Posts

Plasticity can take the lead in adaptive evolution

Posted by on Jul 20, 2019 in Posts | 0 comments

Plasticity-led evolution would be likely if the trait combinations induced by novel environments harbour more than their fair share of genetic variation. Our new paper in PNAS shows that this is in fact quite common. For a nice overview, see this post by Luis-Miguel Chevin on F1000.

Dan Noble and Reinder Radersma collected data from studies that quantified traits and their additive genetic covariance in animals and plants exposed to novel environments. On the whole, the multivariate phenotypic change caused by environmental change were well aligned with the maximum genetic variation – and better than expected by chance.

There are several ways to interpret these results. Perhaps the most interesting from the perspective of evolvability is that developmental systems respond to environmental novelty as they do to genetic mutation. Such developmental bias means that populations that evolve plasticity will tend to continue to evolve in some ways rather than others. The present paper is the first in a series of empirical and theoretical papers that address this problem as part of our group’s involvement in an international research effort. So please keep an eye out for more.

It is time to say goodbye…

Posted by on Jun 7, 2019 in Posts | 0 comments

… to Reinder and Alfredo.

As the EES grant comes to a close, we are sad to see some of our friends move on, but excited about the opportunities they have created for themselves.

Reinder is now a researcher in statistical genetics at Wageningen University & Research Institute, which is THE place to be for agriculture, environmental and food science. His work on maternal effects, plasticity and evolvability will undoubtedly prove useful also to domesticated plants and animals.

Alfredo also leaves us, in this case for a postdoc in Copenhagen. After a couple of years with theory, he is now ready to get his hands dirty with data again. The aim is to reveal the molecular complexities of maternal-fetal communication, a perfect opportunity to transfer skills between evolutionary and developmental biology!

Although it is sad for all of us to see them leave, it is particularly sad for Tobias – they have known each other since the Oxford years, when Reinder did a postdoc with Ben Sheldon and Alfredo his MSc with Tobias. They have been fantastic friends and colleagues – always positive, helpful, and engaged. Hats off for everything you have taught us over the years.

See you soon!!

 

 

 

Summer cottage getaway

Posted by on Jun 3, 2019 in Posts | 0 comments

All visitors to Sweden should experience that summer cottage feeling! Accordingly, the group packed their thermal underwear, swim trunks, shorts and rain coats and headed to Tobias’ family’s cottage in Värmland. All outfits came to good use since we had typical Swedish summer weather – blue sky followed by rain, and then glorious weather when we had to leave. Just like every year.

View from the veranda on day 1…. and day 2…

Germs, lizards and field work cut our numbers this time. But the rest of us had a great time – relaxing, birding, fishing, swimming, and beaver watching, enjoying local art exhibitions, cultural history, snaps, and grillkvällar… or, to quote Yang: “we managed to do and see everything we were promised – and in addition we watched the Champion’s League final!”

What can we catch here – pike? perch? pikeperch?… hang on, what did you just say!?  
Yang and Roman are off for an adventure! They did come back eventually.

 


A beaver with unfinished business, perhaps the one that swam past this morning?

 


Summer lunch with traditional food, snaps and songs. The students are getting younger every year…

 

Geoff While visiting

Posted by on Apr 7, 2019 in Posts | 0 comments

We are very happy to have Geoff While from the University of Tasmania visiting us for three months. Geoff is a fantastic friend and collaborator whose scientific drive, passion for biology, and lizard catching skills are nearly impossible to beat. In addition to the usual wall lizard field season, we have a few old projects to finish off, some that are in full swing, and perhaps one or two new ones to launch. Not to mention all the other things you could get done over a beer or two. Welcome Geoff!

Cheers!

 

Ullergroup at Evolution Evolving

Posted by on Apr 6, 2019 in Posts | 0 comments

The Evolution Evolving at Cambridge was packed with three days of exciting talks – from culture in whales to control theory and the philosophy of explanation. The crew from Lund felt like lizards in the sun – pretty comfy and happy! So much in fact that Alfredo won the prize for best talk, and Illiam the prize for best poster. Congratulations to both!

We are very grateful to our fellow organisers and all the participants for making this such a great event. A full conference report will be posted in due time at the EES webpage, together with recordings of plenaries and key notes. They were brilliant! Until then, you can see what you missed at #evoevolving and #EES_Update


Alfredo on “How does evolution work with strong attractors?”

 

How adaptive plasticity evolves when selected against

Posted by on Mar 12, 2019 in Posts | 0 comments


Yes, that is the surprise title of Alfredo’s new paper in PLoS Computation Biology! When we discover examples of adaptive plasticity we usually think that it evolved because selection favoured it. But can adaptive plasticity evolve when selection favours non-plastic individuals?

Think of a population of insects that hatches, reproduces and dies twice every year: once in spring and once in autumn. Spring and autumn conditions may be very different, but plasticity could allow the insects to cope with both seasons. Yet, insects born in spring never experience autumn, and vice versa, so natural selection cannot directly favour plasticity. In fact, plastic individuals may do worse than individuals that are not plastic, which means plasticity could consistently be selected against.

This problem is similar to tuning the learning rate in Machine Learning. To teach a machine how to solve a problem, we give it a set of example questions we already know the answer to. Each time the machine gives us the wrong answer, we change its parameters to produce a new answer that is closer to the right one. If the examples share a consistent logic, the machine will eventually find this logic. But if we change the model’s parameters too much with every example shown, the machine will just repeat the solution for the last example, which prevents it from finding the underlying logic that connects the examples.

Just like in machine learning, organisms receive a set of questions in the form of environmental cues and need to provide the right answer in terms of a fit phenotype. Adaptive plasticity is the solution that produces the right phenotype for every environment. Organisms that see only one environment per lifetime could easily “forget” that plasticity is adaptive and instead only produce the right phenotype for their last environment. The offspring of insects that live in spring would be better matched to spring, even though they will have to deal with autumn conditions.

So when does learning theory predict that a machine will learn the logic of plasticity rather than the last solution? And do those predictions hold for a simple representation of evolution by natural selection? To find out, have a look at the paper!

Solved: the genetics of colour polymorphism in wall lizards

Posted by on Mar 1, 2019 in Posts | 0 comments

A new paper in PNAS reveals that the orange and yellow ventral colour morphs in wall lizards is caused by regulatory changes in pterin and carotenoid genes. Interestingly, it seems like the alleles are old and occasionally shared between species. Miguel Carneiro and his team at CIBIO and Leif Andersson at Uppsala led the work, and we helped with the genome, samples, and other bits and pieces. The chromosome-scale genome assembly is of high quality and should become a useful resource – so just get in touch if you want to know if the wallies are right for you too!

 

A new take on the epigenetic signatures of prenatal stress

Posted by on Dec 5, 2018 in Posts | 0 comments

The conditions encountered in the womb can have life-long impact on health. It is usually assumed that this is because embryos respond to adverse conditions by programming their gene expression. In collaboration with Bas Heijmans and others, we propose that these effects also can be caused by selection on stochastic epigenetic variation. The paper is published in Cell Reports and there is also a press release.

The concept of fetal programming is based on the idea that embryos modify their physiology in response to the uterine environment. This may be good if conditions stay as predicted. But it may have negative health effects later in life if the conditions change. The concept of programming has been backed up by associations between adverse prenatal conditions and patterns of DNA methylation – an epigenetic mark that regulates gene expression.

Our simple insight is that the uterine environment does not need to induce changes in DNA methylation for this association between adverse prenatal conditions and DNA methylation to arise. In the early embryo, stochastic differences in gene expression can become stabilized by DNA methylation, resulting in embryos with different epigenomic profiles. Not programmed by the environment, these random differences in gene expression (and hence DNA methylation) may nevertheless provide some embryos with a survival advantage when conditions are harsh. In other words, adverse maternal conditions may impose selection on random variation in DNA methylation.

Human embryo at 8-cell stage. (C) Yorgos Nikas/Science Photo Library

We used a mechanistic simulation model to illustrate how selection reduce DNA methylation variance at loci that influence implantation success. The prediction fits very well with empirical data from offspring conceived during the Dutch Hunger Winter, a famine at the end of World War II. This makes selection on stochastic epigenetic variation a reasonable explanation for the epigenetic signatures of prenatal exposure to adverse conditions.

This new hypothesis is not only of academic interest. Fetal programming implies that the behaviour or physiology of the mother causes the offspring phenotype to change. In contrast, a selective process does not bring new phenotypes into being, it changes the distribution of already existing variants. This difference may influence which preventive strategies and treatments that are most likely to be effective. That different mechanisms can be responsible for the same pattern is also relevant to society. As Sarah Richardson has pointed out, careless discussion of epigenetic research on how early life affects health across generations could be harmful.



Developmental Bias and Evolution at Santa Fe

Posted by on Nov 20, 2018 in Posts | 0 comments

The third and final workshop funded by our EES grant took on the role of developmental bias in evolution. Like the meeting in February, Santa Fe greeted us with snow, jetlag, and huevos rancheros for breakfast.

The workshop showcased the extraordinary breadth of approaches used to understand if, and how, developmental processes direct evolution. Ecologists, developmental biologists, and palaeontologists explained what data are out there and what they mean. Theoretical biologists and computer scientists convincingly showed that the role of development not only can be formulated in precise terms, but that there are predictions ready to be tested. Judging from the work presented, we can look forward to some very interesting studies doing just that in the near future.

As there should be, there was both unity and spirited disagreement – with views ranging from development as constraint to development as the main driver of evolution. History and philosophy of biology again proved useful to understand this diversity. While debate over the role of development in evolution is as old as evolutionary science, contemporary research really does seem to bring new insights – conceptually, theoretically and empirically.

One way to think of developmental bias is through the use of morphospaces. The morphospace of several groups of reptiles (including dinosaurs) that lived around 230-200 million year ago, using two (undefined) shape characters. Reproduced from the Palaeobiology Research Group of the University of Bristol, UK

Origin-Of-Life researcher Wim Hordijk kindly summarized his views of the meeting on this blog. The Lund crew – Tobias, Alfredo, Nathalie, Reinder, and Illiam – are very grateful to the SFI for hosting, and the organisers for giving us a lot of things to think of. Next up – the Evolution Evolving meeting at Cambridge. See you there!

 

Another bad day for anticipatory maternal effects

Posted by on Nov 20, 2018 in Posts | 0 comments

A new study on water fleas, headed by Reinder and Alex, suggests that a classic example of adaptive maternal effects is not as adaptive as we might have thought.

Some years ago, Tobias, Sinead and Shinichi did a meta-analysis that seemed to undermine the idea that maternal effects are designed to transfer information about the local environment. Reviewers and editors did not really want to hear that, and the paper proved somewhat difficult to publish (but has been well received and cited). But one ‘anticipatory maternal effects’ appeared well supported: water fleas exposed to toxic cyanobacteria produced offspring that were more tolerant to the toxin.

So, to understand how this maternal effect evolves, Reinder and Alex challenged water flea mothers and offspring with cyanobacteria that produce the toxin microcystin. But rather than just expose the animals throughout their lives, they also exposed mothers at different times during her life. The rationale is that maternal effects that have been selected to transmit information are expected to behave like signals – triggered and delivered by a system well designed to pass on information with limited cost to the receiver.

It turned out that offspring indeed were somewhat better able to handle the toxin when their mothers had been exposed late in their lives. In other words, tolerance or resistance can be transmitted to the next generation through non-genetic means. But there was not much to suggest that the mechanism has been selected to transmit information about the presence of cyanobacteria. Instead, our experimental evidence – along with a meta-analysis of Daphnia research – fits better with a model of passive transfer of tolerance rather than an anticipatory maternal effect. Again, reviewers and editors were not very happy to hear this, and this paper also proved somewhat difficult to publish.

We should not be too surprised of these results, however. Not all plastic responses that allow organisms to cope with stress are properly seen as adaptations to cope with the stressor.

Genetically identical sisters, raised in two different environments. Daphnia raised in the microcystin treatment (on the right) displays smaller body size and carries less eggs than her sister from the control treatment

We can think of these maternal effects as – in Mary-Jane West-Eberhard terms – examples of phenotypic accommodation that have not yet been followed by genetic accommodation.

But while our results question if there really has been selection for maternal transfer of information about microcystin exposure, the study is still not quite conclusive. Two kinds of follow-up studies would be particularly informative.

Endless replications

The first is to contrast responses of populations of water fleas with different evolutionary histories of exposure. This kind of comparison can effectively reveal if plastic responses in naïve animals become fine-tuned over evolutionary time (see a nice example from house finches here).

The second is to reveal the mechanism of the maternal effect. This would not only tell us ‘how it works’, but – keeping the comparison with signals in mind – whether or not the mechanism has properties that we expect of systems designed to transmit information.

We have our ideas about what is going on, and Alex has just completed a set of experiments that can tell us more. In the meantime, we hope that this paper will inspire more studies to look at maternal effects as a window into the evolutionary transition from stress-induced responses to local adaptation. To get started, please see here and here.

