27 November 2014

The things we leave behind



Sometimes I wonder what people would be able to deduce about me from looking at my office. If someone came in snooping I'm sure that they would get some understanding of me, even if I was absent, simply by looking at what I leave behind. Of course there are some obvious things. I have what I like to think of as a typical academic's office, messy, possibly chaotic, a sense of personality, perhaps a sense of busy work. Of course not all academics are like this but there are plenty who are, like one of my corridor neighbours Tim Curran. Another neighbour, John Marris, has an immaculate office with everything in its place but, then, he is the curator of our entomology museum and so being precise and particular comes with the territory. Another neighbour, James Ross, also has a extremely tidy office. He is a regular academic, so no real excuse, and I find entering his office quite daunting. There is certainly some reflection of their offices into how they run the rest of their lives.
Adrian's office - typical academic?

Turning to my office in more detail, such a snoop might gaze at my desk. At first glance (and at multiple glances really) there are many chaotic piles of paper. Perhaps evidence of a person that can multi-task and perhaps they use chronological filing? There is a pile of documents on new course development administration, another with an attempt to write a children's story on insect identification, still another of recent papers (on explanatory power in ecology, self-immolation in plants, evolution of sex chromosomes, convergence of lizard morphology on islands and getting DNA from possums), and another with an odd collection of names of potential candidates for the Canterbury Country Under 15 cricket team, Adrian's postgrad students monthly funding, a design for next year's research methods course and a document about the appraisal of the local primary school principal. What would my snoop make of these? Perhaps that Adrian spends a lot of time on teaching committees, perhaps has had kids and likes to write, has a wide range of research interests, is involved in cricket coaching, supervises postgrad research, is proactive about getting ready to teach a course 3 months away, and is involved in governance at the local school. All correct. Looking closer they might observe some D and D dice (so a nerd!) and a dinosaur (so a science nerd!). Looking around my room the snoop would see from my posters that I have an interest in movies and Darwin and my books and 'toys' would confirm it.

As individuals move through the world they interact with other individuals and other elements of their environment. Every interaction leaves something behind, whether intangible, say a memory, or tangible, say a footprint. Individuals are constantly leaving clues about themselves behind. This is one of the reasons that we are uncomfortable with our new online existence, how it is possible for anyone with the right access to know almost everything about you! Of course, there is something even more personal that you leave behind you everywhere you go - your DNA. We live in a sea of DNA. Every living thing around you has DNA. All of the cells that you are constantly shedding have DNA. The DNA ranges from fully functioning in living cells to various states of decay in nonliving cells. Everything you touch, everywhere you breathe, leaves behind DNA. Most times this is in very low quantities but this can still be detectable. One of my students just found that in a few ml of seawater taken at a local shore that we could detect shark and seahorse species that are swimming about in the area! (More on that at a future time) Because of the presence of this sea of genetic material, DNA is a great potential resource for ecologists and conservationists.
A waxtag, complete with possum bites, saliva and DNA

As ecologists we often deal with animals that are difficult to find or detect. Usually, we want to monitor populations to find out if they are increasing, moving, changing in age structure and so on. For many species this is difficult. They might be nocturnal, or cryptic, or in tough terrain, or small, or dangerous, or - well you get the picture. Being able to detect where individuals have been (even if they have moved on now) is a very useful ability. We have cameras that detect motion, tracking tunnels that record footprints in ink, GPS collars that can be attached to an individual and then followed. These are all useful methods. Here at Lincoln we do a lot of work on possum behaviour. One method for inferring possum presence is to put out waxtags which possums happily bite and leave tooth marks on. We can collect these up and know that at least one possum came past and bit the tag. Sometimes we would like more precision. We want to know how many possums came past and bit the tag. Were they males or females? The bites don't tell us that kind of information. However, the possums leave more than just the bite marks, they also leave DNA that is present in their saliva.

