1. Explain how HIPPO factors contribute to population changes
Readings: 14: 363-370, 379-382, 386-38715: 414-418
Viewing: E.O. Wilson explains HIPPO http://www.ted.com/index.php/talks/view/id/83
(http://www.eol.org/eo_wilson_speech.html ) for the text of the speech
The impacts of human population growth:
H habitat loss/destruction
I invasive/introduced species
P population growth (by humans)
O overuse/overconsumption of native species
93% of earth’s coral reefs
Habitat destruction have been damaged by
human activity Reefs only
occupy about 0.2% of the
We will lose 40-50% of the
reefs in the next 30 to 40
yrs. These reefs are home
to ~1/3 of the planet’s
Fragmented habitat (Amazon)
Prince George, BC (Google Earth) What are the white dots?
Despite laws which require all clear-cut land in BC to be replanted within 5 years, the
amount of old growth forest being lost in BC continues to increase (aside from mt. pine
Fragmentation creates small isolated populations thus increasing extinctions. Loss of
biodiversity is seen along boundaries of natural habitats.
What happens when a habitat becomes fragmented?
1. There is an overall decrease in the amount of habitat area.
2. The smaller fragmented patches have more contact with the second habitat (shown as light
coloured strips). What effect might this have on the species in the green habitat? Imagine that
we have a large contiguous section of Pacific Spirit Park and suddenly it gets fragmented and
the light habitat are open grassy areas. What effect could that have on plant species that
were previously in shady forest with big trees and are now right next to open grassy
- Changing abiotic conditions next to the edge
- Possible increased predation with increased exposure
- Possible increased competition with species found in the second habitat
Which scenario is likely to affect the most species?
a-Some mating pairs need isolation for breeding so fragmentation will INCREASE their reproductive
b-Many breeding pairs mate for life so there will be LITTLE EFFECT on reproductive rate b/c the pairs
will stay together
c-The reproductive rate will DECREASE if individuals have difficulty travelling between patches to find
mates OR there can be inbreeding in these populations causing each to be genetically less fit (inbred
offspring will die more frequently)
It’s harder to breed w/ other individuals if there are few in your patch or if there is difficulty moving to other patches
(animals) or spreading gametes to individuals in other patches (plants)
- Changing abiotic conditions
- Increased exposure to predators in open habitat
- Smaller mating populations
- Loss of genetic diversity
3. A number of small “metapopulations” are created. Imagine we initially have the same number
of species in the green patches compared to the continuous green habitat. (Compare the two
areas below) Why can species more easily be lost from individual patches than when the
habitat is continuous? Consider the habitat below with one animal species shown as males ♂
and females as ♀. Why is this population more threatened now that the species are
found in small patches?
4. Species can become more vulnerable to predators when found in small patches. When motile
species may attempt to move from one patch to another they may be more vulnerable while
traveling from one patch to another in the different habitat. Eg. What if the species below were
deer…why would a deer become more vulnerable when moving from one forest patch
through the open grassy area to another forest patch?
- The deer is more vulnerable because it is easy to see, as compared to other species.
♂♀ ♂ ♀ ♀♂♂♀ ♀ ♀ ♀♂
♂ ♂♀ ♀ ♀♀ ♂♀ ♀ ♀♀ ♀
♂ ♀ ♂ ♂ ♀♂
♀ ♂ ♀♂
♂ ♂ ♂ ♂
♀♀ ♂ ♂
♀♀ ♂♀ ♂♂ ♀ ♂ ♀
♂ ♀ ♂ ♀♀ ♂♂ ♀ ♂ ♂♂ ♂
♀♀♀ ♀♀♀ ♀ ♀
♀ ♂ ♀ ♂
♂ ♀ ♂♂ ♀ ♀♂ ♀
♂♂♂ ♂♂♂♂ ♂♂♂ ♂♂
♂ ♂ ♀♀
♂ ♂ ♂ ♀♀ ♀ ♂ ♀
♀ ♂ ♀ ♂♂ ♀ ♂ ♂♂ ♂♀ ♀ ♂♂ ♂♀
If we know habitat destruction is responsible, what can we do?
- Habitat restoration
Certain species are threatened because of habitat loss. These owls
live along the Shuswap river in hollows within trees like black
cottonwoods. Restoration attempts create habitat (eg by
planting deciduous trees along rivers (riparian areas), exclude
livestock (cows damage habitat) and also create temporary
habitat (bird houses).
Western screech-owl (Otus kennicottii macfarlanei)
You can help: http://www.pacificspiritparksociety.org/Volunteering/Work_Parties.html
Different lower mainland parks and organizations have various volunteer opportunities. http://www.parkpartners.ca/
- Protected areas (some areas exist, others proposed, others needed)
Alaksen National Wildlife Area Endeavour Hydrothermal Vents Bowie Seamount
(snow geese) (tube worms near Black smoker) (salps and red sunflower seastars)
Pacific flyway National Wildlife Area Marine Protected Area Marine Protected Area
Great increases in diversity have been observed where fishing is prohibited. Also the population
increases extend outside of protected area limits
for larger animals (Lake Louise) and reptiles and amphibians (Iowa project)
Invasive and Introduced Species:
American bullfrogs (Rana catesbeiana) are common in eastern Canada
and the U.S. They were brought to B.C. by entrepreneurs that set up
farms in the hope of selling the frogs legs to local restaurants. These
businesses were not successful, the farms were abandoned and the
frogs were free.
As a new species to the community, the frogs have few native predators.
Herons, eagles, snakes, only consume young frogs often certain size range not taken.
Bullfrogs have voracious appetites. They will consume “anything that they can get into their mouths”
Eg. Insects ducklings, songbirds, mice, garter snakes, fish, other amphibians includes red-legged frog (native BC species)
Also competes with red –legged frog for food
Bullfrogs are prolific reproducers. One female can produce and lay up to 20 000 eggs at one time.
They can easily disperse between ponds, lakes and streams. It has been estimated that they have increase
their range on Vancouver Island by 5 km a year. -invade new habitats ,cause increased competition for space
What impact do the bullfrogs have on native frog species?
-outcompete for food and space -prey on the native frogs -native spp. are decreasing
(ironically these bullfrogs are declining in Ontario, one of their native habitats, due to pollution, roadkill and
Scotch broom (Cytisus scoparius) was introduced as a garden plant in 1850. Seed pods produce many seeds
that spread explosively. The plants grow quickly, shading other native plants. Scotch broom has another
advantage in that a symbiotic bacteria lives within its roots. These bacteria fix nitrogen from the soil and
enable scotch broom to live in poor soils or disturbed sites.
The Garry Oak meadow ecosystem is a
relatively small isolated ecosystem
containing endangered species such as
the Garry oak itself. Areas like it which
have endemic plant and animal species
(unique species only found there) are
especially vulnerable to introduced
species becoming invasive.
Scotch broom Garry Oak meadow, an endangered ecosystem in B.C.
Scotch broom is now common in southern B.C. and has invaded Garry Oak meadow communities.
QUESTION: Can you think of any other unique ecosystems full of species found nowhere else which may be in
danger? (Anywhere in the world?)
QUESTIONS: The green crab is slowly moving up the west coast towards British Columbia, in order to
become established here what conditions must exist? In other words, what are characteristics of invasive
You can help remove invasive plant species:
Which of these is not a defining characteristic of invasive species
a. They are aggressive competitors (they have to be able to compete w/ what’s already there)
b. They have many predators (If there were many predators, they wouldn’t be able to get established in the new
c. They have many possible food sources (helps make the species more adaptable to the new environment.
Adaptations to prevent predation, toxins, spines etc in plants)
d. They have many offspring
e. They tolerate a wide range of abiotic vactors