Insights Into Australia's Unique Platypus

Posted on: Monday, 2 November 2009, 10:27 CST

New insights into the biology of the platypus and echidna have been published, providing a collection of unique research data about the world's only monotremes.

University of Adelaide geneticist Dr Frank Grützner and his team have authored five of 28 papers which appear in two special issues of the Australian Journal of Zoology and Reproduction Fertility and Development.

The articles shed new light on the extraordinary complex platypus sex chromosome system.

"For the first time we have looked at how the 10 sex chromosomes find each other during sperm development in platypus," Dr Grützner says.

"We discovered that a remarkably organized mechanism must exist in platypus, where sex chromosomes from one end pair first and then they go down the sex chromosome chain, just like a zipper. There is nothing random about it."

Dr Grützner and his colleagues also isolated and analyzed for the first time the sequence of the male-specific Y chromosomes.

"Previously we knew nothing about the Y chromosomes because only the female platypus genome was sequenced. The data we found has given us valuable clues about the evolution of Y chromosomes in all mammals, including humans," Dr Grützner says.

All 28 published articles in the CSIRO journals have arisen from the Boden Research Conference, "Beyond the Platypus Genome", hosted by the University of Adelaide in November 2008, which attracted researchers from around the world.

The published papers represent a wide range of monotreme research, from genome to field biology, population genetics and captive breeding, evolution to immunology, venom, sperm and milk in both the platypus and echidna.

"I expect these results to make a major impact in the field of monotreme research and mammal evolution," Dr Grützner says.

"We have entered a new era in monotreme research, where we are seeing a more integrated approach using genomics, biochemistry and field biology to tackle important questions in monotreme biology. This knowledge will also help us conserve these iconic Australian mammals," he says.

http://www.redorbit.com/news/science/1778701/insights_into_australias_unique_platypus/index.html

Alien spider species spotted

RIGHT: Photo by Matthew Field

Thursday, Oct 29, 2009
Staff Reporter

KOCHI: A brown widow spider belonging to the widow spider group was spotted at Thiruvalla recently.

It was an adult female spider. The spider collected by Manoj Thomas, a medical practitioner, was identified by Samson Davis and P.A. Sebastian, of the Spider Lab of the Sacred Heart College, Thevara.

The specimen is being kept at the lab of the college. The creature might have been accidentally introduced to the State and more research needs to be carried on the species, said Mr. Davis, who is also the head of the Zoology Department of the College.

Widow spiders are highly poisonous and the black widow spiders found in North America and West Indies are poisonous enough to kill human beings. Though the poison of the brown widow is supposed to be more toxic than that of the black widow, the dose of poison it can inject at a time is very little and has only localised action. The brown spider is not very aggressive, does not defend its web and bites are not common. Hence, one need not be afraid of this spider, said Mr. Davis. The colour intensity of brown widows ranges from light tan to dark brown.

They may also have a red broken stripe or a series of white spots along the top of the abdomen with parallel rows of black spots on either side of the stripe.

There is an orange hourglass mark on the underside of the abdomen. The head is usually dark brown. Legs are usually tanned and black banded, Mr. Davis said.

The spider lab of the college focuses mainly on taxonomical studies and also bio-control of agricultural pests.

http://www.hindu.com/2009/10/29/stories/2009102951290200.htm

Why do animals, especially males, have so many different colors?

RIGHT: A male Hetaerina occisa damselfly with red spots at the base and tip of its wings.

October 31, 2009
By Stuart Wolpert

(PhysOrg.com) -- In new research, UCLA scientists claim that "secondary sexual traits" like coloring may let animals know which species to avoid fighting.

Why do so many animal species — including fish, birds and insects — display such rich diversity in coloration and other traits? In new research, Gregory Grether, UCLA professor of ecology and evolutionary biology, and Christopher Anderson, who recently earned his doctorate in Grether's laboratory, offer an answer.

At least since Charles Darwin, biologists have noticed that species differ in "secondary sexual traits," such as bright coloring or elaborate horns, Grether said. Darwin attributed this diversity to sexual selection, meaning the traits increased an animal's ability to attract mates.

But Grether and Anderson, writing in the Oct. 28 issue of the journal Proceedings of the Royal Society B: Biological Sciences, emphasize another evolutionary factor.

"The cost of attacking the wrong type of male and of being attacked by the wrong type of male favors the rich diversity of coloration and of birdsong and chemical cues, such as odors, to identify rivals," Grether said.

Grether and Anderson studied several species of the Hetaerina damselfly (closely related to dragonflies) and found that differences in coloration served to help damselflies distinguish males of their own species, who are rivals, from those of other species, who are not.

"We found that male Hetaerina damselflies use species differences in wing coloration to distinguish between intruders of their own species and intruders of other damselfly species, but only at sites where the two species naturally occur together," he said. "This provides one of the clearest demonstrations yet of an evolutionary process that is probably very prevalent in nature but which has largely been overlooked. We tested for shifts in what animals recognize as competitors."

Nobel Prize-winning Austrian ethologist and zoologist Konrad Lorenz suggested in 1962 that the spectacularly diverse coloration of coral reef fish was likely due to selection against fighting with the wrong species.