In a new study by masters student Juan Duenas, with James Ross and Rob Cruickshank, just published in New Zealand Journal of Ecology, it is confirmed that possum DNA can be collected from saliva on waxtags. More impressively, enough microsatellites (highly variable areas of DNA) can be distinguished to identify individuals (a kind of genetic fingerprinting). The DNA doesn't come easily though as it quickly starts to degrade in the saliva and then on the waxtag itself. The tags were bitten by possums at some point during the night of collection and their DNA was only just good enough, condition-wise, in the morning to actually be decoded. Still, this is a good step forward, we can use the DNA that possums leave behind to find out how many individuals are in an area, where they might have moved into the area from and what the sex ratio might be. This is all information that is very difficult and labour intensive to collect otherwise. The DNA that organisms leave behind is becoming a very powerful tool for understanding the private lives of these individuals. I wonder if my snoop has a DNA kit....

20 November 2014

Rowan Emberson: entomologist

Rowan Emberson has been awarded a Lincoln Medal for his services to entomology. Rowan was a senior lecturer in the department when I first started at Lincoln University. He became a valued colleague with several shared postgraduate students that we supervised. To me, Rowan is one of the last gentlemen entomologists. He is always, precise, well-mannered and well-spoken. To a farmboy from Balclutha this was a new experience and Rowan become a role-model, not just for me but also for a couple of generations of New Zealand-trained entomologists who were influenced by Rowan’s quiet but determined ways. Even after his retirement in the early 2000s he remained an important fellow researcher, especially with our work on the Chatham Islands biota. The following is taken from his nomination.
John Begg, Rowan, Hamish Campbell and Steve Trewick in the Tuku,
Chatham Island

Rowan Emberson became a Lecturer in Entomology at Lincoln College in late 1968. Rowan spent his entire working career of 33 years at Lincoln College/University, including a period as acting Head of Department. Since his retirement in 2002 he has continued his association with the university as an Honorary Senior Lecturer. Rowan has continued to advise many of the entomology postgraduates at Lincoln University over the last decade for both the Department of Ecology and the Bioprotection Centre.

Rowan graduated from Edinburgh University with a degree in forestry, writing his honours dissertation on mesostigmatid mites in soils in ancient pine forest. This led to further study of soil inhabiting mesostigmata for a PhD at McGill University in Montreal, Canada with Professor Keith Kevan. During the last year of his PhD studies, Rowan taught an entomology course at Sir George Williams University in Montreal.

In his first years at Lincoln, Rowan’s research concentrated on mites and beetles, especially Carabidae and Scarabaeidae, and he accumulated a broad knowledge of the New Zealand Coleoptera fauna. Rowan was involved in many ecological surveys, often in partnership with postgraduate students. One major project was documenting the Chatham Island beetle fauna for conservation purposes, which later led to collaboration with geologists on a project to determine the age of the Chatham Islands.
Rowan on a beetle hunt on southern Main Chatham Island.

Rowan, in conjunction with Professor Roy Harrison, established a Lincoln University insect collection in the late 1960s, which became the basis of the Entomology Research Museum (LUNZ). The collection is one of the largest and most diverse insect collections in the country. It is widely used by students and researchers and contains type material of many New Zealand species. The collection was built up in a series of annual summer field trips to different locations from North Cape to Stewart Island that persisted until 1991. Rowan spent considerable time throughout his career, in weekends and holidays, collecting samples to increase the collection.

Rowan’s research interests were broadened through supervising student projects in agricultural entomology. He developed a particular interest in how pest and beneficial insects have adapted to the New Zealand environment. Many of his students have gone on to play important roles in New Zealand’s bioprotection area.
Rowan named numerous species and had a dozen named in his honor.

Rowan has been an active supporter of the Entomological Society of New Zealand, serving as President from 1993–95. With Dr Eric Scott, Rowan compiled the ‘Handbook of New Zealand Insect Names’ and for a number of years prepared submissions on behalf of the Society to the Environmental Risk Management Authority on proposed new introductions. Rowan served on the Westland/West Coast National Parks Board for a number of years.

