Lecture 15 Flashcards
Levels of biodiversity
I. Genetic variation within populations and species
II. Number of species in an ecological community
III. Assortment of communities at a landscape scale
Richness of communities and why community conservation is important?
- A landscape with a dynamic mosaic of different communities is richer than a uniform landscape
- landscape assess habitat per unit area
ex. Low community diversity in a boreal forest landscape (landscape with one type of ecosystem)
ex. High community diversity in
a tropical forest landscape (different kinds of ecosystems in the landscape scale) - Community conservation is important because: it includes the environmental services they provide (Carbon storage, regulation of water flow, production
of biological resources) - we’re protecting diverse communities species and genetic diversity
- Late-succession communities (communities that have undergone disturbances and have the opportunity to regrow)
- They are becoming increasingly rare
The amount of mature forest is decreasing
- Extent of mature growth forests decrease significantly over the past 400 years
- all that is left is newer growth forests
Levels of biodiversity
I. Genetic variation within populations and species
II. Number of species in an ecological community
III. Assortment of communities at a landscape scale
Measuring genetic biodiversity
- Can be measured using molecular markers (genotyping)
- take genetic samples
- Frequent measures of genetic biodiversity:
– Heterozygosity
– Number of alleles - Quantify variability between species
-Quantification of biodiversity done with samples of organisms, explore how different organisms are
Measuring species biodiversity
- Species richness is the simplest measure of
species-level biodiversity (how many species are in an environment) - Species richness is often measured at the
level of the guild
Guild: a group of organisms that use the same ecological resource similarly - Two biomes at the highest levels of biodiversity: rain forests and coral reefs
- Taxonomic expertise is critical must know what they look like
Terry irwin’s technique
- Sprays insecticide
- Focus on tree at a time
- At the bottom they set up funnel traps
- To catch the bodies
- Quantifying how many species in one tree
ex. Luehea seemannii trees in tropical rainforest and found 1100 species of beetles in the canopy of one tree. - This is a simplistic mesure
Problems with Terry Erwin’s quantification of 2ed level of biodiversity
Richness doesn’t account for relative
abundance of each species
ex. community a and community b
can have same level of species richness but very different evenness
- This doesn’t give you the ability to calculate a parallel effect
Problem 2: Richness doesn’t account for identity of the species
- could be invasive
Species diversity
Species diversity is a measure that includes
both number of species present (i.e. richness)
and their relative abundances (i.e. evenness)
* The Shannon Index
H’=Z pi ln pi
- pi is proportion of individuals belonging
to each species
* In other words, the Shannon Index
accounts for the relative proportions
of species present
- Looks at both richness and eveness at once
Species area curve
- How much area of a species have you measured
How much sampling must be done to accurately
quantify biodiversity? - Species-area curves (aka
rarefaction curves) allow ecologists to
estimate whether biodiversity sampling is
complete - When it starts to even off you have exhaustidly sampled in this region
- you can estimate where the asymptote will occure so you don’t have to actually sample everything.
How do we know what we don’t know?
- Irwin fogged trees in Panama, identifying 1200 beetles per tree; 13.5% were host-specific (163 species)
- He estimated 70 trees per hectare in tropical rainforest
- Therefore 11,410 host- specific beetles per hectare
- With more than 700 known tropical rainforest tree species: 8 million beetles
Taking what he knows about one tree and vaguely generalizes it to the world (only for beetles)
DNA Barcoding
- DNA barcoding: Identifying species with a short sequence of species-specific DNA
- find out a short sequence that can be found on every species on earth
- Canadian Paul Hebert leads the “International Barcode of Life” project
- Uses a mitochondrial region called CO1
- doesn’t vary between individuals, but does vary between species
- More than ten million specimens from 800,000 species have been barcoded to date
- Future way to quantify biodiversity and understand how much biodiversity there is
Measuring community biodiversity
Measuring community-level biodiversity poses
similar challenges to species-level
biodiversity
- Recognize difference ecosystem without taxonomic need
* Modified Shannon index can be used, to account for different biomass or
area of communities within a landscape
- calculate diversity area curve
What is the importance of biodiversity
How do we assign value
to biodiversity?
1.Instrumental value
2.Value of ecological
services
3.Aesthetic and cultural
value
4.Intrinsic value
- Biodiversity provides instrumental value as:
- Food
– Materials
– Energy (biofuels)
– Medicine (ex. rosy periwinkle can
suppress tumour growth
ex. Yew plants important in chemotherapeutic) - Biodiversity prospecting is an active area of
modern medicine
