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The big, bold, redbacks of Buckland
“No, Mr Baggins has gone away. Went this morning, and my Sam went with him: anyway, all his stuff went. Yes, sold out and gone, I teller. Why? Why’s none of my business, or yours. Where to? That ain’t no secret. He’s moved to Bucklebury or some such place, way done yonder. Yes it is – a tidy way. I’ve never been so far myself; they’re queer folks in Buckland. No, I can’t give no message. Good night to you!” JRR Tolkien – The Fellowship of the Ring
One of the greatest illustrations of Tolkien’s work, IMHO, The Gaffer and the Black Rider by Stephen Hickman. I’ve always liked this passage where old Gaffer Gamgee is talking, unbeknown, to a nazghul. It is an important story point but delivered in the type of conversation that you could hear all over the world. ‘Those people that live 20 – 30 km away are just so different and weird!‘ Are the people of Buckland really so different to the good, honest folk of the Shire? If so, how did this happen by simply crossing a river?
There is a question around invasive species whether the individuals that arrive in a new area are just a random selection of the individuals (and their traits) that live in their home area or whether they represent a group of individuals with consistent and particular traits that make them more likely to have successfully invaded the new area.
For example, all humans in Aotearoa/New Zealand have arrived from outside these shores over the last 1000 years. Were the people that made their way here more bold and explorative than the rest who stayed behind? Or were they no different than their neighbours who stayed at home? Maybe they just simply had the opportunity to go?
These ideas are important in thinking about why invasive species are successful at establishing or not. If any old random subset of the population can turn up then they are less often going to successful at establishing (they may not be fit-for-purpose!) compared to if they arrive with skills that allow them to survive better in a new environment (or even to survive the journey).
Being large might help give invasive individuals an advantage over native species. Likewise, producing more offspring, growing faster, being bold, exploring more, dispersing sooner, having a broader diet, could all help with invading and establishing.
What about our Bucklanders?
“Long ago Gorhendad Oldbuck, head of the Oldbuck family, one of the oldest in the Marish or indeed in the Shire [has had high evolutionary fitness over many generations], had crossed the river [successfully able to disperse relative to other hobbits and to explore more], which was the original boundary of the land eastwards. He built (and excavated) Brandy Hall, changed his name to Brandybuck, and settled down to become master of what was virtually a small independent country. His family grew and grew [high fecundity in offspring production], and after his days, continued to grow, until Brandy Hall occupied the whole of the low hill, and had three large front-doors, many side-doors, and about a hundred windows. The Brandybucks and their numerous dependants then began to burrow, and later to build, all round about … The people in the Marish were friendly with the Bucklanders … But most of the folk of the old Shire regarded the Bucklanders as peculiar, half foreigners as it were [suggests a slightly different distribution of traits compared to the parent population].Though, as a matter of fact, they were not very different from the other hobbits of the Four Farthings. Except in one point: they were fond of boats, and some of them could swim [bold and innovative behaviours].” JRR Tolkien- The Fellowship of the Ring
Captive redback with web. Image by Adrian Paterson. We are also told elsewhere that the Brandybucks and Tooks (another bold lineage of hobbits) are generally taller than average Shire hobbits. Tolkien, as I have said in many other places (taxonomy of orcs and hobbits, evolutionary biology ideas, burrow architecture, mammal pest management, fire and ecosystems), was rather accurate when it came to integrating biology into his writing. Did he get it right here?
To test this invasion idea you need a species that is well-studied in it’s native range as well as in its colonising range. You also need to be able to measure all of those traits. Spiders fit the bill nicely. They’re small and have short generations, are easy to fit into small experimental set ups, and some are venomous and, therefore, well studied. Enter the redback spider (Latrodectus hasselti), invasive in Japan and New Zealand and well studied in its Australian homeland.
Cor Vink, New Zealand’s leading arachnologist, joined a group based in Toronto, Canada headed by Monica Mowery, to look at individuals from these three areas. They measured the size of individuals (bigger is usually better in interactions with competitors), their egg sac production (producing more young may give you more opportunities for at least some surviving), and length of generation times in captive populations (shorter allows for faster replacement, longer allows for larger more long-lived individuals).
A redback – amazing photo from the talented Bryce McQuillan They measured the behaviour of the redbacks, such as frequency of cannibalism (you never know when a snack might come in handy!). Also, individual spiders were placed in a new environment and the speeds at which they started spinning webs (exploration) or moving after being exposed to a puff of wind (boldness) were measured. Spiders were also placed into a warm arena with a small simulated breeze to see whether they would balloon (effectively float away in the wind) or rappel (climb using their web silk) away from the start point (dispersal).
The outcomes from this work were published in Biological Invasions. Redbacks from the invasive populations showed more dispersal behaviour than the home populations. They also tended to be larger in size, more cannibalistic, and produced more offspring. Interestingly, the redbacks in Japan and New Zealand did not seem to be more bold or explorative than in Aussie. Overall though, the invasive populations looked and acted differently to the source population.
It appears that populations that successfully disperse and establish in new areas might do so because they are settled by individuals with useful traits that differ a little from the source population. This may help us to figure out which species potentially pose the most invasive threats.
What about those strange Bucklanders? The Gaffer was mostly right. They are a bit different. Bucklanders are a population that managed to successfully disperse to an isolated area. Bucklanders are larger and more fecund. Tolkien does not record whether the Bucklanders tended to be more cannibalistic than hobbits in the Shire, but that would be a prediction!
We can certainly sympathise with the Gaffer’s concerns about his Sam going to live among them.
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All the small things
History, just one damned thing after another.
With the recent death of Queen Elizabeth II, we have had plenty of summaries of the big events during her life. There were tragedies, wars, inventions, politicians, jubilees, corgis and so on. Society when she was born was incredibly different to when she died. It’s tempting to ascribe the overall change in the world to all of these big events. But should we?
In evolution, we tend to focus on some of the big transitions; water to land, cold-blooded to warm-blooded, quadrupedal to bipedal, small brain to large brain. However, if we know one thing about evolution, it is that it occurs in populations not individuals. Yes there was an individual that was the first to be fully terrestrial, but they lived in a population where almost everyone else was 95% terrestrial. And for generations afterwards there would still have been a range of commitment to this completely dry new lifestyle.
Small and steady wins the race… Termites make up for in numbers what they lack in size. Image by Adrian Paterson. Evolutionary change involves hundreds to thousands of interactions each day in a local population of a species (and with just as many individuals of other species in the local ecosystem). It is the outcome of all of these small interactions that ultimately adds up and leads to change. The same applies to human history.
I have just started watching the show It’s always sunny in Philadelphia. The first season was filmed in 2005. What is really noticeable is the lack of phones. 2005 was two years before the iPhone was released. Scenes of people walking down Philly streets are quite unnerving to modern eyes as there are no phones in shot – everyone is looking up and around. There is a scene at a university where students are walking around with sheets of paper! And pens!
The origin of smart phones was a big event. But it was the small actions of billions of people using smart phones in thousands of different ways (not envisioned by the inventors) that have created our current world.
Central Christchurch was wrecked by a series of earthquakes in 2010-11. Image by Adrian Paterson. Closer to home, the Christchurch earthquakes of 2010/11 were Big Events. However, it was the responses of all of the people in Canterbury for the last decade that have created the new buildings, infrastructure, a generation with heightened anxiety, different views about what’s safe and so on. All these small things add up to large changes.
Tim Curran and Azhar Alam from Lincoln University joined 107 colleagues from around the world to look at how termites might respond to climate change scenarios. You don’t get a lot of things smaller than an individual termite. The life of one termite seems fairly inconsequential in the big scheme of things. However, termites have an important role in breaking down wood in ecosystems. At 133 sites around the world, the decay of pine woodblocks was measured over four years by this great gaggle* of researchers.
New Zealand has only nine species of termites, from four families (and five of those are likely to have been introduced). So they are not as dominant in their role here as in many parts of the world. Still, they can be in large numbers locally where they are found.
‘Termite-y’ – a pine tree is eaten one bit at a time! Image by Adrian Paterson. Climate features at each site in the study were measured by local researchers (hence the gaggle!) and there was a clear link between increased wood decay and warmer temperatures. Decay from termites increased by about 7% for every increase in 10 degree C. A consequence is clear. As the world warms, termites will be more likely to expand their ranges, expand their numbers, and decompose more wood.
That sounds great for the termites, and it is. In a warming world they will do very well. But every single tiny termite wood meal will ultimately unlock carbon safely stored in wood so that it is back in play. Multiply that by a trillion snacks and a large amount of extra carbon will end up in the atmosphere and temperatures will continue to increase. All these small meals add up to large changes for an ecosystem and the world.
Big events are really just markers along the way. They are typically no more important than road signs are to a journey. In the end it’s all the small things that really matter.
* not sure on the collective noun for researchers…. a reach of researchers? an N of scientists? an explosion of experimenters?