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Tomtits and robins were the focus of the first question in the 2016 Schol Bio paper. Specifically, Chatham Island tomtits and robins, which are found only on the Chathams. While at one point they were common and widespread on the islands, the tomtit is classified as nationally endangered, while the black robin is nationally critical & at very high risk of extinction.

The question paper provides two pages of resource materials (maps, photos, and text), and asks students to

Analyse the information provided in the resource materialA and integrate it with your biological knowledge to discuss

  • the reasons why the black robin has a higher risk of extinction than the Chatham Island tomtitB
  • the impact of human intervention on the survival AND evolution of the black robin population.

Compared to the more generalist tomtits, black robins are quite specialised in their habitat and diet. The robins prefer mature forest, with a closed canopy and open understory, while tomits live in mature forest but also venture into shrublands and tussock. This means that the tomtits' options in terms of food and nest sites are less limited. The fact that the robins' poweres of dispersal are limited, so they can't move to suitable habitat on other islands, doesn't help.

One of the fun things about encountering robins in bush on the mainland is that they are ground feeders - you can scuff up some of the leaf litter, step back, and watch them come down to peck through it in search of the invertebrates that they prey on. Tomtits feed at multiple levels in the forest, taking fruit & leaves as well as invertebrate animals. Their more specialised diet means the robins are more at risk following loss of habitat - or a dry year that makes their prey harder to come by. Their ground-feeding habit also means that they're more exposed to predation, something that is also the case for their nesting habits: robins prefer cavities in trees, while tomtit nests are generally quite well concealed (not that this would stop a hungry rat, possum, or mustelid from seeking them out). 

It also takes longer for black robins to replace any losses to predation, let alone grow their population. This is because, compared to tomtits, they have a lower reproductive rate: normally the robins produce one (sometimes two) clutches of 1-4 eggs a year, while tomtits may rear up to three lots of offspring a year, with 3-4 eggs per clutch. (The fact that robins can produce that extra clutch, if the first doesn't survive, was crucial to the efforts to save them when their effective population size was down to a single breeding pair.) The result is that the robins are at greater risk of extinction. 

The fact that the robin population got so low (down to 5 birds in total, with that single breeding pair) means that they went through a severe bottleneck event. As a result of this, and of the subsequent unavoidable inbreeding, there is very little genetic diversity in their population, even though there are now around 250 birds on two islands. This means that the population may not have sufficient variation to allow at least some individuals to survive any significant environmental change. The discovery of birds with deformed beaks, poor bone development, or a distinct lack of feathers has been attributed to that high level of inbreeding.

As the resource information (& a couple of the links above) makes clear, human intervention was the only thing that brought the robins back from the brink and ensured their survival to date. Thus, inducing double clutching, by taking the first clutch and placing the eggs with surrogate parents (first warblers & then, when that wasn't successful because the warblers couldn't provide the right food, tomtits) saw a marked increase in population size. (However, this did come with the risk that the robin chicks would imprint on the wrong parents, something that did actually happen.) Translocating the robins to other islands not only provided suitable habitat and food for the growing population, it also meant that their eggs weren't 'all in one basket': if a predator or disease knocked out the birds on one island, the other could still survive. 

However, conservation workers were pretty much developing their techniques with the robins as they went along, and their interventions did have an impact on the birds' gene pool. I've already mentioned the impact of inbreeding, which can result in increased odds of harmful alleles being expressed. Back in 1984, when someone noticed that a robin had laid her egg on the rim of the nest rather than in the bowl, nudging the egg back into the nest seemed the right thing to do. Unfortunately, by 1989 over 50% of the females were laying rim eggs - the DoC team had inadvertently selected for a dominant, harmful, allele (you can read the original paper here). That is, human action had countered natural selection: normally the egg would have fallen from the nest, or at the least would not have been incubated. Once researchers identified the problem, egg nudging stopped, with the result that natural selection kicked in and the frequency of the allele dropped markedly: now only 9% of females lay eggs on the nest's rim. 

Translocation and fostering could also affect the population's gene pool, and thus its evolution. If there are different selection pressures on the different islands, this could change allele frequencies in the gene pool. And, as previously mentioned, using another species as surrogate parents - while essential at the time - can lead to robins imprinting on the wrong parents and hybridising with them, something that's been confirmed by analysis of microsatellite DNA.

But if it weren't for the dedication and hard work of scientists and conservation workers, the black robin (and many other NZ species) would already have gone the way of the dodo.

 

A I wrote about this in my previous post

B Remember, this question asked students to compare the two species. So a good answer would make that comparison explicit; you shouldn't focus on the robin alone.

 

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Like probably everyone reading this, I have always thought that spiders are carnivorous, sucking the precious bodily fluidsA from their prey. I mean, those fangs!

And I was wrong, for it seems that some spiders eat some plant material alongside their liquid meals - and some are almost fully vegetarian. A just-published paper (Painting, Nicholson, Bulbert, Norma-Rashid & LI, 2017) notes that while most of these spiders take nectar from flowers, there's even one - with the delightful name of Bagheera kiplingiB - where much of its diet comprises the nutrient-rich leaf tips of acacia trees (more on that later).

The nectar-eating spiders don't rely exclusively on sweet treats; the sugar they obtain supplements their main diet. Apparently the sugar-sipping habit incurs a certain amount of risk. This is because 'extrafloral' nectaries (eg at the bases of leaves, or on the leaves themselves) are used and guarded by ants. This behaviour itself is an interesting one, as it's an example of a mutualistic relationship between the ants and the plants. The ants obtain nutrients, and their aggressive behaviour towards other animals can reduce damage by herbivores. Painting and her colleagues comment that other invertebrates - such as spiders - typically feed from these nectaries only when the ants are absent, but found evidence that 

the jumping spider Orsima ichneumon guards extrafloral nectaries through active confrontation with ants and by depositing silk barriers to inhibit their competitors.

The researchers were intending to investigate the hypothesis that the flamboyant little spiders are ant mimics, an hypothesis which - given the bright colours of this species and the generally uniform dark colours of ants - sounds a little unusual. Their plan was derailed by a landslide that meant they couldn't get to their field station, but that didn't stop them making roadside observations instead.

Figure 1

Figure 1: a male Orsima ichneumon showing off his medley of colours. From Painting et al., 2017

The team spotted a female O.ichneumon feeding from a nectary on a leaf, a behaviour that didn't take them totally by surprise as other scientists had already reported such behaviour in spiders. What was unexpected was the fact that she then laid down patches of silk around each nectary, after feeding there. Nor was this behaviour isolated to a single individual. And what's more, the researchers also observed the spiders chasing smaller ants away from their feeding spots, and avoiding larger ones. As a result they formed the hypothesis that the silk deposits - made at some energy cost to the spider - act as a deterrent to the ants, although they note that this suggestion has yet to be tested, along with the idea that the silk might be a form of spider GPS, identifying the location of food sources. But why hang around on plants where there are aggressive ants to contend with, rather than go somewhere else with more insect prey & fewer ants? Painting el al. suggest that moving around between plants may increase the risk of predation, whereas staying put might afford some passive protection due to the ants guarding 'their' plants. Plus, the energy pay-off from nectar feeding may outweigh the costs of making the silk & chasing away the smaller ants.

Now, on to Bagheera! I was sent a delightful link about this little jumping spider as a result of tweeting my surprise that vegetarian spiders are even a thing :) B.kiplingi lives on a Central American species of Acacia that's also defended by ants, and which produces structures called Beltian bodies for ant consumption. The spider gives adult ants a miss (although it eats their larvae - and plant nectar), but it eats a lot of the Beltian bodies: in the original paper Meehan, Olson, Reudink, Kyser & Curry (2009) note that these plant structures make up 60-91% of the spiders' diets. This is strange, to say the least, as they turn out to be very high in fibre and low in fat.