 

Lund workshop on the evolutionary origins of individuality

Posted by on Sep 8, 2018 in Posts | 0 comments

The evolutionary process is itself evolving. Perhaps the best example is the origin of new reproductive organizations that are capable of evolving by natural selection. Single celled organisms evolved into multicellular organisms, some of which – leaf cutter ants, for example – appear to have evolved into collectives that deserve the label superorganism.

Last week our group hosted a small workshop to bring together researchers that use different approaches to tackle how and why such transitions in individuality happens. The aim was to share insights from projects within our Templeton-funded grant, and to spread ideas to local Lund researchers.

The presentations generated a lot of great discussions, which continued over dinner and at the pub. Richard Watson showed how learning theory bring clarity to the conditions that are necessary for transitions in individuality to happen. Andy Gardner explained how focusing on lower-level evolutionary individuals – genes – can help to understand how conflicts between cells within bodies arise, evolve and become resolved. Charlie Cornwallis and Maria Coelho-Svensson discussed how one can put theory to the test using green algae that come together in groups. Social insects provide another interesting example, and Heikki Helanterä showed how they can shed light on the transition from solitary to collective life cycles.

Evolutionary transitions in individuality is fundamentally about explaining how a developmental organization evolves from social or ecological interactions between the lower-level individuals. This is difficult to address without paying attention to mechanism. Miguel Brun-Usan showed how mechanistic models of cell behaviour provide a window into the conditions that promote transitions in individuality. Some of the order comes from self-organization, a topic theoretically explored by Edith Invernizzi in the context of nest building in social insects.  Finally, Jonathan Birch discussed another evolving relationship between the organism and its surroundings – the evolutionary route towards organisms that are capable of conscious thought.

Thanks to all the speakers and the many Lund researchers and students that attended the workshop. It was great fun and we cannot wait to see more from all of these projects.

Developmental Bias and Evolution

Posted by on Jul 30, 2018 in Posts | 0 comments


A recurrent theme in evolutionary biology is to contrast natural selection and developmental constraint – two forces pitted against each other as competing explanations for organismal form. A recent Perspective in the journal Genetics explains why this juxtaposition is deeply misleading. There is also a blog about the paper here.

Our starting point is that characters often evolve through changes in how genes, cells, and tissues regulate each other. Once we study the evolution of such regulatory interactions, it turns out that they do not only limit evolution, but also may facilitate the capacity to adapt and diversify. The paper gives an introduction to recent theoretical and empirical research, and explains how this work is now beginning to reveal how evolution of the evolutionary process itself contributes to diversification and adaptation.

 

Three new papers on thermal biology of reptile embryos

Posted by on May 28, 2018 in Posts | 0 comments

Most reptiles lay eggs in sand or soil, under logs or in rock crevices. These are places where the temperature often fluctuates, sometimes becoming dangerously high or low. The pervasive effects of temperature on biological systems begs the question how embryos respond in the short term, and how populations adapt in the long term. This question is now thoroughly explored in a theme issue of the Journal of Experimental Zoology, with contributions from our group.

In a study on wall lizards led by Nathalie Feiner, we reveal a pervasive effect of temperature on gene expression in early embryos. The strongest responses were found for genes involved in transcriptional and translational regulation and chromatin remodelling, suggesting possible epigenetic mechanisms underlying thermal acclimation. In another paper, ploughing through 50 years of experimental studies, Dan Noble, Geoff While, and colleagues summarize research on thermal plasticity in reptile embryos, and demonstrate how future progress can be made through meta-analytic and comparative work. The data are accessible to everyone through a paper in the journal Scientific Data, and can be downloaded through this online data base. More papers in this special issue are available through the Journal of Experimental Zoology online early.

 

Anolis symposium in Miami

Posted by on Apr 4, 2018 in Posts | 0 comments

The organizers had chosen an appropriate setting for the 2018 Anolis symposium – sunny Miami, Florida, at the Fairchild Botanical Garden that ‘hosts’ six Anolis species. Since Nathalie was working at the museum collection of the University of Florida, she took the opportunity to join for two days of Anolis fun.

The meeting was the fifth of its kind, with the first taking place already in 1972. That is an average of one meeting every 9th year! Not very frequent, but it means the symposium already is a classic event. The program was full, but the organizers had scheduled long coffee and lunch breaks to make sure there was enough time to explore the Botanical Garden, in particular to meet our scaly friends, of course.

There were 31 talks. These covered pretty much every question that can be asked about Anolis lizards: behaviour, ecology, population biology, developmental biology, genome biology and evolution. Several talks were on urban ecology since many Anolis species have developed a taste for busy metropolitan environments, something that is easily observed in Miami. Most speakers presented ongoing work which generated a lot of fruitful discussions. Nathalie presented her work on the relationship between transposable elements (TE) and diversification rates in Anolis, and how transposable elements may be responsible for some pretty cool changes in Hox gene expression. TEs were new to many in the audience, but Nathalie managed to get the ecologists excited about genome biology.

The talks were great. But the best thing about the symposium was to meet other Anolis enthusiasts and to talk (and see!) ‘Anolis’ for a whole weekend! For Nathalie – the only representative of the old world, as pointed out by Jonathan Losos – it was a fantastic opportunity to exchange ideas with those who shared an interest in evo-devo. There was a lot of successful exchange of ideas – from practical matters like the best way to image embryos, to the conceptual issues surrounding the role of development in evolution.

And look who turned up! Sozos Michaelides – who finished his PhD in our group three years ago – has abandoned the wall lizards and is now disentangling the introduction histories of Anolis lizards with Jason Kolbe at Rhode Island.

Thanks to James Stroud, Anthony Geneva and Jonathan Losos for a fantastic job with the organization. James, the local amongst the organizers, made sure that everyone got a taste of the Caribbean – serving Cuban delights during coffee and lunch breaks, and homebrewed beer (‘Lizard lager’ and ‘Anole ale’) in the evening. The next meeting is scheduled for the year 2025 – we look forward to it!

 

 

Evolving Evolutionary Biology at the Santa Fe Institute

Posted by on Feb 23, 2018 in Posts | 0 comments

Researchers from around the world gathered at a snow-covered Santa Fe Institute to discuss the evolutionary implications of extra-genetic inheritance. The workshop – Integrating Development and Inheritance – was organized by Tobias and colleagues as part of the EES research program. For two and a half days the participants – biologists, mathematicians, computer scientists, anthropologists, historians and philosophers of science – presented their work and took part in lively and constructive discussions about the nature of inheritance and why it matters to evolution.

The workshop kicked off with some historical background to the separation of inheritance and development, and how this shaped the development of research programs within evolutionary biology. The biology talks covered many different mechanisms by which parents influence the development of their offspring – from epigenetic inheritance in plants to whale culture. Attendees further discussed how empirical work and mathematical modelling best can proceed with constructive views of development and inheritance. For the full program, please see here.

We are very grateful to all the participants for their outstanding presentations and engaging and constructive contribution to the discussions. Nothing beats learning about one’s own field through talking to people with different backgrounds and expertise. Judging from the talks, we have a lot of exciting empirical and theoretical research and philosophy and history of science to look forward to. An extra thanks to Michael Lachmann and the Santa Fe Institute for hosting us. We will be back in November!

Two PhD positions available to study the evolutionary origin of family living

Posted by on Feb 9, 2018 in Posts | 0 comments

We are looking for two students interested in doing their PhD on the evolutionary origin and diversification of social complexity in lizards. The positions are part of a research project funded by the Australian Research Council and the successful candidates will be based either at the University of Tasmania (primary supervisor Geoff While) or at Macquarie University (primary supervisor Martin Whiting). The Lund collaborators are Tobias and Charlie Cornwallis. For more information on the position, please read here, or contact any one of us directly.

 

Winter is coming!

Posted by on Feb 9, 2018 in Posts | 0 comments

Winter is not really the best time of year in Skåne, unless you really enjoy all those different shades of grey. To get a feeling of a proper Swedish winter, the group packed their warmest clothes (and triple pairs of socks) and headed up to Sunne, where Tobias was born and raised. Winter in Värmland is the real thing – snow-covered forests, ice-covered lakes and the hope of a rare wolf spotting.

Tobias’ parents opened up their whole house for us, and his brother served as the cross-country skiing coach and ‘vallachef’. People from eight nationalities put on their skis – some for the very first time – and headed out to the tracks. Everybody had healthy rosy cheeks and slightly frozen toes by the end, and incredibly nobody was injured! In fact, Yang and Mara both proved to be natural talents at skiing, despite the limited snow cover in Chengdu and Murcia. This was extra impressive considering that Yang broke his ‘low Celsius record’ two days in a row and had only once seen this much snow before – an occasion he described as “catastrophic”!

Ice-fishing released a lot of creative forces in the group. Pumping up a groovy atmosphere in the glorious sunshine, Illiam and Alfredo managed to pull up several perch while the others skied across the lake. Back at the house, an old snow racer could of course not be resisted. The greatest daredevil and air-time record-setter was Reinder, perhaps due to limited childhood experience of what happens when you go down hills really fast…

After these lovely but chilly outdoor activities we enjoyed cosy evenings around the fireplace with games and wine. Alex turned out to have the best strategic skills whereas Illiam proved to have the gift of storytelling (a.k.a. lying). Nathalie turned out to be an amazing air pilot, Hanna a master of skull-drumming and Tobias – well, he was still the real Harry even when everyone else had lost track.

Many thanks to the Uller family for an amazing weekend. We’ll see you again next time… ;-)!

 

 

 

 

 

 

 

Live bearing promotes the evolution of sociality

Posted by on Dec 12, 2017 in Posts | 0 comments

Some lizards and snakes tend to hang out in family groups, not unlike the more familiar social groups of birds and mammals. Our recent study, headed by Ben Halliwell and Geoff While and published in Nature Communications, show that the evolution of social grouping is much more likely to have happened in lizards and snakes that give birth to live young. There could be a number of reasons that transitions to sociality are more common for live bearing species.

The most obvious one – and the theoretical rationale behind this study – is that giving birth to live young makes interactions between parents and offspring more likely than in species that lay eggs. And interaction among kin, in turn, is what causes natural selection for group living.

(C) Dale Burzacott

Some lizards – in particular the Egernia – in fact have quite complex kin-based social structures. As expected, such groups have almost exclusively evolved in live-bearing lineages. Interestingly, egg guarding does not seem to have the same positive effect on the evolution of sociality. Maybe this is because the ecology needs to be right as well to select for delayed dispersal and parental tolerance of offspring. For the full story, please download the paper here.

 

Evolutionary adaptation to climate: same same, but different

Posted by on Nov 22, 2017 in Posts | 0 comments

A new study published in Evolution – headed by Nathalie – reveals how embryonic gene expression patterns change as non-native lizards adapt to cool climate.

Populations adapting independently to the same environment provide important insights into the repeatability of evolution. In the 20th century, common wall lizards (Podarcis muralis) from southern and western Europe were introduced to England, north of their native range. We have previously shown that non-native populations of both lineages have adapted to the shorter season and lower egg incubation temperature by increasing the absolute rate of embryonic development.

In this new study, we show that embryos from non-native populations exhibit gene expression profiles consistent with directional selection following introduction. However, different genes are affected in lizards from France and Italy. The biological function of these genes are quite similar, though, and consistent with mechanisms that should speed up development. These results indicate that small populations are able to adapt to new climatic regimes, but the means by which they do so may largely be determined by founder effects and other sources of genetic drift.

 

Heredity in Evolutionary Theory

Posted by on Sep 26, 2017 in Posts | 0 comments

It may not have escaped your attention that biologists are taking a more inclusive view on heredity these days, regularly referring to epigenetic or behavioural inheritance, for instance. It is often difficult to understand what this means, however, or why it matters. Tobias and Heikki Helanterä take a closer look at heredity in evolutionary theory in a new book from Oxford University Press – Challenging the Modern Synthesis: Adaptation, Development & Inheritance, edited by philosophers of biology Philippe Huneman and Denis Walsh. A pre-print version of the chapter can be found here.

In evolutionary biology, there are arguably four main ways to think of heredity:  as transmission of genes and other ‘particles’, as a phenotypic covariance, as transmission of information, and as the outcome of developmental processes. These are not mutually exclusive, and which one that is adopted or emphasized is partly a pragmatic decision based on the research question at hand (e.g., Tobias regularly makes use of all four), and partly a reflection of one’s conceptual framework (e.g., in some people’s minds heredity can only be genetic and strictly separated from development, and if you think otherwise you are either an idiot or, worse, a Lysenkoist in disguise).

 

When empirical research reveals new mechanisms by which parents influence their offspring – like the persistence of DNA methylation from mother to offspring or offspring learning how to forage from their father – researchers naturally accommodate these findings according to how they think of heredity. But it also leads the odd biologist (and non-biologists) to question the coherence of her current conceptual framework, which is why ‘extra-genetic inheritance’ can be perceived as a challenge to the traditional view of evolution (i.e., the ‘modern synthesis’ – if you do not like this term, just think of a colleague who thinks that all fundamental problems in phenotypic evolution can/should be answered without referring to development). And, as we know, conceptual change can make some new research questions appear more interesting or relevant than they did before, whereas others may fade into oblivion.