Sexual arms race drives range expansion in UK diving beetle species

June 29, 2016

A battle between the sexes may be behind a dramatic shift in diving beetle populations over the past three decades, a new study shows.

Female choosiness has led to the evolution of rough body surfaces in some species which make it harder for males to hold on to them during mating. In a few cases, 'rough' and 'smooth' females are found within the same species, sometimes having different geographical ranges.

Now research led by Plymouth University has examined such a situation in a common European diving beetle, Hydroporus memnonius, and found that populations with 'rough' or 'smooth' females also have different males.

In 'rough' populations, males have enhanced suckers on their front and middle feet, representing a male counter-response in the sexual arms race which, it was predicted, would enable the 'rough' female form and its associated male to spread at the expense of the 'smooth' form, replacing it in areas where the two meet.

In the UK, 'rough' and 'smooth' Hydroporus memnonius meet close to the Scottish Border, in a contact zone first identified around 30 years ago. By comparing data collected in the 1970s and 1980s with a recent survey, scientists showed this change is indeed occurring.

The study, published in PeerJ, also shows that this shift, unlike many other recent changes in the distribution of plants and animals, is unlikely to be down to climate change, and instead seems to be the first example of a change in distribution resulting from the battle of the sexes.

Professor David Bilton, lead author on the study, said: "Rough and smooth females have been known in some species of diving beetles for at least a couple of centuries. The roughened surface of some females was mentioned by Charles Darwin in one of his classic works, where he cited it as an example of co-operation, seeing it as a way in which females made it easier for males to hang onto them underwater. We've known for a while that the opposite is actually true, and the rough surface is a way in which females make things harder for males and so exert greater control over mating.

"In this Hydroporus, the male counter-response to female roughness should make it easier for such males to hold on to any surface. In such a situation these males should expand their range, regardless of female form, as they'd be at an advantage across the board. Given that smooth females are less able to resist potentially costly matings, we'd also expect rough females to increase in number. This is exactly what we see where the two sets of populations meet in the UK, and in the end, the process may lead to the disappearance of smooth form altogether."

Hydroporus memnonius is found across continental Europe - from the Balkans and Italy in the south to Scandinavia in the north - and is widespread throughout the British Isles. But locations where 'rough' and 'smooth' females co-exist are relatively rare, with the best recorded contact zone being in the Scottish Borders and Cumbria.

During 2007-08, samples were obtained from 27 populations in northern England and southern Scotland, spanning the transition zone between the two forms. A highly significant change has occurred over this time period, 'rough' females and their associated males expanding north and west by approximately 40-50 km in around 30 years.

The paper concludes: "On the basis of both thermal tolerance data and the wider global distribution of these morphs we argue that the observed range shift is highly unlikely to have resulted in response to climate warming, but is instead consistent with predictions based on the dynamics of sexually antagonistic coevolution in this beetle."

University of Plymouth

Related Climate Change Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.

Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.

Read More: Climate Change News and Climate Change Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to