Thursday, January 26, 2012
This makes me so happy. Its a cladogram of a collection at the American Museum of Natural History showing the evolution of vertebrates. The transition from aquatic environments to terrestrial is one of my very favorite things to think about, this highlights the story as well as demonstrates how DINOSAURS EVOLVED. Woah, yeah, dinosaurs. Whats even better, is that I'm learning the nitty gritty story behind all this in my classes this quarter.
The good stuff in evolutionary history starts once we have some solid evidence for life, I like solid evidence. 3.7 billion years ago (give or take a few million) there were plankton alive and doing what plankton do in Precambrian oceans. They were photosynthesizing happily, and then they reached the end of their little lives, died, and sank to the bottom of the ocean. Then they got fossilized, and discovered in modern Isua, Greenland. They aren't the first cells on Earth, but those lucky cells got fossilized and are the oldest fossilized evidence of life today.
From that point cellular life developed for THREE BILLION YEARS, gradually increasing in complexity to the point of mulitcellularity and sex. Cyanobacteria filled our atmosphere with free oxygen, and diversity radiated on our planet. Bacteria, Archea, and Eukaryotes have since been in competition for resources on Earth, acquiring truly astonishing diversity in every form. Below is amphibian predator Koskinonodon, formerly known as Buettneria perfecta, an animal who lived primarily in aquatic habitats but was capable of walking on land. Not a reptile, evolution is cool.
I'll post new knowledge and discoveries just as soon as I encounter them. Check back soon!
Wednesday, January 25, 2012
It's been a while, sorry! I'll post as often as I can with school. This article is devastating, we desperately need to protect the surviving populations. Shark fins and rhinoceros horns, now manta ray gills.. this mindless harvesting of beautiful rare species must stop.
Manta Rays Fate Worse Than Sharks
January 25, 2012 5:01:06 AM
As the population of sharks has depleted, fishermen are turning more and more to Manta Rays - animals unfit, in the most Darwinian sense of the word, to handle the pressure.
Manta Rays take 10 years to reach maturity and females give birth to "a single pup every two to three years," ray researcher Mike Bennett of the University of Queensland told ABC Science:
By comparison, a Great White Shark, which is widely considered to be one of the world's most vulnerable marine species, may produce as many pups in one litter as a Manta Ray does over its entire lifetime.The worldwide decline in Manta and their cousins the Mobula Rays, is documented in a recent study released by the conservation organizations, Shark Savers and WildAid. The study, Manta Ray of Hope: The Global Threat to Manta and Mobula Rays, began by following the trade in gill rakers, the cartilaginous part of the rays that helps them filter feed.
"We first came across manta and mobula ray gills in Asian markets several years ago and followed the trail to the dried seafood markets of Southern China. It's sad to see these animals follow the same path to extinction as sharks," conservation photographer and lead investigator Paul Hilton said in a statement.
Currently the IUCN Red List of threatened species lists both the Giant Manta Ray (Manta birostris) and the Great White Shark (Carcharodon carcharias) as vulnerable and Smoothtail Devil Rays (Mobula thurstoni) as only in a slightly better situation, that of near-threatened.
The study also valued the life of a Manta Ray at US$1 million, the income one animal makes for local eco-tourism. The market value for gill rakers? An estimated $11 million annually, according to the study. Making the value of the animal alive a much more lucrative investment. The tourism industry for snorkling and scuba diving with rays is estimated at over $100 million per year, globally.
Vulnerable Giant Manta Ray (Manta birostris) entangled in a fisherman's net, in Yap, Micronesia. (Corbis)
Near-threatened Smoothtail Devil Rays (Mobula thurstoni aka Mobula lucasana) slaughtered on a beach in Baja California, Mexico. (Norbert Wu, Corbis)
Giant Manta Ray hooked on long line near Cocos Island, Costa Rica - Pacific Ocean. (Jeffrey Rotman, Corbis)
Tuesday, January 10, 2012
Monday, January 9, 2012
I love this article!!! Museum collections are a personal favorite, and by utilizing them researchers have been able to determine that at least one male of a thought extinct species of giant tortoise is ALIVE! That's awesome. They compared genomes of wild giant tortoises with museum specimens and determined that a"lonesome George" C. elephantopis is still alive!
