Migration & Biodiversity Flashcards
(39 cards)
1
Q
What is migration?
A
- Seasonal mass movement
- Long or short distances
- Can occur many times throughout an individuals life or just once
- Typically involves a switch from one habitat to another
2
Q
Who migrates?
A
Animals from all major taxa: fish, crustaceans, amphibians, reptiles, insects, mammals
3
Q
Examples of daily migration
A
Golden Jellyfish
- Symbiotic relationship with zooxanthellae algae
- Daily migration to sun their algae
Some fish, zooplankton
- Daily vertical migration
- Feed at surface at night
- Retreat to depths during day
4
Q
How is the migration of amphibians and reptiles?
A
- Migrate to aquatic breeding ground (amphibians) or egg laying site (reptiles)
- Crossing roads is a major hazard
- In some locations, crossing tunnels or culverts have been constructed beneath roads to allow animals safe passage
5
Q
What are migration stars?
A
- Bar tailed godwit
- Migrates from Australia/New Zealand to Alaska
- One non stop flight: 11,000 km, 9 days
6
Q
Whats another migration stars?
A
- Bar headed goose
- Migrates over the Himalayas
From Southern Asia to summer breeding grounds in central asia - Extreme altitudes where there is less than 10% of oxygen found at sea level
- These geese have been seem flying over the top of Mount Everest
7
Q
Why migrate?
A
- Seasonal changes in the local environment
Temp, drought, food availability - Changing needs at different life stages
- Move to a suitable habitat reproduction
E.g. many birds breed in the arctic in the summer
E.g. Pacific salmon live in ocean but migrate to freshwater streams to spawn
8
Q
How do they prepare for migration?
A
- Migration requires a lot of energy
- Hyperphagia
Excessive appetite
Intense period of feeding prior to migration
Fat is stored for the long journey - Hyperphagia is observed in diverse species including birds, whales, insects, and caribou
E.g. birds can double their body weight before migration - Many species save energy by taking advantage of wing patterns and water currents
9
Q
What is the shorebird stopover?
A
- Many species of shorebirds congregate in Delaware Bay, NJ
- Feast on horseshoe crab eggs
Plentiful
High in fat
10
Q
Are the shorebirds in decline?
A
- Horseshoe crabs overgarvested
1992-1997 - harvested increased from <100,000 to > 2.5 million
2008 moratorium on crabs for bait
Estimated 60 years for recovery - Shorebirds in decline in last 2 decades in Delaware Bay
1.5 million to 350,000
11
Q
How is the migration in birds?
A
- Not all birds migrate
Most N.A species do - Many migrate as far as the arctic
- Advantages of breeding in the arctic
Long daylight hours and very productive ecosystem
Ample resources
Space (reduces competition)
Relatively few predators - Migration routes generally follow set paths
Can be innate or learned - Some birds travel very fast
Bat tailed godwit (11,000 km in 9 days) - Others travel at a leisurely pace
Some warblers take 50-60 days to get from Central America to breeding ground in Canada - Birds navigate
Chiefly by sight (topographical landmarks)
Earths magnetic field
Sun and stars
12
Q
What is the Arctic tern?
A
- Weighs only 100g
- Longest migration of any animal (70,000 km yearly)
Pole to pole: breeds in colonies north of the Arctic circle, spends the summer in the Antarctic - Over its lifetime (up to 30 years) can migrate 2.4 million km
Equivalent to three trips to the moon and back
13
Q
How do the freshwater eel (fish) migrate?
A
- American eel
- Endangered species
- Lives in freshwater estuaries and spawns in the ocean
- A palmitic species
All members of the species mate randomly and are considered to form one large population - Eels are catadromous
- Live in freshwater (migrate to the ocean to spawn)
Coastal rivers of North America - migrate to the Sargasso Sea - Spawn at a depth of 300 m then die
- Tiny larvae begin the long migration back to the coast, growing along the way
Takes them 1 year to reach N.A estuaries
14
Q
How do the salmon (fish) migrate?
A
- Most salmon are anadromous
- Spend adult lives at sea and return to freshwater to spawn
Atlantic salmon makes multiple runs throughout their lives
Pacific salmon make a single run and then die - Pacific salmon migrate downstream as juveniles
- Spend 3-4 years in the Pacific Ocean (growing)
- Return to spawn in the headwaters of its parent stream
15
Q
How do salmon find their way back to parents stream?
A
- Guided by olfactory senses
- Can recognize particular door of their stream (caused by characteristic vegetation and soil)
- May navigate by the sun to find the right spot on the coast and then use olfaction
16
Q
What is osmoregulation?
