The Biology Refugia

A group blog highlighting ecology, evolution and biodiversity, and other aspects of biology.

Thursday, July 28, 2005

Evolution could have progressed faster than previously thought

I have always been a firm believer of gradualism. A packet of light sensitive cells is better than no such cells at all, half an eye is better than none. Life changes in small gradual steps. Whatever 'miraculous' structures we see today are the result of millions of years of change and adjustments.

How could I have forgotten about hybridisation? Afterall, being a botanist, I know that plants do it all the time. Animals do hybridise too and this has been suggested to be a powerful driving force for evolution.

Bruce McPheron and his colleagues (1997) at Pennsylvania State University in University Park, US, noticed a fruit maggot infestation on introduced Asian honeysuckle bushes in north-eastern Pennsylvania. Genetically, McPheron found that the fruit maggot infesting the introduced plant is the result of hybridisation between two native species - the blueberry maggot and the snowberry maggot. This phenomena is confirmed by The Penn State University team, this time led by Dietmar Schwarz, in five different geographic locations. Their findings suggest that hybridisation could lead to shift in host preference by parasites and this could be a powerful factor in generating biodiversity and speed up the rate of evolution.

Read the complete article at New Scientist

The same story was reported at National Geographic Magazine
For more information - Nature (vol 436, p 546)

Friday, July 22, 2005

China's national flower

Can't decide between peony or plum blossum? Just have both lah!

("Debate over China's national flower." By Joel Martinsen. Danwei, 22 Jul 2005.)

Saturday, July 16, 2005

Chinese officials attack Nature paper

"Nature bird flu paper 'wrong'". By Katherine Schlatter. The Scientist, 15 Jul 2005. Chinese officials say H5N1 research published last week was incorrect and unauthorized.

'A paper about the deaths from avian flu of geese in China, published in the July 6 online issue of Nature, was criticised as being incorrect and conducted without government approval.

The paper, by University of Hong Kong researcher Guan Yi and colleagues, including Robert G. Webster and Malik Peiris, concluded that an H5N1 outbreak among bar-headed geese and gulls at Qinghai Lake Nature Reserve was triggered by the introduction of a strain from southern China.

Last week, Guan told The Scientist he feared that new research regulations imposed by the agriculture ministry would lead to legal reprisals for his sequencing of Qinghai Lake H5N1 strains.

And last weekend, China's Ministry of Agriculture spokesman made strong statements carried by China's state-controlled Xinhua news service, dismissing the research. "An article on bird flu carried in the renowned journal Nature made the wrong conclusion," stated the article, which went on to say that, "no bird flu has broken out in southern China since [the beginning of] this year. "The writers' laboratory lacks the basic conditions for biological safety," the article said. "The writers did not apply [for] government approval for carrying out such bird flu virus research."'

More here.

Sunday, July 10, 2005

Palaeoecosystem collapse - evidence in the egg shells

A report in Science suggests that the arrival of humans on Australia altered the continent's ecosystem, changing it to the desert scrub we see today.

Chemical analysis on hundreds of fragments of fossilised eggshells suggested that the change in diet could be due to the alteration of the birds' natural habitats by humans burning the grassland for hunting, clearing or even for signalling other bands.

The resultant scrubland vegetation forced the birds to change their diet, in turn causing a change in the chemical composition of the eggshells. Birds such as Genyornis newtoni, a prehistoric bird the size of an ostrich, failed to adapt and died out.

There is a belief that the arrival of modern humans on other continents led to mass extinctions. In Australia, more than 85% of Australia's megafauna went extinct after human arrived. But others believe that megafaunal "extinctions were not caused by any single event, but reflect compounding factors."

In an earlier post, Siva highlighted an article that revealed that Australia megafauna coexisted with humans for as much as 15,000 years.

"'Fires wiped out' ancient mammals." By Helen Briggs. BBC News, 08 Jul 2005. See also Science Daily, 10 Jul 2005 and related articles listed therein.

Original article: Miller, GH, ML Fogel, JW Magee, MK Gagan, SJ Clarke & BJ Johnson, 2005. Ecosystem Collapse in Pleistocene Australia and a Human Role in Megafaunal Extinction. Science, 309 (5732): 287-290. 8 July 2005. DOI: 10.1126/science.1111288.

Abstract - Most of Australia's largest mammals became extinct 50,000 to 45,000 years ago, shortly after humans colonized the continent. Without exceptional climate change at that time, a human cause is inferred, but a mechanism remains elusive. A 140,000-year record of dietary 13C documents a permanent reduction in food sources available to the Australian emu, beginning about the time of human colonization; a change replicated at three widely separated sites and in the marsupial wombat. We speculate that human firing of landscapes rapidly converted a drought-adapted mosaic of trees, shrubs, and nutritious grasslands to the modern fire-adapted desert scrub. Animals that could adapt survived; those that could not, became extinct.

Thursday, July 07, 2005

"Extinction looms for wild tigers in Asia"

"Extinction looms for wild tigers in Asia." By Nirmal Ghosh. The Straits Times, 06 Jul 2005.

LAST Saturday, police at an intersection in Udon Thani in north-eastern Thailand stopped two pickup trucks bound for China via Laos. Packed in huge iceboxes, they found the carcasses of three full-grown wild Malayan tigers.

The men in the trucks said they had been paid 15,000 baht (S$620) to ferry the dead tigers - and 150 dead pangolins crammed into fruit crates - into China.

The seizure was depressingly routine, because hundreds of pangolins are discovered on the Malaysia-China land route every month.

But it was spectacular because of the tigers. This pointed to the growing challenges faced by conservationists trying to save a species at the heart of Asia's identity.

There are now only 5,000 to 7,500 tigers believed to be found in their natural wild habitat.
Asia has already permanently lost three of its original eight species. The rest are sliding rapidly towards extinction.

The Caspian, Balinese and Javanese tigers are already extinct. The South China tiger is likely to be the next to disappear, with fewer than two dozen believed left in the wild.

In India's Rajasthan state, poachers wiped out almost three- quarters of the entire population of 30-plus wild tigers in two reserves during last year's monsoon season.

The dismembered parts were believed to have been sold to buyers in China, where a belief in the medicinal or aphrodisiacal qualities of tiger bones and organs have kept poachers in business.

The debacle showed that small, scattered populations of tigers can be eliminated in just a matter of weeks if political support for the cause is lacking.

Popular support is often not forthcoming. Poor local villagers generally see wildlife conservation as an elitist luxury, and resent the setting up of tiger reserves as an encroachment on their rights to the surrounding forests.

To them, if a poacher kills a tiger, too bad for the beast.

When the Rajasthan case sparked an international uproar, Prime Minister Manmohan Singh set up a wildlife crime unit - something activists had been urging for a decade. He also set up a task force to look into devising long- term strategies to save the tiger and its habitat.

India has between 2,500 and 3,000 wild tigers - the biggest population of any single Asian country. But the creatures are scattered in isolated groups, making them vulnerable to poachers. Protection in habitats is often on paper, with low priority given to wildlife and forest protection departments.

By contrast, there is big money in hunting them down. A dead tiger can fetch up to US$40,000 (S$68,000) in China, where the market is growing because of rising affluence. Demand is fuelled by the belief that consuming ground tiger bones can relieve rheumatic pains, and tiger penises can enhance sexual vigour. Tiger fur can be seen on coats in the markets of Tibet.

Research in China itself has found the properties of tiger bones and organs are not very different from those of dogs, pigs and goats. But the myths refuse to die. Conservationists put the value of the illegal wildlife market at around US$160 billion annually, just behind the trade in contraband arms and narcotics. In terms of individual animals, the tiger is among the most valuable for a smuggler.

To make matters worse, the conservation community is torn on how best to save Asia's remaining tigers.

An old idea has been revived - breeding tigers in farms and harvesting them to flood the market, thereby driving prices down and reducing the incentive to poach. But critics say farming of seriously endangered species can worsen the problem. They like to point out that there are plenty of crocodile farms in Thailand, but hardly any left in the wild.

Professor G. Agoramoorthy, a primatologist teaching at Taipei University, says: 'I have seen wildlife farms from South America to South-east Asia, all somehow directly or indirectly putting pressure on the existing wild populations of endangered species.'

Today, trade in tiger products is banned worldwide under the Convention on International Trade in Endangered Species (Cites). Ms Debbie Banks of the London-based Environmental Investigation Agency warns that if the sale of farmed tiger products is legalised, a surge in demand may lead to the development of a black market for the wild product, and hasten the end of the last remaining tigers.

Conservationists say there are just too few tigers left to try risky strategies. 'Cites has explored and rejected tiger farming as a conservation tool on a number of occasions,' Ms Banks says.

Mr Adam Roberts, of the US-based Born Free Foundation, points out that China started bear farming in the 1980s with the argument that it would reduce pressure on wild populations. 'The exact opposite is true. Bear farms still deplete wild populations to stock their farms. Bears continue to be poached in the wild.'

