Chapter 9: Biodiversity and Plant Adaptations Flashcards
Define Biodiversity.
Biodiversity is the number of species in a certain area, the distribution of species, the genetic variation within populations, or the role that species play within the ecosystem.
Mountains contain compressed climatic zones, or ___, along vertical, elevational gradients.
Microclimates.
Who was Alexander von Humboldt?
One of the first people to document these patterns of mountain diversity was the Prussian geographer and naturalist, Alexander von Humboldt. His 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 sketch of Chimborazo, a massive, 6310 m stratovolcano and the highest mountain in Ecuador.
Humboldt: Between 1799 and 1804, travelled extensively in Latin America, (pic of Chimborazo), his quantitative work on botanical geography laid the foundation for the entire field of biogeography. Describe his cross-section.
His cross-section, pictorial representation and detailed descriptions of the cross-section was called “Ein Naturegemalde Der Anden” / “Picture of Nature in the Andes” provided detailed info about temp, altitude, humidity, and the animals and plants found at each elevation. Basis for comparison with other major peaks in the world.
Speciation:
What is speciation?
The process that creates new species. Occurs when populations genetically diverge to a point when they are no longer able to interbreed.
Speciation:
For speciation to happen, populations need to be isolated so that there is no movement of individuals from one place to another. What is allopatric speciation?
Geographic isolations.
Allopatric speciation is common in mountains because these rugged landscapes impose topographical barriers that isolate smaller populations.
Speciation:
Give an example of allopatric speciation.
E.g. ridges and valleys of Andes in SA create physical barriers that both limit animal dispersal and create local variations in rainfall. Resulted in physical isolation of animal populations and variation in animal habitat productivity. Both factors contributed to the evolution of high species diversity. Diversity seen in genetic and morphological variation in Peruvian populations of the Tyrian Metaltail (hummingbird living in montane forests of elevations at 1700-3800 m). Geographic isolation rather than variation in climatic conditions explain most genetic variations in various subspecies.
Speciation:
Give another example of allopatric speciation.
E.g. Speciation of bellflowers living in the NA mountains diverged with geographic isolation between multiple mountain refugia.
Bellflowers: climatic variability ass. With quaternary glacial cycles and the rugged topography of these mountain landscapes provided many opportunities for speciation. Factors contributing to the high diversity of bellflowers incl. combined effects of climate oscillations, rugged alpine habitats and variable floral morphology. Studies found that speciation over the past 1mys was ass. With geographical isolation between multiple mountain refugia in W N A.
Speciation:
Define Refugia.
Places in the mountains that have maintained favourable conditions during periods of past environmental change, often ass. with periods of glaciation.
Measuring biodiversity:
What is species richness measure?
The simplest way to measure biodiversity by counting the total number of species present.
Measuring biodiversity:
What is a second index of biodiversity?
Evenness:
Measures how similar species are in their relative abundances.
E.g. large differences in the abundance of species , community has low evenness.
Measuring biodiversity:
What is a third measure?
Species diversity, which accounts for both species richness and evenness.
Species diversity can provide insights into how ecosystems function in mtn. environments.
Measuring biodiversity:
What is DNA barcoding?
A technique for characterizing species using a short DNA sequence. It also provides a measure of genetic diversity within populations and communities.
DNA Barcoding, Sarah Adamowicz, Geneticist at UofGuelph.
Give an example of an endemic species.
E.g. Found only in the Rockies is the Banff Springs snail (Physella johnsoni). It is a small air-breathing freshwater snail in the family Physidae. The largest individuals are about 1 cm long, and they survive on a diet of algae, microbes and detritus. Unusual because they are adapted to thermal springs where water is low in O2 and high in hydrogen sulfide. Snail was first identified in 1926, in the nine sulphurous hot springs of Sulfur mountain in Banff. Range has shrunk to 5/9 hot springs.
Cave and Basin, Banff, Mark Taylor, Aquatic Ecologist with Parks Canada: Live in water 20 degrees warmer, Endangered, Wet seasons (spring) populations fall, dry seasons (summer, fall, winter) rises (explode from dozens to hundreds).
Mountains are biodiversity hotspots:
What are hotspots of biodiversity?
Regions containing high concentrations of endemic species that are also facing threats of rapid species loss.
Mountains are biodiversity hotspots:
More than 35 biodiversity hotspots have been identified around the world. ___ of them are located in mountains regions.
1/2
Mountains are biodiversity hotspots:
Although hotspots represent just over 2% of the Earth’s land area, they’re home to about ___ of the world’s endemic species.
1/2
Mountains are biodiversity hotspots:
Give an example of one of these hotspots.
The Andes region of SA, these natural alpine habitats are also among the most threatened area of the world.
Mountains are biodiversity hotspots:
Explanations for this concentration of endemic species include…?
Past climate shifts and tectonic events, modern ecological interactions, and limited dispersal.
Andes: Historically, the uplands were isolated from lowlands by Andean uplifts which began 25-30 mya, created complex mosaic of high mountains and deep valleys. Ancient uplift and resulting isolation were important drivers in speciation.
Mountains are biodiversity hotspots:
Two hypothesis that could explain these patterns of biodiversity ae the geographical area hypothesis and the productivity hypothesis. What is the geographical area hypothesis?
Larger areas can support more species. Decreasing species diversity at higher latitudes and elevations may just be a consequence of inherently smaller areas of habitat availability.
Mountains are biodiversity hotspots:
Two hypothesis that could explain these patterns of biodiversity ae the geographical area hypothesis and the productivity hypothesis. What is the productivity hypothesis?
Proposes that higher primary productivity (forms the resource base of food webs), associated with higher temperatures in the tropics and at lower elevations, contributes to higher biodiversity.
Mountains are biodiversity hotspots:
Habitat fragmentation, as a result of past environmental changes such as glaciation, can be particularly influential in determining …?
Patterns of mountain biodiversity.
Professor Terry Callaghan from Tomsk State University in Russia and Sheffield University in UK has spent decades studying these patterns (Spoke to him visiting Altai mountains in Siberia):
Importance of N-S running corridors of distributions of plants, following movements of previous iceages. After little iceage and early cold periods, Nunatak (tops of mountains sticking out of ice sheiths), most famous is in SW Greenland, 100 km from any ice free area. There are plants growing. Will spread along rides connecting Nunataks as ice recedes. Can also be separated by distance and forests, mtns in those situations are resevoirs (refugia).
___ ___ systems are more stable, or less susceptible to risk when subjected to change.
Species rich.
The diversity of vegetation in mountains is also crucial for slope stability.
What is the diversity-stability hypothesis?
Based on the observation that species vary in their morphology and physiology, and that in a highly diverse system there will be some species that can compensate for the loss of others after disturbance.
Define ecosystem services.
Defined in 2005 Millennium Ecosystem Assessment as a way of quantifying the benefits people obtain from both natural and managed ecosystems.
What are conifers?
A type of plant that reproduce from seeds in cones and can be easily recognized by their needle-like leaves.
E.g. White Spruce and White Bark Pine