In his retirement, Rowan has continued to work in the entomology area. He followed up on his studies of the New Zealand and UK faunas of Macrochelidae with a revised classification of the family, which is now widely used internationally by researchers using these mites for control of nuisance flies. Rowan has spent much of the last decade working with Department of Conservation surveying invertebrate diversity for tenure reviews in areas like the Murchison Mountains, Bankside and Coopers Knob. Rowan has also continued his interest in dung beetles, through collaboration in research projects in Thailand and Nigeria. Further, Rowan’s expertise is still being put to good use as a member of the editorial board of the Fauna of New Zealand.

Congratulations to Rowan. This is a well-earned honour.
Always searching!

A small selection of some of Rowan’s 84 papers:

Emberson, RM. 1973: Macrochelid mites in New Zealand (Acarina: Mesostigmata: Macrochelidae). New Zealand Entomologist, 5(2): 118–127.

Emberson, RM. 1995: The Chatham Islands beetle fauna and the age of separation of the Chatham Islands from New Zealand. New Zealand Entomologist, 18: 1–7.

Emberson, RM. 1998: The size and shape of the New Zealand insect fauna, pp. 31–37 in Ecosystems, Entomology and Plants. Proceedings of a Symposium held at Lincoln University to mark the retirement of Bryony Macmillan, John Dugdale, Peter Wardle, and Brian Molloy. The Royal Society of New Zealand. Miscellaneous series 48: 1–143.

Hanboonsong, Y., Chunram, S., Pimpasalee, S., Emberson, RM., Masomoto, K. 1999: The dung beetle fauna (Coleoptera: Scarabaeidae) of Northeast Thailand. Elytra, 27: 463–469.

Scott, RR., Emberson, RM. 1999: Handbook of New Zealand Insect Names: common and scientific names for insects and allied organisms. Bulletin of the Entomological Society of New Zealand, 12: 1–97.

Brown, B., Emberson, RM., Paterson, AM. 2000: Morphological character evolution in hepialid moths (Lepidoptera: Hepialidae) from New Zealand. Biological Journal of the Linnean Society, 69: 383–397.

Emberson, RM. 2010: A reappraisal of some basal lineages of the family Macrochelidae, with the description of a new genus (Acarina: Mesostigmata). Zootaxa 2501: 37–53.

Leschen, RAB., Marris, JWM., Emberson, RM. , Nunn, J., Hitchmough, RA., Stringer, IAN. 2012: The conservation status of New Zealand Coleoptera. New Zealand Entomologist 35: 91–98.

03 November 2014

The answer is blowing in the wind

It is springtime here in Canterbury. That means lambs are frolicking in the fields, cricketers are filling our domains, we go from 12C, three days ago, to 26C days, yesterday. Mostly, the wind has returned (although it never really goes away). Lincoln is a windy place. Our supermarket has windmills in the parking lot! With all of that wind, pollen levels are off the charts as they waft about. It was so windy yesterday that my father-in-law's hearing aid blew away while he was out walking and never seen again! While the wind can cause issues; itchy eyes, storms that knock down trees, slow trips home on the bike, it can also provide benefits; dried laundry, drift on an arm ball, fast trips to work. Perhaps living in a windy environment accustoms one to thinking about how wind can help in moving things about. If you are a species that flies, especially if you are small, then the wind is going to influence how easy it is to move in certain directions. Even organisms that have no wings can still be affected by wind.

Tussock grasslands on top of the Lammerlaw Range
I have worked a lot with spider species. Spiders do not have wings but their distributions are still influenced by wind. In many spider species the young use a line of silk that they produce to lift themselves off the ground in a process known as ballooning. On a warm day, the silk line drifts upwards and lifts the spiderling off the ground. The wind does the rest. At some point the spiderling returns to earth after a short trip.

Another consequence of living in a windy environment is that the local habitats dry out and become prone to fires. A couple of summers ago we had a major fire that burnt out of control through the shelter belts near Lincoln, stopping just a couple of kilometres from the University. We are looking at another dry summer this year. It has been interesting watching what has grown in the areas that were burnt. Usually the plants that have returned are not necessarily the same as those that were there before. Sometimes it depends on what seeds/plants survived the fire but often it depends on which seeds have turned up from outside the burned area. One can ask the question of whether there are certain types of traits that allow some species to colonise first. Being able to be moved by wind could be an important trait. In addition to the plants, we also might want to know about the animals and how they respond to these crises, especially the invertebrates.
Spiders are important predators in most habitats.