Fig. 2 Evidence of herbivory in the jumping spider Bagheera kiplingi. (A) Adult female consumes a Beltian body harvested from the tip of an ant-acacia leaflet. (Photo: M.Milton.) (B) B. kiplingi diet estimated from field observations. Beltian bodies contributed more to the spider's diet than did other food sources, especially in Mexico (sample sizes refer to numbers of food items observed). From Meehan, Olson, Reudink, Kyser & Curry (2009)

Meehan & his colleagues noted that the spiders live almost exclusively on acacias guarded by ants, living mostly on older leaves where ant patrols are less frequent, and avoiding ants when they're encountered. That they can survive on a high-fibre diet suggests that their gut physiology is quite different from that of their carnivorous relatives; either that, or they've acquired some gut commensals that do the job for them. The fact that they've cut out the 'middle man' (the ant larvae) to consume plant material directly may allow more spiders to live on a single plant than would be the case if they were still carnivorous.

Meehan et al. conclude by noting how the spider's unusual change in diet was dependent on the ant-Acacia relationship:

The host-specific natural history of B.kiplingi demonstrates that commodities modified for trade in a pairwise mutualism can, in turn, shape the ecology and evolutionary trajectory of other organisms that intercept these resources. Here, one species within an ancient lineage of carnivorous arthropods - the spiders - has achieved herbivory by exploiting plant goods exchanged for animal services. While the advanced sensory-cognitive functions of salticids may have preadapted B.kiplingi for harvesting Beltian bodies, this spider's unprecedented trophic shift was contingent upon the seemingly unrelated coevolution between an ant and a plant.

 

A Sorry, couldn't resist a Dr Strangelove reference :)

B how could you not love a cute little creature with a name like this?

 

CJ Meehan, EJ Olson, MW Reudink, TK Kyser & RL Curry (2009) Herbivory in a spider through exploitation of an ant-plant mutualism. Current Biology 19(19) R892-893. doi: http://doi.org/10.1016/j.cub.2009.08.049

CJ Painting, CC Nicholson, MW Bulbert, Y Norma-Rashid, & D Li (2017) Nectary feeding and guarding behaviour by a tropical jumping spider, Frontiers in Ecology and the Environment 15(8). DOI: 10.1002/fee.1538

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"Kerikeri award entry turns possums into burning issue", proclaims a headline in the Northern Advocate. 

The story is about an entry in the WWF-NZ's Conservation Awards for 2017; I hope the judges have a good grasp of science & scientific method. From the article: 

The entry from Kerikeri promotes a new take on an old-world biodynamic method of ridding fields of rodents and other furry pests.

It is called peppering, and involves burning the pelts and carcasses of said pests until they're little more than ash, grinding it finely, mixing it with water and "spray painting"; the substance back on the affected land.

Apparently this version of the 'traditional' practice is 

new in the sense that so far it has not been applied because it lacked 'scientific background'.

And it still lacks that background; using a drone to disperse possum ash doesn't make the practice any more scientific.

This is something I first wrote about back in 2010. As I said then, there's no plausible mechanism by which 'possum peppering' might work (vague appeals to 'energy forces' don't count). The anecdotal claim cited in the Northern Advocate, that the stuff is 'effective', is presented in the article without evidence. However, science has already tested that claim:  back in 1992 Eason & Hickling summarised their controlled experiments thusly: 

Bio-dynamic control involves burning pest tissue or organs and spreading the ash on areas to be protected. In New Zealand, bio-dynamic methods have been suggested for repelling possums where they damage forests or spread disease. We assessed the repellent effects of five bio-dynamic tinctures. First we tested these materials on possums in pens and noted their effects on foraging behaviour, food consumption, and body weight. Then we monitored bait consumption from treated and untreated feeder stations in the field. Although an orthodox herbivore repellent significantly deterred possums, we detected no behavioural or repellent effects of the biodynamic tinctures in any of our trials. We are unable to recommend these tinctures for possum control.

The saddest part is that the native forests in Northland are already collapsing under a combination of pressure from introduced pests such as possums & chronic shortage of funds for conservation operations in the region, and opposition to the use of 1080 isn't helping things. Suggesting pseudoscientific woo as an alternative is hindering rather than helping those doing their best to ensure the survival of these forests and the native species dependent on them.

