Mark and recapture project for students!

I’ve had the pleasure of teaching many groups children from preschool to high school age during the last decade or so in a variety of settings: camps, classrooms, field trips and informal natural history discoveries on the sidewalk (just recently jumping galls in the Central Valley here).

One activity that I have done a few times, and particularly enjoyed, was doing a mark and recapture study on dragonflies with elementary/middle school students. In my opinion, it is a pretty perfect project – you get to teach the scientific method, a little bit of math, and a good bit of natural history. I didn’t come up with this project (I think Taylor Yeager, of Mass Audubon, suggested doing it with grasshoppers, initially – but that was the summer of 2006 or 2007, so my memory is a bit hazy) but I’ve run it a few times with kids from ~9 years old to high school age.

Hetaerina americana, the American rubyspot, my favorite odonate in California. A damselfly, these are just as suitable for the study described here, though a little more fragile.

The goal of the project is simply to estimate the number of dragonflies in a given area such as a large field or a pond. You could easily adapt this to grasshoppers, milkweed beetles or any other larger invertebrate that can be easily handled and marked (bumblebees or butterflies might not be as good). Mark and recapture is a standard technique used in wildlife studies and the basic idea of it is very simple – you mark a known number of animals, then you go back and capture a bunch and see what proportion of that sample was marked. Obviously, in real-world applications, the math is much more complicated, but for our purposes, if we mark ten bugs the first day and capture 10 the second day, two of which are marked, we have a population size of 50.

 

You’ll almost certainly see Pantala flavescens, the world’s most widespread dragonfly. Catching them is a bit harder – they fly high and fast! This is a female.

Dragonflies are supremely suited to this activity however. They are often abundant, easy to handle and mark, children generally have no aversion to them and they are just challenging enough to catch to occupy students for hours (and to get lots of energy out while running around the field with nets!).

Rhionaeschna sp. Chiloe Island, Chile. WHO DOESN’T LOVE DRAGONFLIES?!?

Of course, the first thing you should do is to get all the students to guess the number of dragonflies in that area. They generally have no idea; guesses vary by orders of magnitude (from 10 to 1 million!). Then it is just a matter of giving everyone nets, teaching them to safely handle dragonflies and going out and catching ’em. We’ve used normal sharpies and put a dark band on both forewings of the individuals we captured as a mark. For easier record-keeping, we set up a station in the center with the sharpies. I found with younger students, it was easier (and safer for the insect) if I took it out of the net and marked it (those being the two steps where wings are easily shredded or broken), then let the students identify and measure it. Taking dragonflies out of nets isn’t hard – put your pointer and middle fingers on opposite sides of their body and gently move their wings up so that you have all four together and remove from net. Even 12 year-olds can remove and mark with proper instruction. Most dragons will need a few seconds to pump haemolymph back into their wings after this process; you can place the dragonfly on the catcher’s nose – this is especially entertaining for all others involved!

An Aeshna/Rhionaeschna sp. This is the proper way to hold dragonflies; using two fingers, pinch the four wings together gently. To mark it with sharpie, it helps to put the wings flat on a clipboard and gently put a small mark. This is a female – note the lack of a bulge on the bottom of the first couple abdominal segements (compare to photos below).

 

The other way to hold dragonflies is to firmly grip the upper segments of their legs (I usually try to hold two – though I am holding only one in this photo) between thumb and forefinger. This allows viewing of the wing pattern and veination, but is trickier and requires some practice to not rip off legs and let the dragonfly get away. They can also bite you in this grip, not a problem for little ones, but big Aeshnids can draw blood!

With high school groups, I’ve taught them how to sex the dragonflies and then made comparisons of male and female sizes and sex ratios. This is an interesting activity, as in upland areas, most caught are females and near water bodies, most are males (you can count on this result with all but a few uncommon species). The reason is that males of most species patrol territories near prime egg-laying spots and catch the females and mate with them immediately prior to egg laying. Females, being harassed constantly near water, generally forage in areas farther away. This is especially pronounced in Enallagma damselflies – the bright blue males may be found by the hundreds at any pond, but its really hard to find the duller females nearby – sex rations on a local scale may be 100:1 or more!

Blue dasher, Pachydiplax longipennis, one of the most abundant dragonflies in the US. Note the water mites on its abdomen – these have really interesting natural histories (too long to describe here, but look them up). Also, note the bulge on the lower side of the first couple abdominal segments – this is a male (compare above).

The next day, we go back out and catch them again – to avoid double counting individuals, we use a second color sharpie on these. Then we conclude by doing the calculation of total population size, figuring out who was closest (the most exciting part for the students) and discussing the drawbacks. The students have always come up with good hypotheses for why the estimate might not be accurate (there were too many high-flying dragonflies, one day was cloudy, etc.) and it generally provides good fodder for a short and informative discussion. With older students, summary statistics on sex ratio, the body size measurements and population sizes of each species can be done and discussed.

The only individuals we don’t mark are tenerals – these are just emerged and they have not fully dried their wings and marking would almost certainly hurt them). Note the glistening wings and really pale body. In another day or two, this Sympetrum sp. will be cherry red!

 

No dragonfly post would be complete without this monster. Arguably the world’s largest dragonfly, Phenes raptor lives in bogs in Patagonian Chile and Argentina and has somewhat terrestrial nymphs, an oddity for an odonate. Males also have the coolest set of abdominal claspers (those projections at the tip of the abdomen) of any of the hundreds of species I’ve seen!

 

The eyes of emeralds, family Corduliidae, lend them that common name.

 

What you’ll need (not very much!):

1) Nets – 1 per student is ideal, but partners are fine, too. Wooden-handled aerial nets are not expensive (<$10) and will last a long time and take a good bit of abuse.
2) Sharpies
3) A good field guide. I use Dennis Paulson’s excellent guides for the US, though there are really good regional ones, like Blair Nikula’s Massachusetts guides and others. Identifying dragonflies and damselflies in all but a few genera (Sympetrum, Enallagma) is really simple and can be done by most high school age children with pretty good accuracy.
4) Clipboard, data sheets.
5) Two days of predicted sunny weather!

You could have students make nets. During a trip to Peru, my net was stolen within a week. I bought some mosquito netting, bailing wire and made this net for <$1. It lasted me the whole season without issue – several of the dragonflies on this page were caught with it.

Do give this a try next year if you have students for a couple days! Let me know if you do, I’d love to hear how it goes.

Another interesting thing to note – and could be measured by the students – is the size of the wings (length, width). This dragonfly, Pantala flavescens, has HUGE wings for its size. Unsurprisingly this species is probably the most migratory and best dispersing insect – of any group – on earth. You can find this species near you – pretty much nomatter where you live!

 

A meadowhawk (Sympetrum sp.) like above. This is a male – told by the bulge in the abdominal segments as well as its red color (females of this genus are yellowish).

 

Classic Natural History II: Netje Blanchan’s Wildflowers

Say what you will about Google Scholar’s dominance of scientific literature searching and potentially indexing too much (see specific critiques here and here), but its inclusiveness means that it turns up a wide array of literature that I wouldn’t normally encounter reading the citations of papers or using a more traditional scientific search tool. I often need to spend some time separating the wheat from the chaff (this somehow got archived as a scholarly work), but its often worth it.

Part of the columbine paper I published recently was a list I had been working on for awhile; all the insect-entrapping plants I had come across myself, friends and colleagues had mentioned and I’d encountered in the literature. I hoped it would be a jumping off point for future investigations into the functions of sticky exudates in these plants. It is a most-incomplete list, especially in lesser-studied parts of the world. I added quite a few new genera to it while travelling in Chile (and Chile is well-studied, plus I did spanish language searches as well!). So I expect the list to grow steadily in the coming years.