Fires are not particularly common in New Zealand, but one area where they can occur in the montane grassland zone. Tussock grasslands tend to be in dry parts of New Zealand where fires can be natural (lightning), accidental (camp fires) or deliberate (set by farmers managing pasture). As more of these areas are transferred into conservation land, it is important that we understand the effects of fire. A great opportunity to study this has been available in the Deep Stream area of east Otago (about an hour inland from Dunedin). This area has never been cultivated and had not been burned for at least 30 years before our study began. Areas were selected to be either burnt in spring or summer as well as control areas with no burning. Invertebrate diversity was then measured in these areas for the three years before burning and four years after burning to examine the effect of fire and the timing of the fire on these populations. We were particularly interested in what happened to the spider communities. Spiders are top predators in these systems and can tell us a lot about the health of these ecosystems. If there are a lot of spiders about then there must be a lot of spider food species.
Jagoba sampling spiders in a cool and windy habitat.

My former PhD student, Jagoba Malumbres Olarte, worked closely with researchers from AgResearch, especially Barbara Barratt, in collecting spiders from pitfall traps and by digging out whole tussock plants and extracting spiders in a Tullgren funnel. The outcome of this work has been published in the journal Biological Invasions. Jagoba found over 4500 spiders in the seven years of samples and sorted them into 66 species and 22 families. Ten of these species were exotic (not native to New Zealand) and increased markedly in the burned samples while native species had significantly less resilience. This is a real concern as it suggests that one reason that introduced species can take over a habitat is because they are better at colonising and establishing after a crisis. Jagoba also looked at some of the traits that might explain the advantage of exotic species. Whether a species could balloon was important for colonising after summer burns. Exotic species tend to be good ballooners and can easily waft into burnt habitats from elsewhere. Jagoba also found that large spiders were able to colonise burnt habitats more easily after both summer and spring burns. This may because larger spiders find it safer to walk through the landscape compared to smaller species. Many of the exotic species, especially the Linyphiids, are large. So the wind does help species move about and gives exotic spider species an advantage over natives. One unintended outcome of burning native grasslands is that this provides exotic species with a way into these areas to colonise and then dominate, reducing the local native diversity. More worryingly, any crisis that impacts on an area, say landslides, floods, human modifications, will result in the same benefits for these ballooning, large, exotic spiders. The answer to why introduced species do so well in New Zealand really is blowing in the wind.

20 October 2014

Winning the battle for our birds (but losing the war?): 1080, rats, possums and the NZ bush

Sometimes common sense is not actually our friend. In our society common sense is usually seen as a virtue that those so-called experts could do with more of. But common sense can fall down on the common side of things. The All Blacks have gone into every rugby world cup as the favourites to win over all. They have won only two. This is a case where 'common' is a statistical concept in which there is a higher likelihood of something happening, but no guarantee that it will happen. Common sense can also fall down on the 'sense' side of things as well. Looking at our modern lifestyle it seems obvious that we are much less active than our ancestors would have been. It's no wonder we have issues with weight in our societies. However, data points to the fact that we are actually just as active as our hunter-gatherer ancestors and we need to look at other reasons for obesity. This is a case where 'sense' is a statement that needs data to confirm it. So although common sense is a useful concept, allowing us to make predictions based on experience, it can be misled through probability and through not having correct facts. Common sense is particularly a problem when we are faced with emotion-charged debates. In New Zealand one of the more emotionally charged debates is with the use of toxins to kill mammalian pest species, like rats, possums and stoats, at very large scales.
There's a whole lot of seeds up there!

