Scientists observed this new reproductive mode in critically endangered white spotted bush frogs in South India’s Western Ghats
Researchers from the National University of Singapore (NUS) have discovered a new reproductive mode in frogs and toads - breeding and laying direct developing eggs in live bamboo with narrow openings - which was observed in the white spotted bush frog (Raorchestes chalazodes). This critically endangered frog is currently only one of two species known to adopt this novel reproductive strategy. The findings were published in The Linnean Society of London’s Biological Journal of the Linnean Society, in October 2014.
Life history strategies to increase reproductive success are termed as reproductive modes. Frogs and toads currently exhibit 40 known reproductive modes, including 17 aquatic modes and 23 terrestrial modes. This study reports the discovery of the 41st reproductive mode which is different from all other known modes – breeding in live bamboo with narrow slits through which adults enter and deposit direct developing eggs and provide parental care. Direct-developing eggs are eggs that hatch as frogs directly.
The species of frogs that exhibit this behaviour, R. chalazodes, was thought to be extinct for over 100 years until it was rediscovered recently in the wet evergreen forests of the Kalakad Mundanthurai Tiger Reserve in the Western Ghats. This biodiversity hotspot of India is listed as a UNESCO World Heritage Site.
In this study, Mr Seshadri K S, a PhD student, and Assistant Professor David Bickford from the Department of Biological Sciences at the NUS Faculty of Science, discovered the reproductive strategy of R. chalazodes. Mr Seshadri observed that adult male frogs enter hollow internodes of the flute bamboo Ochlandra travancorica where they vocalise to attract mates.
They make their way into the bamboo through a small opening, possibly made by insects. Female frogs are attracted to the calls and follow suit, laying about 5 to 8 eggs inside the bamboo. Other females may also choose to mate with the male frog and deposit egg clutches in the bamboo. The male stays in the bamboo to take care of the eggs, which develop directly into froglets.
Although the adult frog is small, under 25 millimetres in length, it enters the bamboo with considerable resistance as the narrow openings are often less than 5 to 10 millimetres long and 3 to 4 millimetres wide. The researchers observed that R. chalazodes only breeds in bamboo that have openings at the base of the internode as those with openings at the top would result in collection of water, possibly flooding the eggs or drowning the froglets.
The adult males actively search for openings in bamboo and possibly defend territories. They leave the bamboo for a few hours in the evening to feed and return to look after the eggs. The researchers made these findings after conducting field observations over a period of six months between 2009 and 2012.
Asst Prof Bickford said, “This is a significant discovery in two ways. First, it reiterates that natural history observations, often ignored, are fundamental for understanding evolutionary ecology. Second, it sets a theoretical foundation to ask several interesting questions about the diversity of reproductive modes and the evolutionary pathways behind such amazing amphibian behaviors.”
The second author of the paper, Dr Gururaja K V from the Centre for Infrastructure, Sustainable Transportation and Urban Planning at the Institute of Science, Bangalore, India, had observed that another species of frogs, known as the Ochlandra reed frog (Raorchestes ochlandrae), breeds in internodes of bamboo. While the geographic ranges of these two species do not overlap and nesting occurs inside different species of bamboo, the reproductive mode is comparable.
R. ochlandrae was previously ascribed to a reproductive mode characterised by direct developing eggs deposited in a nest above ground or in the trees. In this study, the researchers did not observe any nest-making behaviour and thus, the mode was reclassified to be the same as R. chalazodes.
The study is timely as R. chalazodes is currently critically endangered with small populations occurring in fewer than five localities. As this species only breeds in bamboo, unregulated overharvesting of bamboo for paper and pulp may destroy breeding habitats and have a negative impact on the long-term viability of populations. It is critical to conduct more studies on these unique frogs, in particular, those that look into developing frog-friendly harvesting techniques in order to conserve them.
Mr Seshadri, the lead author, said, “Amphibians are among the most threatened creatures on earth and yet, we know very little about them. I was enthralled when we observed this behavior and it opened a whole new world for me. There are several evolutionary questions that could be answered by studying this fascinating group of frogs. For example, what transpires inside the bamboo internodes is still a mystery. The Western Ghats is a well-known hotspot for amphibian diversity which is facing threats primarily from habitat loss. If we do not initiate conservation efforts, we may lose everything before we even document anything.”
Dr Gururaja said, “While species diversity has increased, very little ecological information has been added. The recent discoveries of interesting behaviour such as foot-flagging in the dancing frog (Micrixalus kottigeharensis), and clay nest-building in the potter frog (Nyctibatrachus kumbara) are a case in point that there is much more to be discovered in India and Southeast Asia.”
Assistant Manager, Media Relations
Office of Corporate Relations
National University of Singapore
Kimberley WANG | newswise
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy