Gone with the birds

1 09 2011

ebaumsworld.com

Another great post by Salvador Herrando-Pérez.

Through each new species, evolution assembles a unique combination of genes. Ever since living forms have populated our planet (> 3 billion years), the number of combinations is incalculable. That is why evolution resembles a cocktail shaker. Contemporaneous biogeographers look for order in that shaker to explain the history of life, as much as historians look for monarchs and revolutions in a library to explain the history of humanity.

The ethnic diversity of our suburb, village or city obeys factors of different temporal extent. Recent factors such as wealth, politics (war, segregation), culture (tradition, religion), and technology (airplanes, bridges, tunnels) determine racial migration, mixing and extinction. On the other hand, pre-historical factors express the expansion of the earliest hominids from Africa to the other continents – what makes a bantu ‘bantu’, or an inuit ‘inuit’.

Present ecological conditions and the macro-evolutionary past stock the elements by which biogeography attempts to understand the mechanisms shaping the spatial distribution of species, e.g., why kangaroos are restricted to Oceania, or why you could believe you were in Spain while strolling through a Greek forest. Read the rest of this entry »





Evolution here and now

17 02 2011

Here’s a guest post from one of my PhD students, Salvador Herrando-Peréz. Salva is working on theoretical aspects of density feedback mechanisms among different species, and is especially eclectic with his interests in biology. Salva regularly contributes to lay natural history magazines, especially in his native tongue Castellano (Spanish), and he is an active member of the Spanish organisation Bioestudios Saganta, a non-profit national organisation fully devoted to scientific research and its popularisation with a focus on biodiversity conservation.

I’ve asked my students to start contributing to ConservationBytes.com, and Salva is leading the charge.

Evolution evokes ideas such as fossils, geological eras and time scales of hundreds of thousands to millions of years. Only recently have we started to appreciate that such ‘macro-evolution’ is the result of accumulated changes in the morphology and genes of species from one generation to the next: days for HIV strands, months for a planktonic rotifer, or years for a poplar.

The Britons Peter and Rose Mary Grant published in 2002 a 30-year study on Darwin’s finches from Daphne Major (Galapagos, Ecuador) – a popular study organism since Charles Darwin’s Origin of species (Grant & Grant 2002). In such a short period of time, covering only six generations of these granivorous birds, several extreme droughts altered the type and abundance of seeds, and potentially triggered the evolution of body size, and beak shape and size, up to three times (Figure 1). The two biologists from Princeton reveal that:

  1. evolution is reversible – generations of finches experiencing overall increase in body and beak sizes can lead to future generations with smaller sizes (of course within limits; a finch will never develop the beak of a stork or a hummingbird), and
  2. phenological shifts across generations are unpredictable in so far as they respond to random climatic fluctuations – should droughts of contrasting intensity have occurred in different years over the study period, beaks and bodies might have evolved in other particular fashions. Read the rest of this entry »




Charles Darwin, evolution and climate change denial

5 08 2009

DarwinThis week a mate of mine was conferred her degree at the University of Adelaide and she invited me along to the graduation ceremony. Although academic graduation ceremonies can be a bit long and involve a little too much applause (in my opinion), I was fortunate enough to listen to the excellent and inspiring welcoming speech made by the University of Adelaide’s Dean of Science, Professor Bob Hill.

Professor Hill is a world-renown expert in plant evolution, systematics and ecophysiology, and he gave a wonderful outline of the importance of Darwin’s legacy for today’s burgeoning problem solvers. I am reproducing Prof. Hill’s speech here (with his permission) as a gift to readers of ConservationBytes.com. I hope you enjoy it as much as I did.

Chancellor, Vice Chancellor, distinguished guests, members of staff, friends and family of graduates, and, most importantly of all, the new graduates, I am very pleased to have been asked to speak to you today, because 2009 marks one of the great anniversaries that we will see in our lifetimes. 200 years ago, on February 12th 1809, Charles Robert Darwin was born. To add to the auspicious nature of this year, 150 years ago, John Murray published the first edition of Darwin’s most famous book, titled On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life, better known to us all today as The Origin of Species.

I believe that from a modern perspective, Darwin was the most influential person who has ever lived. Darwin’s impact on how we think and work is much more profound than most people realise. He changed the entire way in which we go about living. Today, I want to talk to you briefly about how Darwin had this impact.

Darwin was a great observer and a great writer, but above all he was a great critical thinker. He became a scientist by a round about route, planning to be a doctor and a minister of religion along the way, although his passion was always natural history. He was not a great undergraduate student, but he benefited enormously from contact he had with University staff outside the formal classroom. His potential must have been obvious, because he was strongly recommended at a relatively young age, to take the position of naturalist and gentleman companion to Captain Robert Fitzroy on his famous five year voyage of the Beagle. Following this voyage, Darwin never physically left Britain again, but intellectually he roamed far and wide. Darwin was one of the great letter writers. He wrote thousands of letters to contacts all over the world, requesting specimens, data and opinions, and he worked relentlessly at analysing what he received back.

Over many years as a practising scientist I have met a lot of people with a passion for natural history, some of them trained scientists like Darwin, some of them gifted amateurs. There is a very obvious distinction between those with and without formal scientific training at a Tertiary level, but it took me a long time to work out what that distinction is. Let me digress slightly before I explain it.

In today’s terminology we talk a lot about graduate attributes. For some graduates, it is reasonably simple to define the kinds of attributes you expect them to have. I prefer engineers whose bridges don’t fall down, lawyers who keep me out of jail unnecessarily, accountants who can add up and doctors who do their best to keep me alive and healthy. However, the key attributes we expect of Science graduates are not so simple to define. You will all have one or more specialities where you have more knowledge than those who did not do the relevant courses, but if you are anything like I was when I was sitting out there waiting to graduate, you probably think you did what you had to do in order to pass your exams and you now think you have forgotten most of what you were taught. I can assure you that you haven’t, but I can also assure you that specific knowledge of a scientific subject is not the most important thing you have been taught here.

So what is that special something that separates out a professional scientist? It is the capacity for critical scientific thinking. You are now ready to work as professionals in many fields, and employers will actively seek to hire you because they know you have been trained here to apply a particular approach to problem solving. That approach is not easily obtained and has been taught to you in the most subtle way over the full breadth of what you have been exposed to during your time here. I suspect most of you don’t even know that you now have this skill, but you do. Darwin had it in the most sublime fashion.

When Darwin published the Origin of Species it was the culmination of decades of data gathering, backed up by meticulous analysis. Darwin never swayed from that rigorous approach, which strongly reflected the training he received as a student.

When you are exposed to a new problem, you will approach the solution in a similar way to Darwin. Let me consider the example of climate change. There is a remarkable parallel between the public reaction to the publication of the Origin of Species and the current public reaction to climate change. Darwin suffered a public backlash from people who were not ready to accept such a radical proposition as evolution by means of natural selection and this was reinforced by a significant number of professional scientists who were willing to speak out against him and his theory. As time went by, professional scientists were gradually won over by the weight of evidence, to the point where mainstream science no longer considers evolution as a theory but as scientific fact.

The reality of climate change and its potential impacts has not had a single champion like Darwin, but it has involved a similar slow accumulation of data and very careful analysis and critical thinking over the implications of what the data tell us. Initially, there were many scientists who spoke against the human-caused impact on climate change, but their number is diminishing. Most significantly, the critical analysis undertaken by thousands of mainstream scientists has gained broad political acceptance, despite the best efforts of special interest lobbyists. I suspect Darwin would be fascinated by the way this debate has developed.

Lobbyists who write stern words about how scientists as a whole are engaged in some conspiracy theory to alarm the general population simply do not understand or choose to ignore how scientists work. The world needs the critical and analytical thinking that scientists bring more than ever before. We live on a wonderful, resilient planet, that will, in the very long run, survive and thrive no matter what we do to it. But we are an extremely vulnerable species, and our survival in a manner we would consider as acceptable, is nowhere near as certain. That is the legacy of my generation to yours. I have faith that your generation will be wiser than mine has been, and I know that good science will lead the charge towards providing that wisdom.

Charles Darwin was the greatest scientist of all, and that is partly because he was a great observer and a great writer. But most of all, Darwin was the consummate critical thinker – he collected masses of data himself and from colleagues all over the world and he fashioned those data into the most relevant and elegant theory of all. I will conclude with a brief and well known passage from the first edition of the Origin of Species, which clearly demonstrates the power of Darwin’s writing:

Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.

I hope that the next Charles Darwin is sitting amongst you today. I know that at the very least I am standing in front of a group of people who have all the attributes necessary to be great contributors to the well-being of society and the planet. Be confident of your training and use your skills well. You have a grand tradition to uphold.

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