Italian Wall Lizards and Rapid Evolution

The last few years have been busy but have brought with them an opportunity to travel and to learn about new places, but little time to write.  Each year I spend a bit of time in Europe and extend my work trips to include a bit of time off.  Usually these trips are centered on Germany but I try to visit a few more places and in 2015 I had the opportunity to spent a few weeks in northern and central Italy.

A number of things caught my attention, for example how Virginia Creeper (Parthenocissus quinquefolia) has become invasive in much of Europe but especially in northern Italy, how different the color pattern of the Hooded Crow (Corvus cornix) is to what I’m used to seeing in the Americas or Asia, the deep similarity of vegetation assemblages and species to those in North America occupying similar habitats, and, of course, the fantastic views and towns perched on hills or nestled into narrow canyons, like Riomaggiore.

Riomaggiore pan above 085-091 small.jpg

Riomaggiore, one of the Cinque Terre, in La Spezia

Of the things I saw in Italy there is one I’d like to focus on for this post.  It is a small, common lizard, often overlooked.

The Cinque Terre coast is very similar to parts of the California coastal chaparral and dry coastal forests, so it was no surprise to find lizards sunning themselves on the trails, hiding in the stone walls of the terraced vineyards, and rustling through the oak, laurel, and chestnut leaf duff layer.  Lizards are funny beasts, sometimes bold as you please standing on their rocks as though they own the world, other times bolting at the bend of a blade of grass.  Unfortunately, these lizards were wary and fled my approach, leaving me with only vague, scaly impressions of what they looked like.

It was in Florence where I finally saw one of the little fellows clearly.  I’d had enough of the noise and crowds and escaped to the Boboli Gardens, where I paid a bit more attention to the plants than I did to the impressive array of statuary.  Near a hedge a slight twitch amongst the dried leaves caught my eye and revealed itself to be a beautiful small green lizard with black and tan patterning sunning itself on a bed of withered sycamore leaves.  It was almost done shedding its skin and the colors were vivid.

Florence Italian Wall Lizard (Podarcis sicula) 112.jpg

Italian Wall Lizard (Podarcis sicula subsp. ?) in the Boboli Gardens, Florence

This is, of course, the Italian Wall Lizard (Podarcis sicula), a highly adaptable small lizard native to Italy and nearby regions.  This not an endangered or even rare species, on the contrary, it is quite common within its range, and its adaptability has led to the development of at least 62 recognized subspecies.  I did not know any of this when I first encountered the species, but something about it seemed familiar.  It wasn’t until I came across several more of them in Bracciano and had the time to identify them that the niggling sense of familiarity clicked.

In 1971 scientists transplanted 10 individuals of this species (5 breeding pairs) from the island of Pod Kopište to Pod Mrčaru, Croatia, a small island; only a few hundred meters long on its longest axis; with a resident population of a different lizard species, the Dalmatian Wall Lizard (Podarcis melisellensis) .  The goal of this experiment was to test competitive exclusion in island biogeography theory.

Pod Mrčaru map.jpg

Unfortunately the 1970s were a troubled time for that part of Europe and Yugoslavia began its fragmentation into what are now Slovenia, Croatia, Bosnia/Herzegovina, Serbia, Montenegro, Kosovo, and Macedonia.  Trouble mounted through the 1970s and in 1980 Josip Broz Tito died, opening up a power vacuum exacerbated by ongoing ethnic conflicts.  It wasn’t until the mid-1990s that the dust more-or-less settled.

The long lasting conflicts in the region put a halt to the experiments of Eviatar Nevo  and his team on  Pod Kopište and Pod Mrčaru.  The lizards, of course, were undisturbed by the commotion of the excitable bipeds and the tiny island was left undisturbed until about 2004 when tourism was allowed in the area. Researchers returned to the island shortly afterward.

To the researcher’s surprise, they found that the initial 10 introduced Italian Wall Lizards had increased to a population of over 5,000 and that the native Dalmatian Wall Lizard was now locally extinct.

Further investigation revealed the real shocker; in the brief time the island had been left alone, some 30 lizard generations (abut 36 years), the introduced Italian Wall Lizards lizards had undergone profound evolutionary changes.

This is what had been tickling the back of my mind when I saw that first lizard in the garden of Florence.  Long before my trip to Italy I had seen a documentary discussing the rapid and unexpected changes these lizards had undergone.  I must have remembered the morphology of the lizard, but had lost the connection of that particular lizard to the documentary.  I can’t find the original video I saw, but there is a Richard Dawkins video on the subject:

Italian Wall Lizards are primarily insectivores, but in their new habitat they changed to become primarily herbivores.  For a omnivore like us this doesn’t seem to be a startling thing, we regularly shift back and forth between different types of foods, sometimes craving meat, other times preferring vegetables and many people make long-term dietary commitments to avoiding animal products entirely while other cultures have traditionally had a diet consisting almost entirely of animal products.  We are large animals and have evolved to be generalist gourmands.

For the lizards this switch is not so simple.  Plant matter needs time to ferment and break down to make digestion possible.  Plant matter can be extremely tough, requiring more effort to consume.  The shift from eating insects to eating plants is akin to shifting from eating exclusively fast food to eating primarily home-cooked meals.  Before you just ate what you bought, but now you need a working kitchen and utensils for preparing and cooking the food.

The introduced lizards developed a host of traits to aid in the consumption of tough plant matter; cecal valves (muscles that separate the large and small intestine, slowing down food digestion and effectively creating fermentation chambers – a bit like ruminates with their multiple stomach compartments-, allowed them to process the tough plant cellulose), larger, stronger jaws and bigger muscles to assist in the harvesting plant matter, changes in head morphology, and an over-all larger body size.

These changes may not seem like much, but they’ve been likened to humans evolving a new appendix in only a few hundred years.

Interestingly, the changes in food supply also changed the social behavior of the Italian Wall Lizards, leading them to be less territorial.

Changes in general should not come as a surprise considering the variability of Podarcis sicula.  After all there are some 62 subspecies of this lizard.  Even the between the individuals I saw in Florence and Bracciano there appear to be differences in head shape, color, and patterning.

Wall Lizard comparison (Podarcis sicula) Bracciano 173 Florence 115 small.jpg

Comparison between Italian Wall Lizards (Podarcis sicula) in Florence and Bracciano

What is surprising is how rapidly major evolutionary changes took place.  We tend to view evolution as a gradual process taking place over millennia with changes taking place so gradually that they are almost unnoticeable in human relevant timescales.  We know this is not true, but this view is so prevalent that it forms the backbone for one of the common critiques of evolution by those so inclined. Here we have a lovely example of evolution in action on a human relevant timescale. Better yet, it is an unexpected change, one that could well lead to a new species developing, if given enough time.

This is the largest change seen in this species, but it is far from the only case.  Italian Wall Lizards have been introduced in Turkey, Spain, and the US.  One of their populations in the US in New York, where they were introduced in 1966 or ’67 (most likely via the pet trade) has revealed an interesting an unexpected adaptation.  In the home range of the Italian Wall Lizard the temperatures rarely drop below about -7C and do not remain cold for prolonged periods.  As a result the lizards are active throughout the year with only brief periods of inactivity.  In New York, however, temperatures can drop to -20C and remain below freezing for extended periods.  It turns out that these robust little reptiles have a hidden ability and can supercool themselves and hibernate through the colder months in New York, a behavior not seen in their native range.

Bracciano Italian Wall Lizard (Podarcis sicula) 174.jpg

Italian Wall Lizard (Podarcis sicula) in Bracciano outside the Italian Air Force Museum

It is easy to overlook the little things and to take the common things for granted, but it is often those very things that open our eyes and our minds to greater understanding of the world around us.

These humble little lizards provide a window into evolution and adaptability, a window that might never have been noticed if not for the happenstance of a lost experiment carried out decades prior.

Blue-Eyed Grass, diminuitive irises

From California to New England, from Alaska to Texas there is a small, easily overlooked wildflower that is blooming now and will continue to do so for several more months, depending on where you are of course.  The flowers of this plant are small, only a little more than a centimeter across have six petals, a yellow center, and are often blue in color, hence one of the common generic names, Blue-Eyed Grass, although there are yellow and white variations.  To see them clearly you have to get close, crouching or laying on the ground.

Common Blue-Eyed Grass (Sisyrinchium montanum)

You can see from the photo that the leaves of this diminutive plant are broad and flat, much like the leaves of the grass it grows amongst.  In Vermont there are several variations of this plant, Sisyrinchium montanum being the most common, hence the name, Common Blue-Eyed Grass, which is, unfortunately, not tremendously imaginative.  When it is not flowering it’s easy to see why it might be mistaken for a grass, it has a similar leaf shape and is of a similar height to the grass it grows amongst.  The flowers clearly set it apart though.  Petals are little flags to attract insects, birds, and in some cases lizards or mammals to the flower for pollination for which they are rewarded with nectar.  Grasses have no such need, like willows, poplars, and pines they rely on wind to distribute their pollen and petals are a hindrance and a waste of energy for a plant that uses wind rather than animals for pollination.

Wind pollinated grass flowers with Blue-Eyed Grass flowers in the background

Sisyrinchium, the Blue Eyed-Grasses are tiny irises.  The Iridaceae family is widespread and often used as ornamental plants in gardens or in bouquets.  The larger irises have showy, ornate, soft flowers that fold and flow in complicated shapes, looking little like the small, robust Sisyrinchium flowers.  In the wild, the larger irises tend to grow in places that are either damp, shady, or both.  The Blue-Eyed Grasses live in harsher regions, open meadows, occasionally on rocky ledges, the edges of open areas, in short, places that can get hot and dry.  This may partially explain their small, robust stature.

Like other irises Sisyrinchium has inferior ovaries, this is not a commentary on the quality of the ovaries, it is a botanical term meaning that the ovaries are below the flower rather than the flower surrounding the ovaries.  These little plants produce globular three-part capsules about the size of a BB filled with numerous little seeds.

Blue-Eyed Grass with immature seed capsules

I grew up looking at these little flowers on the wildflower rich coastal prairie of Northern California, but just a few days ago I discovered something new (to me) about them.  They are active, they open their flowers for the day and close them for the night.  I tried my hand at a time-lapse of a flower opening.  It’s a bit rough, but you get the picture.

Blue-Eyed Grass flower opening animation

I love finding out things, being surprised by life, experiencing the unexpected, and encountering things I do not know.  I’m glad that these little irises reminded me that such a small, seemingly mundane thing can be interesting and exciting.

Chickadees, survivalists extraordinaire

It seems likely that weather is the only killer so devoid of both humor and dimension as to kill a chickadee.”

Aldo Leopold wrote this line back in 1949 in his incredibly influential book, A Sand County Almanac.  He was commenting on the extraordinary longevity of chickadee 65290, a bird that had survived for at least 5 years following its banding in 1937.  Little 65290 may have been extraordinary, but a brief walk in the winter New England woods will rapidly convince you that chickadees as a group are exceptionally resilient little creatures.

Chickadee in the spring sun

Chickadees are very vocal, calling to each other throughout the year. You can hear some of their calls at the Cornell Bird Lab website.  Chickadees often travel in loose flocks, flitting about, hanging upside down from branches, stealing insects from spiders, scrounging for seeds, and chasing each other about in the forest like a group of excited 5 year old children just released from a long, boring bus ride.  Their colors are subdued, yet distinctive: black, gray, white, often with a hint of yellow or tan on their underbellies.

Chickadee acrobatics

Black-Capped Chickadees (Poecile atricapillus) are cold weather specialists with a home range extending from Alaska to New England and dipping as far south as the mountains of Arizona and New Mexico and along the spine of the southern Appalachians (map).  I find this is extraordinary.

There is a principle of physics called the square-cube theory that relates the volume of an object to its surface area.  Basically, this can be simplified to the idea that a mouse has more surface area compared to its volume than does an elephant, and that for every time you double the size of an object its mass goes up by eight times (Length x Width x Height).  In terms of survival in cold climates this is really important because smaller things lose their heat far faster than large things because of that ratio of surface area to volume.

Chickadees are tiny.  Their bodies are barely larger than a golf ball, and much of that is feathers.  All told they probably weight as much as an emaciated mouse, yet they live in a part of the world that is well below freezing for great portions of the year.  During the winter nights chickadees huddle in cavities in trees in semi-torpor, burning fat at a prodigious rate.  At first light they are up and spend the day searching for food.

Feeding Chickadee silhouette


All living things have to balance the payoff of their behavior with the potential risk that behavior carries.  Some species are extremely risk-averse, in political terms these species might be the Ron Paul’s of the world, insisting on a gold based currency.  Chickadees are the opposite, they are inquisitive, curious, bold, and fearless.  As in many animals, their willingness to take risks is dependent on availability of resources.  You see this in humans, a far greater proportion of low income people spend their money on lottery tickets than high income people, despite the abysmally low chance of getting a winning ticket.  If you have few resources you will take more risks to get a large reward.  The costs of those risks are higher for those with fewer resources as well.  For chickadees this means of food and a place away from that humorless weather.

Keeping warm in winter takes more food than in summer, and food is more difficult to find.  Chickadees take risks to get that food, they investigate new objects almost as soon as they encounter them, they come closer to humans and stay longer than many other birds, and they try new things.

