Professor Yvonne Buckley, the Head of the Zoology Department at Trinity, has co-authored a report mapping out the varied life cycles of 121 species of organism, which could have an impact on conservation strategies and help predict how species fare in the global climate emergency.
The report pinpoints the “pace” and “shape” of life as the two key elements in animal life cycles that affect how different species exist in the world. In their study, the scientists used population data to compare detailed life cycles for species ranging from sponges to corals, salmon to turtles, and vultures to humans.
The research was conducted in Trinity in collaboration with researchers from the National University of Ireland Galway, Oxford University, the University of Southampton, and the University of Southern Denmark.
The research showed that the wide variety of lifespans of species is greatly connected with the timeline of when a species is most likely to reproduce and to die, and whether this is confined to short periods or spread out across a longer portion of the species’ life. This means that effective conservation efforts may have to focus on broadening periods of reproduction, rather than simply aiming to increase the lifespan of different species.
Dr Kevin Healy, Lecturer of Zoology at the National University of Ireland Galway, is the lead author of the study. He said: “When we mapped out the range of life cycles in the animal kingdom we saw that they follow general patterns. Whether you are a sponge, a fish or a human, your life cycle can, in general, be described by two things – how fast you live and how your reproduction and chance of dying is spread out across your lifespan.”
“As we expected, species with low metabolic rates and slow modes-of-life were associated with slower life cycles. This makes sense; if you don’t burn much energy per second, you are restricted in how fast you can grow. Similarly, if you are an animal that doesn’t move around a lot, such as a sponge or a fish that lives on the sea bed, playing a longer game in terms of your pace of life makes sense as you may need to wait for food to come to you.”
The scientists investigated whether certain life cycles made animals more susceptible to ecological threats, by looking for associations between an animal’s life cycle and its position on the IUCN red list of endangered species. The researchers found that animals with very different and opposing lifecycles faced similar levels of threats on the IUCN list.
Prof Buckley, the co-senior author, said: “We found that extinction risks were not confined to particular types of life history for the 121 species. Despite these animals having very different ways of maintaining their populations, they faced similar levels of threat.”
“Populations of a particular species, like the Chinook salmon or Freshwater crocodile, vary more in how mortality and reproduction are spread across their life-spans than they vary in their pace of life. This is important for the animal populations that we need to conserve as it suggests it may be wiser to consider actions that boost reproduction and/or impart bigger effects on the periods of the life cycles when mortality and reproduction are more likely – rather than simply aiming to extend the lifespans of these animals.”
The report suggests that the findings could have a major impact on conservation strategies and gives indications as to which species are naturally most resilient given the current global climate crisis, as well as providing a deeper insight into the complex and varied lives of different animals.
The research was funded by Science Foundation Ireland, the UK’s Natural Environment Research Council, the Australian Research Council, the Danish Council for Independent Research and the Max Planck Institute for Demographic Research from Germany.