Eason, CT & Hickling, GJ (1992) Evaluation of a bio-dynamic technique for possum pest control. New Zealand Journal of Ecology 16(2): 141-144

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There's a lovely, life-size bronze sculpture of a Powelliphanta land snail sitting on my china cabinet. I love it because a friend made it for us - and because snails in this genus are rather special, for they are all carnivorous.

Now, I 'knew' this fact, but I'd never actually seen one feeding. Snails being normally rather slow, sedate creatures, it was hard to imagine how they'd ever catch anything other than even slower prey. That was until I saw this video

Every earthworm's nightmare!

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Demodex mites are tiny little creatures that live in mammals' hair follicles. I first heard about them years ago, when I watched a documentary with my science class back at PN Girls' High. It was about animals that are parasitic on humans, and after the segment on eyelash mites, I don't know about the girls but I felt itchy for days!

For eyelash mites live where the name suggests, in the follicles of our eyelashes. (There are 2 species: Demodex folliculorum and D. brevis.) The common name gives an idea of just how small they are: adult length is 0.3 to 0.4 mm. They spend a lot of time inside the eyelash follicles, snacking on the sebum and dead cells (or maybe the bacteria) that accumulate there. But at night... at night, they come out and wander across our faces as we sleep, achieving a speed of 10cm/hr or more. Which doesn't sound much, but when you remember how small they are, that's quite an achievement. Presumably that's also when they mate, which they do where an eyelash follicle opens to the skin's surface. 

I was surprised to discover that these mites lack an anus. This sounds somewhat problematic, but the eyelash mites have survived, with their human hosts, for at least tens of thousands of years, so they obviously cope somehow. And when they die, their little bodies degrade and release their contents. On your face. Or in the follicles where they spent most of their lives.

Though demodex mites are tiny, there are an awful lot of them. There may be only one or two per hair follicle (they don't restrict themselves to the eyelashes), but an individual human has around 5,000,000 hairs on their body (Thoemmes et al., 2014), so that's an awful lot of available places for a mite to set up home in.

Thoemmes & her co-workers were interested in the genetic diversity of these mites. They predicted there'd be geographically-distinct lineages, because the tiny animals are very closely associated with their hosts and don't seem to be particularly mobile between hosts. However,

if Demodex lack strong geographic structure, it suggests the movement of mites among humans must occur very frequently (perhaps even with social greeting rituals) and across large geographic distances.

To test this hypothesis, the team examined adults (from a single North American population) visually, but also tested skin scrapings for the presence of mite DNA. The results showed that despite being able to see mites on only 23% of their sample population, 16S rDNA sequencing indicated that 100% of those sampled actually had mites present. The latter matched other research showing that 100% of dead bodies tested positive for the presence of Demodex.

Figure 2 from Thoemmes et al. (2014): Maximum likelihood (ML) phylogeny of mites based on 18S rDNA sequences.

While the results of their phylogenetic analysis of the mite DNA are based on samples from only 29 people, they're interesting nonetheless. It appears from that analysis that the 2 species, D.folliculorum & D.brevis, probably colonised humans at different times. Because D.brevis' DNA indicates that their nearest living relatives are mites living on dogs, then the researchers suggest that we acquired this species from our doggy friends, perhaps as recently as 11,000 years ago but possibly as many as 40,000 years ago. There does appear to be some regional variation (based on a comparison of the US data with earlier sequencing results from Chinese populations), but there's also quite a bit of variation within populations, due perhaps to individual humans picking up different mites on different occasions as individual humans came into close physical contact.

And after reading all this & watching a few videos, I feel itchy again!

Thoemmes MS, Fergus DJ, Urban J, Trautwein M, Dunn RR (2014) Ubiquity and Diversity of Human-Associated Demodex Mites. PLoS ONE 9(8): e106265. doi:10.1371/journal.pone.0106265

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Once upon a time, I wrote about traumatic insemination in bedbugs. (Those of my friends who are still traumatised by learning about the reproductive habits of various slug species may not wish to follow that link.) Now, two papers just published in Nature Communications describe the results of sequencing & examining the genome of the common bedbug, Cimex lectularius

Bedbugs have probably been with us since humans first lived in caves, where the bugs jumped (possibly literally) from bats to Homo. They're now a widespread human ectoparasite (found on every continent apart from Antarctica) and have developed resistance to the pesticides once used to control their populations. In introducing their paper on their analysis of the C.lectularius genome, Rosenfeld & his colleagues (2016) comment that

There is a limited molecular understanding of the biology of the bed bug before, during and after feeding on human blood, which is essential to their life cycle since bed bugs are temporary ectoparasites, whereby they access their hosts for blood feeding and then seek the refuge of the indoor environment for digestion, waste production and mating.

To increase our understanding of the bugs' life cycle, Rosenfeld's team looked not only at the genome sequence but at changes in gene expression, finding the most pronounced changes occurred after the insect had sucked its fill of human blood. They also found that these changes in expression 

included genes from the Wolbachia endosymbiont, which shows a simultaneous and coordinated host/commensal response to haematophagous activity. 

In other words, gene expression in both host and parasite changes in a synchronous way after the bug has fed. (Just as an aside, Wolbachia is a bacterium that has a significant impact on the reproductive lives of its host.) In the bugs the change could be described as huge: "20% of all stage-regulated genes" showed differential changes in expression after a blood meal.

As you'd expect, the bugs have a number of genes with anticoagulant activity - after all, having blood coagulate in their needle-like mouthparts while feeding would really gum things up - plus other genes associated with blood-feeding. The research team also identified a number of mutations that confer resistance to pesticides such as pyrethroids & cyclodienes, plus others that may underlie metabolic changes that speed up detoxification. Genes that have an impact on the thickness of the bugs' cuticle also have an impact on resistance (also noted by Benoit et al. 2016). 

In the second paper, Benoit and his colleagues (2016) also analysed the common bedbug genome to produce

a comprehensive representation of genes that are linked to traumatic insemination, a reduced chemosensory repertoire of genes related to obligate hematophagy, host–symbiont interactions, and several mechanisms of insecticide resistance.

Traumatic insemination involves male bugs stabbing their sexual partners pretty much anywhere on their bodies with a sharp, pointy, penis. It's a habit that can lead to the females picking up a range of pathogens, and unsurprisingly natural selection has driven the evolution of a range of adaptations minimising the physical harm and risk of infection. 

Because the bugs are obligate blood-feeders (haematophagous), their chemosensory system has evolved to allow them to find their particular hosts (ie us). The team observed that the genes involved in this system differed between C.lectularius & the related species that feeds on bat blood, as the 2 species have specialised on different hosts. They identified a total of 102 genes involved in chemosensory pathways, well down on the number found in related bugs (hemipterans) that feed on a range of plant species. (On the other hand, they have a much-expanded repertoire of salivary enzymes, compared to the plant-sucking bugs.)

The bedbugs' specialisation on human blood as their sole food source did have some potential pitfalls, as apparently vertebrate blood lacks some of the micronutrients that arthropods require. And that's where Wolbachia comes back into the story: 

such specialization also drives obligate associations with symbionts, including Wolbachia, that generate critical micronutrients that are deficient in vertebrate blood (Benoit et al., 2016).

Wolbachia does this by providing its host with 

a cocktail of specific B vitamins that are critical for reproduction and development

The research team also found genes encoding proteins (aquaporins) that allow the bugs to rapidly shed the excess water imbibed in a blood meal, and concluded that differential expression of aquaporin genes (and others) allow the bugs to survive periods of starvation and dehydration in between hosts.

In their conclusion, Benoit et al. comment that the wealth of information uncovered by these genomic studies may allow us to move towards an answer to a pressing question: 

What triggered the current bed bug resurgence?

To which harassed travellers would probably add, and how can we bring them back under control?

