WEEK 9-10 Flashcards
(102 cards)
What is Biodiversity?
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Biodiversity - the number of species in a certain area.
- 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.
What is the Typical conditions in mountain environments?
Typical conditions in mountain environments: cold temps throughout the year, exposure to more intense solar radiation, and lower partial pressures of atmospheric gases like carbon dioxide and oxygen.
What are factors that contribute to the biodiversity of 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 micro climates 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 nationalist Alexander von Humbolt: Between 1799 and 1804 von Humbolt travelled extensively in Latin America, exploring and descriibing these regions (like Chimborazo) from a modern scientific perspective.
- his quantitative work on botanical geography laid the foundation for the entire field of biogeography.
- Von Humbolt’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 his cross-section of Chimborazo, a massive 6,310-metre strato volcano and the highest mountain in Ecuador.
- This pictorial representation and detailed descriptions of the cross-section of Chimborazo was called a Ein Naturegemalde Der Anden, or “Picture of Nature in the Andes” → provided detailed information about the temperature, altitude, humidity and animals found at 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.
What is Speciation?
- The processes that create new species
- Speciation occurs when populations diverge genetically to a point where they are no longer able to interbreed.
- For this to happen, populations need to be isolated from each other so that there is 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 - is common in mountains because these rugged landscapes impose topographic barriers that isolate small populations.
- Eg. the ridges and valleys 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 Montaden forest at elevations of 1700-3800 metres.
- Recent studies have shown that geographic isolation, rather than variation in climatic conditions, could explain most of the genetic variants among several subspecies of this widespread hummingbird.
- The story is very similar for species of bell flowers living in North American mountains.
- Climatic variability associated with quaternary glacial cycles and the 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 the speciation of bellflowers over the past 1 million years was associated with geographic isolation between multiple mountain refugia in western North America.
- Refugia - places in the mountains that have maintained favourable conditions during periods of past environmental change, often associated with periods of glaciation.
What are the different ways scientists can quantify biodiversity?
- Simplest: a count of the total number of species present, called species richness.
- A 2nd index is called evenness, which measures how similar species are in their relative abundances.
- Eg. 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, the community would have high evenness.
- A 2nd index is called evenness, which measures how similar species are in their relative abundances.
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Species Diversity, which accounts for both species richness and evenness.
- 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.
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Species Diversity, which accounts for both species richness and evenness.
- One increasingly popular way to assess biodiversity is known as DNA barcoding.
- DNA barcoding is a technique for characterizing species using short DNA sequence.
- DNA barcoding also provides a measure of genetic diversity within populations and communities.
What is Sarah Damowitz’s description of DNA Barcoding?
- uses barcodes to study biodiversity.
- How they can be used to improve our understanding of biodiversity and change in mountain environments:
- DNA barcode is a small portion of the total genome
- It’s a small segment of DNA 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.
- So the analogy with the barcode is such that if you think about going grocery shopping, eg, you can quiclly can, the cashier can quickly scan all the items that you’re buyiing.
- 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.
- this technology is especially useful in hyper-diverse groups like 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 ask questions that were not previously possible before.
- DNA barcodes can play an important role in helping us understand the biodiversity of mountain systems as well as environmental change.
- One of the great benefits of the DNA barcoding approach is that all organisms have DNA. → so 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 1 by 1.
- Many studies historically focused on charismatic species, like large mammals, birds, eg, but through this technique we’re increasing able to compare different sites in terms of their instinct biodiversity.
- We can also use the method to study reclamation efforts such as how has recolonization occurred after a mine has shut down, for example.
What are endemic species?
- 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.
- Eg. an endemic species found only in the Rocky Mountains is the Banff Springs Snail.
- or Phycella johnsoni.
- the Banff Spring Snail is a small, air-breathing freshwater snail in the family Cyidae.
- The largest individual is about one centimetre long and they survive on a diet of algae, microbes, and detritus.
- was first identified in 1926 in the nine sulphurous hot springs of Sulphur Mountain in Banff National Park in Alberta. → they have not been found anywhere else.
- these snails are very unusual bc they are 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 out of the nine hot springs.
What is the Banff Spring Snail?
An endemic species.
- Banff Spring Snail is a small globe-shaped snail with a short spire sticking out its side, and maximum size of about 1 cm.
- What’s special about the snails is the environment they live in: live in water that’s roughly 20 degrees warmer than all the rest of the water in the park, makes for some interesting adaptations in terms of the food they eat and their seasonal fluctuations.
