Target of illiams PhD work – Agnostus pisiformis fossil. Scalebar is 2 mm.

It is often pointed out that there is a strange gap between evolutionary biology and palaeontology. Particularly considering that it is hard to find something so obviously relevant to evolution as the fossil record… Anyway, we now hope to reduce this gap thanks to Illiam Jackson. Illiam did his PhD in palaeobiology in Uppsala under the supervision of Graham Budd (although he likes to point out that his first degree was in Biology). He joins us with a passion for morphometrics, and for making development relevant also to the study of fossils. Illiam will continue his work on plasticity and evolution of trilobite-ish arthropods here at Lund, but he will also – together with Nathalie Feiner – explore if developmental plasticity shapes adaptive radiation of lizards. Welcome Illiam!

This year’s European Society for Evolutionary Biology meeting was held in Groningen. ESEB is always a great opportunity to see old friends, learn new things, and – somewhat jealously! – see the progress on the most famous study systems in evolutionary biology, such as cichlids, Heliconius butterflies, and bird beaks. And progress there was. Among the most memorable were further evidence from the Seehausen group – presented by Joana Meier and others – that hybridization has played a creative role in fish evolution in both African and European lakes, and a tour-de force of Heliconius evolutionary genomics in a plenary by Chris Jiggins (there is a book, not only for butterfly lovers!). Hybridization was hot at the meeting so it was a shame that Yang was unable to join this year. Wallies were represented, however, by a nice talk on the ventral colour polymorphism by Pedro Andrade. Chances are they will make a big splash next year in Montpellier!

To be fair, ESEB has never been a hotspot for development and this year was no different. Manhattan plots abound, but there was generally little process-oriented research to allow us to connect genotype and phenotype. Exceptions included an excellent plenary by Renee Duckworth, where she demonstrated how to integrate proximate and ultimate causation to understand why organisms change over time or, in this case, why they may not do so. Another exceptional talk was delivered by Alex Badyaev, expanding on his recent papers on the evolution of carotenoid colouration in birds. Describing evolution as transitions between external and internal control in regulatory networks, this work demonstrated the potential for taking a comparative network approach to study innovation and diversification from a developmental perspective.

Other welcome islands in the sea of genomics of adaptation include Andreas Wagner’s plenary on innovation and modularity, or a talk by Christoph Thies from Richard Watson’s group who presented some refreshing ideas on evolutionary transitions in individuality and demonstrated how to capture this process formally. Plasticity and evolution was represented here and there, including an update on the spadefoot toad story by Ivan Gomez-Mestre.

Judging from the ESEB talks, evolutionary biologists are very interested in extra-genetic inheritance. Most talks – including a pretty well-attended symposium keynote by Tobias – revealed this interest to largely be about adaptive function, but with some nice links to life history and ageing (many thanks to Foteini Spagopolou and the other organisers). With a better integration between development and evolution we may look forward to more work on how inheritance systems actually originate and evolve. Chances are Daphnia will deliver some of the pieces of the puzzle and Reinder’s poster – showing preliminary data that quantify the extent of extra-genetic inheritance – was indeed well attended.

The poster sessions were actually one of the meeting’s highlight. Taking place in what resembled an aircraft hangar, it was cool and spacious. And there was wine. Nathalie – presenting her work on the evolution of embryonic gene expression in wall lizards adapting to cool climate – was super busy explaining her findings to other attendees. The whole meeting was full on – I did not even manage to talk to many of the people I know well!

It is always nice to visit Groningen, a place where many of the most creative researchers in evolutionary biology took their first steps as MSc students. With 1600 attendees, these meetings are really too big to take on, but the organising committee – headed by Leo Beukeboom and Simon Verhulst – did a great job pulling it all together. We are already looking forward to see what Turku and Prague can come up with in the years to come!

Small encounters can have large impacts. This counts for animals as well. Particular for social animals – such as great tits – encounters with others affect how they move around and where they eventually settle. And this influences with whom they mate and how successful they are in life. In a new paper published in Molecular Ecology, Reinder Radersma and colleagues from Oxford and Sheffield show that the social environment has a large impact on the movement of great tits – a bird species roaming around Wytham Woods and many other Eurasian forests. These movements affect the distribution of genotypes, which is crucial for how the population can evolve. After all, the distribution of genotypes across an area shapes the genetic combinations that arise and thus, the opportunity for local adaptation.

A particular difficulty when investigating how movements are affected by social interactions is that it is very hard to separate social effects from other factors which vary in space. For instance, when food is not equally distributed – as is often the case – animals might aggregate in food-rich areas. It may look like individuals choose to interact, because many individuals are at the same location. However, it is simply the food, not the company, that is the attraction.

Reinder and his colleagues used techniques recently developed for spatial statistics and extended its use to analyze social networks to separate the effects of spatial variables and social interactions on tit movement.

They show that the movement of individuals and therefore the distribution of genotypes is strongly affected by the preference to move around with the same individuals, in other words, hanging out with “friends”. In addition, the birds do not befriend simply individuals that live in close proximity, because neighbors have similar genotypes. Instead, they pick friends that are genetically different from themselves. As a result, the genetic structure of the population is affected by both social and spatial effects.

Many male lizards produce secretions that they rub on the ground of their territories. The function of these secretions remains contentious, in particular whether or not they serve as indicators of male fighting ability or suitability as a mate. A new paper, published in Evolution, suggests that sexual selection on chemical composition is, in fact, quite weak.

Headed by recent PhD graduate Hannah MacGregor, and in collaboration with Geoff While and Patrizia d’Ettorre, we analysed the chemical composition of secretions from male lizards from France and Italy. The results confirmed previous work showing that chemical profiles can correlate with male secondary sexual characters. However, the correlations were generally weak and inconsistent across the season and between populations. More importantly, there was little evidence that a male’s chemicals make him have more offspring.

That sexual selection on the femoral secretions is weak was further supported by the overall neutral pattern of introgression of chemical profiles in the hybrid zone between the highly sexually selected form (the ‘Tuscan’ lizards) and the ancestral phenotype (details on this hybrid zone can be found here). Nevertheless, three candidate compounds were candidates for asymmetric introgression via direct selection or genetic linkage with visual or behavioural characters.

On the whole, these results are bad news for the hypothesis that chemical communication is sexually selected in wall lizards. Instead, femoral secretions probably function as signature mixtures; that is, they help lizards to keep track of who’s who and to resolve territorial disputes. Yet, every now and then, a particular compound may become consistently selected – perhaps due to genetic linkage – and evolve a more signal-like function. May we speculate that this process can be facilitated by introgressive hybridization?

Ever wondered why there is such intense disagreement over the evolutionary significance of development, non-genetic forms of inheritance, and niche construction? If so, you may be helped by a recent analysis by Tobias and Heikki Helanterä. The paper, accepted in the premier philosophy of science journal British Journal for the Philosophy of Science, uses niche construction as a case study to demonstrate how the way we think of causality in biological systems shape the structure of evolutionary explanations.

Richard Lewontin famously described evolution by natural selection in terms of three principles: variation, differential fitness and inheritance. Organisms fulfil these principles and so they evolve, diversify and adapt. But this does not tell us how the principles are causally related, nor how they should best be construed.

The classic instantiation of Lewontin’s principle describes evolution in genetic terms. This version is what we are taught at school. What we are not often taught, however, is that the genetic instantiation imposes a large degree of autonomy on the biological processes that produce variation, differential fitness, and heredity. Variable rates of survival determine what features will occur in the next generation. But selection does not affect the process of inheritance; inheritance is merely the passing on of whatever genes were selected. The variation that fuels evolution is similarly autonomous. Mutations occur randomly with respect to their consequences for development and fitness, and the acquisition of new variants does not change how variation is transmitted down generations. The result is an ordered set of causally autonomous processes; each step determines (partly) the inputs for the next step, but not how those inputs will be processed.

The autonomy of variation, differential fitness and inheritance is deeply entrenched in contemporary evolutionary biology. But it is a convenient heuristic and not a logical necessity, and it may or may not accurately capture biological reality. Many biologists suspect that it does not and that, in the real world, causes of variation, fitness, and heredity are intertwined. Tobias and Heikki show that such alternative instantiations of the principles of evolution by natural selection can affect the structure of evolutionary theory. And this, in turn, can make it perfectly valid to consider both natural selection and niche construction part of an evolutionary explanation for why organisms are well suited to their environments.

Failing to appreciate how different instantiations of Lewontin’s principles affect causal explanation in evolution is a major source of communication failure surrounding not only niche construction, but also developmental plasticity, extra-genetic inheritance and other phenomena.

Tobias and Heikki also suggests another reason people do not seem to understand each other: the views held by scientists on how science works. Many scientists expect their deep-held views, such as the core of the genetic instantiation of evolution by natural selection, to be falsified by data before they consider alternatives. Other scientists put less emphasis on anomalies and evaluate conceptual frameworks primarily on their ability to stimulate useful research. These different perspectives on scientific progress cut across disciplines but are rarely made explicit in scientific debates.

Nevertheless, philosophy of science is important to understand what the contention actually is about. If one considers niche construction theory an attempt to formulate an alternative research programme, it should be evaluated on the basis of its ability to stimulate new questions and predict patterns and phenomena that would otherwise appear surprising; not on the basis of whether or not it falsifies the genetic perspective. On the other hand, those arguing for more substantial conceptual change must strive towards showing that their framework leads to a different, theoretically and empirically progressive, research programme. Maybe the need for scientific pluralism is a good topic to bring up at your next coffee break?