Simple arithmetic explains why the farm approach fails: It costs around US$2,000 a year to raise a tiger to adulthood in captivity in passable conditions, and just US$5 to have a wild tiger killed by a local village hunter.

Observers say conservationists and the tourist industry are partly to blame for the sad state of Asia's tigers, because they have failed to make an adequate case that wild tigers can sustain a huge tourism industry, providing thousands of jobs to locals.

Some also blame economists who have not quantified the ecological services rendered to people by habitats protected in the name of the tiger: clean water, clean air, flood control, rainwater catchment, medicinal plants and biodiversity.

Thousands of tourists flock to countries like India each year just to see tigers. At Thailand's Sri Racha tiger farm, thousands of tourists queue up to see bored tigers in cages; there are more tigers in Sri Racha than in all of the country's forests. Such is the drawing power of the giant cat.

Conservationists say that unless governments crack down seriously on the illegal trade in wildlife, and sharpen protection of tiger habitats, the big cats will be hunted to extinction in the wild precisely because of their charisma.

Viewing a tiger in a farm or zoo is just not the same as seeing one in its natural habitat. Indian wildlife biologist Ullas Karanth once said that 'when you see a tiger, it is always like a dream'.

Many experts fear that the tiger may become extinct in the wild in 50 years. And then it really will be merely a dream.

DWINDLING NUMBER OF WILD TIGERS
IT IS estimated that there are only 5,000 to 7,500 tigers alive today in their natural wild habitat.
The Caspian, Balinese and Javanese tigers are extinct. The South China tiger is likely to be the next to disappear; it is reckoned that fewer than two dozen survive in the wild.

The distribution of tigers:
Amur or Siberian tiger (Russia, with some possibly in China and North Korea): 360-406
Indochina tiger (Myanmar, Thailand, Laos, Cambodia, Vietnam, Malaysia): 1,227-1,785
Sumatran tiger (Sumatra, Indonesia): around 400
South China tiger: 20-30
Bengal tigers (India, Bangladesh, Bhutan, Nepal): 3,000-4,500

Copyright © 2005 Singapore Press Holdings. All rights reserved.


See also news about the Bengal tiger: “Tiger, tiger, losing fight.” By Vibha Sharma. The Tribune, 29 May 2005. Another 15 years, and the big cat could be extinct.

Wednesday, July 06, 2005

The Australian Snubfin Dolphin

Beasley, I., K. M. Robertson & P. Arnold, 2005. Description of a new dolphin, the Australian snubfin dolphin Orcaella heinsohni sp. n. (Cetacea, Delphinidae). Marine Mammal Science: 21(3): 365–400.

"Abstract - Comparisons of the Irrawaddy dolphin, Orcaella brevirostris, between Australian and Asian sites documented geographic differences in height of dorsal fin, presence or absence of a median dorsal groove in front of the dorsal fin, and coloration (presence or absence of a dorsal cape). Analysis of genetic data provided support for two clades within the Asian samples, the Mekong River samples from Cambodia and southern Laos, and all other marine and freshwater sites from Thailand, Indonesia, and the Philippines.

The major separation, however, was between sites in Asia and those from Australia (5.9% of base pair differences, compared with 1.2% for within Australia and 1.5% for within Asia). Within a 403 base segment of the mtDNA control region, Australian specimens had 17 diagnostic sites with 16 fixed base pair differences and one insertion/deletion. Consistent, statistically significant differences in skull characters of Australian specimens have previously been demonstrated and are reviewed in this paper. There was a high concordance in character differences demonstrated between O. brevirostris from all Asian sites and Australian specimens, especially in the genetic and osteological characters.

Based on the range and concordance of character differences, we propose that the Australian dolphins be recognized as a new species, Orcaella heinsohni (suggested common name: Australian snubfin dolphin)."

Sunday, July 03, 2005

Fatherless sons

"Some insects, specifically most species of the Hymenoptera, do things differently, with a sex determination system called haplodiploidy.

Males are always haploid, having only one set of chromosomes, and they produce only one kind of gamete, and all of their gametes are genetically identical. Females are diploid, and produce haploid eggs.

If the eggs are fertilized by a male, they develop into females; unfertilized eggs develop into males. Fathers can only have daughters, and mothers produce sons without the contribution of a male. Males don't have fathers, literally."

Read more in "Clone war of the sexes." By PZ Myers. Pharyngula, 01 Jul 2005.