Conservationists are happy when there are many tadpoles in a pond. Yet at high density, tadpoles are stressed; they need longer to develop, are smaller at metamorphosis, and survive less well as juvenile toads. To reduce the density stress, we need to build larger ponds.
A high number of tadpoles in a pond is pleasing but can cause density stress. Using an experimental approach with the natterjack toad, we show that such density stress extends the larval period up to threefold. Extending the larval period increases the risk of failing to reach metamorphosis before the pond dries up. Also, at high densities the tadpoles are more than 50 percent smaller—and on land small toads survive poorly.
For the highly endangered natterjack toad, these findings are particularly problematic. To reduce density stress for this species, it is important to build large ponds (ideally with an area larger than 100 m²). Also, these ponds should dry up, but not until autumn. This can be achieved by building drainable ponds.
Our findings are also important for population monitoring. In a pond with high tadpole density, the tadpoles are present throughout the summer, providing evidence of reproduction. In a pond with low tadpole density, the tadpoles reach metamorphosis after just 20 days. As a consequence, reproduction may go undetected.
My name is Megan, and I was an intern in this lab over the summer in the Biology Undergraduate Summer School, or BUSS program. That’s a very simple way of summing up all the amazing experiences I had thanks to the program and my host lab, and I think it would be best to start this blog post by talking about the BUSS program itself.
The BUSS program aims to unite students from all over the world with varying levels of experience in different biological fields to teach them new and exciting things. It was inspirational to witness the kind of devotion amongst all the people I had the pleasure to meet. The program allowed me to learn about topics from various fields, especially those outside of what I was used to. Seminars, retreats, and interactions with some of the top researchers reminded me of why I enjoy science so much. I was guided through by these amazing mentors as well as my peers who attended the program with me and the two months went by very quickly.
Zürich in summer (photos taken by Megan)
I worked with Koen van Benthem in theoretical biology on modelling techniques and gained new skills in different programming languages, practiced giving scientific presentations, and even learned to LaTex. My project itself was working on increasing the biological significance of Inverse Integral Projection models which use maximum likelihood to estimate parameters such as survival and growth within populations. As always, it was difficult to get started on a new project, but my host lab was very supportive. I learned many techniques and got to discover what theoreticians do. I also got to hear about all the things the other members of the lab do; and they’re all truly extraordinary people who really care about their work. Perhaps most importantly, it was very obvious to me that this lab works well as a unit. There was so much friendship and it was a wonderful environment; that’s an extremely important thing when you’re learning.
Altogether it was an extraordinary experience, and thank you to all who allowed me to come here and took the time to make feel so welcome.
Click the BUSS logo for more information on the program
As an undergraduate student at the Istanbul Technical University from the molecular biology and genetics department, my journey in the field of ecology started with voluntary based projects in the TEMA* foundation in Turkey. In this foundation, I had several opportunities to attend ecological literacy instructions, meet people involved in ecology and even share my experience as well as learn with peers. However, guided by my dearest friend Burcu Arık Akyüz in the foundation and inspired by ecologists that I’ve met in my country, a will for deepening the knowledge and understanding for ecology started to grow inside. Since the education I take at my university is focused on molecular biology concentrating mostly on micro level studies, I was unsatisfied and lost. Sure, I was interested in genetics and other molecular based courses but I was deeply curious about several other questions. Namely: “What is the relationship between the environment and populations?” “How are populations and individuals affected by environmental changes?” “Is there a way to formulate and show these relationships and even predict the consequences of environmental changes?” and many more. I was looking for a way to link my education with this new ambition. Thus, thankfully I found out about Arpat. First by name, then in an interview online, then in his publications and at last I had the courage to email him to ask for an internship in his working group. Thankfully again, he accepted! So, I lived the most inspiring month of my life – academically and emotionally. Mainly I worked on rotifers in the laboratory, resurrected the resting eggs from 50 years ago coming from Lake Orta (Italy), a lake that was once contaminated with copper but then recovered. I conducted experiments to collect life table data (survival, and reproduction) and measure body sizes of individuals. During my first week in Zurich, I read different articles mostly about my experiment. I had the chance to take an introductory lecture to matrix modeling and LTREs (Life-Table Response Experiments) analysis from Arpat and we designed the experiment together with the group. In the second and third week, I conducted the experiment and hence encountered different problems in lab. The real experience was not the experiment itself, rather finding solutions to different problems with the group. Finally I learned how to do matrix population modeling and during the last week I analysed the data and sometimes really felt all neurons in my brain… Recalling all those math lectures I once took, trying to learn R-programming and learning something totally new for me… However, at the end I was fascinated by the intelligence behind connecting mathematics with ecology and creating the possibility to use this outcome for conservation biology and for deepening our understanding of ecology and evolution. From the first day to the last, all days passed with learning and curiosity to learn more. And finally my mind was totally clear! This was what I want! Finally I had found my curiosity, my inspiration and my topic for my future study. This feeling was really precious, giving an aim in life and willing to wake up as early as I can in the morning to go to work immediately, discovering more and more, always with a smile on my face and the ambition to carry on.
And now? Now I have many plans and goals for my upcoming years in my undergraduate studies. I have many projects in mind, many articles and books to read, many scientists to meet, many workshops to take… I want to improve my skills in this field on my own due to limited scientific opportunities in my country. However, I am also excited to study ecology in my home country because of its rich biodiversity and different ecosystems.
With this occasion, I want to thank all PopEcol group members to welcome me so friendly, helping me with my other projects and help me to survive socially in Zurich. I want to thank especially Naomi and Stefan for teaching me all these lab skills with discipline and guiding me through the experiment. And for sure I want to thank Arpat to give me the opportunity to be the part of this inspiring group, their scientific work and helping me to find my way in this marvelous journey of ecology.
*TEMA: The Turkish Foundation for Combating Soil Erosion for Reforestation and the Protection of Natural Habitats