The southern beech (Nothofagus) forests of New Zealand are prone to heavy seed crops every 4-6 years (known as a beech mast). Mast events provide a huge amount of food for rodents whose populations swell over the next few months. With the rise in rodent numbers we get a similar, though slower, response by their predators, particularly the stoats (a mustelid). The following year is almost never a mast event and so rodent numbers crash as there is not enough food around. The inflated predator population will continue to eat rodents where they can but, with the rodent population decline, they often switch to other prey. In New Zealand this other prey is mainly birds, and in beech forest these are usually native species. So a mast event will usually lead to a massive reduction in bird populations the following year, when the stoats get hungry. This year has been a mast year in our beech forests. What can we do to ensure that our threatened bird species are not decimated over the next year?

The Department of Conservation has launched the 'Battle for our birds' campaign. Common sense would suggest that if we could keep the rodent numbers down during the mast event, then their populations will not increase and, therefore, stoat numbers will not increase as a result. So, no  problems for birds next year. Department of Conservation are delivering the toxin 1080 to several hundred thousand hectares of key beech forest habitat throughout New Zealand this year. The toxin is dropped into the forest where is can be encountered by rodents (usually rats) who will store some of the cereal bait, eventually consuming a lethal dose. Stoats eating recently dead rats may also accumulate a lethal dose and their populations don't increase as their food supply does not increase. Happy birds in 2015. Problem solved.

Rats: In action on the forest floor

Maybe. There are a number of studies now that have looked at the long term effects of intense control of mammal pest populations. In a seminar at the Department of Ecology, Lincoln University, Dr James Ross talks through a couple of studies that he has been involved with which looks at what happens to populations that have had pest control done. Long-story short (but you should listen to that entertaining talk!), 1080 does a great job of knocking down rodent and possum populations (and stoats as a by-product). The forests habitats respond positively to the removal of the pests, particularly the small bird species. However, different species recover at different speeds. Mice are not particularly troubled by toxin drops (as rats are usually dominant and grab the baits) and their numbers begin to grow after control as they have no competition from rats. This is not such good news for forest invertebrates that are in the food size range of mice. After a few years, the rat populations start to bounce back (mostly by re-invasions from the edges of the control areas) and at a much faster rate than stoats. So there is a period of time where rat populations will not be checked by stoat predation. So will the battle for our birds work? It depends on the timeframe and what follow up work is done. Control will certainly put a break on rat (and then stoat) populations and preserve bird populations in the following year, that's just common sense. However, if follow up control of rats is not done after three or so years then rat populations may rebound ahead of their predators and we will have a problem similar to that of a mast season occurring, lots of rats that lead to a surge in stoats. So we might win the battle but lose the war if we are not careful. And that, perhaps, isn't such common sense.

13 October 2014

Tolkien made me an evolutionary biologist

I've been an evolutionary biologist for over two decades now and I have been reflecting recently on how I came to join this profession. I started re-reading Stephen Jay Gould's Ever since Darwin, Goulds first collection, and have to acknowledge that Gould's amazing essays played a role as an undergraduate. Darwin's On the origin of species was also influential around the same time. Dawkin's The Selfish Gene was one of the first science books I read, so that has to be part of it. But, really, I have to go back further as I arrived at university with the passion for zoology and evolution already forming. In fact I can go back to when I was about 9 years old and read The Hobbit, followed by The Lord of the Rings a couple of years later. That's where it started.

Tolkien and evolution. These are not things that normally go together. Tolkien has often been portrayed as a romantic, always looking at the good old days, anti-technology and progress (especially by sf author David Brin). And this is hard to argue against. However, and perhaps ironically, there are many themes in Tolkien that help to prepare one for a life in evolution.

Min: The journey is important.
Summarising The Lord of the Rings as "short tourist loses valuable heirloom at volcanic destination" loses the whole sense of the journey, which is actually what the story is about. All the characters change (or evolve) significantly during the story. Evolution is about the journey, exposing the history of lineages. Ecology is about the destination, looking at the interactions that are here now. Tolkien helped my young mind to understand that everything has a history and that this journey is important.

Tad: Lineages are important.
Tolkien loves his genealogies. Frequently in his writings we are told who is related to who. It matters that Elrond has links to certain elven and human lineages. There are lineages in his appendices. This was a revelation to a young me. Relationships are important. Closely related characters respond in different ways to distantly related characters. Tolkien helped my young mind to understand that everything has a history and that lineages are important.

