Lecture 14 Flashcards
What is Biodiversity?
- It is the variability among living organisms from all sources, including diversity within species, between species, and of ecosystems.
(UN’s formal legal def)
Canada was the first country to sign on
What are the 3 levels of biodiversity?
- Genetic variation within population and species (genetic variation)
- Number of species that are found within an ecological community (species variation)
- Assortment of communities at a landscape scale (community variation)
What is Genetic variation?
Each organism has a unique genome (most similar to parents and siblings)
* Variability of individuals is based on pool of
genetic variation within a population, and
the expression of genetic information (phenotypic plasticity)
Clonal reproduction
Lower genetic variability
Some species can reproduce
asexually so that offspring are
genetic clones of their parents
* The largest known trembling aspen
covers more than 43 ha, consists of
47,000 stems, and weights more than
6 million kg
Clone-genetic identical offspring
no differential separation to protect them from arising challenges
Sexual reproduction
Sexual reproduction has a powerful influence on genetic diversity
* Haploid sex cells from both parents undergo
recombination to create unique diploid
organisms
* High genetic variation is typically observed in
sexually reproducing organisms drives variation
- Biodiversity is higher
Low genetic diversity
Genetic diversity allows populations to respond to environmental changes
* Populations with low genetic diversity are at
risk in changing environments
* They are also vulnerable to pests and disease
ex. if 10% of us harbour an immunity to a plague, then humanity is likely to continue
- As environment changes faster, organisms with higher genetic variation have an advantage
ex. Aurora trout have low diversity
- they faced nickle poisoning
- breed in captivity
Endemic species and other taxa
Endemic species occur in a restricted area-represent local adaptation
* Remote islands are often rich in endemic
species:
ex. darwin’s finches
e.g. prior to discovery by humans, Hawaiian flora was 98% endemic
* We are trying to understand is there enough of the first level biodiversity in the environment or are they facing extinction
limited genetic diversity
The Florida panther
- Pumas are apex predators found in
North and South America - They provide an interesting case-study of
the effects of small endemic populations - They were once widespread throughout North America (now only on west coast and Florida)
- by late 20th century, there were only 20 to 25 adults in Florida they were at risk of being extirpated
- Genetic diversity was rapidly lost
- Genetic analyses indicated inbreeding
within this population
Solution:
Catch pumas in Texas put them in Florida (8 females) - Pumas were genetically rescued from the influx of new genes
-Heterozygosity went up - average age got younger (more young were able to survive)
What is species richness
Number of species in a particular area
- Can focus at diff taxonomic level don’t always have to look at everything
* Richness can be measured at different
scales (within a community, park,
country, etc.)
- Must have knowledge in systematics and taxonomy
- Species must be classified by their Latinized binomial name
- 2 million species named
Global species richness (table 12.1)
Number of described and estimated species
varies across taxonomic groups
* In some groups, most species have not yet
been described
* Small tropical arthropods are especially poorly known
- Temperate versus tropical dichotomy:
* About 65% of named species live in the
temperate zone (lots of universities)
*Hidden biodiversity is mostly in Beatles
* About 90% of yet-to-be discovered species live in the tropical rainforest (one biome)
* Science suffers from a temperate-zone bias
The modern syntheses
Canadian species richness
- In Canada, a large number of species
have not yet been discovered - Most of the species yet to be named in Canada are Beatles
Species richness decreases with ……
Latitude.
- Most species we don’t know yet are in the tropics
Diversity extremes
- Luehea seemannii tree was found to
have 1100 species of beetles in its canopy,
14.5% were unknown to science
Diversity extremes
- 742 tree species (DBH>10cm) were found
on a 3 hectare plot in Malaysia with 50% as
single individuals - In all of Canada, there
are ~300 tree species! - Three times that number in one plot then we have in all of Canada