Two of my favorite plants (I have a lot of them). Blanchan writes of the Impatiens: “These exquisite, bright flowers, hanging at a horizontal, like jewels from a lady’s ear, may be responsible for the plant’s folk name; but whoever is abroad early on a dewy morning, or after a shower, and finds notched edges of the drooping leaves hung with scintillating gems, dancing, sparkling in the sunshine, sees still another reason for naming this the jewel-weed.”

Today, while looking up plants for another project, I happened on Netje Blanchan’s book Wildflowers Worth Knowing (free pdf here – thanks Project Gutenberg). The copy I read, with that title, is an adaptation/reprint of her 1900 book Nature’s Garden. Blanchan was a popular science writer who authored another natural history book, Bird Neighbors (1897), that I picked up at a used book sale awhile back and really enjoyed. Her observations on both birds and wildflowers are astounding – she knew her subjects well and wrote about them effortlessly. Her observations on the ecology and behavior are astounding and the book reads quite differently from modern field guides on wildflowers.

This is a very pretty plate, but imagine trying to find an unknown word in a key from this…

She notes the key characteristics of each plant, as well as her observations of it, including ecology, mostly focused on pollination (apparently a passion of hers), but also herbivores, interactions with other plants, and interesting anecdotes and even literary references. This is the sort of guide that guides a nature walk (with discussion and appreciation of each organism), not just an identification (i.e. a latin name).

For instance, while discussing Pseudognaphalium, she notes: “Ever conspicuous among the larger visitors [is] the beautiful Hunter’s butterfly (Pyrameis huntera) [the American Painted Lady, Vanessa virginiensis], to be distinguished from its sister the painted lady, always seen about thistles, by the two large eye-like spots on the under side of the hind wings. What are these butterflies doing about their chosen plants? Certainly the minute florets of the everlasting offer no great inducements to a creature that lives only on nectar. But that [shelter], compactly woven with silk and petals, which hangs from the stem, tells the story of the hunter’s butterfly’s presence. A brownish-drab chrysalis, or a slate-colored and black-banded little caterpillar with tufts of hairs on its back, and pretty red and white dots on the dark stripes, shows our butterfly in the earlier stages of its existence, when the everlastings form its staple diet.” Not only do you get your flower identified, but you are encouraged to look for the butterfly and the caterpillar – which are, as she notes, very common around this genus, in my experience in both New England and California.

 I’m not sure whether these are post-processing colored, or produced in color (apparently available commercially at that time, according to Wikipedia). The left plant is now Aureolaria virginica, and like all Aureolaria is a hemiparasite (photosynthesizes and obtains some nutrition from its host). On this genus, she describes nectar-robbing as: “Sometimes small bees, despairing of getting into the tube through the mouth, suck at holes in the flower’s sides, because legitimate feasting was made too difficult for the poor little things”.

To get back to the list of sticky plants that I referenced earlier, Blanchan includes quite a number of observations of sticky plants in the descriptions, including a couple that I didn’t have on the list! She had me at the introduction – noting “Is it enough to know merely the name of the flower you meet in the meadow? The blossom has an inner meaning, hopes and fears that inspire its brief existence, a scheme of salvation for its species in the struggle for survival that it has been slowly perfecting with some insect’s help through the ages. … Do you doubt it? Then study the mechanism of one of our common orchids or milkweeds that are adjusted with such marvelous delicacy to the length of a bee’s tongue or of a butterfly’s leg; learn why so many flowers have sticky calices or protective hairs…. What of the sundew that not only catches insects, but secretes gastric juice to digest them? What of the bladderwort, in whose inflated traps tiny crustaceans are imprisoned, or the pitcher plant, that makes soup of its guests?”