'Extinct' Giant Tortoise Found on Remote Island
January 9, 2012 9:00:00 AM
A species of giant tortoise believed extinct for 150 years was actually just moved from its original home and now lives on the volcanic slopes of the northern shore of Isabela Island in the Galapagos archipelago.
A genetic analysis, published in the latest Current Biology, found that DNA footprints of the long lost tortoise species, Chelonoidis elephantopus, exist in the genomes of its hybrid offspring. These tortoises turn out to be a mix of C. elephantopus and another giant tortoise from the area, C. becki.
While researchers have yet to isolate a purebred C. elephantopus individual, such tortoises must exist, based on the DNA data. The study marks the first time that a species has been rediscovered by way of tracking the genetic footprints left in the genomes of its hybrid offspring.
"This work also underscores the importance of museum collections in facilitating new discoveries," co-author Ryan Garrick told Discovery News. "Here, we were able to extract DNA from tortoise bones that were collected many decades ago, and use this DNA to characterize the gene pool of purebred C. elephantopus."
Garrick is a former Yale postdoctoral researcher who is now an assistant professor at the University of Mississippi.
He and his colleagues visited Volcano Wolf on the northern tip of Isabela Island and took blood samples from more than 1600 tortoises. The scientists then compared them to a genetic database of living and extinct tortoise species.
The matching process detected the genetic signatures of "extinct" C. elephantopus in 84 of the Volcano Wolf tortoises, meaning one of their parents was a purebred member of the missing species.
In 30 cases, breeding took place within the last 15 years. Since the lifespan of the tortoises can exceed 100 years, there's a high probability that many purebreds are still alive.
The Galapagos tortoises are famous for their influence on Charles Darwin's ideas about evolution by natural selection. It's no wonder they captured his attention: individuals can weigh nearly 900 pounds and grow to almost 6 feet in length.
The tortoise's size and slow moves also led to its downfall. Garrick explained that "populations were heavily decimated by buccaneers in the late 1600s and 1700s, and then by whalers, fur sealers, merchantmen and the crews of naval vessels."
"Largely owing to the exploitation of tortoises for oil and as a source of food aboard ships, C. elephantopus from Floreana Island (its original home) was reported to be extinct soon after Charles Darwin's historic voyage to the Galapagos in 1835," he added. "Indeed, it has been estimated that up to 200,000 tortoises were eliminated from the archipelago within only two centuries of intensive harvesting."
Co-author Gisella Caccone, a senior research scientist in Yale's Department of Ecology and Evolutionary Biology, told Discovery News she hopes to now find actual C. elephantopus individuals and restore them to their island of origin.
"We plan to go back to Volcano Wolf in December 2012 and attempt to find all the individuals of mixed ancestry (we have them all tagged with PIT transmitters), and if we are lucky also the pure ones," she said.
The work is important, she continued, "as these animals are keystone species playing a crucial role in maintaining the ecological integrity of the island communities."
It remains unclear how the tortoises wound up on Isabela Island, but Caccone and her colleagues suspect that humans transported them as food. Whalers may have also thrown them overboard or simply left them on the shore of this other island.
Garrick said he's hopeful that other "extinct" species might be rediscovered using the same genetic methods used to detect the missing giant tortoise.
There's already hope that the giant tortoise C. abingdoni from Pinta Island, now represented by the single known purebred individual "Lonesome George," is alive and well elsewhere.
Tuesday, January 3, 2012
Ahhhhh my true love deep sea biology!!