Neledh: Spatial scale is important.
Tolkien loved maps. One of the cool things to a nine year old was the map in the front of The Hobbit (as well as the runes!). Even in an imaginary world it matters where things are. It matters that the Lonely Mountain is on the Long Lake or that the Misty Mountains need to be crossed to get to Mirkwood. It matters that Farmer Maggot's farm is next to the Buckleberry Ferry. Tolkien helped my young mind to understand that where things are located spatially is relevant to explaining the journey.

Canad: Species distributions are important (as is how they came about).
Part of Tolkien's fascination with maps is that he uses them to explain where races are located. You learn about the distribution of dwarves, hobbits, elves and so on. You also learn about how these distributions have changed over time. Tolkien had detailed notes on the dispersal of races. For example, the hobbits had colonised The Shire relatively late in the piece, dispersing from Bree and prior to that from the shores of the great river Anduin across the Misty Mountains. Tolkien helped my young mind to understand that species move around, that what you see today has not always been the case, and that dispersal is a powerful force.

Leben: Landscapes are not permenant.
Tolkien presented different eras. The Lord of the Rings is set at the end of the third age which had been going for 3000 years. Two long ages preceded this one, giving a perception of deep time. Moreover, even the continental landscapes had changed during this period. Large parts of western Middle-Earth had submerged beneath the seas, cataclysmic battles had raised mountain ranges. Tolkien helped my young mind to understand that there is no long term permanence in geological features.

Eneg: Diversity is important.
Tolkien valued diversity. It is no accident that the fellowship is successful because it is made up of different races, each with skills that help achieve the final goal. Or that it is the hobbit joining the dwarven company that makes the difference. Tolkien also invented languages (I have used elven numbering here!) to emphasise this diversity. Tolkien helped my young mind to understand that diversity creates useful outcomes.

Tolkien was an author that pushed the importance of lineages, history, spatial scale, species distributions and dispersal, landscape impermanence and diversity through all of his stories. If this is not the ideal preparation for a young evolutionary biologist (especially one who specialises in biogeography) then I'm not sure what is!

Namárië !



16 September 2014

A tangled story: the coevolution of lichen


I'm a sucker for multi-volume books. Whether it is GRR Martin's Game of Thrones, Robert Jordan's Wheel of Time, Tad William's Shadowmarch, Dennis McKiernan's Mithgar or JRR Tolkien's Middle-earth, I like nothing more than getting lost in the depth and sheer volume of story that these authors have created (all that history, setting, scale, and characters, all those interactions). Often these books are in the fantasy line but they can just as easily be science fiction, say David Brin's Uplift, or historical fiction, like Patrick O'Brian's brilliant Master and Commander. Friends often ask me to summarise these series, "What is the story about?". That's a tricky question because their scope defies a meaningful simplification. Most people are familiar with A Game of Thrones now. A simple description of this story (even more complex in the books than the TV series) is either too broad to be helpful (a fantasy version of the War of the Roses) or misses a lot (a bastard, who know nothing, talks to wolves and becomes a leader; a spoiled princess domesticates dragons and sits around in conquered cities; or a dwarf with father issues loses a nose and has a fairly miserable time).  The Wheel of Time series stretches to 13 large books with umpteen viewpoint characters and could be summarised as 'shepherd boy heals the world' but this only takes up a tenth of the story amid all of the braid tugging, gender politics and nonrandomness of events. O'Brian's series about the British navy in the Napoleonic wars stretches to 21 books and follows the career of Aubrey (as captain of larger and larger ships) and Maturin (ship's doctor, naturalist and spy) with little overarching story other than that of following the lives and careers of these fascinating characters. Even The Lord of the Rings, with a reasonably linear story, loses something when condenced to 'short tourist loses heirloom at volcanic destination'. Sometimes, then, stories are complicated and refuse to be simplified. Much the same happens in history and most definitely it happens in natural history, especially when we are dealing with evolution.