J.B.Benoit, Z.N.Adelman, K.Reinhardt, A.Dolan, M.Poelchau, E.C.Jennings, E.M.Szuter, R.W.Hagan, H,Gujar, J.N.Shukla, F,Zhu, M.Mohan, D.R.Nelson, A.J.Rosendale, C.Derst, V.Resnik, S.Wernig, P.Menegazzi, C.Wegener, N.Peschel et al. (2016) Unique features of a global human ectoparasite identified through sequencing of the bed bug genome. Nature Communications 7 Article number 10165 doi:10.1038/ncomms10165

J.A.Rosenfeld,D.Reeves, M.R.Brugler, A.Narechania, S.Simon, R.Durrett ,J.Foox, K.Shianna, M.C.Schatz, J.Gandara, E.Afshinnekoo, E.T.Lam, A.R.Hastie, S.Chan, H.Cao, M. Saghbini, A.Kentsis, P.J.Planet, V.Kholodovych, M.Tessler et al. (2016) Genome assembly and geospatial phylogenomics of the bed bug Cimex lectularius.  Nature Communications 7 Article number: 10164 doi:10.1038/ncomms10164

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By now many of you have probably seen images of green-glowing zebrafish, or pigs whose snout & trotters glow in the dark. In both cases the animals are genetically modified and are expressing a fluorescent protein originally sourced from a jellyfish. (The body form of a jellyfish is a medusa, while that of sea anemones & their freshwater relative, Hydra, is called a polyp.) There are a range of these proteins, which collectively belong to a group called the Green Fluorescent Proteins (what else?), and while a wide range of jellyfish produce them1 there are only occasional reports of glowing polyps.

However, in a paper just published in the open-access journal PLoS ONE, Andrey Prudkovsky & his colleagues describe finding tiny (~1.5 mm) fluorescent polyps living in the Red Sea. More specifically, growing in colonies on the shells of small gastropods, a relationship described as epibiotic. The snails are active at night on the sandy seabed, and the researchers noted that the little gastropods buried themselves in the sand when a torch shone on them. They also noticed that the snails, as they moved about in the moonlight, were covered with tiny pinpoints of green light.

Where fluorescence has been described in other polyps, it's mostly been in the 'stalks' of the little animals, but in all the polyps Prudkovsky's team studied, the intense green glow came from a region known as the hypostome - the region around the animal's mouth & encircled by its tentacles. Because both the intensity and the site at which the proteins are expressed is so unusual, the researchers suggest that this could be a useful taxonomic characteristic, given that it's hard to tell one colonial polyp species from another.

They also speculate on the adaptive significance of a polyp having a green glow around its mouth, suggesting that 

[f]luorescence in the hypostome of Cytaeis sp. has probable ecological significance as prey are likely to be attracted to the tentacles and mouth of the polyps

although I do feel that until there's actual observational evidence of this happening, it's a little like an evolutionary just-so story. But isn't the combination of little snails and glowing polyps rather beautiful?

Fig 3.  Hydroid polyps of Cytaeis sp. from the Saudi Arabian Red Sea, scale bar 2 mm; (A) fluorescence of living polyps on the shell of the gastropod Nassarius margaritifer; (B) polyps on the shell of a N. margaritifer specimen, scale bar 2 mm; (C) close-up of polyps, scale bar 0.5 mm.

Fig 3 From Prudkovsky et al., 2016: Hydroid polyps of Cytaeis sp. from the Saudi Arabian Red Sea, scale bar 2mm; (A) fluorescence of living polyps on the shell of the gastropod Nassarius margaritifer; (B) polyps on the shell of a N.margaritifer specimen, scale bar 2mm; (C) close-up of polyps, scale bar 0.5mm. doi:10.1371/journal.pone.0146861.g003

1 And also in comb jellies, marine arthropods, and cephalopods cephalochordates (thanks to herr doktor bimler for picking up the evidence of my brainfade).

