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I've always rather liked ducks, ever since we hand-reared some ducklings back when I was still a school-kid. Mind you, the innocent me of those days didn't know what I know now about the effects of sperm competition and sexual selection on their reproductive organs. (Those of an enquiring mind will learn more - much more! - in this excellent piece by Ed Yong.) I liked them enough to make mallard behaviour the focus of my Honours dissertation, before moving on to swans.


Ducks were domesticated multiple times by humans perhaps beginning around 4,000 years ago in Egypt, but dated to around 500BC in China (Zhou, Li, Cheng, Fan et al., 2018). Domestic breeds - with the exception of Muscovy ducks - are all derived from the mallard, Anas platyrhynchos. Selection by humans has given rise to quite a range of different phenotypes, with breeds differing most obviously in size and colouration. One of the most striking is the Pekin duck breed (image below), with its white feathers, very large size relative to the ancestral mallard, and its excellent rate of egg production. (Those yummy duck legs in the supermarket chiller are quite likely from Pekin ducks.) These characteristics made the Pekin duck an ideal focus for Shuisheng Hou, Yu Jiang, and their colleagues in their just-published search for the 'fingerprints' of artificial selection in domesticated waterfowl.  (However, as we'll see, their work has wider relevance.)


The paper is based on a large sequencing exercise: the team carried out whole-genome resequencingA of 40 wild mallards, 36 ducks from 12 different indigenous domesticated breeds in Southern China, and 30 Pekin ducks from three separate populations, plus another 1026 individuals produced by crossing mallards and Pekin ducks.

It seems that in China there were two phases of artificial selection during duck domestication. The first saw the development of the various indigenous domestic breeds, and the second, the specific development of Pekin ducks. There appears to have been a genetic bottleneck at the point where that breed first formed, followed by either quite a bit of genetic drift, or else artificial selection targeting those desirable white feathers and large bodies.

The researchers identified 45 'candidate divergent regions' (CDRs) on the ducks' chromosomes that appear to be related to domestication, some of which were 'markers' for various genes. For example, two CDRs were closely associated with genes involved in reproduction and nervous system activity: bear in mind that the behaviour of domesticated animals differs from that of their wild brethren.

One CDR was used to identify a gene (MITF) involved in the production of melanin. Mutations in this gene result in a loss of pigment, apparently by down-regulating the activity of all other genes downstream of it in the melanin-producing metabolic pathway. Further genomic work led the team to decide that a mutation in MITF is the underlying cause of the striking white plumage of Pekin ducks, one that would have been strongly selected for once it appeared as the down, in particular, is much valued for quilts and padded clothing.

And other CDRs appeared to be associated with a part of the genome linked to body size - traits such as the weight of various body parts & of the body as a whole. Additional genomic work traced this to a 'growth factor' gene (IGF2BP1) that's "consistently expressed in Pekin ducks but ... barely expressed in mallards" from hatching to at least 8 weeks of age. And feeding studies suggested that the Pekin duck form of IGF2BP1 affected both the feed intake of the birds and the efficiency with which they converted food to body mass, resulting in their bigger body size.

This finding has implications beyond the ducks, though: the researchers feel it's likely that

consistent postnatal expression of IGF1BPa in other animals may also enlarge their body size. Therefore, IGF2BP1 is a strong performance target for meat production ... in animals.

And from an evolutionary point of view, it's notable how quickly these genetically-controlled traits - white plumage and larger body size - became fixed by artificial selection in just over 2,500 years of duck domestication.


A This technique's also been used in a recently-published study on domestication of cattle in East Asia.


Z.Zhou, M.Li, H.Cheng, W.Fan, Z.Yuan, Q.Gao, Y.Xu, Z.Guo, Y.Zhang, J.Hu, H.Liu, D.Liu, W.Chen, Z.Zheng, Y.Jiang, Z.Wen, Y.Liu, H.Chen, M.Xie, Q.Zheng, W.Huang, W.Wang, S.Hou & Y.Jiang (2018) An intercross population study reveals genes associated with body size and plumage colour in ducks. Nature Communications. DOI: 10.1038/s41467-018-04868-4

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There's a lot of rhetoric these days around educating students 'for the 21st century', and the need for '21st century skills', while (not always but often) disparaging what is currently taught & how it's delivered. Catherine Kelsey has a good op.ed. on this on the Education Central site, in which she comments on two other opinion pieces that I - like her - had found somewhat polarising in their approaches (see here and here), and says: 

[They] are both right and both wrong: right because today we do need to ensure that we do teach the "ability to think critically, to persevere, to solve problems and relate to others" and that "great teachers improve student learning by providing a relevant and engaging curriculum ... by supporting the personal growth of each individual student". Where they are both wrong is in the suggestion that this is "new" and a shift in "paradigm"...

[G]reat teaching has always been there and has always encompassed the skills raised in both articles as well as inspiring a passion for knowledge

and delivery of those skills is particularly important: as Sun Kwok observes in his perspective article, Science education in the 21st century, "students are going into increasingly diverse careers", and not necessarily the roles traditionally expected of science graduates. His reflective paper argues for an integrated approach to teaching science, as a means to prepare students for those diverse careers (many of which may not even exist at the moment), and makes for an interesting read. 