- they’re omnivores → they eat a combination of bacteria that actually oxides sulphur and algae and dead plant matter.
- Predator to the Banff Spring Snail: some of the springs that these snails live in are 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 in recent years compared to the past.
- One of the other things that’s easier to manage for them is the historical use of this kind of landscape.
- in the past, there was actually bathing in a pool like this and in more recent years once they had acknowledged sort of the Banff Springs Snail and its status in our environment, they’ve actually closed these springs to bathing and keep visitors out of the water and on boardwalks like this so they can just look at if from a distance.
- In Canada the snails are legally protected → 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 Parks Canada is legally mandated to 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.
- they can be found year-round and are confined to the wetted perimeter of the warm spring.
- However, the populations do fluctuate seasonally.
- So in the wet periods of the year, in the spring, the populations go down.
- In some springs, it could be only dozens of snails
- In the dry period, in the late summer and fall and into the winter, the populations will explode even up to hundreds of snails.
- These springs are actually quite diverse areas in terms of byrophyte communities for example → there are 75 different mosses found in the 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.
What are Hotspots of Biodiversity?
- Hotspots of Biodiversity - regions containing high concentration of endemic species that are also facing threats of rapid species loss.
- More than 35 biodiversity hotspots have been identified around the world.
- Half of them are located in mountain regions.
- Although these hotspots represent just over 2% of the Earth’s land area, they’re also home to about half of the world’s endemic species.
- Identifying hotspots of diversity has become an important tool to help managers prioritize and focus their conservation efforts.
- Protecting hotspots of biodiversity and the abundance of endemic species they support offers one of the best opportunities to curb high rates of extinction.
- The Andes Region of South America is one of these hotspots of species diversity, and these natural alpine habitats are also among the most threatened areas of the world.
- Explanations for this concentration of endemic species include
- past climate shifts
- tectonic events
- modern ecological interactions
- historically, the uplands were isolated from the lowlands by the Andean uplifts which began 25 to 30 million years ago.
- → this eventually created a complex mosaic of high mountains and deep valleys.
- this ancient uplift and resulting isolation were important drivers for speciation, resulting in high concentrations of endemic birds, mammals, amphibians, and plants.
- limited dispersal
Where would you expect to find the highest biodiversity?
- There are several hypotheses that could explain these patterns of diversity in mountains:
- the geographical area hypothesis
- the productivity hypothesis
What is the Geographical Area Hypothesis?
- According to the geographical area hypothesis, larger areas can support more species.
- Therefore, decreasing species diversity at high latitudes and elevations may just be a consequence of inherently smaller areas of habitat availability.
What is the Productivity Hypothesis?
- Productivity Hypothesis proposes that the amount of primary productivity, which forms the resource base of food webs, determines the number of species that can be supported in an area.
- Therefore, the higher primary productivity, associated with higher temperatures in the tropics and lower elevations contributes to higher biodiversity.
What are the factors that influence the distribution of species in mountain environments at various geographical scales?
- Habitat fragmentation, as a result of past environmental changes such as glaciation, can be particularly influential in determining patterns of mountain biodiversity.
- Prof Terry Calligan on Studying these Patterns
- Mountains are extremely important in determining the distribution of many species on planet earth.
- They all effect distribution in many ways.
- At the small scale, you find distributions of plants according to their altitude, the species that cannot tolerate shade but can tolerate low temperatures tend to be at the tops of mountains.
- Those that are the best adapted to cold conditions are found on the side of the mountain away from the Sun, so in the northern hemisphere, it’s on the north side of the mountains.
- At the larger geographical scale, mountains that are connected that run north-south are important for allowing corridors of distribution of plants from the south to the north, following the ice movements after the last ice age and previous ice ages.
- For the moment, after the little ice age and earlier cold periods, we have something called Nunataks.
- These Nunataks are the tops of mountains that are sticking out of our ice sheets.
- The most famous one is in southwest Greenland, a hundred km from any ice-free area, and there, there are plants growing.
- As we see climate warming, those individual Nunataks, separated from neighbouring Nunataks are going to become connected as ridges, and then the species will move along.
- At the moment, those isolated species are endemics very often bc they’ve been separated, isolated from other gene pools for a long time.
- Of course, when they meet again, then we’ll have a new evolutionary trend, a new mix of species as the genes flow again.
- At the moment, as the mountains are isolated and it depends where you are in the cold regions, they’re isolated because of maybe ice between them.
