Evolution Facts

[Mystical]

ANYways.. More cool shit.



Wolffish
(Anarhichas lupus)
Antifreeze Production - Type III Antifreeze

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Antifreeze proteins (AFPs) or ice structuring proteins (ISPs) refer to a class of polypeptides produced by certain vertebrates,plants,fungi and bacteria that permit their survival in subzero environments. AFPs bind to small ice crystals to inhibit growth and recrystallization of ice that would otherwise be fatal. [3] There is also increasing evidence that AFPs interact with mammalian cell membranes to protect them from cold damage. This work suggests the involvement of AFPs in cold acclimatization. [4]

The remarkable diversity and distribution of AFPs suggest the different types evolved recently in response to sea level glaciation occurring 1-2 million years ago in the Northern hemisphere and 10-30 million years ago in Antarctica. This independent development of similar adaptations is referred to as convergent evolution. [4] There are two reasons why many types of AFPs are able to carry out the same function despite their diversity.

In particular, there is an ongoing argument over whether the binding of certain proteins to ice is reversible. Additionally, opinions vary on whether the continued presence of these proteins in a solution prevents ice growth.

The challenge in unraveling these questions is finding viable solutions to produce an experiment in a controlled setting. The growth and tracking of tiny ice crystals in an environment that mimics the surroundings of the antifreeze proteins in nature give rise to a host of technical problems.

To circumvent such problems, Israeli and North American researchers studied the antifreeze protein of the yellow mealworm. This protein is a hyperactive AFP with a potency to arrest ice growth hundreds of times greater than the potency of those present in fish and plants.

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Seals'ancient ancestor found!

A newfound, flipperless prehistoric seal (at top in an artist's conception) is the first concrete link between the land ancestors of pinnipeds (seals, sea lions, and walruses) and modern ocean-going, flippered pinnipeds, such as the California sea lion (bottom), an April 2009 study says.
Many marine mammals, such as whales and manatees, are believed to have roots on land—an idea that originated with Charles Darwin 150 years ago.

But hard evidence for land-to-water evolution in seals and other pinnipeds was lacking until the new discovery—aptly named Puijila darwini ("Darwin's young marine mammal" in an amalgamation of an Inuit language and Latin).

"We know that some sort of land-dwelling ancestor existed, but how did we get to the fully marine form?" asked Rybczynski, a vertebrate paleontologist with the Canadian Museum of Nature.

More..

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The most primitive pinniped fossil skeleton yet found, the P. darwini specimen was discovered in 2007 in an impact crater in the Canadian Arctic.

The inland location on Devon Island, Nunavut, suggests that pinniped evolution featured a freshwater phase, according to the study.

During that period the animals frequented the then temperate Arctic's lakes and rivers. The species may have gradually adapted to an ocean lifestyle after lakes had begun to freeze over in winter, depriving the seals of food.

This first evidence of early Arctic pinnipeds suggests that the region may have been a hotbed of pinniped evolution, Rybczynski said. The Arctic experiences amplified climate shifts, which could speed evolution as animals are forced to adapt—or disappear.

http://news.nationalgeographic.com/news/...97773.html

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New genetic research says that without a doubt: Whales, cattle, deer, hippos, dolphins all related.



Whale and hippo 'close cousins'

A water-loving mammal that lived 50 to 60 million years ago was probably the "missing link" between whales and hippos, according to a new analysis.

Biologists have argued over the relationship between hippos and whales for a period of almost 200 years.

The findings come from an analysis of features in different animal groups carried [out by a US-French team.

Their report is published in the science journal Proceedings of the National Academy of Sciences.

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Jean-Renaud Boisserie, Michel Brunet and Fabrice Lehoreau found that the semi-aquatic ancestor of whales and hippos split into two groups: cetaceans and the anthracotheres.

Cetaceans eventually spurned land, lost their legs and became fully aquatic.

Flourishing group

The pig-like anthracotheres, flourished over 40 million years and died out less than 2.5 million years ago. They left only one descendent: the hippopotamus.

The study places whales firmly within the cloven-hoofed group of mammals known as Artiodactyla, which includes cows, pigs, sheep, antelopes, camels and giraffes.

Scientists had assumed hippos were cousins of pigs because they shared distinctive ridges on their molars.

But then genetic analyses indicated that hippos had more in common with cetaceans, the group to which whales and dolphins belong.

"If you look at the general shape of the [hippo] it could be related to horses, as the ancient Greeks thought, or pigs, as modern scientists thought, while molecular phylogeny shows a close relationship with whales," Dr Boisserie explained.

"But cetaceans - whales, porpoises and dolphins -don't look anything like hippos. There is a 40-million-year gap between fossils of early cetaceans and early hippos."

"Cetaceans are artiodactyls, but very derived artiodactyls."



http://news.bbc.co.uk/2/hi/science/nature/4204021.stm

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