Turtle Power! Farewell and thanks Mark Hamann

This is a creek that our curator for the last week, Dr Mark Hamann, cleaned up just a week before.  This is what it looks like two days after it rained:

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It’s just a small example of the challenges that faces environmental scientists and environmentalists everywhere in dealing with pollution and its effects.

This week, environmental scientist Mark Hamann gave us an insight into this world, and into the world of turtles, dugongs and other marine animals. Now, every week at Real Scientists HQ, we say “this curator is the best one so far,” and it’s true, and yet again we were privileged to host a wonderful scientist who was also a wonderful communicator.  Mark Hamann specialises in turtles and based at Townsville’s James Cook University, was a popular and outstanding curator for Real Scientists, tweeting live from beaches, the Great Barrier Reef, even a turtle hospital! Mark showed us the challenges of having to manage the expectations and limitations of government, industry, community in dealing with environmental issues. He also talked about his work with Indigenous scientists and the importance of Indigenous knowledge in environmental management. We got to see first hand what happens to turtles when our carelessness and indifference results in rubbish in our waterways and oceans. But most of all, we got to look at BABBY TURTLES IS THERE ANYTHING CUTER:

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One of the highlights of the week was when Mark hosted a session – via twitter, of course – with @DugongClass, a Year 1/2 from Newtown, Sydney. Asking questions of Mark live over Twitter, they also got to pass on questions that Mark then asked of the foremost dugong expert in the world, Prof. Helene Marsh. It was a fantastic exercise in direct access and a very proud moment for us at RS.  The Storify of that extreme cuteness is here. This is what it’s all about – reaching out.  We welcome more interaction with school students, please get in touch with us if you’d like your class to engage with a – well, a Real Scientist!  Checkout the Storify for more awesome photos and tweets from Mark’s week.

So massive thanks from Real Scientists – admin and community for being such a great sport.  We’re looking to host Mark at our Facebook space and Google hangout sometimes in the near future, and we hope you’ll join us then.

Next up, we welcome superstar science communicator Eva Amsen – @easternblot, tweeting from England!  Welcome, Eva.

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Why sex is bizarre

No, we haven’t gone all Carrie Bradshaw on all of y’all. Last evening’s enthralling discussions with this week’s fantastic @RealScientists curator @turtlesatJCU about temperature-dependent sex determination in turtles – how the temperature of the sand they are surrounded by dictates the sex of the developing turtle embryo – reminded this particular RS admin just how wonderfully bizarre sex determination is in an evolutionary sense.

boneIt’s generally the case that if something’s important, it’s important to make sure that the instructions for making it aren’t easy to lose. Anyone who’s tried to assemble a flat pack Ikea wardwobe without the cartoon diagrams or the Allen key would attest to this. So it is with vertebrate development. The developmental pathways – the basic blueprints, floorplan, instructions, Lego pieces, however you want to think of them – which underpin key developmental structures are, in general, strongly conserved (that is, they’ve not changed much through evolution.) The genes which are expressed and the cell types which are involved in directing the making of a limb – in particular its outgrowth and its ‘patterning’ (a developmental biology term for how future adult structures are laid out in the developing embryo) – are the same between all vertebrates. All there is, really, is a little tweaking in terms of expression domains (i.e. the precise timing of when key developmental regulators are switched on and off, and in what cells of the developing limb) to produce a whale flipper from the same basic genetic ‘blueprints’ as the bat wing. This idea that if it’s important, it’s conserved, runs right through evolution (and particularly ‘evo devo’, the research field at the intersection of evolution and development). One of the most important genes in human heart development is the analogue of one which directs development of the heart in the fruit fly Drosophila, called Tinman.*

Except you can chuck all that out the window with sex determination. You’d think that since sex was such an important evolutionary construct – the ability to reshuffle the genes of your offspring to create the potential for evolutionary advantage is clearly crucial to the success of the majority of animal species, since so many have it – that the instructions for how to create different genders which can make with the bunga-bunga in order to recombine chromosomes and create new genotypes would go right back in the evolutionary lineage.

Nup.

