May 28, 2014,
Source: National University
of Singapore
Researchers from the
Department of Biological Sciences at the National University of Singapore (NUS)
Faculty of Science have discovered that a Southeast Asian species of treefrog
practices parental care to increase the likelihood of survival of its
offspring. Chiromantis hansenae (C. hansenae), is currently the only species in
the treefrog family in Southeast Asia that is
known to exhibit such behaviour. This discovery was recently published as the
cover story in a popular magazine of nature and science, Natural History, in
May 2014.
The study investigates parental care in a
frog of Southeast Asia, specifically, the small treefrog, C. hansenae, which is
found in mainly in the northeastern forests of Thailand
and parts of Cambodia
The researchers, Assistant Professor David
Bickford and Ms Sinlan Poo, a PhD student, from the NUS Department of
Biological Sciences, observed that C. hansenae exhibits a form of parental
care, known as egg attendance, in which a parent remains with the egg mass at a
fixed location. These frogs care for their offspring by covering the egg mass
with its body. Occasionally, the females will make trips down to the pond,
presumably to soak up more water, and return to secrete the liquid over the egg
mass, keeping it moist.
By comparing offspring survival between
natural egg masses and egg masses where parent frogs were experimentally
removed, the researchers found that although C. hansenae breeds very close to
water sources, there is still an extremely high risk of the eggs drying out, a
process called egg desiccation. As such, the behaviour of the parent is
essential to the survival of their offspring. The researchers made these
findings after conducting a total of 1,448 field observations of the 126 egg
masses over two years, from July 2011 to October 2012.
While egg attendance is the most common
form of parental care in amphibians, C. hansenae has a number of life-history
characteristics that deviate from other species with parental care. For
example, most frogs with parental care have fewer and larger eggs, breed in
more terrestrial habitats, and males care for direct-developing eggs, which are
eggs that hatch as frogs directly. In contrast, C. hansenae has lots of tiny eggs,
breed above ponds, and females care for non-direct-developing eggs, which are
eggs with a free-swimming tadpole stage. The researchers concluded that the
unusual parental care in C. hansenae plays a critical role in preventing egg
desiccation and is a possible mechanism for buffering environmental pressures
for their offspring.
The study is timely as C. hansenae is
listed as Data Deficient under the International Union for Conservation of
Nature’s Red List of Threatened Species. A recent study by Dr Samuel Howard
from the Evolutionary Ecology and Conservation Lab at NUS led by Asst Prof
Bickford, showed that Data Deficient amphibians are likely to be more
threatened than species that are fully assessed. The research also highlights
the importance of field research in a region where very little in known about
the life history and behavior of most species.
Said Ms Poo, “Our study is the first
experimental investigation of parental care in Southeast
Asia , a region with over 700 species of amphibians. This highlights
the need for more of such natural history studies. Currently, much of the
mechanisms, adaptations, and driving forces of egg attendance in C. hansenae
require further exploration, through which a more coherent understanding of
parental care can be formed.”
Said Asst Prof Bickford, “This research is
significant because Sinlan has shown how parental care works in Asian
treefrogs, at least in the context of her study system in Thailand
Story Source:
The above story is based on materials provided by National University
of Singapore. Note: Materials may be edited for content and length.
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