A
- Most freshwater fish will die if you put them in salt water and vice versa
- Euryhaline species can survive in a range of salinities
Freshwater: low salinity
Brackish water: medium salinity (found in estuaries where rivers meet the ocean)
Saltwater: high salinity - Two types of euryhaline species of fish:
Catadromous: migrate downstream to spawn
Anadromous: migrate upstream to spawn
17
Q
How is the migration in mammals?
A
- Many marine mammals migrate
- E.g humpback whale (longest mammalian migrant)
Up to 8,000 km each way - Spend summer eating in Arctic or Antarctic
Store energy in blubber - Breed in tropical waters
- More difficult for terrestrial mammals than for birds, fish, or marine mammals
Terrestrial locomotion is more energetically costly than swimming or flying - Few terrestrial mammals migrate
Have a defined home range
Notable exception: caribou
18
Q
What is biodiversity?
A
- Biological diversity
- Simple: a simple counting of the number of species in an ecosystem
19
Q
What are the 3 levels of biodiversity?
A
Genetic
Species
Ecological
20
Q
What is the distribution of species?
A
- Biodiversity is not evenly distributed across the earth
- High biodiversity
Tropical rain forests
Coral reefs - Low biodiversity
Arctic regions
21
Q
What are endemic species?
A
- Distribution limited to small area
- E.g. Marine islands -> large number of endemic species
E.g. the birds, plants and insects of the Galapagos islands are found nowhere else - Vulnerable to extinction
- Conservation is generally directed towards regions with high diversity and lots of endemic species
22
Q
What is the maintenance of biodiversity?
A
- Speciation is faster than extinction (on average) because otherwise we would have no biodiversity
- Biodiversity is created/maintained through speciation
- Speciation and extinction do not occur at steady rates throughout evolutionary history
23
Q
What are the types of extinction?
A
Background
Mass
Anthropogenic
24
Q
What is background extinction?
A
Gradual loss of species in a natural population as conditions gradually change
25
What is mass extinction?
- Loss of a large number of species during a short period of time due to a natural catastrophe (volcanoes, meteor impact, prolonged drought)
- Can eliminate nearly all (or all) species in a region
26
What is anthropogenic extinction?
- Loss of species due to human activity
| - Rate of extinction is currently far above background levels
27
Are we in a 6th mass extinction?
- Some claim yes
- Extinction rates are well above natural background rates
8-100x higher
- Others argue that we are in a biodiversity crisis but not a mass extinction
28
What are the threats to biodiversity?
- Habitat loss and fragmentation
- Invasive species
- Overexploitation
- Others (pollution, climate change)
29
What is habitat loss and fragmentation?
- E.g. coastal forests of Brazil
- If you destroy a species habitat, they will not do well
- Fragmentation happens in little patches
30
What are the effects of fragmentation?
- Cowbird is a brood parasite (lays eggs in the nests of other birds)
- When the patches of forests are small, Kentucky warblers are more likely to be parasitized by brown headed cowbirds
- Example of how fragmentation can put pressure on a species
31
What are examples of invasive species?
Exotic species
Invasive species
Invasion of new ecosystems is a natural process
32
Explain exotic species?
- Any species that is not native to the ecosystem
| - Also called alien or non native species
33
Explain invasive species
Exotic species that has a negative impact on the ecosystem
34
Explain how invasion of new ecosystems is a natural process
Greatly accelerated through human intervention (purposeful and otherwise)
35
Why are invasive species the second most important threat to biodiversity?
- Cause diseases
- Act as predators or parasites
- Act as competitors
- Alter habitat
- Hybridize with local species
36
Whats an example of an invasive species?
- Brown tree snake
- Native to Australia, Indonesia
- Introduced to the island of Guam in the 1950s by cargo ships
- Eliminated 11 of the 12 native bird species endemic to Guam
37
Whats an example of an invasive species from here?
- North American species are invasive on other countries
| - The Eastern grey squirrel threatens native populations of squirrels in Europe (and West coast of N.A)
38
What is the overexploitation of the passenger pigeon?
- 1914: Last passenger pigeon died at a Cincinnati zoo
- Once most abundant bird in N.A
- Flocks hundreds of km long
Containing millions (possibly billions) of individuals
- Hunted to extinction
Habitat loss played a role as well
- Migratory bird Treaty Act was established in 1918
39
Is biodiversity worth preserving?
- Moral considerations (is it our moral responsibility to protect nature?)
- Economic considerations (food resources, ecotourism, ecosystem services)
- Environmental quality
Loss of biodiversity is a sign of the poor quality of our environment
These species extinction are early warnings
- Maintenance of ecosystem function
Species diversity stabilizes ecosystem function
More resilient to harsh conditions (more diverse systems are more likely to contain species capable of withstanding the stress)
