Research into a group of Australian native bees may answer the question why some species create sterile worker castes and others don't.
Associate Professor Michael Schwarz of Flinders University in Adelaide and colleagues argue the group may be the result of genetic changes in response to harsh environmental conditions.
The research, which focuses on a small red bee, known as Allodapini, appears today in the journal Proceedings of the Royal Society B.
Allodapini, which are found across Southern Africa, Madagascar and remote parts of Australia, live in a variety of different social set-ups. Most allodapine bees form small social groups, with many fertile females in a nest.
But some live in nests with a single fertile female and a large sterile worker caste that forage for the hive - similar to the common honey bee (Apis mellifera).
Schwarz says, in places like central Australia and the deserts of central Madagascar where the foraging season is limited to a brief period while the desert is in flower, the allodapine bees have developed sterile worker castes.
"The most important thing about this study is that it sets out to show that the genetic changes which are associated with having a worker caste come about because of ecological pressures," says Schwarz.
Schwarz says to gain a better understanding of the genetics and ecology of native bee species around the world, the first step is to understand their social organisation.
"There are a couple of take home messages from our research. If we want to understand the evolution of sociality and then the evolution of worker castes we need to look at ecological factors that shaped the change. We need to look at genes but in the context of ecology."
Schwarz says native Australian bees are likely to be increasingly important as disease kills off many of the world's honeybees. The consequences for plant pollination could be drastic. Schwarz says native bees will have to take up the slack.
"Overseas there have been a worldwide decline in honeybees which are important pollinators. It will happen in Australia sooner or later as those diseases come over here and then our native bees will become a crucial fallback pollinator", he says.
Schwarz also believes native bees could also become an important tool in monitoring climate change.
"As we better understand the ecology of these bees then that can become important in managing their biodiversity," he says.
"For example we now have a major project in the Southwest Pacific looking at the native bee fauna there and how that might be affected by climate change.
"To understand that we have to understand their ecology and to understand that we have to understand their social behaviour as well."