Ever seen this ….it
is dusky hopping mouse – photo courtesy : Ben Moore, australiangeographic.com.
Cricket World Cup
is just over ~ many Indian fans travelled to Australia for witnessing the
matches – now it is IPL – many players from Australia, New Zealand, West
Indies, South Africa, Sri Lanka are in India representing various sides. The dingo (Canis lupus dingo) is a free-ranging dog found
mainly in Australia. Its exact ancestry is debated, but dingoes are generally
believed to be descended from semi-domesticated dogs from East or South Asia,
which returned to a wild lifestyle when introduced to Australia.
Contrary
to popular belief, Australia may not have been as isolated for the 40,000 years
prior to European colonisation as once thought, according to a new study which
has found evidence of substantial gene flow between Indian populations and Australia
about 4000 years ago. The research also suggests the dingo
might have arrived on Australian shores about that time – along with tool
technology and food processing – though other experts are sceptical. The study, published in the journal PNAS, says
it was commonly assumed that Australia remained largely isolated following
initial colonisation some 40,000 years ago, though the genetic history of
Aboriginal people has not been explored in detail. Researchers of Max Planck Institute for Evolutionary
Anthropology in Germany, joined colleagues in analysing large-scale genotyping
data from Aboriginal Australians, New Guineans, Island Southeast Asians and
Indians that suggest a new possibility. The
researchers say this supports the view that these groups represent the
descendants of an ancient southwards migration out of Africa. The authors suggest that Indian genes might
not have come directly from Indian and they are too uniformly spread across
northern Aboriginal genomes to have come from European colonists.
Some are sceptical
though contending - genetic data for dingoes suggests they came from Island
Southeast Asia, not India. So linking the human genetic evidence to the idea
that they also imported a range of new technologies and dingoes is something
that needs further investigation,” they
say. Away from dingoes, feral cats are
causing devastation to more than 400 native species, according to a new survey
of their impact. A large collaboration
of researchers analysed faeces and stomach contents of feral cats across the
entire continent to ascertain the diets of these feline pests. What they found
was bad news for our wildlife.
From a total of 49
published and unpublished data sets, the researchers determined that the menu
of feral cats is more extensive than previously thought. In a similar study in
Europe data from different islands around the world showed a less varied menu. "On
40 islands across the globe where feral cat diet data was available, they
recorded cats killing and eating 179 species; whereas here in Australia we have
400 different species," says lead author Tim Doherty, a wildlife ecology
PhD candidate at Edith Cowan University in Perth. In Australia feral cats have already
contributed to the extinction of 16 mammals. Small and medium native animals
have been declining catastrophically, and huge ferals are wreaking havoc in
areas like Arnhem Land.
Another
quite significant finding of the study was that across the continent, where
cats eat [fewer] rabbits, they eat more native small mammals. It is called 'prey-switching', according to them. This means that culling a local rabbit
population may inadvertently lead to cats eating more of the native animals in
that area. Getting
back, Dingoes may be the unlikely saviour of the native and endangered dusky
hopping mouse (Notomys fuscus), new research reveals. Higher numbers of the
dusky hopping mouse have been recorded in Central Australia's Strzelecki
Desert, which has a healthy population of dingoes, compared to other areas the
native mouse inhabits. An apex predator, the dingo seems to be offering
indirect protection to the dusky hopping mouse by hunting on its predator:
feral cats. That is a two-way effect ! –
the dingoes suppress cat abundance by outcompeting for food resources; cats
also provide a food resource for them" says lead authour of the study,
Christopher Gordon, from the University of Western Sydney.
The numbers of
dingoes, cats and hopping mice were detected using nocturnal spotlight and sand
plot techniques, over 47 sites. The dingoes' presence also encouraged
behavioural changes in dusky hopping mice, says Christopher. With fewer feral
cats around, the dusky hopping mice were less fearful of coming out to forage
for food. Christopher tested this
concept by placing small feeding trays in open areas where either feral cat or
dingo numbers were high. Feeding trays containing 40 hopbush seeds were filled
each night before dusk, and counted the following morning. Significantly more
seeds were consumed at the sites where dingoes rule.
The study provides
evidence that 'size-dependant predation' occurs when dingoes are absent or in
low-density, says Christopher. This is where smaller predators, such as feral
cats and foxes, whittle down populations of prey species like the dusky hopping
mouse, which are too small to be hunted by apex predators. The study suggests dingoes could be
introduced to areas with small mammals that are hit hardest by feral cats,
which hunt more than 400 of Australia's animal species.
Dingoes
as conservation tools !!!
- that takes back to the ‘food chain’
concept – a linear sequence of links in
a food web starting from "producer" species (such as grass or trees)
and ending at apex predator "decomposer" species (like grizzly bears
or killer whales). A food chain also shows how the organisms are related
with each other by the food they eat. Food
chains were first introduced by the African-Arab scientist and philosopher
Al-Jahiz in the 9th century and later popularized in a book published in 1927
by Charles Elton, which also introduced the food web concept.
Interesting
indeed.
With regards – S.
Sampathkumar
8th Apr
2015.
Article source : http://www.australiangeographic.com.au/news/
No comments:
Post a Comment