- In other latitudes it may be just distance and forest or even tropical forest between them. → those mountains in those situations are reservoirs, they’re refugia, reservoirs of old species, endemic species and species that cannot tolerate or move across the barriers below the mountains.
Why does Biodiversity Matter, and in Particular, Why is Species Diversity Important in Mountains?
- One argument for protecting biodiversity is simply the beauty of nature itself.
- People derive great enjoyment from experiencing the diversity of life in mountains.
- The variety of unique and charismatic species in mountains attracts tourists, and therefore can be economically important as well.
- Beyond its aesthetic value, maintaining biodiversity is critical for the functioning of mountain ecosystems.
- Biodiversity acts as insurance, buffering ecosystems against losses of individual species in the face of environmental change.
- Different species have different tolerances for environmental change, so higher species diversity generally increases the probability that mountain ecosystems can cope with an extreme environmental events such as winter rainfall or icing, increased fire frequency or a drought.
- The diversity of vegetation in mountains is also critical for slope stability.
- The steep terrain of mountains increases the susceptibility of soils to erosion.
- Soil erosion in mountain landscapes increases the risk of avalanches and landslides, that can increase sedimentation in streams, degrading the quality of water supplies.
- While bare soils are highly prone to erosion, the roots of vegetation anchor soils to enhance their stability.
What is the Diversity Stability Hypothesis?
- Is based on the observation that species vary in their morphology and physiology, and that in highly diverse systems there will be some species that can compensate for the loss of others after disturbance.
- Thus, species-rich systems are more likely to be considered stable or less variable and subject to change.
- Sites that only contain a few, rare species with one dominant species are less able to withstand environmental disturbances.
What are Ecosystem Services?
- All these values associated with mountain biodiversity can be thought of as ecosystem services - defined in the 2005 Millennium Ecosystem Assessment as a way of quantifying the benefits people obtain from both natural and managed ecosystems.
- Mountain ecosystems provide a vast array of goods and services to humanity, both for people living in the mountains and for people living far away from mountains.
- so there is a lot of reasons to care about mountain biodiversity.
What are some factors organisms have to deal with in living at high altitudes in mountain ecosystems?
- There is a reduction in partial pressures of oxygen, carbon dioxide and water vapour at higher elevations.
- As a consequence or reduced water vapour, the capacity of the air to absorb and retain heat diminishes, leading to lower temperatures.
- Additionally, the thinner atmosphere at higher elevations results in greater solar radiation and an increased fraction of ultraviolet radiation.
- Slope aspect and steepness, poor soil development, water drainage, wind, and the seasonally variable patterns of precipitation also create challenging conditions for species to cope with.
What are biological adaptations and what is their significance for organisms living in the mountains?
Mountains are home to truly unique ecological communities, and although mountains environments may seem to be hostile and difficult places to live, most mountain dwelling organisms have evolved a wide variety of biological adaptations, or traits that enhance their ability to survive and reproduce in these high places.
What are Conifer Trees?
- One of the most noticeable changes in the landscape as you trek up a mountain is the increasing prevalence of coniferous trees such as white spruce and white bark pine.
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Conifers are a types of plants that reproduces from seeds in cones and can be easily recognized by their needle-like leaves.
- These needles allow coniferous trees to thrive in cold and dry conditions at high elevations.
- The compactness and small surface area of needles compared to broader leaves helps reduce evaporative water loss.
- The needles also have a waxy coating called a cuticle that helps retain moisture and provides protection from ultraviolet radiation.
- Plants need to retain water in mountain environments bc thin soils have a poor capacity to retain moisture.
- However, many conifers also have extensive root systems that increases their capacity to obtain water and nutrients from the soil.
- Plants need to retain water in mountain environments bc thin soils have a poor capacity to retain moisture.
How are needles an adaptation for conifer trees?
- The compactness and small surface area of needles compared to broader leaves helps reduce evaporative water loss.
- The needles also have a waxy coating called a cuticle that helps retain moisture and provides protection from ultraviolet radiation.
- Needles are the sites where photosynthesis takes place.
- Photosynthesis is the process by which plants us light energy to convert carbon dioxide and water into sugar and oxygen.
- CO2 + Water + Light→ Sugar + Oxygen
- these sugars are, in turn, converted into biomolecules that form plant biomass, the leaves, stems, roots and reproductive structures.
- Photosynthesis is the process by which plants us light energy to convert carbon dioxide and water into sugar and oxygen.
- Conifers can photosynthesize at relatively high rates, even at low temperatures, compensating for the smaller surface area of needles.
