2021-04-15

Size is not a panacea: the mystery of the extinction of giant animals

By yqqlm yqqlm

Size is not a panacea: the mystery of the extinction of giant animals

Now, by Corey of Flinders University -Research led by Professor Bradshaw and the Australian Research Council’s Centre of Excellence for Biodiversity and Heritage of Australia (CABAH) uses sophisticated mathematical models to assess the susceptibility of different species to extinction – and what it means for the survival of living things today .

Using various characteristics, such as body size, weight, lifespan, survival rate and fertility, they created a population simulation model to predict the possibility of these species to survive under different types of environmental disturbances. The simulations included everything from increased drought to increased hunting pressure to observe which of the 13 extinct megafauna and the 8 comparative species that are still alive today, which species have the highest chance of survival.

Bradshaw and his team, published in eLife magazine, compared the results with the extinction times of different megafauna species we know from the age-old fossil record. They hope to confirm that the species most likely to become extinct are the first species-but this is not necessarily the case.

Although they found that species with slower growth and lower fecundity, such as the rhino-sized wombat relative, Diprotodon, are generally easier than more fecund species such as marsupial “tiger” animals Extinct, but the relative susceptibility level of each species does not match the time of extinction recorded in the fossil record.

“We found that there is no clear relationship between the inherent susceptibility of a species-such as being slower and heavier and/or slower to reproduce-and the time of extinction in the fossil record,” Professor Bradshaw explain. “In fact, we found that most of the living species used for comparison-short-beaked echidna, emu, brush turkey, and common wombat, are on average more susceptible than their now extinct counterparts.”

Researchers have concluded that the true extinction cascade is likely to be the result of complex and partial scenarios, including the effects of regional climate variability and the different pressures brought by humans from different regions. Said Vera Weissbecker, an associate professor at Flinders University and co-author of the study. “The relative speed of different species evading hunters and whether the species digs protective burrows may also lead to a mismatch in extinction sensitivity and time.

“For example, the fast-leaping red kangaroo that is still alive today may It has an escape advantage over some extinct slow-walking short-faced kangaroos. Small wombats that dig burrows may also be more difficult to hunt than giant animals that are larger and don’t like to burrow. ”

Co-author Dr. Frédérik Saltré of Flinders University added: “Based on the biological characteristics of kangaroos, we have determined that the kangaroo species is the least likely to be extinct, followed by the single kangaroo (Echidna ), and the giant’wombat’ species. Interestingly, large, flightless birds like emu and Newton’s giant bird are the most susceptible.

“Our research results support the concept that according to the special ecology of the species, the extinction risk of all body types may be high, which means that the future climate change and human beings are predicted based on the first principles of biology. The extinction of the impact is not always straightforward,” Professor Bradshaw concluded.