Kwok led the Faculty of Science at the University of Hong Kong (UHK) through the implementation of some fairly significant changes in its curriculum. The intention was to give students the competencies and the flexibility to allow them to move into careers well outside those for which the traditional scientific disciplines might have prepared them: a curriculum "for the 21st century". His perspective piece is a description, an explanation, and a challenge to other institutions to reconsider their own curriculum development and delivery.

He suggests that universities "should develop students as people, prepare them to think, and set the foundation for life-long self-learning and self-improvement". However, there are barriers to this, in that

there is often a mismatch between educators' and students' expectations. Many students believe that universities will provide them with a meal ticket for a better job

and one of the challenges faced by those leading changes in tertiary curricula lies in the need to carry both current and prospective students along with them. And staff: academics can (in my experience) be somewhat suspicious of alternative methods of teaching delivery.

Kwok believes that a key problem with science education (at all levels) is that it can be seen as irrelevant to the real world. I'd have liked to see citations for the statement that students in physics & maths "feel that their discipline contents are abstract" & that they can't relate what they learn to the world outside the classroom. But I completely agree that many students fail to grasp that "the scientific method is widely applicable to different aspects of their lives". Some years ago now a colleague & I surveyed university students from a range of different year levels and were startled to find that the 3rd-years had no better understanding of the nature of science than did the 1st-years. But then, many of us do tend to assume that such understanding is gained by osmosis, rather than by explicitly teaching it. For Kwok, 

the problem is not just how much science students learn but how they connect science to their lives and society.

We need to address this, and also ensure that all students gain a set of fundamental skills - those "21st century skills" that aren't really a new paradigm at all, but essential in any time: good language/communication skills, and a set of quantitative skills that let them think about the world in a scientific wayA, regardless of what they ultimately end up doing. Research is a big part of a university academic's life, but we need to remember that perhaps the majority of our students are not going to go on to academic careers (see here and here for commentary on that); the skills we help them develop should be useful to them in a range of other professions. 

Thus Kwok believes that, despite the fact that science curricula - both in schools & at university - tend to focus on mastering factual knowledge, 

it is more important to teach the process of science, ... mastering methods such as building models, constructing experiments, taking data, revising models based on data, and communicating results. Students should acquire the ability to solve problems by studying examples of previous work. In the process, they should develop free, bold, independent, and creative thinking. 

[They should] develop their sense of curiosity and acquire the confidence to ask questions and challenge assumptions ... be knowledgable about our world and awre of how nature works ... think analytically and quantitatively, keep an open mind ... [and] be versatile enough to take on any job.

Now, I do think that, in my own Faculty & institution anyway, the curriculum changes we've instituted as a result of a university-wide review have helped us move towards this: the requirement for 'discipline foundations' papers for all degrees, for example, the expectation that all science majors will take 'numeracy' papers (in quite a broad sense of the term), our inclusion of a "Science and Mātauranga Māori paper" in the science degrees (and its equivalent in engineering), and the move from my engineering colleagues to increase the amount of experiential learning in their programs. But I think we still have a way to go, and could take a leaf out of the UHK reforms, specifically by considering the two science foundation papers introduced thereB. Why? Because the goal of these papers is

to give students a broad view of science's nature, history, fundamental concepts, methodology, and impact on civilisation and society.

and to 

[introduce] general principles and unifying concepts to describe diverse natural phenomena ... emphasising the relationships between science subjects.

The reform also includes non-discipline-based classes (I think I'd love to take his paper "Our Place in the Universe"!) that

are designed to develop broader perspectives, critical assessment of complex issues, appreciation of our and other cultures, and the qualities necessary to be a member of the global community. 

And then there's the reform of the discipline-based papers themselves, with the caveat that while we should definitely be looking at moves away from the traditional lecture format for teaching, that shouldn't overshadow changes in curriculum content and focus.

There's also something of an elephant in the room, when we talk about curriculum development. And that elephant is assessment. While we may claim to teach critical thinking, critical assessment of problems, and the ability to integrate information across the disciplinesC, unless those attributes are actually targeted by assessment as well as by teaching, nothing much is going to change. 

Kwok concludes with a plea: he hopes that

more scientists will think about how we educate our next generation. They are the people who will keep science alive.


Sun Kwok (2018) Science education in the 21st century. Nature Astronomy.


A I'd like to hope that increasing this particular competency among graduates, even non-science majors who've taken a couple of 'interest' papers in the sciences, would help to counter what seems like a rising tide of pseudoscience; the idea that science is 'just another way of knowing'.

B And some of their other innovations. I really like the idea of an induction for new first-years that includes a thorough introduction to "the differences between learning in university and in high school". 

C One of my gripes about the Achievement Standards of our NCEA system in NZ is that they do tend to result in many students being quite compartmentalised in their learning. Perhaps as a result of the pressure many teachers feel to teach 'to the assessment', many of our incoming first-years are not particularly good 'big-picture' thinkers, able to link concepts from various areas of biology. In fact, at the Schol Bio day I ran just last weekend in Hawkes Bay, some of the students commented on how different the scholarship exam is, with its emphasis on the need to integrate concepts across the curriculum, from the way they're assessed for Level 3 NCEA.


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