Mammals like us (assuming you are a human, which I feel is a reasonable leap of confidence) have a system based on the inheritance of the sex chromosomes X and Y, where embryos with two Xs develop as females and those who inherit an X and a Y develop as males. This was pinned down in the late 80s/early 90s to a particular gene on the Y chromosome called SRY (sex determining region on the Y chromosome – mouse and human researchers aren’t as interesting with their gene names as Drossie peeps) which acts as a ‘switch’ midway through gestation. If it’s there, its expression is switched on briefly in the embryonic precursor tissue of the gonad (which, uniquely in development, is a developmental structure that can go on to form two completely different organs from the same origin tissue) and the testis development pathway is kicked off – if it’s not, i.e. if you’re XX, SRY isn’t expressed, and the pathway ‘defaults’ to female (and yes this is a slightly patriarchal view which has been challenged but we’ll set that aside for the moment). But SRY and XX/XY is by-and-large a mammalian deal. Reptiles, as discussed on @RealScientists last night, have temperature-dependent sex determination; it’s thought a reptile with TSD may have been the evolutionary precursor of vertebrate species with chromosomal sex determination. Birds such as chickens have chromosomal sex determination, a bit like XX/XY (it’s ZZ/ZW) but there’s no analogous sex determining gene driving the development of one sex or the other. Some fish have sex determining chromosomes or genes a bit like an SRY in broad function, but nothing like it in terms of molecular or genetic similarity; other fish have TSD. Drosophila have an inheritable sex chromosome (XX/X0) but again the molecular ‘bits of Lego’ involved are nothing alike other species. Nematode worms (C. elegans, another invertebrate ‘model organism’) have an unrelated XX/XO system which directs development of males, females and hermaphrodites. What we have here then is a critical developmental process, central to the survival of the majority of successful animal species on Earth, which has bugger-all in common at the level of how that process is switched on between those species. It looks like case after case of evolutionary novelty – that is, nearly each species has evolved a completely different way of determining sex, and has run with it.

What’s interesting though is the ‘downstream’ stuff often IS conserved, even in species with very different means of reproduction, or gonad structures. Hormones like aromatase, and key regulatory genes such as DAX1, DMRT1 and SOX9 which are critical in mammalian sex determination and gonad development keep turning up in the pathways of other species, even those without ‘genetic’ sex determination like reptiles with TSD. In an evo-devo sense, pretty much the same genetic players and partners are deployed in the process of making boy and girl bits – they’ve just been co-opted into the process by completely different switch mechanisms, which are evolved and selected for with no apparent commonality.

For further reading on this, have a search for ‘evolution of sex determination’ on Google Scholar. Or look it up on Wikipedia, which is generally pretty good for SCIENTS stuff.

And to finish, BABBY TURTLES.

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*Drosophila researchers have always been big on the quasi-amusing gene names, usually named for some characteristic of a ‘mutant’ strain generated with that gene ‘knocked out’. They go a bit weird cooped up in fly rooms counting and classifying wing variants on tiny fruit flies. Many of which have a habit of flying up the noses of the investigators, if not anaesthatised correctly. Apparently they taste like sesame seeds. Don’t ask.

Possibly Ninja Turtle Power – Mark Hamann joins Real Scientists

Azure, tropical water, golden beaches, turtles…This week’s Real Scientists curator may have the coolest job ever. I know we say that every week, but it’s true.  Real Scientists takes you to sunny, semi-tropical Townsville, Australia to meet Environmental Scientist Dr Mark Hamann (@turtlesatJCU), Senior Lecturer in Environmental Science at James Cook University.  Mark’s research focuses on minimising human impacts to tropical marine wildlife and their habitats.  Originally hailing from Adelaide, South Australia, Mark completed his PhD at the University of Queensland, spent some time in the Northern Territory and went on to work for the International Union for the Conservation of Nature. He travelled the Vietnamese coast, talking to people about turtles.  So he got to look at the scientific and social aspects of turtle habitats and conservation.

Mark in water- no ropes JCU

Mark returned to Queensland to research the effects of a new mega-dam on the habitats of freshwater turtles, and ended up staying in Queensland.

Mark has four main areas of research. He assesses the vulnerability of marine wildlife (marine turtles, dugong and inshore dolphins) to climate change, plastic pollution and coastal development. He also gets to attach gadgets to marine turtles and dugongs to study their behaviour in coastal environments.  In looking at how human waste affects the environment, he is developing techniques to quantify plastic pollution in river and coastal environments.  And he also carries out research associated with developing community-based projects for marine turtles in Torres Strait.

As with many scientists who are not lab-based, Mark’s work involves complex environments, systems, varied work and multiple stakeholders:

Within these projects I combine field based and experimental biological science with quantitative and qualitative social science. Most of my research involves working alongside Industry, Government agencies, Indigenous communities and NGOs to strengthen management options for marine wildlife in Australia. I am involved with several national and international marine turtle initiatives. For example I am the Co-Vice Chair of the IUCN Marine Turtle Specialist Group and a member of the IOSEA Marine Turtle MoU’s Science Advisory Panel. I have a great group of post-graduate students who help keep me sane and ensure that I actually go out and look at turtles every so often.

Mark Hamann

We asked Mark how he ended up in science:

My path into science has taken a few turns. I enjoyed science at school, but I did not really think of it as a career because I did not really know what scientists did. I loved the outdoors and the environment and by chance I met some biologists at Innes National Park and after a few camp fire chats I was convinced to apply to a University. I started with an environmental science major at UNE, switched to zoology and biochemistry at Flinders and then did a PhD in anatomy at UQ. I took a similarly convoluted path to from post doc to academic.

So the path to science isn’t always a straight one, but it can mean that you get to combine all your loves and interests in one rewarding career.  Welcome, Mark, and we hope the weather leads  to some excellent turtle photos [Ed: Beach shots will suffice in the meantime].