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Handicaps, Honesty and VisibilityWhy Are Ornaments Always Exaggerated?

Thu, 23 Oct 2014 13:30:30 +0000

Sexual selection is a form of natural selection that favours traits that increase mating success, often at the expense of survival. It is responsible for a huge variety of characteristics and behaviours we observe in nature, and most conspicuously, sexual selection explains the elaborate ornaments such as the antlers of red deer and the tail […]

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Why Are Ornaments Always Exaggerated?
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PREDICTS Project: Land-Use Change Doesn’t Impact All Biodiversity Equally

Mon, 13 Oct 2014 09:17:53 +0000

Humans are destroying, degrading and depleting our tropical forests at an alarming rate. Every minute, an area of Amazonian rainforest equivalent to 50 football pitches is cleared of its trees, vegetation and wildlife. Across the globe, tropical and sub-tropical forests are being cut down to make way for expanding towns and cities, for agricultural land […]

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Calculated Risks: Foraging and Predator Avoidance in Rodents

Fri, 03 Oct 2014 10:07:08 +0000

Finding food is one of the most important tasks for any animal – most animal activity is focused on this job. But finding food usually involves some risks – leaving the safety of your burrow or nest to go out into a dangerous world full of predators, disease and natural hazards. Animals should therefore be […]

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Foraging and Predator Avoidance in Rodents
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Applying Metabolic Scaling Laws to Predicting Extinction Risk

Thu, 25 Sep 2014 10:32:49 +0000

The Earth is warming. That much were are now certain of. A major challenge for scientists hoping to ameliorate the effect of this on biodiversity is to predict how temperature increases will affect populations. Predicting the responses of species living in complex ecosystems and heterogenous environments is a difficult task, but one starting point is […]

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The Importance of Size in the Evolution of Complexity in Ants

Tue, 16 Sep 2014 10:14:37 +0000

Ants are amongst the most abundant and successful species on Earth. They live in complex, cooperative societies, construct elaborate homes and exhibit many of the hallmarks of our own society. Some ants farm crops, others tend livestock. Many species have a major impact on the ecosystems they live in, dispersing seeds, consuming huge quantities of […]

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Mitochondria and the great gender divide - GEE's Profs Andrew Pomiankowski, Rob Seymour and Dr Nick Lane and Zena Hadjivasiliou publish paper in Proceedings of the Royal Society B

13 December 2011

8 December 2011

Eukaryotic cells

Why are there two sexes? It’s a question that has long perplexed generations of scientists, but researchers from UCL have come up with a radical new answer: mitochondria.

Using a new mathematical model, the team led by Dr Nick Lane and colleagues from the UCL CoMPLEX, and the Research Department of Genetics, Evolution and Environment showed that inheriting mitochondria from only one parent – in effect, the ‘female’ – improves fitness by optimizing the interactions between the two genomes. The paper is published today in Proceedings of the Royal Society B.

Dr Lane said: “The difference between the sexes boils down to the need to keep fit when energy demands are high”.

Descended from free-living bacteria, mitochondria were swallowed whole by another cell between one and a half to two billion years ago. But despite being engulfed, these tiny power packs have retained their own tiny genome, encoding just a handful of proteins, all of which are necessary for generating energy in the cell. 

The strangest thing about this odd arrangement is that cell respiration relies on proteins encoded by two genomes, the tiny mitochondrial genome and the nucleus, where most DNA is stored. For respiration to work properly, the two genomes must work together to encode proteins that interact with nanoscopic precision. 

"This difference seems to be the deepest evolutionary difference between the two sexes" - Zena Hadjivasiliou

Zena Hadjivasiliou, a PhD student in CoMPLEX and first author of the paper, said: “A clue to the answer was found in simple single celled organisms called protists. These tiny creatures normally have two sexes, despite the fact that it is impossible to tell them apart even with an electron microscope. 

“The only real difference between these ‘sexes’ relates to mitochondria, the tiny power packs found in all complex cells. In simple protists, one sex passes on mitochondria, the other does not,” added Hadjivasiliou. 

While the model shows that two sexes are only borderline necessary in simple cells like protists, but by the time large, energetically demanding organisms had evolved, two sexes made a big difference to maintaining fitness. 

Hadjivasiliou said: “This difference seems to be the deepest evolutionary difference between the two sexes. As a result all the gender wars throughout nature ultimately stand on this pinhead.”

Image: Altmann's Bioblasts - The four seasons (Credit: Odra Noel)

Links

Nick Lane
Energy revolution key to complex life
UCL’s Nick Lane wins the 2010 Royal Society Prize for Science Books
Research in Proceedings of the Royal Society B
UCL CoMPLEX
Research Department of Genetics, Evolution and Environment

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