[MUSIC] Welcome back to Mountains 101. There's two parts to this lesson. We will begin by discussing some ecological and evolutionary processes that account for the remarkable biodiversity of species that live in mountain environments. Biodiversity is often defined as the number of species in a certain area, but this is not the only definition. We can also think about biodiversity in terms of the distribution of species, the genetic variation within populations, or the role that species play within the ecosystem. In the second part of this lesson, we'll explore some of the unique adaptations that plants have evolved to survive and thrive in mountains. As you know by now the typical conditions in mountain environments include cold temperatures throughout the year, exposure to more intense solar radiation, and lower partial pressures of atmospheric gasses like carbon dioxide and oxygen. Even so, plants, animals and even humans that live in mountain regions tend to be well adapted to those often extreme conditions, and have evolved specific traits that help them to survive in the challenging mountain environment. There are many different factors that contribute to the rich biodiversity in mountains. One of the most important factors supporting high species biodiversity is the corresponding diversity of habitats that result from the rapid change in elevation on mountain slopes. Mountains contain compressed climatic zones or microclimates along vertical elevational gradients. As a result, mountains provide access to many different habitats within a small geographical area. The high diversity of habitats allows organisms with different environmental requirements to coexist. Thereby, increasing the variety of species found in mountains. One of the first people to document these patterns of mountain diversity was the Prussian geographer and naturalist Alexander Von Humboldt. Between 1799 and 1804, Von Humboldt traveled extensively in Latin America. Exploring and describing these regions from a modern scientific perspective. Indeed, Von Humboldt’s quantitative work on botanical geography laid the foundation for the entire field of biogeography. Von Humboldt’s 1807 essay on the geography of plants was based on the then novel idea of studying the distribution of species along gradients of varying physical conditions. These patterns were famously depicted in this cross section of Chimborazo, a massive 6,310 meter stratovolcano and the highest mountain in Ecuador. This pictorial representation and detailed descriptions of the cross section of Chimborazo was called Ein Naturgemalde Der Anden, or picture of nature in the Andes. It provided detailed information about the temperature, altitude, humidity and the animals and plants found on each elevation. This novel and complex information provided the basis for comparison with other major peaks in the world. It was now possible to describe corresponding climate zones across the continents. To explain why mountains support so many species, we need to understand the processes that create new species. Speciation. Speciation occurs when populations diverge genetically to a point that they're no longer able to interbreed. For this to happen, populations need to be isolated from each other, so that there's no movement of individuals from one place to another. One way that this can happen is through geographic isolation, which is known as allopatric speciation. Allopatric speciation is common in mountains because these rugged landscapes impose topographic barriers that isolates small populations. For example, the ridges and valley of the Andes in South America create physical barriers that both limit animal dispersal, and cause local variation in rainfall. This has resulted in physical isolation of animal populations and variation in habitat productivity. Both factors have likely contributed to the evolution of high species diversity. This diversity can be seen in the patterns of genetic and morphological variation in Peruvian populations of the Tyrian Metaltail. A hummingbird living in montane forest at elevations of 1,700 to 3,800 meters. Recent studies have shown that geographic isolation, rather than variation in climatic conditions, could explain most of the genetic variance among several subspecies of this widespread hummingbird. The story is very similar for a species of bellflowers living in North American mountains. Climatic variability associated with quaternary glacial cycles and rugged topography of these mountain landscapes provided many opportunities for speciation in this group of plants. Factors contributing to the high diversity of bellflowers include the combined effects of climate oscillations, rugged alpine habitats, and variable floral morphology. Recent studies have found that speciation of bellflowers over the past 1 million years was associated with geographic isolation between multiple mountain refugia in Western North America. Refugia are places in the mountains that have maintained favorable conditions during periods of past environmental change, often associated with periods of glaciation. There are several different ways that scientists can quantify biodiversity. The simplest is a count of the total number of species present. This measure is called species richness. A second index of biodiversity is called evenness. Evenness measures how similar species are in their relative abundances. For example, if there are large differences in the abundance of species then a community has low evenness. If the abundance of all species is approximately the same, then the community would have high evenness. A third measure is species diversity, which accounts for both species richness and evenness. Species diversity can provide some insights about how ecosystems function in mountain environments. Of course, there are potentially millions of species living in mountains around the world, and counting all of these individual species would take a very long time when increasingly popular way to assess biodiversity is known as DNA barcoding. DNA barcoding is a technique for characterizing species using short DNA sequences. DNA barcoding also provides a measure of genetic diversity within populations and communities. Sarah Adamowicz is a geneticist at the University of Guelph. She uses barcodes to study biodiversity. Let's hear her explain how barcodes can be used to improve our understanding of biodiversity