Faster evolution in warmer climates

An interesting study from researchers at Auckland University suggests that molecular evolution happens faster in warmer climates.   This in itself is not a novel finding, as the relationship has been found previously for ectothermic organisms -”cold-blooded” organisms whose body temperature is directly linked to climate.  What makes this new study interesting however is that this relationship also appears to hold for warm-blooded animals.  Because warm-blooded animals regulate their own body temperature, it was previously assumed that rates of genetic change in these organisms would be independent of climate. 

The study measured the rate of evolution at a mitochondrial gene (cytochrome b) in 130 pairs of mammalian species, where one species in the pair occurs at lower latitude or elevation (warmer climate), and the other occurs at higher latitude (cooler climate).  The rate of evolution was about 1.5 times higher in species found in warmer climates, and the results held even when the effect of differences in body size or population size were taken into account.  Of course this study only used one mitochondrial gene (probably because of the availability of data for this gene across a wide range of species), and there are many reasons why what goes on in the mitochondria might not be the same as what goes on in the rest of the genome, particularly for factors likely to be associated with metabolic rate.  So we can’t really say that species in the tropics are evolving faster on the basis of this result. But it will be interesting to see if this relationship holds across the rest of the genome. 

The study has just been published online in Proceedings of the Royal Society London B – see more about it here.  And the original paper here

New Zealand Evolution Survey

Just saw this on Scepticon, via Open Parachute:

Just a quick post to spread the word about a survey covering the public acceptance of evolution in New Zealand and the effect (if any) of religious/spiritual beliefs on the the extent to which evolution is accepted in the wider community. The survey can be found Here, and the results will be presented around November 2009.

The survey is being conducted by Drs Marc Wilson and Peter Ritchie of Victoria University in Wellington. I hope to secure an interview with the two Drs closer to the release of the data to get their views on the implication of the findings. In the mean time go participate in the survey, it will only take a few minutes and will be time well spent.

I”m looking forward to see the results of the survey – are creationist beliefs as pervasive here as they are in the US? Somehow I doubt it, but it will be interesting to see the results.

Modelling for better management

Conservation management in New Zealand often involves translocating endangered species to predator-free sanctuaries.  These translocations are often not as successful as they should be, but it can be difficult to pinpoint the reason why.  A major problem for newly established populations can be the loss of genetic diversity that comes with establishing new populations from only a few founders.  Loss of genetic diversity can increase the risk of extinction by reducing a population’s ability to adapt to new threats or environmental changes.  Generally, conservation management programs for threatened species should aim to retain 90-95% heterozygosity over 100-200 years, but in reality management practices are often dictated more by convenience or by what can be realistically achieved in the field at the time. 

Tuatara ready for release

New research (to be published soon in Molecular Ecology) by Victoria University PhD student Kim Miller has the potential to improve translocation planning for our native reptiles by offering guidelines for maximising genetic diversity and managing populations over time.  

A round-up of NZ science blogs

Since I became interested in science blogging a few months ago, I’ve been wondering how many other New Zealand-based science blogs there are out there.  So I endeavoured to compile a list. Straight away I ran into the issue of how to define a science blog -  should it just be restricted to a blog about science written by a scientist? Where do you draw the line between blogs about natural history or the environment and blogs about science?  In the end I decided that a science blog should be mostly made up of posts about peer-reviewed science – this includes posts about the research itself, political/cultural issues surrounding research, and science communication.  Most of the ones below are written by scientists (but not all) 

Where did swine flu come from?

Swine flu is at the forefront of the news again, so it is timely that an analysis of the origins of the virus has now been published online in Nature.  A team of researchers from the UK, Hong Kong and the US used evolutionary analysis to reconstruct how and when this strain of the virus (which is now referred to as swine-origin influenza-A (H1N1) virus, or S-OIV) developed.  By comparing the genome sequences of the pandemic strain with 100s of other strains from pigs, birds and humans that represent the full spectrum of influenza A viruses, the team was able  to build a family tree of S-OIV and date its emergence. 

Their analysis shows that S-OIV is derived from several viruses already circulating in pigs, some of which were originally of avian or human origin.  The initial transmission of S-OIV to humans occurred several months before the outbreak was recognised.

How to improve science communication?

Some new initiatives in science communication have been suggested in an article in Nature Biotechnology this week.  The article is based on a science communication workshop that was held in Washington DC earlier this year, and one of the authors, Matthew Nisbet, has a run-down of it on his blog Framing Science – see here.

The eight main recommendations of the article are…

Photo of the month

I’ve decided to start a couple of monthly series, in order to keep this blog on track and create a few themes.  Photo of the month is quite obvious, but the “rules” are that it will be an native species from the NZ forest, in its natural environment*.