Traveling in groups is one way to offset the individual risks these brave little birds take.  More companions means more eyes to watch for danger (and food as well), and chickadees have a very well developed warning system that alerts their companions not only to danger, but to the degree of danger.

The risks they take, their small size, and the harsh weather they endure takes its toll and chickadees do not live long, hence Aldo’s comments on chickadee 65290.

Chickadee and hungry young

Chickadees may not live long, but their lives seem bright and full of vibrancy.  They are a reminder of the importance of curiosity, companionship, and communication.

Discoveries in the Moss

Yesterday I saw an unfamiliar flower blooming outside my window atop the moss covered rocky ledge and I went outside to see what it was.  It looked a little like soaproot (Chlorogalum  spp.) flowers, but those do not grow in Vermont.  As it turned out the “flowers” were the unfurled, pubescent new leaves of a young striped maple (Acer pensylvanicum), a very common plant in New England, and not as interesting as the other thing I found outside my window.

Crane Fly pupating

You see crane flies (Tipulidae spp.) often, they look like large mosquitoes and often go by the common name “mosquito hawk”.  Unfortunately, they only look like mosquitoes and do not hunt them.  Fortunately, they only look like mosquitoes and do not act like them.

I didn’t know much about crane flies, so I did a little reading about them and now know minimally more than I did.  Not enough to identify this species unfortunately.  When I first found the pupating insect it was holding its wings wide, but when I returned with a camera it had folded them back along its body.

Crane fly wings

The larvae of some species live under water, much like caddis fly larvae, other species have terrestrial larvae.  In either case the larvae eat dead vegetation.  The larvae of terrestrial species have tough skin, leading to the common name “leather jack”, which I think is pretty cool.  Skunks and moles eat the grubs, as, I expect, do birds when they can get them.  The adults of most species do not eat, and in some species only the males have wings.

I turned my back for a minute to take a photo of a leaf-hopper sitting nearby, and when I turned back, the crane fly had gone.

Leaf-hopper or Sharpshooter, not sure which

Hunting around with the half-formed though that if I had seen one, there might be others (always worth checking, sometimes it pays off).  I did not find any others hatching, but there was evidence that others had hatched recently.

Case left behind by a hatched crane fly

Insects are one of the most mysterious and magical things.  They transform themselves in ways that seem impossible, ones that pupate completely breaking down their bodies and reconfiguring them in radically different configurations.  Tests on butterfly caterpillars indicate that, despite pretty much liquifying themselves, they retain memories and lessons learned through the process.  Insects are so successful that nearly every ecosystem and terrestrial living thing is now dependent on them, if not directly, then removed from direct dependence by only a step or two.

We don’t know how many species exist, and often fail to grasp their importance.  We try to kill the insects we dislike with poisons and within a few generations they develop immunities.  They are mind bogglingly tough and adaptable, despite their individual fragility.

They are ubiquitous, fundamental, and wondrous.

What is Nature?

For most of my life I have been immersed in the natural world.  My early memories are of mud, water, ferns, tide-pools, insects, birds, amphibians, and trees to climb.  Nature surrounds us, enfolds us, and directs our lives in ways we often fail to realize.

Despite our reliance on computers, cars, oil, and all the rest, and the damage our irresponsible use of these things has done to our planet and ourselves, these things all derive from nature.  The location of oil deposits are a relic of past distributions of plant and microbial life. Distribution of plants, animals, and other resources such as iron, gold, and bauxite deposits are a product of geology, which in turn is a result of solar system formation.  At each step we can look a little further back and deeper into the picture and see more of nature and how it affects us physically and socially.

Gold comes from supernovae, thus, indirectly, the Spanish conquering of Central and South America was, in part, due to the interaction of gravity, nuclear fusion, and the age of the universe.  Stars that become supernova are a result of the specific balance of elementary forces in our universe.

Tools are made in the shapes they are due to the evolutionary forces that shaped our bodies, which in turn are a result of the same elementary forces that lead to supernovae and the creation of gold.  Toast more often lands butter-side down because of the height of our tables.  The height of our tables is determined by our height, which is limited by the physical constraints imposed by the molecular bonds that hold the component pieces of our bodies together under the influence of one standard Earth gravity.  Toast falls butter-side down because of the strength of our bones.

This is nature, just as much as the metamorphosis of a caterpillar to a Monarch butterfly, and the many thousand mile migration of those butterflies to a forest in northern Mexico.

There is not just a whole world to explore, there is a whole universe to explore, perhaps more than one.  In this blog I intend to explore those bits I can reach, physically or mentally.

I hope you enjoy what emerges on these pages.

Bristol Pond, Vermont