Live fast and die young, or play the long game? Scientists map 121 animal life cycles

JULY 8, 2019

by Trinity College Dublin

Scientists have pinpointed the "pace" and "shape" of life as the two key elements in animal life cycles that affect how different species get by in the world. Their findings, which come from a detailed assessment of 121 species ranging from humans to sponges, may have important implications for conservation strategies and for predicting which species will be the winners and losers from the global environment crisis.

"Pace of life" relates to how fast animals reach maturity, how long they can expect to live, and the rate at which they can replenish a population with offspring. "Shape of life", meanwhile, relates to how an animal's chance of breeding or dying is spread out across its lifespan.

The scientists, from the National University of Ireland Galway, Trinity College Dublin, Oxford University, the University of Southampton, and the University of Southern Denmark, have today [Monday July 8] published their work in leading journal, Nature Ecology & Evolution.

The wide range of animal life cycles

Animal life cycles vary to a staggering degree. Some animals, such as the turquoise killifish (a small fish that can complete its life cycle in 14 days) grow fast and die young, while others, like the Greenland shark, (a fish that glides around for up to 500 years), grow slowly and have extraordinarily long lifespans.

Similarly, the spread of death and reproduction across animal life cycles also varies greatly. Salmon, for example, spawn over a short period of time with the probability of dying being particularly high both at the start of their life cycle and when they reproduce. Fulmars and some other sea birds, on the other hand, have wider time periods of reproduction and face relatively similar chances of dying throughout their lives.

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