Prudkovsky AA, Ivanenko VN, Nikitin MA, Lukyanov KA, Belousova A, Reimer JD, et al. (2016) Green Fluorescence of Cytaeis Hydroids Living in Association with Nassarius Gastropods in the Red Sea. PLoS ONE 11(2): e0146861. doi:10.1371/journal.pone.0146861

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I love words (to the extent that I've been known to peruse dictionaries for pleasure). The Story of English was one of my favourite TV programs, back (long way back) in the day. So of course when I saw positive reviews for Robert Macfarlane's book, Landmarks, of course I had to get hold of a copy. For, as the author says, 

This is a book about the power of language,... It is a field guide to literature I love, and it is a word hoard of the astonishing lexis for landscape that exists in the comparison of islands, rivers, strands, fells, lochs, cities, towns, corries, hedgerows, fields and edgelands uneasily known as the British Isles.

I could tell I was going to enjoy the book as soon as I read that first paragraph. This isn't going to be a book review, because I haven't finished it yet. But I do want to share my thoughts on something else that Macfarlane says, very early on (in explaining his reasons for writing it). 

For he dicovered that a new edition of the Oxford Junior Dictionary (my kids had to have their own copies for school) had removed a number of words from its lexicon:

A sharp-eyed reader noticed that there had been a culling of words concerning nature. Under pressure, Oxford University Press revealed a list of the entries it lno longer felt to be relevant to a modern-day childhood. The deletions included acorn, adder, ash, beech, bluebell, buttercup, catkin, conker, cowslip, cygnet, dandelion*, fern, hazel, heather, heron, ivy, kingfisher, lark, mistletoe, nectar, newt, otter, pasture and willow.

In their place, the editors had added terms bearing on modern technology, including "attachment, block-graph, blog, broadband, bullet-point, celebrity, chatroom, committee, cut-and-paste, MP3 player and voice-mail".

Now, I'm not someone who resists changes to the language. I know words change their meaning over time (which is why etymology is so much fun), and I know that words fall out of favour and into disuse, eventually to be lost. But that's different from an editorial board making a conscious decision on what words are more, or less, important for children to know and understand. 

The OUP editors were happy to explain the changes to Macfarlane: earlier editions had a reasonably large contingent of 'nature' words because a larger proportion of the population lived in semi-rural areas and would see plants, animals and the seasons on a regular basis.

"Nowadays the environment has changed." There is a realisim to her response - but also an alarming acceptance of the idea that children might no longer see the seasons, or that the rural environment might be so unproblematically disposable.

Now, words have a certain power. Of course you can convey a powerful message in relatively few short words! But a complex vocabulary allows precision in description, and (Macfarlane thinks, and I agree) also allows a sense of connection with the world. Not only is it sad to think that children may see less of the natural world these days, but it's a concern if with the loss of vocabulary comes a reduction in the ability to engage with any precision in describing and understanding the natural world.

There is, after all, a big difference between knowing that something's a tree, and knowing that it's a particular type of tree with its own particular niche. If we lose the feeling of the specific that's associated with the ability to name plants or animals with exactitude, do we also lose some amount of care for their individual survival, and for their wider environment? Macfarlane certainly thinks so, & says it far more eloquently than I can.

He quotes a colleague's observation that 

as people's 'working relationship with teh moorland [of Lewis] has changed, [so] the keen sense of conservation that went with it has atrophied, as has the language which accompanied that sense.

And

there are fewer people able to name [the features of the natural world], and that once they go unnamed they go to some degree unseen... As we further deplete our ability to name, describe and figure particular aspects of our places, our competence for understanding and imagining possible relationships with non-human nature is correspondingly depleted ... Or as Tim Dee neatyly puts it, 'Without a name made in our mouths, an animal or a place struggles to find purchase in our minds or our hearts.'

And so the loss of these words diminishes us all.

 

* Dandelion's gone? Really? Dandelions pop up even in concrete jungles. If  there was one flower I might expect city kids to see, it would be that.