The lichen Usnea draps a beech tree
Evolutionary biologists are interested in the history of life, we want to recover the story of how life on Earth ended up as we see it. We use data from fossils and DNA, species distributions and unusual traits to recreate our best guess at summarising the evolutionary story. One area of evolutionary biology that I have been involved with since my PhD is that of coevolution - where we try to recover the story of interacting evolutionary lineages, such as parasites and hosts or pollinators and plants. Sometimes the story is fairly straightforward. The work that I did for my PhD and in various projects since has been with chewing louse species that live on seabird species (like petrels and albatrosses). Lice are insects that live in the feather forests of their hosts and are mostly passed from seabird parents to their offspring. The story of this interaction is reasonably simple, we have two lineages, one insect and the other bird, that codiverge together. When the birds speciate their lice will also become isolated and often cospeciate at the same time. Feather lice have been studied as a nice model of cospeciation for a couple of decades now. We can tell this story well. Sure there are a few quirks here and there but it is now a reasonably predictable story. Louse-host coevolution stories are like nature's little rom-coms. Not all coevolution stories are this simple.
Lichen and mistletoe colonise a beech.

Lichens, commonly seen growing on fences or trees, are composite individuals,  a symbiosis that results when a fungus cohabits with a green algae (or sometimes a cyanobacterium, or, even less commonly, with both an algae and a cyanobacterium). The fungus provides a safe habitat and food for the green algae who, in turn, use their photosynthesis ability to provide products for the fungus. Lichens are the result of this win-win coevolution relationship and would seem a prime candidate for coevolution. Hannah Buckley and her PhD student Arash Rafat joined forces with other Lincoln University ecology staff to recover the coevolution story of lichens which has now been published in the journal PeerJ. Arash collected lichens from around New Zealand. Much of the sampling was from southern beech forests and focused heavily on the lichens Usnea and Ramalina. Genes were analysed from the fungi and algae that made up the lichens. It turns out that when it comes to coevolution in lichens, it's complicated.

Lichen taxonomy is woefully understudied. There were many instances of samples that looked like the same species being genetically very different species, there were many instances of samples that looked like there were from different species being genetically similar. Certain strains of algae were found with lots of different fungal species. Geographical scale, how far sites were from one another, played a role - sites close to one another shared similar diversity. Sometimes. It seems that for lichens to function there only needed to be a fungus and alga paired and it didn't really matter which ones. All of these complications meant that the 'standard' method of analysing coevolution, by comparing phylogenetic trees for fungus and algae, was not going to be very useful, the trees were just too tangled. Hannah and Arash used a distance (principle coordinates) approach to analyse the data rather than a tree-building approach. Surprisingly, give all of the uncertainty of the lichen component species, there was  significant congruence between the genetic variation of the fungal and algal partners. The was particularly true at small spatial scales where fungi and algae species seem to co-disperse and co-adapt with each other. These patterns started to break down at larger scales and were different between lichen genera.
Lichen diversity.

So what is the story with lichens? Well, like a multi-volumed series, it's complicated. Focusing on some of the species provides a story of cospeciation. However, other species have no evidence of codivergence. Sometimes geographical scale is important, sometimes it is not. We can say that there is probably more codivergence occurring than we might have predicted. Overall, though, there is no simple summary, the evolutionary story of lichens are not very predicable. To know more we need to research more. Lichens are not rom-coms, they are art-house. Or a multi-volume series of books.

19 August 2014

Counting Katipo and the known unknowns


Former US Secretary of Defence Donald Rumsfeld made the following observation: "because as we know, there are known knowns; there are things that we know that we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns, the ones we don't know we don't know". Although this sounds a little torturous (and not in the washboarding sense!) it conveys a useful view of the world which is particularly relevant to ecology and evolution. When we do research we are usually in the business of moving 'unknown knowns' to 'known knowns'. In the process we sometimes discover some 'unknown unknowns' which then become 'known unknowns'.  Obviously, the big issues for science are the 'unknown unknowns', things that may impact on how we model the world which we currently do not take into account. In short, we can't fully explain a system if part of the explanation contains 'unknown unknowns'. Not torturous at all! 
Kaitorete Spit looking north to Banks Peninsula - Katipo country!