"Just as there could be selection against mating with the wrong species, there can also be selection against fighting with the wrong species," Grether said. "Lorenz said there was no advantage to coral reef fish attacking species that are close in proximity but are not competitors. The idea never really reached the level of attention in evolutionary biology that it deserved."

Lorenz's idea may not accurately explain the color diversity of coral reef fish, Grether said, but it may explain the diversity of coloration of other animal groups.

"When species are found in the same location, they do a better job of telling apart males of their own species from males of the other species than they do in places where they do not occur together," Grether said.

At sites where only one damselfly species occurs naturally, the researchers tested their theory by using members of that species whose wings had been artificially colored to resemble males of another damselfly species.

"We can test their responses at both kinds of sites, and we found they show greater discrimination between males of their own species and of other species at places where they actually have to contend with the other species than at places where they don't. They differentiate based on color," Grether said. "That this ability has evolved as a result of selection against fighting with other species is suggested quite strongly by the fact that in places where the other species do not occur, they do not make that distinction.

"If there is no reason for two species to interact aggressively with each other — as Lorenz argued with coral reef fish — then you would expect evolution to favor the ability for them to tell the difference by, for example, an exaggeration in the initial difference in color between them," Grether said. "Differences in color might enable females to more readily tell their own males apart from males of other species. Selection against interspecies aggression could favor the evolution of increased differences between species in color."

Some damselflies species also differ more in coloration where they occur together than where they occur alone, but "this finding can be explained either by selection against mating with the wrong species or selection against fighting with the wrong species," Grether said.

In future research, Grether hopes to learn what proportion of species can tell the difference between members of their own species and members of other species and whether they respond more strongly to their own species in a competitive context. Interspecies aggression and the evolutionary effect it has are understudied scientific questions, Grether said.

In addition to studying several species of damselflies in Mexico and Texas, Grether and Anderson collaborated with modeler Kenichi Okamoto to construct a mathematical model of what happens when species with similar secondary sexual traits come into contact. The model, published in the November 2009 issue of the journal Biological Reviews, predicts rapid evolutionary shifts in secondary sexual traits and also in what the animals recognize as competitors.

"My reading of the evidence," Grether said, "is that these evolutionary processes are important."

http://www.physorg.com/news176195425.html

Aping Evolution

Next on:
Today, 21:00 on BBC Radio 4

Professor of Genetics Steve Jones challenges evolutionary psychology, the controversial new science of how our brains and minds developed.

Girls like pink better because in Stone Age times they needed to be good at picking berries and women have better sex with rich men - or so some evolutionary psychologists would have us believe. Critics say this isn't science, but conjecture.

Evolutionary psychology seeks to explain human behaviour from the hunter-gatherers or our nearest relatives, the chimpanzee, and has some seductively simple theories. One argument is that we have Stone Age brains in 21st-century skulls, from which we can account for everything from the violence that men show to their stepchildren to why racism exists. Is evolutionary psychology a truly useful addition to the canon of ideas to come out of Darwinian evolution or a just-so science that can be adjusted to suit the researchers' prejudices?

Steve Jones examines the history of the new science, the methods used and asks if it can explain the human drive to language, religion and culture.

Broadcast: Mon 2 Nov 2009, 21:00, BBC Radio 4

http://www.bbc.co.uk/programmes/b00nk0wl

Extinct bison could rewrite Canadian archaeological record

27 October 2009

The carcass of an extinct steppe bison, discovered two years ago melting out of a cliff in a remote village in the Northwest Territories, is shedding new light on the Ice Age species - and could rewrite the history of human migration in Canada as glaciers began retreating in the region nearly 14,000 years ago.

An analysis showed the specimen was one of the last of its kind in ancient Beringia - the ice-free, northwest corner of the continent that was once linked to eastern Siberia. But the rare find, documented by a team of Canadian, British and American scientists in the latest edition of the journal Quaternary Science Reviews, has wider implications for dating the retreat of the glaciers in northern Canada and the possible entry of human hunters from Asia - the ancestors of today's aboriginal
Canadians - into the continental interior.

The 'partially mummified' steppe bison was found two years ago in Tsiigehtchic, N.W.T. The animal's distinctive skull and wide horns were largely intact, but more tantalizing were portions of preserved limbs, hide and intestines - that permitted detailed genetic analysis allowing scientists to accurately situate the specimen in the evolutionary history of North America's bison populations.

"Based on the genetics, this animal was one of the last of the remaining steppe
bison in Beringia," Yukon government paleontologist Grant Zazula said.

"Shortly after this, populations in the North are completely replaced by bison that evolved in the mid-continent."

What the find also shows is that the post-glacial ecosystem inhabited by the steppe bison must have supported large mammals earlier than previously known. That, say the scientists, suggests human hunters may well have entered the area around this time and - potentially - left traces of their own activities at sites still waiting to be found by archeologists.

"Given that steppe bison inhabited the northern portal to the 'ice-free corridor,' data from the Tsiigehtchic bison raises the potential for discovery of archaeological sites in the lower Mackenzie River Valley," the study states.

Sources: Canwest News Service, Calgary Herald (27 October 2009)

http://www.calgaryherald.com/technology/Bison+could+rewrite+Canada+archaeological+record/2150110/story.html

(Submitted by Terry Colvin)