Female frogs modify offspring development depending on reproduction date

Breeding male of Rana arvalis from the study area. Credit: Germán Orizaola

Global warming is altering the reproduction of plants and animals, notably accelerating the date when reproduction and other life processes occur. A study by the University of Uppsala (Sweden), including the participation of Spanish researcher Germán Orizaola, has discovered that some amphibians are capable of making their offspring grow at a faster rate if they have been born later due to the climate.

Over recent decades many organisms, both plants and animals, have experienced a notable advance in the date when many of their life processes (like reproduction, migration or flowering) occur, attributed to the impact of climate change. An article published in the journal Ecology examines the effects that these changes in the reproduction date have on the life cycles of the amphibians.

"We specifically examined whether changes in the reproduction date of a common amphibian species in the north of Europe, Rana arvalis, can condition the growth and development of their offspring," the Spanish researcher Germán Orizaola, from the University of Uppsala (Sweden) and co-author of the study, said.

Results revealed that female frogs have the ability to influence both the growth rate and the development of their offspring, and they adjust it depending on the date of reproduction.

According to Orizaola, "the mechanism by which the female frogs can condition the growth of their larvae could be due to the genes associated with the maintenance of their biological clock being transferred to the embryos and becoming active even before fertilisation. This would provide the larvae with the exact information regarding the progression of the growing season."

The later the birth, the faster the growth

One of the characteristics associated with climate change is an increase in the interannual variability of climatic conditions, so organisms are also exposed to greater uncertainty when it comes to determining the right time to reproduce. This explains why the existence of mechanisms adjusting growth and development rates depending on the variation in the start of breeding is highly advantageous for many species.

In particular, as part of this study they observed that by delaying the date of reproduction (which simulated a time of environmental instability), the result was an equivalent reduction in the growth period for the larvae. "That means the later this species of frog breeds, the faster the larvae develop," explains the scientist.

An interesting aspect of the study is that the acceleration in growth is produced under constant lab conditions. "The larvae were not exposed to any outside sign that would indicate the progression of the growing season," adds Orizaola.

"This result is very novel and demonstrates that the acceleration in the development of the larvae is conditioned by the breeding females, which reveals the existence of a 'transgenerational effect' in which the breeding adults are capable of altering key aspects of the life cycle for the following generations, to better prepare them to survive the environmental conditions that they are going to experience," concludes the expert.

Source: Plataforma SINC.

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Managing coasts under threat from climate change, sea-level rise

Sea levels are rising. Experts say that we need to address human-led and other non-climatic changes. Credit: Image courtesy of University of Southampton

Coastal regions under threat from climate change and sea-level rise need to tackle the more immediate threats of human-led and other non-climatic changes, according to a team of international scientists.

The team of 27 scientists from five continents, led by Dr Sally Brown at the University of Southampton, reviewed 24 years of Intergovernmental Panel on Climate Change (IPCC) assessments (the fifth and latest set being published in 2013 and 2014). They focused on climate change and sea-level rise impacts in the coastal zone, and examined ways of how to better manage and cope with climate change.

They found that to better understand climate change and its impacts, scientists need to adopt an integrated approach into how coasts are changing. This involves recognising other causes of change, such as population growth, economic development and changes in biodiversity. Dr Brown emphasised that: "Over the last two and half decades, our scientific understanding of climate change and sea-level rise, and how it will affect coastal zones has greatly increased. We now recognise that we need to analyse all parts of our human and natural environments to understand how climate change will affect the world."

The scientists also acknowledged that long-term adaptation to climate change can greatly reduce impacts, but further research and evaluation is required to realise the potential of adaptation. "Many parts of the coast can, with forward planning, adapt to sea-level rise, but we need to better understand environments that will struggle to adapt, such as developing countries with large low-lying river deltas sensitive to salinisation, or coral reefs and particularly small, remote islands or poorer communities," said Dr Brown.

For example, in the Maldives, many small, remote low-lying islands are at risk from climate change and will struggle to adapt. But around the densely populated capital city and airport, adaptation has already occurred as land claim is a common practice in order to relive population pressure. Sea-level rise has already been considered into newly claimed land. 

Thus in decades to come, potential climate change impacts, such as flooding, will be reduced for this island, benefiting both the local population and economy.

Dr Jochen Hinkel from Global Climate Forum in Germany, who is a co-author of this paper and a Lead Author of the coastal chapter for the 2014 IPCC Assessment Report added: "The IPCC has done a great job in bringing together knowledge on climate change, sea-level rise and is potential impacts but now needs to complement this work with a solution-oriented perspective focusing on overcoming barriers to adaptation, mobilising resources, empowering people and discovering opportunities for strengthening coastal resilience in the context of both climate change as well as existing coastal challenges and other issues."

This new research, published as a commentary in Nature Climate Change, will help in the understanding of the impacts of climate change and how to reduce impacts via adaptation. Its multi-disciplinary approach could be useful if future IPCC assessment reports are commissioned.

Source: University of Southampton

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