Antarctic Hot Springs Yields Ghostly New Species
January 3, 2012 2:00:00 PM
The discovery of new deep-sea hot springs off Antarctica may rewrite theories of how marine creatures populate the world's oceans.
Scientists say the underwater plumes -- located between the southern tip of South America and the Antarctic Peninsula -- are chock-full of new species, including a pale, ghostly-looking octopus, a predatory seven-legged sea star and a hairy-chested "yeti" crab.
Experts say the strangest thing is what they didn't find -- tube worms, shrimp and mussels that have been found at the world's other deep-sea hydrothermal vent communities.
"It wasn't just one creature, virtually everything we saw was new to science," said Alex Rogers, professor zoology at the University of Oxford and lead author of the new report.
"It was a remarkable experience. You're not quite sure if these things are mineral or biological structures. That's a very unusual feeling to see all this stuff for the first time and saying I don't understand what's going on here."
Rogers and his colleagues at the University of Southampton described their findings in today's PLOS Biology.
The discoveries came during a January and February 2010 expedition to the region and were made using a remote-operated vehicle (ROV) called Isis.
Rogers said it took nearly two years to get the findings published because there were so many undescribed species that his team had to send samples out to experts around the world for identification.
He recalled watching a small video screen on board the British oceanographic vessel James Cook as the ROV camera descended 2,600 meters (8,530 feet) down to the seafloor.
"The robot camera captured images of smoking plumes of hydrogen sulfide and minerals billowing up from fissures in the undersea ridge up to 382 degrees Celsius (720 degrees Fahrenheit) and surrounded by vast living mats of barnacles, anemones, crabs and other critters."
"It's probably the most exciting scientific cruise I've ever taken part in," Rogers said from his office in England.
"The wonderful thing was that the discoveries just kept coming right through the trip. Seeing the images for the first time was absolutely breathtaking, just stunning."
But beyond the giddy excitement of finding new animals, marine biologists say that the mix of deep-sea fauna at these vents will stir debate about how these creatures got there.
"The Rogers paper fills in a piece of the bio-geographic puzzle for global vent faunas and raises new questions about evolutionary alliances and pathways to hydrothermal vents," said Cindy Van Dover, director of the Duke University Marine Laboratory, and a leading expert in undersea hot springs biology, in an email to Discovery News.
"Their discovery of dense populations of crabs related to the yeti crab is especially intriguing. This family of crabs was discovered in 2005 at hot springs in the southeastern Pacific -- there must be an evolutionary link between the two regions."
That means that the creatures living at underwater hot springs must be able to colonize other vents, even though the plumes often are short-lived, lasting only a few decades before the seafloor shifts and the hot springs disappear.
Another big question is whether the extremely cold water that circles Antarctica helps or hinders dispersal of the larvae of the strange life that thrive at the vents.
"Depending on the group of deep-sea organisms, the Southern Ocean can be an ecological dead end or a jumping-off point for colonizing other parts of the world," said Rich Aronson, head of the department of biological sciences at the Florida Institute of Technology who studies Antarctic undersea life.
"This paper is a start to figuring out if one or the other scenario is the rule for vent faunas."
While most Antarctic marine animals lay eggs that include an embryonic sac, the creatures found at the new hot springs do not. That's one key to figuring out how they get from one vent to another, according to James McClintock, an evolutionary biologist at the University of Alabama, Birmingham.
"This would suggest that getting from one vent community to another is important, and having a small swimming feeding larvae is something that is being selected for," McClintock said.
The first deep-sea hot springs were discovered in 1977 on the Galapagos Rift west of Ecuador by researchers at Oregon State University. Since then, they've been found in the Indian, Pacific and North Atlantic. But this is the first discovery in polar waters.
McClintock says he expects there are more hidden places out there for scientists like him who are trying to understand the world's animal and plant life.
"The scientific community has gotten used to seeing the same assemblage of organisms at each of the vents," McClintock said. "Here you have a whole different suite of organisms. I would definitely say that the book is not written."