Featured Research

from universities, journals, and other organizations

Predators predict longevity of birds, study concludes

Date:
April 30, 2014
Source:
Max-Planck-Gesellschaft
Summary:
Aging inevitably occurs both in humans and in other animals. However, life-span varies widely across species. Researchers have now found a possible general mechanism explaining differences in longevity. They investigated life history data of nearly 1400 bird species and found that avian life span varies considerably across the entire Earth, and that much of this variation can be explained by the species' body mass and clutch size and by the local diversity of predator species. The researchers were able to confirm a key prediction of the classical evolutionary theory of aging that had been proposed more than 50 years ago.

Water thick-knee (Burhinus vermiculatus) defending it nest against a monitor lizard.
Credit: © MPI for Ornithology Seewiesen/ Wolfgang Goymann

Aging inevitably occurs both in humans and in other animals. However, life-span varies widely across species. Researchers of the Max Planck Institute for Ornithology in Seewiesen have now found a possible general mechanism explaining differences in longevity. They investigated life history data of nearly 1400 bird species and found that avian life span varies considerably across the entire Earth, and that much of this variation can be explained by the species' body mass and clutch size and by the local diversity of predator species. With their data the researchers were able to confirm a key prediction of the classical evolutionary theory of aging that had been proposed more than 50 years ago.

It is well-known that organisms vary widely in life-span. Whereas some fish, turtles or even invertebrates can become hundreds of years old, the neon pygmy goby -- a small fish -- reaches ripe old age at only 60 days. In birds, variation in life-span extends from parrots such as the Sulphur-crested cockatoo that can become more than 100 years old, to the small Allen's hummingbird with a maximum life-span of only 4 years, a 25 fold difference. How can this variation be explained?

The classical evolutionary theory of aging, first proposed by the famous evolutionary biologist George C. Williams over 50 years ago, gives an answer. The theory predicts that high mortality rates in adult animals due to predation, exposure to parasites and other randomly occurring events will be associated with shorter maximum life-spans. This is because under high external mortality most individuals will already be dead (eaten or succumbed to disease) before natural selection can act on rare mutations that cause healthier aging. The theory has since been further developed and tested in a number of experimental and comparative studies. Yet contradictory results have caused scientists to cast doubt on its validity.

Mihai Valcu and Bart Kempenaers from the Max Planck Institute for Ornithology in Seewiesen together with colleagues from New Zealand and Switzerland have now tested this theory using a comprehensive database on estimates of maximum life-span of 1396 bird species, 1128 from free-living species and 268 from birds kept in captivity. The researchers used a global distribution map of these species, included data on their morphology and reproductive rate, and estimated predation rate.

By means of complex statistical analysis methods they found that in the investigated bird species maximum longevity is negatively related to the number of predator species occurring within the same geographical area. This means that the more predator species are present in the same habitat and the more evenly they are distributed, the lower is the life span of the respective species. This relationship supports the classical theory of aging, and remains valid when other life history traits known to influence longevity such as body mass and clutch size are included into the statistical model. Indeed, larger species live longer, and those that reproduce fast (lay more eggs) live shorter lives.

Remarkably, the observed pattern showing longer life-spans when fewer predators are present emerges no matter how the analysis was done: at the species level, at a finer regional scale (groups of species within a certain area) or even when comparing entire bioregions. "With our results of a negative relationship between predation pressure and longevity that is largely independent of other key life history traits we were able to confirm the universality of the 50 year old evolutionary theory of aging on a broad geographical scale" concludes Mihai Valcu, first author of the study. At least in birds, where the necessary data are available for many species, the theory seems to hold.


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal Reference:

  1. M. Valcu, J. Dale, M. Griesser, S. Nakagawa, B. Kempenaers. Global gradients of avian longevity support the classic evolutionary theory of ageing. Ecography, 2014; DOI: 10.1111/ecog.00929

Cite This Page:

Max-Planck-Gesellschaft. "Predators predict longevity of birds, study concludes." ScienceDaily. ScienceDaily, 30 April 2014. <www.sciencedaily.com/releases/2014/04/140430133141.htm>.
Max-Planck-Gesellschaft. (2014, April 30). Predators predict longevity of birds, study concludes. ScienceDaily. Retrieved August 21, 2014 from www.sciencedaily.com/releases/2014/04/140430133141.htm
Max-Planck-Gesellschaft. "Predators predict longevity of birds, study concludes." ScienceDaily. www.sciencedaily.com/releases/2014/04/140430133141.htm (accessed August 21, 2014).

Share This




More Plants & Animals News

Thursday, August 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Possible Ebola Patient in Isolation at California Hospital

Possible Ebola Patient in Isolation at California Hospital

Reuters - US Online Video (Aug. 20, 2014) — A patient who may have been exposed to the Ebola virus is in isolation at the Kaiser Permanente South Sacramento Medical Center. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Flower Power! Dandelions Make Car Tires?

Flower Power! Dandelions Make Car Tires?

Reuters - Business Video Online (Aug. 20, 2014) — Forget rolling on rubber, could car drivers soon be traveling on tires made from dandelions? Teams of scientists are racing to breed a type of the yellow flower whose taproot has a milky fluid with tire-grade rubber particles in it. As Joanna Partridge reports, global tire makers are investing millions in research into a new tire source. Video provided by Reuters
Powered by NewsLook.com
Unsustainable Elephant Poaching Killed 100K In 3 Years

Unsustainable Elephant Poaching Killed 100K In 3 Years

Newsy (Aug. 20, 2014) — Poachers have killed 100,000 elephants between 2010 and 2012, as the booming ivory trade takes its toll on the animals in Africa. Video provided by Newsy
Powered by NewsLook.com
Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Newsy (Aug. 19, 2014) — Scientists have developed a new device that mimics the way octopuses blend in with their surroundings to hide from dangerous predators. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins