Nav: Home

Yellow or black, large or small? Ant color and body size respond strongly to environment

September 08, 2016

A University of Liverpool study of ants across three continents has revealed that their colour and size is strongly influenced by their environment, and that the dominant colour and average body size can change from year to year as temperatures vary. This finding has implications for how ant communities will cope with rising global temperatures.

Ants are ectotherms and so rely on the temperature of their surrounding environment to control their metabolic activity. Previous studies from individual locations or single species have found that larger bodied ectotherms with dark colouration do well in cold places. Large bodies retain heat whilst dark colours help individuals to gain heat quicker than their paler counterparts do. Combined, these two traits are highly beneficial as they allow ectothermic individuals to forage and remain active for longer even under cool conditions.

Researchers at the University's School of Environmental Sciences wanted to test whether these ideas of ectotherm thermoregulation held across species and at large geographic scales. They collected and analysed information on the abundance, body size and colour of ants on 14 different mountains from locations in South Africa, South America and Australia. Some of the sites were sampled repeatedly for up to seven years. This diversity of elevations and latitudes provided a huge range of external ambient temperatures (from 0.5 to 35°C).

They found that the colder the external temperature is, the larger and darker ants were, and vice versa. Consequently, communities of ants in sites closer to the South Pole or near the tops of mountains, where it was colder, would tend to be dominated by dark and large bodied ants. In warmer places the ant species were smaller and lighter in colour.

They also found that this effect depended on the amount of UV-B radiation present at the sites. Melanin, the pigment which makes ants darker, also protects against harmful UV-B rays. It effectively acts as a sunblock. This caused ants in the central Australian desert to be dark in order to counter the extremely high UV-B radiation. Ordinarily, the ants here should have been pale to reflect the harsh desert sun.

Interestingly, these same patterns were seen through time and the study was able to show that when temperatures changed from year to year so did the makeup of the local ant community. Darker species were more abundant in cool years and paler species were more abundant in warmer years.

Dr Tom Bishop, who led the research, said: "Our results have two key messages. First, that the environment has a really strong influence on the identities and relative abundances of the ant species that you may find at a given location - this is mediated by the colouration and size of those different species.

"Secondly, these effects can operate over across mountains and continents but also across short time periods. These results will help us to understand why ant species are distributed in the way that they are across the globe, but also highlight that as the climate changes there may be certain ways in which the ants respond. On a warmer planet, for example, we would expect that smaller and lighter coloured ants will come to predominate and this may have important cascading effects on ecosystems as different ants have different functions."

Co-author and Liverpool Ecologist, Dr Kate, Parr, added: "Our findings could be applied to many other insect or ectotherm groups too and could explain a lot of the observed colour and body size diversity patterns globally."

The research is published in the journal Global Ecology and Biogeography.

University of Liverpool

Related Ants Articles:

Using seaweed to kill invasive ants
Scientists at the University of California, Riverside have developed an inexpensive, biodegradable, seaweed-based ant bait that can help homeowners and farmers control invasive Argentine ant populations.
Ants rescue their injured
Ants operate a unique rescue system: when an insect is injured during a fight, it calls for help.
Wasps, ants, and Ani DiFranco
A University of California, Riverside graduate student has discovered several news species of wasps, including one that she named after musician Ani DiFranco.
Ants find their way even while traveling backward
Some of us struggle to find our way back home while walking from an unfamiliar location in the usual, forward direction.
Stabilizing evolutionary forces keep ants strong
Researchers are finding evidence of natural selection that maintains the status quo among ant populations.
Ants and epiphytes: A longstanding relationship
The first farmers on the Fijian archipelago were ants: For millions of years, an ant species on the islands has nurtured epiphytes, which provide them with nesting sites.
Carpenter ants: When social instructions may be dangerous
Why do social beings sometimes put their own common sense aside to follow the lead of others, even though by doing so they could be brought to death's door?
Are red imported fire ants all bad?
Red imported fire ants have earned a justifiably bad rap across the south and most Texans would be hard put to name a single redeeming quality the ants have.
Ants have dual navigation systems
Ants visually track the motion of objects as they move through their environment in order to determine the distance they have traveled, a new study reports.
Reversing ants navigate successfully despite going backwards
Desert ants are remarkable navigators, but how do they locate home when they have to shift into reverse when dragging a heavy load?

Related Ants Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...