Male deer are born to live fast, die young

Aug 31, 2007
Iberian Red Deer
Roaring male Iberian red deer with females (photograph by Juan Carranza).

In the September issue of The American Naturalist, Juan Carranza (Biology and Ethology Unit, University of Extremadura, Spain) and Javier Pérez-Barbería (Macaulay Institute, United Kingdom) offer a new explanation for why males of ungulate species subjected to intense competition are born with lower survival expectancies than females.

The research reveals that male ungulates have smaller molars relative to their body size – and hence less durable teeth that will wear out sooner, which might contribute to their shorter lives compared with females.

Natural selection favors reproduction rather than survival; the cost of reproduction compromises survival. Males of species subjected to intense male-male competition for access to females are known to have shorter life expectancies than females. Earlier aging in males might be related to higher reproductive costs, especially when lifetime reproductive success in males takes place within the few years when they can win contests and maintain their dominance.

By comparing body and dental size of males and females of 123 species of ungulates, the authors offer another compelling explanation for why male ungulates lead shorter lives. They estimated the pattern of change of these traits along the evolutionary development of the group and found that for species where a single male has many females and where the males and females are different sizes, the rate of increase of dental size was lower than that of body size.
As a result, smaller teeth (in comparison to body size) are produced in males. It is possible that natural selection did not produce larger, more durable teeth because there was no reproductive return from it, since males in these species do not generally increase their success by living longer after prime age.

“These findings,” the authors state, “provide us with interesting insights into how natural and sexual selection design our bodies and their longevity.”

Citation: Juan Carranza and F. Javier Pérez-Barbería, "Sexual selection and senescence: male size-dimorphic ungulates evolved relatively smaller molars than females", The American Naturalist (2007) volume 170:370–380. DOI: 10.1086/519852

Source: University of Chicago Press Journals

Explore further: 'Killer sperm' prevents mating between worm species

add to favorites email to friend print save as pdf

Related Stories

Google made failed bid for Spotify

2 hours ago

Internet titan Google tried last year to buy streaming music service Spotify but backed off for reasons including a whopping price tag, the Wall Street Journal reported on Tuesday.

Thieves got into 1K StubHub accounts

3 hours ago

(AP)—Cyber thieves got into more than 1,000 StubHub customers' accounts and fraudulently bought tickets for events through the online ticket reseller, a law enforcement official and the company said Tuesday.

Microsoft CEO sees 'bold' plan as 4Q tops Street

3 hours ago

(AP)—Microsoft Corp. CEO Satya Nadella painted an upbeat vision of the future Tuesday, saying that the next version of Windows will be unified across screens of all sizes and that two money-losing units—Nokia ...

Recommended for you

'Killer sperm' prevents mating between worm species

2 hours ago

The classic definition of a biological species is the ability to breed within its group, and the inability to breed outside it. For instance, breeding a horse and a donkey may result in a live mule offspring, ...

Rare Sri Lankan leopards born in French zoo

5 hours ago

Two rare Sri Lankan leopard cubs have been born in a zoo in northern France, a boost for a sub-species that numbers only about 700 in the wild, the head of the facility said Tuesday.

Japan wraps up Pacific whale hunt

6 hours ago

Japan announced Tuesday that it had wrapped up a whale hunt in the Pacific, the second campaign since the UN's top court ordered Tokyo to halt a separate slaughter in the Antarctic.

Researchers uncover secrets of internal cell fine-tuning

6 hours ago

New research from scientists at the University of Kent has shown for the first time how the structures inside cells are regulated – a breakthrough that could have a major impact on cancer therapy development.

User comments : 0