ECR Spotlight is a series of interviews with early-career authors from a selection of papers published in Journal of Experimental Biology and aims to promote not only the diversity of early-career researchers (ECRs) working in experimental biology during our centenary year but also the huge variety of animals and physiological systems that are essential for the ‘comparative’ approach. Alexander Hansson is an author on ‘ Sex and early-life conditions shape telomere dynamics in an ectotherm’, published in JEB. Alexander conducted the research described in this article while a PhD student in Mats Olsson's lab at the University of Gothenburg, Sweden, and Erik Wapstra's lab at the University of Tasmania, Australia. He has a particular interest in the effects of early-life conditions on telomere dynamics and life history traits in ectotherms.

Alexander Hansson

How did you become interested in biology?

During the final year of high school, I had the opportunity to participate in a biology specialisation course, in which we travelled 30 h by bus from northern Sweden to the Black Forest region in southern Germany. The enthusiasm of my biology teacher as we explored the local flora and fauna left a lasting impression on me. This experience was one of the main deciding factors leading me to pursue a bachelor's degree in biology. As I progressed through each stage of my academic journey, it became increasingly clear that biology was a perfect fit for me. Regardless of the organism or field of study, what captivated me was the scientific process itself – from designing studies to conducting experiments and crafting final conclusions, building on the work of my predecessors.

Describe your scientific journey and your current research focus

I had not intended to continue my study of biology after my bachelor’s degree, but this changed during my final thesis project under supervision from Andreas Svensson at Linnaeus University. I studied ecological interactions between sticklebacks and a parasitic tapeworm capable of altering its host's behaviour, rendering it more susceptible to predation by birds: the parasite's next host. I captured both infected and non-infected individuals and performed trials to explore the extent of these behavioural manipulations. During this time, I found my affinity for the scientific process and decided that there was no other option for me than to continue my studies and pursue a master's degree. The subsequent, more extensive project under supervision from Mats Olsson at the University of Gothenburg only served to strengthen my determination to pursue science. During this time, I explored the impact of temperature during development on the morphology and sex determination of an Australian lizard. This project paved the way for a dual PhD position, with supervision split between Erik Wapstra at the University of Tasmania and Mats Olsson at the University of Gothenburg. During this time, I continued to study early-life effects in lizards, delving into the interplay among developmental temperature, sex, telomeres and life history traits. Currently, I am furthering this research, with specific emphasis on understanding the influence of early-life effects on the rates of ageing in lizards.

A baby sand lizard (Lacerta agilis) poking its head out of the egg, pausing for a moment before emerging completely.

A baby sand lizard (Lacerta agilis) poking its head out of the egg, pausing for a moment before emerging completely.

How would you explain the main findings/message of your paper to a member of the public?

Telomeres are regions on chromosomes essential to maintain DNA stability across all animals, and their shortening has been linked to both reproductive success and lifespan. The telomere biology of cold-blooded animals, however, remains elusive, but we know that it is incredibly diverse among species. Telomeres in this group can undergo shortening, lengthening or remain stable as the animals age. Consequently, the study of telomere biology in this group presents a new frontier in telomere research and a golden opportunity to explore the association between telomeres and the health of individuals, populations and species. Importantly, some cold-blooded animals have demonstrated the ability to compensate for telomere shortening in adulthood, making the early-life effects on telomeres particularly influential. Early life is characterised by rapid growth and a heightened sensitivity to environmental changes, both of which are associated with increased telomere shortening with potential negative effects on the animal's ability to reproduce and survive. In our study ‘Sex and early-life conditions shape telomere dynamics in an ectotherm’, we investigated how developmental conditions and sex influenced the telomeres of young Swedish sand lizards. We observed that telomeres shortened the fastest in offspring that developed under hot conditions. This suggests that warm spells, which are expected to become more frequent as a result of ongoing climate change, could lead to long-term negative effects on the telomeres and health of reptile populations. The sex of the offspring was, however, the strongest factor influencing telomere biology in the young sand lizards. Females hatched with significantly longer telomeres than males, and these telomeres continued to lengthen in the initial weeks of life, while those of males continued to shorten. We propose that the observed difference in telomere biology between males and females stems from their distinct strategies for survival and reproduction. Females that reproduce once annually may invest more energy in telomere protection to increase their lifespan and therefore maximise the number of times they are able to reproduce. In contrast, males, capable of mating with multiple females each year, might prioritise competitive ability over longevity as they maximise their number of partners.

What do you enjoy most about research, and why?

I find the diversity of tasks in a researcher's role to be unparalleled. A year's work might involve hunting for lizards on a Tasmanian mountain in January and a Swedish island in June, caring for lab animals and their offspring, conducting experiments, and collecting valuable data. Then there is desk work, involving statistics, coding, graphical tasks and writing. Throughout, very little goes exactly to plan, given the inherent challenges of working with living organisms and the complexity that comes with. The work is indeed never boring, and the ongoing variety often presents physical, mental and intellectual challenges.

What is the most important piece of equipment for your research, what does it do and what question did it help you address?

A fishing rod and a line threaded through, taped at both ends to form two loops. With a bit of practice, this becomes a powerful tool for capturing small lizards. Once a lizard is spotted, perhaps basking on a rock or foraging in tall grass, you approach it slowly and quietly, making sure not to cast your frightening shadow onto it. Once you're within about 2 m – or a rod's length – you carefully loop the front ‘noose’ around the lizard's head and pull the back loop tightly with your finger. If executed correctly, the lizard becomes ensnared in the tiny noose and can easily be retrieved by hand. This method, known as ‘noosing’, is a gentle yet remarkably effective way of catching small lizards. The importance of this tool cannot be overstated, as without a reliable method for capturing these animals our scientific pursuits would end in the field.

Alexander Hansson's contact details: Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, 405 30 Gothenburg, Sweden.


G. M.
Sex and early-life conditions shape telomere dynamics in an ectotherm
J. Exp. Biol.