R.Macfarlane (2015) Landmarks. pub. Hamilton Hamilton

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In 2012 the world was introduced to some of the smallest-known vertebrates: tiny chameleons. My good friend Grant wrote about them at the time, & I set an essay assignment for my first-years on these tiny beasties. How tiny is tiny? The following images are from the original paper, published in PLoS one by Glaw, Kohler, Townsend & Vences, 2012.

thumbnail

Brookesia micra sp. n. from Nosy Hara, northern Madagascar. (A) adult male on black background, showing orange tail colouration; (B) juvenile on finger tip; (C) juvenile on had of a match; (D) habitat along a small creek on western flank of Nosy Hara, where part of the type series was collected. doi: 10.1371/journal.pone.0031314.g008

Anyway,Science News has an article on the speed with which chameleons shoot out their tongues to capture prey. It's based on this paper by Christopher Anderson, published in Scientific Reports.

When a chameleon shoots out its tongue, the movement's driven not only by muscle contraction but by utilising the potential energy stored in stretched elastic tissues. This allows the animal

to release energy more rapidly than by muscle contraction directly, thus amplifying power output. Chameleons employ such a mechanism to ballistically project their tongue up to two body lengths, achieving power outputs nearly three times greater than those possible via muscle contraction.

Noting that small animals are often capable of greater performance in the same feat than larger ones (think about the relative heights that fleas can jump, for example, or the loads that ants are capable of carrying), Anderson hypothesised that smaller chameleons would be able to outperform larger ones when it came to thrusting out their tongues.

To test this, he watched feeding by chameleons from 20 different species, and found that smaller species could indeed reach further: 2.5 times  body length in an individual just 47mm long. And they also achieved much greater accelerations: while larger species send forth their tongues at accelerations as high as 486 m s-2, the smaller ones Anderson studied managed far greater acceleration and power:

peak accelerations of 2,590 m s-2, or 264 g, and peak power output values of 14,040 W kg-1

The interesting question here is, why? Why can smaller chameleons shoot their tongues our further & faster? The answer may lie in the animals' metabolic rates: smaller chameleons will have higher mass-specific metabolic rates, and better feeding effectiveness could mitigate the impact of this. Anderson's data support this: because they also have proportionately longer jaws, larger tongues & associated structures, and higher relative tongue projection distances, 

small chameleons have effectively increased the relative size of their entire feeding apparatus. In doing so, small chameleons have increased the functional range of their prey capture mechanism, and are likely able to capture and process larger prey items than they would otherwise be able to if their muscle cross sections and jaws were not disproportionately large for their body size. This inference is supported by the selection of proportionately larger prey items by the smaller of two morphological forms in Bradypodion. These patterns are thus consistent with those that would be predicted for mitigating metabolic scaling constraints, which may be involved in driving the observed morphological scaling patterns.

Dr Anderson has produced a number of videos showing just what happens when a chameleon strikes, and has kindly given permission for me to use one of them here: 

C.V.Anderson (2016) Off like a shot: scaling of ballistic tongue projection reveals extremely high performance in small chameleons. Scientific Reports 6, article number 18625. doi: 10.1038/srep18625

 

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A few days ago there was a story in the Herald about an Australian huntsman spider that had been found by NZ's border security workers at Auckland airport. With a legspan of up to 15cm these are not small creatures! And yes, we do have them in NZ as well, but they're a different genus: NZ readers may know them as the Avondale spider. 'Our' version was most famously used - and viewed - in the film Arachnophobia

I was reminded of that story when my Facebook feed brought up an article, complete with video, about how the Australian spiders are used by parasitic wasps as incubators for their babies. (A photo in the linked article will give you a good idea of just how big both wasps and spiders are.) Once a spider's been paralysed and dragged back to the wasp's nest, its stuffed into the cavity and a single egg is laid in its body. Once hatched, the growing wasp larva eats its paralysed host, avoiding any vital organs until the last minute (after all, no self-respecting larva would want to dine on rotting spider if that were avoidable!).

Many people would probably find this quite gruesome, but it is simply the wasp's natural behaviour, and something that Darwin himself commented on in a letter to Asa Gray in explaining his thoughts on evolution and religion (it's a most interesting letter to read):

I cannot persuade myself that a beneficent & omnipotent God would have designedly created the Ichneumonidæ with the express intention of their feeding within the living bodies of caterpillars.

Ickily fascinating.

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