- This makes them very well suited to cold environments.
- Conifers are also evergreens, meaning that they retain their leaves throughout the years.
- As a result, evergreens are able to photosynthesize longer into the fall after deciduous trees have already lost their leaves and then start again earlier in the spring as soon as temperatures rise above freezing.
- This allows evergreens to take full advantage of the short growing season at high elevations.
- The small surface area of needles also means that evergreens do not accumulate snow that might otherwise weigh down and damage the trees.
- The cone shape of evergreens and the flexibility of their branches allows them to shed snow as it accumulates.
- The wood of conifers is also adapted for cold conditions at high elevations.
- The tissue that forms wood in the trunks on the trees contains vessels that transport water and nutrients upwards from the roots.
- During winter, water freezes in the vessels and gas bubbles can form, similar to the gas bubbles that form in ice cubes.
- These gas bubbles can be problematic for trees because they block the transport of water.
- To deal with this issue, conifers have narrower transport vessels called tracheids, which decreases **the likelihood that gas bubbles will develop.
What are the similarities of White Bark Pine and Limber Pine?
- → both grow at the highest tree line elevations in the Rocky Mountains
- Their canopies provide shade for winter snow and can prolong the timing of snowmelt, therefore regulating downstream flows.
- Individual tress do not reach full cone production until they are 60 to 100 years old, and even some 1,000 year old trees have been known to reproduce.
What are White Bark Pine?
- Conifer trees w/specific adaptations for life on alpine environments
- Fire has historically played an integral role in providing suitable regeneration habitat.
- White bark pine is more resistant to low-severity ground fires than other competing species, such as Seville pine fir and Engelmann Spruce.
- The open areas produced by these fires attract seed-dispersing species, such as Clark’s Nutcracker.
- This active movement of whitebark pine seeds into burned areas gives them a competitive advantage over other species, with wind dispersed seeds in the mountains.
- Whitebark Pine is in the upper alpine region, which is a very harsh, windy, dry area.
- Whitebark Pine is considered a keystone species:
- it primarily regulates snow melt in its region, where it’s in thick canopies, it’s a bigger, bushier tree in that area and prevents the sunlight from melting the snow over, it blays that melt into the summer.
- so they are a very important part of the hydrological cycle.
- the burning is typical for their environment and necessary for their regeneration.
- the seedlings of a whitebark pine can’t stand a shaded environment to grow up in → they need that open stand.
- How their seeds disperse is a unique factor of them
- whitebark pine, in particular, their cones don’t open on their own. → they don’t open through fire like some other species of pine. They require the nutcracker to come in and pry open that cone and take that seed and cache that seed in those openings created by fire or avalanche or other disturbances.
- Whitebark pine is a species at risk, with 3-4 main threats:
- the change in the fire regime over time in this system.
- so the Park’s past fire management practices is to every fire we must put it out. → they’re changing practices on that → introducing fire back into the landscape and that will help in letting fire, that natural process do its thing on the landscapes.
- Climate change
- the whole changing regime of snowpack and snowmelt and that type of thing is having a long-term impact.
- An introduced pathogen called the white pine blister rest.
- is a fungus that infects the trees through its needles into the stem, into the main trunk.
- the change in the fire regime over time in this system.
What are the threats to White Park Pine?
- Whitebark pine is a species at risk, with 3-4 main threats:
- the change in the fire regime over time in this system.
- so the Park’s past fire management practices is to every fire we must put it out. → they’re changing practices on that → introducing fire back into the landscape and that will help in letting fire, that natural process do its thing on the landscapes.
- Climate change
- the whole changing regime of snowpack and snowmelt and that type of thing is having a long-term impact.
- An introduced pathogen called the white pine blister rest.
- is a fungus that infects the trees through its needles into the stem, into the main trunk.
- the change in the fire regime over time in this system.
What is Limber Pine?
- Characteristics:
- Limber Pine is in the same area as White Bark Pine (upper alpine region, which is a very harsh, windy and dry area) BUT it does migrate down into the montane region as well.
- is it a five needle pine? → should be five needles at each of the fascicles.
- has pollen cones
- has first year growth female cones where the seeds are going to be produced.
- it will take a year before the female cones will grow into a bigger cone and around pine-cone size is about the stage where we want to start protecting it from predators if we were interested in protecting the seed and then we come back in September, October and collect that seed.
- limber pine’s cones will open up on its own and the seeds will just fall out.
- a single, mature cone will produce maybe about 40 to 60 seeds in a cone.