Welcome all to the final podcast of the series, and my final episode with the Life Sciences podcast team. I’ve been extremely lucky over the past year to be immersed in science communication at the University of Manchester and have been able to share my passion for the research conducted here in the Faculty of Life Sciences through the medium of podcasts and this blog. Therefore, although slightly self-indulgent, this episode is all about a science podcaster’s passions. As a zoology graduate myself, these passions include amazing animal adaptations and science communication.
I discuss with Dr Gina Galli how some water-dwelling vertebrates have evolved the remarkable ability to survive for extended periods of time in the absence of oxygen. These species offer a particularly unique insight into molecular mechanisms that could protect against human-related diseases associated with severe hypoxia. I was then able to speak with Dr Jonathan Codd about the cost of breathing and locomotion in the Svalbard ptarmigan, an arctic species adapted to live in extremely harsh conditions throughout the year. Finally, we hear from the prolific science writer and blogger Ed Yong, speaking about his passion for science communication and blogging with Quentin Cooper, a successful science presenter and journalist, at a PhD conference held at the university earlier this year.
Living without Oxygen and Life in the Freezer: The freshwater turtle and the Svalbard ptarmigan
For most animals, severe hypoxia or anoxia (defined as the complete absence of oxygen) is synonymous with death. In humans, for example, ischemia, which is the disruption of a continuous supply of oxygen to tissues, can result in loss of consciousness within seconds. In fact, even in the most hypoxic-tolerant mammals, the maximal level of tolerance for the cessation of breathing is a mere two hours. With the exception of deep-sea diving mammals and animals living at high altitude, there is little selection pressure for the evolution of anoxia tolerance in mammals or birds, as environmental oxygen levels are plentiful. However, for the water-dwelling lower vertebrates, continuous access to oxygen can be limited. With oxygen concentrations much lower in water and a slower diffusion rate, waters can become hypoxic or anoxic very easily. Some species of lower vertebrates, including some fish, amphibians and reptiles, therefore have evolved physiological coping mechanisms to this environmental stress, developing a high level of anoxia tolerance. Freshwater turtles of the genera Chrysemys and Trachemys are excellent examples of this; they have evolved a remarkable ability to survive unharmed for an extraordinary length of time in an anoxic environment due to their life history. These animals can overwinter under ice in ponds for several months, preventing them from accessing the water surface to breathe air, and hence have to remain in the anoxic water.
We find out about the strategies employed by both the freshwater turtle and crucian carp that enable them to survive for extended periods of time in the absence of oxygen with Dr Gina Galli. These animals evade the detrimental consequences of anoxia, including a reduction in production of ATP leading to a mismatch between ATP supply and demand, and the generation of toxic end-products from anaerobic respiration such as lactic acid through a variety of different means. We discuss both whole-animal adaptations and potential cellular mechanisms that confer protection against such detrimental effects following oxygen deprivation.
From living without oxygen to life in the freezer, we speak to Dr Jonathan Codd about his research looking at the energetic cost of locomotion in the Svalbard rock ptarmigan (Lagopus muta hyperborean). The Svalbard ptarmigan is a non-migratory bird that inhabits the arctic archipelago of Svalbard year round. This species experiences extreme photoperiodic and climatic conditions and is therefore highly adapted to live in this harsh environment. A unique trick seen in these birds is their ability to double and then half their body mass throughout the course of the year through the deposition, prior to onset of winter, of fat stores. Jonathan’s research has looked into whether this fat, although crucial to the birds’ survival, places any constraints on both their breathing and locomotion. As these birds can still move energetically efficiently with this additional mass, we discuss with Jonathan the mechanisms that may be utilised by these birds to allow for efficient locomotion.
Domesticated birds are often selected for rapid growth rates and increased edible muscle mass however, unlike the ptarmigan, these traits often come with associated health problems. Jonathan highlights how understanding the ventilatory mechanics and locomotor biomechanics of the ptarmigan, a bird with naturally-occurring increases in body mass, can be applied to investigating the underlying causes of welfare issues in poultry.
Hear more about Jonathan’s research looking at the Svalbard ptarmigan here: