Washington, July 13 : A new research has determined that smaller families, which are a result of a safer environment, face higher extinction risk than larger families.
According to a report in Discovery News, the research was carried out by Doctoral student Daniel Falster from Sydney's Macquarie University, and his colleagues.
They have developed a model that mimics the evolutionary process across the plant and animal kingdoms from butterflies to fish, to gorillas and even humans.
By estimating the evolutionary pressure on a particular characteristic, such as the amount of parental time and energy spent on each offspring, it can predict how that character will change.
"Our model was able to explain some of the major offspring size patterns seen across species, such as why larger parents have proportionately smaller offspring," said Falster.
One of the findings from the model is that the more dangerous or threatening the environment is, the more offspring you need to produce, but the smaller they will be.
Larger animals and plants, which are "more comfortable" with their surroundings, can reduce the number of offspring they have and spend more energy nurturing their growth, according to Falster.
"(Some) mammals live in a relatively safe environment and can therefore have fewer offspring, and that works well, provided those conditions continue," he said.
Despite being larger, the reduced number of offspring places many species in danger of becoming extinct if their environment changes.
"If conditions change or new predators enter the system, it places them in a precarious situation," said Falster. "A lot of endangered species also have very large offspring. They have low population growth rates, and this makes it hard for them to endure, or recover from, any sort of harvesting or loss," he added.
According to Falster, his model will help biologists struggling to understand what makes some species vulnerable to extinction.