Australasian Science 11

(Jacob Rumans) #1
APRIL 2016|| 13

Dingo Skull Resists


Cross-Breeding
The dingo is resistant to one of the main threats to its survival as
a species – changes to skull shape brought about by cross-breeding
with dogs, according to a University of NSW study published in
Evolutionary Biology(tinyurl.com/gt58s6h).
The study found that the dingo’s skull shape has remained
unchanged by cross-breeding, overturning long-held fears that
cross-breeding with dogs may result in the loss of the predator’s
ecological niche.
“We know that cross-breeding has an effect on the dingo gene
pool, but what we didn’t know until now is whether cross-breeding
changes the dingo skull,” said lead author Dr William Parr. “This
study has shown us that the dingo skull shape, which in part deter-
mines feeding ability, is more dominant than dog skull shapes.”
Conservationists and ecologists had worried that any change
in the animals’ skull shape through hybridisation could alter feeding
habits, potentially causing knock-on effects throughout the entire
ecosystem.
The team used CT scanners to make 3D models of the skulls
of dingoes, domestic dogs and hybrids. They then analysed the
scans to determine whether skulls could be correctly assigned to one
of the three groups based on their shape, and found that hybrid
skulls were indistinguishable from those of the dingo – either with
the naked eye or statistically.
Canis dingowas largely isolated from other canids – dogs, wolves,
foxes and jackals – after it was introduced to the Australian conti-


nent around 3000 years ago. However, this changed when Euro-
pean settlers arrived with domestic dogs.
The researchers think that the dominance of the dingo’s skull
shape is most likely due to recessive, and potentially adverse, traits
ixed in dogs, with many breeds having narrower gene pools than
the dingo. “This is the result of selective breeding to maintain
breed standards, or selecting for useful working traits,” Parr said.

d 3000 H h h d h E

A 3D skull reconstructed from a CT scan superimposed on
an image of a dingo in the outback. The coloured points on
the cranium indicate regions of cranial shape that change
together through evolution and breed development, but
not during hybridisation. Credit: Karen Black 2012, modified by W.C.H. Parr

Blue Whales Split into


Three Breeding Groups
Flinders University scientists have uncovered crucial
DNA evidence about the number and distribution of
populations of the world’s largest animal, the critically
endangered Antarctic blue whale.
Using the largest genetic dataset to date, the
researchers have discovered three genetically different
groups that represent different populations of the
animal. This means that when Antarctic blue whales
breed, they may split into three different oceans that
equate to the three populations.
“What really surprised us was that these popula-
tions co-occupy areas throughout the Antarctic, rather
than occupying discrete areas like their humpback whale
cousins,” says Dr Catherine Attard. “The blue whale populations
likely move around the Antarctic to locate their sole food source,
krill. Blue whales require high densities of krill to support their
massive energy requirements.”
Antarctic blue whales feed in the Antarctic during the summer
and migrate towards the Equator to breed in the winter. This
means that when Antarctic blue whales breed, they may split into
three different oceans that equate to the three populations.
“We have provided a piece of the population puzzle, but still have
far to go before we can properly monitor and conserve these popu-
lations. We need to determine their breeding ground locations and
then conirm their population structure,” says A/Prof Luciana Möller.


The indings have been published in Scientiic Reports
(tinyurl.com/zhcfqrq).
International whale surveys have been conducted in the Antarctic
since 1978. Non-lethal biopsy samples have been collected from blue
whales during these surveys.
“By comparing similarities and differences in the DNA of blue
whales, we can tell which individuals are part of the same popula-
tion and estimate the number of populations,” says Prof Luciano
Beheregaray.
The researchers say this would ideally be performed by contin-
uing the international vessel surveys in the Antarctic and conducting
satellite tagging of Antarctic blue whales to determine their migra-
tory destinations.

Credit: Paula Olson courtesy IWC
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