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: Pollen on birds shows feeding grounds

add to favorites email to friend print save as pdf

Related Stories

New research reveals clock ticking for fruit flies

2 hours ago

The army of pesky Queensland fruit flies that annually inflict many millions of dollars-worth of damage on the nation's horticultural industry may be about to see their numbers take a significant dive thanks ...

Young blue sharks use central North Atlantic nursery

Aug 13, 2014

Blue sharks may use the central North Atlantic as a nursery prior to males and females moving through the ocean basin in distinctly different patterns, according to a study published August 13, 2014 in the ...

Recommended for you

Researchers look at small RNA pathways in maize tassels

Aug 22, 2014

Researchers at the University of Delaware and other institutions across the country have been awarded a four-year, $6.5 million National Science Foundation grant to analyze developmental events in maize anthers ...

How plant cell compartments change with cell growth

Aug 22, 2014

A research team led by Kiminori Toyooka from the RIKEN Center for Sustainable Resource Science has developed a sophisticated microscopy technique that for the first time captures the detailed movement of ...

Plants can 'switch off' virus DNA

Aug 22, 2014

A team of virologists and plant geneticists at Wageningen UR has demonstrated that when tomato plants contain Ty-1 resistance to the important Tomato yellow leaf curl virus (TYLCV), parts of the virus DNA ...

User comments : 0