Organized by flower color and shape, it is easy to see how dogwood (Rosaceae) and button-bush  (Rubiaceae: coffee family!) got placed next to each other. Of button-bush she writes ” the vicinity of this bush is an excellent place for a butterfly collector to carry his net. Butterflies are by far the most abundant visitors; honey-bees also abound, bumblebees, carpenter and mining bees, wasps, a horde of flies, and some destructive beetles; but the short tongues can reach little nectar”

Her list of sticky plants include three new ones for my list:

Persicaria amphibia “When the amphibious water persicaria (P. amphibium) lifts its short, dense, rose-colored ovoid or oblong club of bloom above ponds and lakes, it is sufficiently protected from crawling pilferers, of course, by the water in which it grows. But suppose the pond dries up and the plant is left on dry ground, what then? Now, a remarkable thing happens: protective glandular, sticky hairs appear on the epidermis of the leaves and stems, which were perfectly smooth when the flowers grew in water. Such small wingless insects as might pilfer nectar without bringing to their hostess any pollen from other blossoms are held as fast as on bird-lime”

This is extremely interesting and represents a whole new plant family for the list. While I’ve encountered this plant many times, I’ve never looked closely enough at it. I wonder if in this environment the glandularity serves as a direct or indirect defense, or whether it reduces water loss? I’m going to pay a whole lot more attention to this plant now.

Pseudognaphalium macounii: A new genus for the list, though I know that other Pseudognaphalium species I’ve seen do not catch insects. She writes: “Ants, which are trying to steal nectar, usually getting killed on the sticky, cottony stem”.

Aureolaria pedicularia is another new genus and species for the list. I found it in August in Massachusetts and noted its stickiness, but did not observe as Blanchan did: “Pilfering ants find death as speedy on the sticky surfaces here as on any catchfly.”

She notes several other genera, which are on the list, notably Cuphea, Rhododendron, Kalmia (Charley Eisemann has excellent photos of this here), Saxifraga, several Polemoniaceae and, of course, the catchflies – Silene.

 

A. canadensis is not a sticky columbine, but it is hummingbird pollinated and beautiful. “Fragile butterflies, absolutely dependent on nectar, hover near our showy wild columbine with its five tempting horns of plenty, but sail away again, knowing as they do that their weak legs are not calculated to stand the strain of an inverted position from a pendent flower”.

She waxes eloquently several times of Silene‘s stickiness: “Alas, for the tiny creatures that try to climb up the rosy tufts to pilfer nectar, they and their relatives are not so innocent as they appear! While the little crawlers are almost within reach of the cup of sweets, their feet are gummed to the viscid matter that coats it, and here their struggles end as flies’ do on sticky fly-paper, or birds’ on limed twigs. A naturalist counted sixty-two little corpses on the sticky stem of a single pink. All this tragedy to protect a little nectar for the butterflies which, in sipping it, transfer the pollen from one flower to another, and so help them to produce the most beautiful and robust offspring.”

“Although a popular name for the genus is catchfly, it is usually the ant that is glued to the viscid parts, for the fly that moves through the air alights directly on the flower it is too short-lipped to suck. An ant catching its feet on the miniature lime-twig, at first raises one foot after another and draws it through its mouth, hoping to rid it of the sticky stuff, but only with the result of gluing up its head and other parts of the body. In ten minutes all the pathetic struggles are ended. Let no one guilty of torturing flies to death on sticky paper condemn the Silenes!”

“Hapless ants, starting to crawl up the stem, become more and more discouraged by its stickiness, and if they persevere in their attempts to steal from the butterfly’s legitimate preserves, death overtakes their erring feet as speedily as if they ventured on sticky fly paper. How humane is the way to protect flowers from crawling thieves that has been adopted by the high-bush cranberry and the partridge pea (q.v.), among other plants! These provide a free lunch of sweets in the glands of their leaves to satisfy pilferers, which then seek no farther, leaving the flowers to winged insects that are at once despoilers and benefactors.”

While a perfectly valid hypothesis – taken from careful observation, we now know that extra-floral nectaries usually assist the “pilferers” in defending the plant (but maybe not always – I bet that her situation occurs sometimes!). It is worth noting that in some species, having EFNs separated from flowers may keen the defending ants from attacking pollinators, so the separation of the “pilferers” from the flowers, as she notes, may be important for the plant’s success.

Of bee balm, she writes “Gorgeous, glowing scarlet heads of bee balm arrest the dullest eye, bracts and upper leaves often taking on blood-red color, too, as if it had dripped from the lacerated flowers. Where their vivid doubles are reflected in a shadowy mountain stream, not even the cardinal flower is more strikingly beautiful. Thrifty clumps transplanted from Nature’s garden will spread about ours and add a splendor like the flowers of salvia, next of kin, if only the roots get a frequent soaking. ” Even horticultural advice is proffered!

I’m going to use this book now to look up any new plant I come across; her excellent observations and interesting thoughts (an appendix for “Unpleasantly scented” plants), I’m sure will come in handy in guiding my future research, and just as importantly, my enjoyment of nature. Like Thomas Huxley once said “To a person uninstructed in natural history, his country or seaside stroll is a walk through a gallery filled with wonderful works of art, nine-tenths of which have their faces turned to the wall.” Blanchan’s book turns those pieces around; giving valuable natural history information, in an easy to read fashion, for each species covered.

*”Liming” refers to the practice of coating a branch with a sticky substance to entrap songbirds, usually for consumption. While illegal in many places, it is still practiced and was the subject of an article in Nat Geo a couple years ago. A pretty illustrative picture accompanies the article

Trichostema laxum research update: the first interesting data?

Awhile back, I wrote about the beginnings of some research on Trichostema laxum. I’ve been slogging through the disappointing amount of data I gathered this field season and doing a little bit of writing. While I was, and still am, really excited about the project on T. laxum, it took a backseat to columbine and tarweed work this field season (most of which burned up). I did get some new data and perhaps gained some insight into the system.

A normal array of plants in the site: normal purple Trichostema laxum, an individual with the common white and purple lower lip phenotype and some Zeltnera trichantha intermixed (a really cool plant)
My main question in the system is: how is this polymorphism in flower color maintained? If it were a fitness benefit, we might expect a high proportion of it. If it were deleterious, it should be lost (especially as it is at reasonably low frequency). If it is neutral, it might be drifted out. I actually suspect the answer is quite a bit more complicated.
Once you start looking for variation, you find it! I don’t know what this doubled lower lip is about (it showed up in a plant grown in the greenhouse – on most flowers). The plant was male-sterile, I believe. I’ll be looking for it in the field though!
The first question is, of course, how common is the color polymorph? I censused the focal patch/population (separated by ~300 meters from others) in 2014 and 2015. In 2014, the polymorph was 2.0% (46/2278 individuals) in 2015, 3.7% (102/2757). Neither of these censuses was a complete census of the population – necessarily, I cannot assess the phenotype of any pre- or post-flowering individuals. Both were done roughly in the peak flowering time (over several days), so I do think it is close to accurate. I think its safe to conclude that the proportion stayed the same or even went slightly up in 2015.
A rather large w/p morph individual.
The next logical question is: do the two morphs have similar field fitness? Any “fitness” measure (e.g. reproductive success, height, etc.) of these plants is dictated mostly by microhabitat location. In this rocky, heavily serpentine site, most plants stay under 20 cm tall and never put out more than 50 flowers (mints have 4 ovaries per flower, so maximum seed set is four times flower number). In a wetter, less serpentine and rocky meadow, I once found a plant on a gopher mound (which brings up nutrients) that was nearly a meter wide and better than a half meter tall. It probably had >5000 flowers throughout the season.
A veritable field of Trichostema! Not my field site – this site has huge plants (~500 flowers/plant) and very little flower color variation. It is a nice place to look at the insect communities on T. laxum, as it has really high densities of herbivores and predators (T. laxum gets most of the sticky plant predators)
Because of this microhabitat variation, the best comparison to make is nearest neighbors which differ in flower color. In both 2014 and 2015, I took data on 41 pairs (coincidentally!) of white/purple and purple/purple neighbors. I found no significant differences, either year, between any fitness variables (number of buds, flowers, fruit, height and, in 2014, number of leaves and herbivory [too low in 2015]).
A more normal-sized (for this population) individual.
This, ostensibly, seems like the trait is fitness neutral (and lab growouts seem to bear this out – more data soonish). Given that this site burned in August this year (after most had flowered, but some [probably few] were still maturing seeds), I was curious about whether the morphs differed in phenology. Hindsight is 20/20 (I should have censused biweekly!), but the neighbor pairs data can be used to examine this in a roundabout way; I have data on buds, flowers and fruit, so later phenology plants should have a higher proportion of buds to flowers and fruit than earlier phenology plants.
In both years, the white/purple plants had a lower proportion of buds than the purple plants (it is marginally significant). This suggests that they have a earlier phenology – which could be what is under selection – not the flower color itself. I am super, super, super, excited about this (the only positive result so far from anything in T. laxum) – there was possibly a big selective event (a fire) on 12-August (I think – could have burned on the 13th). From this, I’d predict that the w/p morph may have dehisced a higher proportion of their seed set by the fire. I’ll be paying far more attention to the phenology, and recensusing more often this upcoming season.
I also analyzed the pollinator data from 2014 and got no particularly useful insights (I wondered if there was some degree of isolation between the morphs). The pollinator communities using each morph were pretty similar and the only real differences were:  a bee on a purple flower was more likely to visit a w/p next than a bee starting on a w/p* and, only bees that started on w/p flowers next visited a snapdragon, Antirrhinum cornutum (but only 3% of the time). This last result is interesting as the snapdragon also has whitish purple flowers AND the T. laxum population with the w/p flowers is the only one  (out of ~15) I’ve found interspersed with large numbers of A. cornutum. I’ll have to get MUCH better data for any hypotheses about its effect.
Antirrhinum cornutum, grown in lab, showing the pale purple/white flowers.
I’m working now on the “genetics” (well, inheritance, but that’s as close as I ever get to ATGC) of the polymorphisms (this one and selfing). Could w/p be recessive and heterozygous in more individuals (~25% under HW assumptions)? I don’t think it is (entirely) developmentally induced, as in the first grow out, I only got this polymorphism from this population (I grew individuals out from 4 populations). More soon! Do let me know if you have other ideas about the system!
Heliothis phloxiphaga was a very common herbivore on T. laxum in 2014 (this plant had two – I didn’t stage this), but nearly absent in 2015 – though it was still common on columbines and tarweeds.
*I think this is confounded, as I watched two plants during each observation – nearby plants that were similar in size. Therefore, I suspect that it was more likely that a bee on the p/p plant would encounter a w/p than one from the w/p.

Classic Natural History I: Anna Bateson’s botany

I’ve lately had a little bit more free time, having had my experiments burned (more burned in the Jerusalem fire after I wrote the blog post about the Rocky Fire) and having just submitted a manuscript I’d been working on. So I’ve decided to spend a few hours a week reading older natural history and ecology papers. I’ve been working through the 1800’s in American Naturalist, Annals of Botany and Science Gossip – a wonderful popular magazine including observations of natural history, short articles and summaries of research. I’ve done this haphazardly, reading the table of contents to find interesting articles. I surely let many interesting ones through, but there is practically limitless material, so that is unavoidable. 

I’m going to try to highlight some of these papers – the astute observations, clever experimentation, often beautiful writing, and a little history, too. I probably would have left out the last piece, but several things – including Charley Eisemann’s beautiful history/biography/natural history piece on Annette Braun, a forgotten but influential naturalist; Graham et al‘s the Essential Naturalist, and Bernd Heinrich’s biography of his father – have inspired me over the past few years to think a bit more about the people and history behind old natural history.
Many also have beautiful illustrations (like this domestic hybrid pitcher plant). From M.C. Cooke’s Freaks and Marvels of Plant Life (1882).
A few papers I found that seemed quite cool were those of Anna Bateson (1863-1928). She was sister to William Bateson, a famous botanist of the day. She worked at as an “assistant” in Cambridge’s Balfour Biological Laboratory for woman students, closely with Darwin’s son Francis and built upon Darwin’s plant work herself. She helped found the Cambridge Women’s Suffrage society in 1884
One thing I often appreciate about older papers is the lack of the standard paper formula (Intro, Methods, Results, Discussion), instead a more narrative style that presents data and observations where necessary in the story. Bateson’s “The effect of cross fertilization on inconspicuous flowers” from Annals of Botany in 1888 is a really nicely laid out concise argument. She starts with Charles Darwin’s observation that while many small flowers are selfing and not visited often by pollinators, it would be strange that they would still be open if they were completely selfing. 
Darwin did not do these experiments because of the “difficulty of [crossing] them”. Bateson did this tedious job for three species (of three families!) and found clear outcrossing benefits in all. Her experimental prowess is obvious, as is her sense of experimental design (“it would have been a better method to have obtained the self-fertilized seeds by artificial fertilization also”). And her conclusion – that outcrossing is a benefit to even usually-selfing plants is certainly correct. 
Also from Cooke’s book, where he explains the actions of plant tendrils, a phenomenon still being researched mechanistically.
Another clever experiment concerned geotropism. She and Francis Darwin hypothesized, based on prior theory, that a stem lying directly on the horizontal is the most stimulated to move. They note that this is actually harder to test than it might seem, as if you simply let a stem curl, it will be subjected to varying stimulus as it curls upward (if the hypothesis is correct). Cleverly, they came up with a method to expose plants to varying stimuli independent of their response, by pinning them down for two hours at a given angle (they use three: stem pointed 60 degrees up, 60 degrees down and horizontal). They then released all three treatments for an hour and measured the angle. They got quite clear data supporting their hypothesis. In both cabbage (n=36) and plantain (n = 148), horizontally-placed stems curved more intensely than either down-sloped or up-sloped stems. I don’t know much about geotropism, so I can’t actually comment on the lasting scientific value of this experiment, but it was an elegant and simple experiment (science fair? lab demonstration?). 
The last paper is more of a monograph and concerns irregular flowers (i.e. not radially symmetric). Anna and her brother William detail many examples of abnormalities in flowers. They suggest that irregular flowers must have evolved from regular ancestors (we know macroevolutionary patterns and part of the molecular basis for this now) and that the best way to study the possibly evolutionary pathway is to look at variation in flowers now, to see what variation evolution is acting on in the present.
Plate of floral mutants in Bateson and Bateson 1891.
They write very clearly about natural selection and macroevolution in the introduction, making clear difficulties with the lack of intermediate forms, determining descent, and the apparent lack of utility of intermediate forms of an organ (essentially Paley’s watchmaker argument addressed by Dawkins). They even mention punctuated equilibrium versus gradualism “Supposing, then, that such a series of ancestors were before us, the matter to be determined would be the degree to which the series is continuous or discontinuous: that is to say whether the differences between any one member and its immediate successor are so small as to be imperceptible, or whether there are distinct and palpable difference between them; or whether they are sometimes small, and sometimes so great as to cause interruptions in the series and divide it into groups”. They follow this with a nice metaphor of evolution as chemistry or physics. They fall into Gould’s camp, clearly thinking that evolution proceeds with discontinuities (“the objections to supposing that the process of evolution of forms is discontinuous are derived, firstly, from the scarcity of observed instances of sudden and large variation,,, it is in the hope of dispelling [this] objection that the present observations are recorded”) [1].
The crux of their careful observations of toadflax, speedwell, gladiolus, and Streptocarpus lie in the fact that they are characterizing mutants that show a phenotype of different regularity from the parent. Especially interesting are their findings of apparently radially symmetric speedwell (#19 in the plate) and varying symmetries in all the species examined. They conclude these detailed observations by pointing out that while gradualism may be common, mutations that fundamentally alter an essential feature of a species (regularity of the flower; or Lenski and lab’s digestion of citrate by E. coli) do occur. They state “The facts now given, though few, are a contribution to such evidence and, in our judgement, are a sample of the kind of fact which is required to enable us to deal with the problems of descent”. Given that we now know that during plant evolution, both to and from irregular flowers has occurred many times, it is likely that the Batesons’ work was prescient, it was certainly detailed, well-written and well-reasoned (they present a section at the end detailing the many limitations of their observations that is nowadays hardly admitted in a question and answer session, let alone in the published paper!). 
I spent an enjoyable couple hours reading this papers and composing this post. I’d love to hear suggestions of other interesting papers, comments on these papers, and really anything else natural history. 