and ecosystem change in mountain environments. >> So a DNA barcode is a small portion of the total genome. It's a small segment of DNA that is occurs in all living things, and it is sequenced to differentiate different species. So this area can help us to quickly identify species, and it can also help us to discover new species. And so the analogy with the barcode is such that, if you think about going grocery shopping for example, you can quickly scan, the cashier can quickly scan all the items that your buying, and imagine shopping without that technology. With the diversity of life on this planet, the DNA barcode helps us very quickly identify the species that we've got in front of us. And this technology is especially useful in hyper diverse groups like the insects. There are millions of species of insects on Earth, and without a rapid digital technique, it's very difficult to study them. But through this technique, we can and ask questions that we're not previously possible before. DNA barcodes can play an important role in helping us to understand the biodiversity of mountain systems as well as environmental change. So one of the great benefits of the DNA barcoding approach is that all organisms have DNA, so this helps us to study whole groups of species at the same time. We can study as we move up in elevation, how does species composition change going from lower elevation to high elevation? And we can do this across many species at the same time, rather than just one by one. And many studies historically focused on charismatic species, large mammals, birds for example. Though through this technique we're increasingly able to compare different sites in terms of their insect biodiversity. We can also use the method to study reclamation efforts, such as how has recolonization occurred after a mine has shutdown for example. Those are just a few applications where barcodes can play an important role in studying mountain systems. >> Many mountain regions contain a high proportion of unique species that do not occur anywhere else in the world. We refer to these unique species as endemic species. An endemic species found only in the Rocky Mountains is the Banff Springs Snail, or Physella johnsoni. The Banff Springs Snail is a small air-breathing freshwater snail in the family Physidae. The largest individuals are about 1 centimeter long, and they survive on a diet of algae, microbes, and detritus. The Banff Spring Snail was first identified in 1926 in the nine sulfurous hot springs of Sulphur Mountain in Banff National Park in Alberta in Canada. They've not been found anywhere else. These snails are very unusual because they're adapted to life in thermal springs, where the water is very low in oxygen and very high in hydrogen sulfide. Since its discovery, its range has shrunk to just five of the nine hot springs. We're here at the Cave and Basin in Banff National Park with Mark Taylor. Mark is an aquatic ecologist with Parks Canada. Mark, what is a Banff Springs Snail? >> The Banff Springs Snail is a small globe shaped snail with a short spiral sticking on its side. So maximum size is about a centimeter. >> Right, and what's special about these snails? >> Well, what's special about these snails is the environment that they live in. They live in water that's roughly 20 degrees warmer than all the rest of the water in this park, and that makes for some pretty interesting adaptations in terms of the food that they eat, and their seasonal fluctuations. >> I'm curious, what do they eat in this pond? >> Well they're omnivores. They eat a combination of bacteria that actually oxidizes sulfur, and algae, and dead plant matter. >> So species that tend to live in specialized environments, often face a number of threats. Is there anything threatening the Banff Spring Snail? >> There certainly is. So, one of the main things that we find in recent years is that some of these springs that the snails live in, they're quite small and they are susceptible to drying up, and we lose the entire population when the pond dries up. And that's been happening at a higher frequency more in recent years compared to the past. One of the other things that's easier to manage for us is just sort of the historical use of this kind of landscape. So in the past there was actually bathing in a pool like this. And in more recent years once we acknowledge the Banff Spring Snail and its status in our environment. We've actually closed these springs to bathing, and we actually keep visitors out of the water and on boardwalks like this so they can just look at it from a distance. >> Great, and in Canada, the snails are legally protected, is that right? >> That's right. So the snails were actually listed by Canada's National Species At Risk Act, and they're listed as endangered, which is the highest rank within that scale. And that means that Park's Canada is legally mandated to actually, first of all, come up with a recovery strategy for the snails with a series of very specific actions as to things that we can do to stabilize and actually bring those populations back. >> Good, can we go see if we can find some? >> Definitely. Here we are, David, at the upper spring at the Cave and Basin. And you can see a population of snails, just on the end of that log there. >> I see them, that's pretty neat. Now, could I find them here all year round? >> You certainly can. So they are confined to the wetter perimeter of the warm spring. However, the population do fluctuate seasonally. So in the wet periods of the year in the spring, the population goes down, in some springs it could be only dozens of snails, and then in the dry period, in the late summer, the fall and into the winter the populations will explode even up to 100s of snails. >> I see, and these hot springs are obviously very unique environments, so there are other species that are found in these places as well? >> Yes, there are, it is actually quite the diverse area in terms of bryophyte communities, for example. So there's 75 different mosses found in thermal springs at the Cave and Basin. Roughly, a dozen of those are actually considered rare, and there's another dozen liverworts and three of those are considered rare. >> So we could call this a real hotspot of biodiversity? >> Yes, for sure. >> Good, well, thanks for bringing me here Mark. This is really nice. >> No problem, David. >> Yeah. >> Thank you. >> Thank you.
