham University has a select number of paid research opportunities for undergraduate students for our Calder Summer Undergraduate Research (CSUR) program. The CSUR program will run from May 28 through August 19, 2008. This is an NSF-REU Site.
http://www.nsf.gov/crssprgm/reu/list_result.cfm?unitid=5047
Research Experience for Undergraduates
Syllabus
I. Conservation Biology: philosophy and definitions II. Extinctions past and present A. Causes of extinction B. Early mass extinctions C. The great South American Interchange D. Blitzkrieg in the Pleistocene E. Recent extinctions
How to quantify variation in effects of environmental stochasticity
Mean
Frequency
Growth Rate
Tolerant to variation
intolerant
SD environmental = standard deviation
Stochasticity
Demographic stochasticity
Population fluctuations Sex ratio
Genetic stochasticity
Mutation Inbreeding Recessive alleles
Effect of Population Size on Stochastic Threats
ln(N)
ln(N) extinction time time
Quiz
ln(N)
time
What IS Causing Extinction?
Extinction Threats for North American Freshwater Fishes (IUCN)
Habitat destruction Introduced species Chemical pollutants Hybridization Overharvesting
73 68 38 38 15
Remote Croplands
Colombia Basin, Washington, USA
Credit: GWMA <http://www.gwma.org/images/CroplandAdjusted.jpg>
Effects of road salt
Salinity in streams in Maryland approaching 25% of that of seawater (100 times that of pristine forest streams) Watersheds where roads are densest are under severe pressure If salinity continues to increase, water may become unfit for human consumption and toxic to freshwater organisms by 2100.
PNAS 102:13517 (2005)
Data from Baltimore LTER site
Nile perch
Introduced species
Felis catus domesticated from Felis silvestris Estimated 90 million in the US (30 million in 1970, 65 million in 2000) 30% of households nationwide, 60% in rural areas Estimated 1 billion birds and small mammals killed each year
Science 315:167; The Wildlifer #336:7
Hunter Jim Martell, left, and others pose with the bear he shot on Banks Island in Canada's Northwest Territory. DNA tests later showed the bear had a polar bear for a mother and a grizzly bear for a father.
CHESAPEAKE BAY Md. Crab Harvest Dropped in 2007 2nd-Lowest Tally Linked to Pollution, Drought, Overfishing By David A. Fahrenthold Washington Post Staff Writer Tuesday, February 5, 2008; Page B03 Last year's catch of blue crabs from Maryland waters of the Chesapeake Bay was the second-lowest on record, as environmental damage, drought and past overfishing helped drive down the state's most valuable seafood harvest, state officials said yesterday. About 21.8 million pounds of blue crab was taken by watermen during the April-toDecember season, officials at the Maryland Department of Natural Resources said. That was about 6 million pounds less than in the previous year and not much more than the all-time low, 20.2 million pounds in 2000. "We're concerned about the health of the blue crab fishery and about the health of the blue crab itself," said Lynn Fegley, a fisheries biologist who oversees blue crab programs at the department. The "fishery," in this case, means the industry that depends on the crabs. In response, Natural Resources officials said Maryland would soon begin seeking comment from watermen, scientists and other government agencies about the possibility of altering harvest rules.
Historical Extinctions
What is the background rate of extinctions? What are mass extinctions? How long does recovery from mass extinctions take? Causes of select prehistoric extinctions. What is the current rate of extinctions?
What is a species lifespan?
From New Scientist 23 October 1999
What is the background rate of extinctions?
In the fossil record, an individual species lasts about 1 10 million years before it goes extinct or evolves into a new species. As a ballpark figure, estimate 10 million species living now. Then 1 10 species would be lost each year due to natural events.
Over the last 200 million years, mean extinction rate: ~ 1 species/year ~ 3-4 families/1000 yr
Stratigraphic Geology
(study of layered rock)
Sedimentation Beds = strata > 1 cm (stratum = singular) Lamina(e) = stratum(a) < 1 cm Lithification Fossils
Sideling Hill, MD
The Rockwell and Purslane Formations were deposited during the early Mississippian, about 330 to 345 million years ago. For more information: www.mgs.md.gov/esic/brochures/sideling.html
George Cuvier (1786): catastrophism Charles Lyell (1830s):
Dynamic Equilibrium
= uniformitarianism = gradualism
Charles Darwin (1859):
Origin of species Inevitability of extinction
Gradual Extinction
Number in strata
Catastrophic Extinction
time
Syllabus
I. Conservation Biology: philosophy and definitions II. Extinctions past and present A. Causes of extinction B. Early mass extinctions C. The great South American Interchange D. Blitzkrieg in the Pleistocene E. Recent extinctions
Characteristics of a ME
Brief relative to the expected duration of the taxa Involve considerable numbers of taxa
Mass Extinctions
Permian Extinction
From National Geographic, September 2000
Causes of the Permian ME?
How long did it take? Estimates have changed from 10 my (last century) to 165,000 years (1998) to thousands (2000) to maybe much faster. A 6-mile wide asteroid off the coast of Australia? The Siberian Traps? A million-year volcanic eruption that left lava over a mile deep across five time zones of Russia. [more next lecture]
Reasons why it might be difficult to tell if Mass Extinctions are for real (ME rate >> Background rate; Statistical significance, not anecdote):
The relationship between taxon rank and number of individuals therein is highly variable The difference between background rate of extinction and the rate during a ME is not great Its difficult to determine when a taxon is actually extinct Taxon evolution is not considered
Evidence that mass extinctions exceed background levels 1) Robert Ansteys work on Bryozoans (moss animals) unusually low extinction rates normally BUT, high extinction rates during Ordovician, Devonian MEs
Skeletons of colonial bryozoans
See: www.ucmp.berkeley.edu/bryozoa
Fossil skeleton
Are Mass Extinctions Predictable? Periodicity of mass extinctions
Alfred Fischer and Michael Arthur (1977): 32 x 106 years David Raup and Jack Sepkoski (1984): 26 x 106 years
If Mass Extinctions ARE Predictable:
They must be explained by extra-terrestrial forces
10C
http://www.darkstar1.co.uk/extinctions.html
Common Themes in Mass Extinctions ?
Proposed agents of Mass Extinctions
1. Climate shifts (glaciation, marine regression) 2. Cosmic radiation and the Earths magnetic field. 3. Biotic factors (evolution of predators) 4. Asteroid impacts (especially K/T ME) 5. Volcanic eruptions 6. Oxygen starvation (Permian ME) 7. Gamma rays (Ordovician)
7-1
10C-b