[1] This is of course, a sort of contrived analogy on my part, as they are taking a saltatory view – a mutant occurs in one generation in the Batesons’ argument, though in my reading, they are taking a wider view in the introduction, even with the preceding “between one member and its immediate successor”.

Fire, transpiration, local hydrology and some very happy sunflowers

The Rocky fire swept through McLaughlin Reserve at the end of July. Nearly five weeks later, I resurveyed some sites that I went through the week after. The amount of life that had survived in the completely wrecked sites was astonishing, as was the quick resprouting of some plants (Rhamnus, Salix, Quercus, Vicia, Brassica, Asclepias, etc.). But the most surprising thing was the “winners” of the fire. I’ve walked columbine this seep many times a week during the past two summers. This time, I was struck by how large several serpentine sunflowers (Helianthus exilis) and tumbling orache (Atriplex rosea) had become.

Several stupendously super-sized serpentine sunflowers stoutly standing in foreground. A couple orache visible in the background.
Before the fire and all of last year, these were quite small plants, reaching maybe 1-2′ tall with a couple dozen flowers. In many places, they end at 6-10″ with just a few flowers. These plants were over 3′ tall and each had a hundred or more flowers. What happened?
Last year there was a little bit of odd late-summer weather, with a few overcast cooler days (it is usually above 90 and not a cloud in the sky here). On those days, one very small seep that I had a columbine population in would fill up a couple tiny puddles that hadn’t had water for months. After a couple times, I mentioned this to the reserve manager here and she pointed out that the plants around the seep don’t transpire as much on cloudy days, so the water being put out by the seep was not being used up before it got to the ground. 
What transpires less than plants in overcast conditions? Dead plants. Right after the Rocky Fire, the seep with the sunflowers was flowing again big time (it is much larger and had much denser vegetation around it than the one that I could see the changes before). The amount of water in this seep now is greater than it’s been since April or so. While the sunflowers and Atriplex are past the end of the visible water in the seep by a few dozen yards, it is still flowing belowground and these are pretty much the first plants that would be getting any of that water, as all plants upstream are fried.  
This section had been completely dry for months before the plants stopped sucking up all of the water flow. Also note all the greenery. That is resprouting of Aquilegia eximia, Stachys albens, Salix sp. and a few grasses and sedges (you can fire me as your naturalist if you’d like – I have no idea what species are here).  
This was an cool and unexpected – though completely logical – thing to find in the aftermath of the fire. I’m sure its been described before, but it was really eye-opening to me to see how much water those plants were transpiring and just how much influence this had on the hydrology and the success of other plants far below them (it seems like asymmetric resource competition – the manzanita and willows above were dictating the reproductive potential of the sunflowers below).
Something similar may have been happening to trigger this flowering of Mimulus guttatus, but I’m a bit puzzled, as this was in a strange location for that to occur and nothing else around it was doing particularly well. It was certainly a pleasant surprise to see some spring-like color at the end of the summer!
I’ll write a longer post about the Jerusalem fire (more lost experiments… but not all!) and some other interesting observations that I’ve had during my last couple days of wanderings. But I’ve got more field work to do now. 
Dragonflies were hanging out in the seep like nothing had changed. I believe this is Aeshna walkeri (common last year here and with the same gestalt), though I didn’t have my net with me to confirm and I wouldn’t have wanted to disturb her egg-laying anyway (I’m a bleeding heart when it comes to dragonflies… and snakes… and beetles… and others).