For this month, here is a northern rata flower (Metrosideros robusta) to remind you of summer.  Taken on the slopes of Mt Kapakapanui in the western Tararua ranges, just north of Wellington.   Interesting that the flower was quite yellowish instead of red - can any botanists out there shed some light on why this is?

 

*Rules may be subject to change

Sex determination – even more complicated than you thought

Reptiles do all sorts of crazy things when it comes to sex determination.  Some use good old fashioned sex chromosomes like mammals do, but in other species the temperature that the egg is incubated at determines the sex of the offspring.  For instance in the tuatara, eggs that are incubated at 23 degrees are uniformly male, and eggs incubated at 18 degrees always turn out female.   Some reptiles seem to use a combination of both - they have sex chromosomes, but these are overridden when the eggs are incubated at extremely high or low temperatures.  Now it seems it could be even more complicated for some species, as a recent study out of Rick Shine’s lab at the University of Sydney has found that egg size is also a determining factor.  In their study of the Eastern three-lined skink (Bassiana duperreyi), they found that sex chromosomes, temperature and egg size interact to determine the sex of the offspring, with larger eggs incubated at low temperatures producing females, regardless of their sex chromosomes.   

Ed Yong from Not Exactly Rocket Science has a nice write-up about this paper - go check it out!

The paper citation is: Radder, Pike, Quinn and Shine (2009) Offspring Sex in a Lizard Depends on Egg Size. Current Biology in press doi:10.1016/j.cub.2009.05.027

Sniffing out disease

We all know that other mammals have a far more finely tuned sense of smell than we humans do.  In fact, the olfactory abilities of mice even extend to being able to identify individuals infected with parasites.  Now the discovery of a new class of olfactory receptors, reported in Nature last week, has provided an insight into what underlies this ability. 

The mammalian olfactory system comprises two major divisions: the main olfactory system, which deals mainly with environmental odours, and the vomeronasal organ, which plays a role in detecting pheromones.  The mammalian capacity to distinguish between a huge array of odours lies with the fact that individual sensory neurons in the olfactory system express only a single type of receptor protein on their surface. Each of these receptor types is tuned to a specific type of odorant and transmits signals to a specific part of the brain.  Until now only 4 major types of receptor were known: odorant and trace-amine associated receptors, mostly expressed in the main olfactory system, and vomeronasal type 1 and type 2 receptors expressed in the vomeronasal organ.  All these receptor types are members of the G-protein-coupled receptor (GPCR) superfamily, which initiate signalling pathways within chemosensory cells. 

Riviere and colleagues at the University of Geneva screened mouse vomeronasal tissue for new types of GPCRs and discovered that some sensory neurons express a class of protein known as formyl peptide receptors (FPRs).  FPRs were previously known to be expressed in the immune system where they have a role in mediating cellular responses to disease, inflammation and cell damage.  Riviere and colleagues found that the FPRs expressed in the vomeronasal tissue respond to the same activators that stimulate the immune system FPRs – that is, peptides and lipids derived from bacteria or associated with inflammation.  Five different types of FPR were found in the vomeronasal tissue.  In keeping with other types of olfactory receptor, each FPR responds to a distinct, but overlapping array of compounds and individual vomeronasal sensory neurons expressing FPRs do not express any other types of olfactory receptor. 

Although the role of FPRs has yet to be confirmed by behavioural studies, this report provides compelling evidence that they represent a novel class of olfactory receptor that allows the detection of diseased individuals or spoiled food.  And in case you’re wondering, there’s no evidence that FPRs are found in the olfactory system of humans – we only appear to have them in our immune system.

Rivière, S., Challet, L., Fluegge, D., Spehr, M., & Rodriguez, I. (2009). Formyl peptide receptor-like proteins are a novel family of vomeronasal chemosensors Nature, 459 (7246), 574-577 DOI: 10.1038/nature08029

Dead Duck Day – 5 June

 

An important announcement  just arrived in my inbox:

Dead Duck Day – 5 June

On 5 June 1995 an adult male mallard (Anas platyrhynchos) collided with the glass façade of the Natuurmuseum Rotterdam and died. Another drake mallard raped the corpse almost continuously for 75 minutes. Then the author, Kees Moeliker, disturbed the scene and secured the dead duck. Dissection showed that the rape-victim indeed was of the male sex. It is concluded that the mallards were engaged in an ‘Attempted Rape Flight’ that resulted in the first described case of homosexual necrophilia in the mallard.

For the pdf of the paper visit   http://www.nmr.nl/nmr/pages/showPage.do?itemid=1930&instanceid=16 

This paper was awarded an Ig Nobel Prize for Biology in 2003

See also http://moeliker.wordpress.com/the-duck/

It is the organizers’ wish that Dead Duck Day becomes a worldwide event on June 5th to commemorate the dramatic death of any duck anywhere and to find ways to prevent the deaths of ducks by traffic, hunting, windows, poison and other unnatural causes.