As an example, the history of the New Zealand biota was thought to be well known, that is there are 'known knowns'. A fragment of the supercontinent Gondwanaland broke away around 80 million years ago, gradually subsided until it was left with New Zealand and other islands. The present day biota was derived from this long isolation, one feature of which was the absence of terrestrial mammals (other than a handful of bat species). Some of the 'unknown knowns' were just how much land area remained above sea level by the period of maximum submergence around 23 million years ago, which lineages had survived in the New Zealand region versus those that had successfully colonised these islands and when these events had happened. A few years ago an 'unknown unknown' surfaced in the form of a mammal fossil from 16-20 million years ago. Fossils make for great 'unknown unknowns'. They are hard facts that are sitting out there in the crust waiting to be found. In this case the fossil became a new known and generated a bunch of known unknowns', such as how many other mammal lineages might have been around at that time, what happened to these mammal lineages as they were extinct when humans arrived in these shaky isles and how did they come to be in New Zealand?

Another area of ecology and evolution where we spend a lot of time thinking about unknowns both known and unknown is in population estimation and monitoring. For most species it is difficult or impossible to locate and count all members of a population.  We are left with trying to estimate how many individuals are out there. This could be a 'known unknown' if a species has been found to be present or an 'unknown unknown' if we are just surveying an area to see what is there (like in a biodiversity assessment). Having an accurate estimate of populations allows us to manage and conserve populations. 

Katipo (Latrodectus katipo) is New Zealand's representative of the widow family, a close relative of the the Australian red back. Katipo live in a fairly restricted and threatened habitat - the dunes of sandy beaches. Katipo are under multiple threats from land fragmentation from seashore developments, competition from an introduced spider species, and the introduction of exotic plants into dune areas. Counting katipo is a difficult enterprise. They are small and relatively cryptic. Although they build nests at the base of dune grasses, these can be obscured by storms. A recent method for counting has been developed using artificial cover objects (ACOs), in this case two small sheets of corrugated roof cladding, with wooden dowels placed between them, are placed in the field. The cladding becomes a warm and dry location that is ideal for katipo to live in. The ACOs can be placed in the dunes for weeks or months and local katipo may eventually move in, providing an estimate for local numbers. Using ACOs can help you to map put areas into dune areas of high and low densities as well as areas with no katipo.
Katipo in pingao nest, note the white egg sacs.

Lincoln University student Vikki Smith has used the ACOs to go a step further. Vikki was interested in the effect that the introduced marram grass (Ammophila arenaria) had on katipo populations (a 'known unknown'). Marram has replaced much of the native plant diversity around the dunes of New Zealand. A major casualty has been the pingao (Ficinia spirals) which is generally a smaller plant that forms less dense clumps compared to marram. Pingoa does not bind dunes together as much as marram, meaning that beaches are not as wide with marram in the dunes, as they are more resistant to wind and sea. Vikki wanted to see if katipo had a preference for the native species over the introduced. Vikki took her ACOs out to Kaitorete Spit, a thin strip of land separating Lake Ellesmere from the ocean. The spit has a good population of katipo and is one of the few places in New Zealand where you can find substantial pingao as well as marram. Vikki placed her ACOs in katipo areas with equal numbers beside marram and pingoa clumps. Vikki visited the ACOs over the next year recording katipo that she found there and reporting her findings in the Journal of Insect Conservation. Over the course of the year Vikki was 2-3 times more likely to find katipo under ACOs next to pingao compared to marram. This was most noticeable in summer and autumn. The inference is that katipo numbers are greater in pingoa and the they are more likely to colonise the ACOs through chance. So the preference of katipo for pingoa over marram has become a 'known known'. Although katipo were found in marram, the low density of katipo in this habitat may increase the chances of the local extinction of a population. How marram affects katipo populations is currently a 'known unknown' (long roots drying out the local habitat, reduction of local prey species densities, marram growth structure excluding many sites for nests). These 'known unknowns' provide a useful guide for future research. There may also be an unknown unknowns waiting for us to locate them, invisible for now until further research unearths it. that is the thrill of science!