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Organisms 2 > Migration & Biodiversity > Flashcards

Migration & Biodiversity Flashcards

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
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2
Q

Who migrates?

A

Animals from all major taxa: fish, crustaceans, amphibians, reptiles, insects, mammals

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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
Q

What is mass extinction?

A
  • 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
Q

What is anthropogenic extinction?

A
  • Loss of species due to human activity

- Rate of extinction is currently far above background levels

27
Q

Are we in a 6th mass extinction?

A
  • 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
Q

What are the threats to biodiversity?

A
  • Habitat loss and fragmentation
  • Invasive species
  • Overexploitation
  • Others (pollution, climate change)
29
Q

What is habitat loss and fragmentation?

A
  • E.g. coastal forests of Brazil
  • If you destroy a species habitat, they will not do well
  • Fragmentation happens in little patches
30
Q

What are the effects of fragmentation?

A
  • 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
Q

What are examples of invasive species?

A

Exotic species
Invasive species
Invasion of new ecosystems is a natural process

32
Q

Explain exotic species?

A
  • Any species that is not native to the ecosystem

- Also called alien or non native species

33
Q

Explain invasive species

A

Exotic species that has a negative impact on the ecosystem

34
Q

Explain how invasion of new ecosystems is a natural process

A

Greatly accelerated through human intervention (purposeful and otherwise)

35
Q

Why are invasive species the second most important threat to biodiversity?

A
  • Cause diseases
  • Act as predators or parasites
  • Act as competitors
  • Alter habitat
  • Hybridize with local species
36
Q

Whats an example of an invasive species?

A
  • 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
Q

Whats an example of an invasive species from here?

A
  • 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
Q

What is the overexploitation of the passenger pigeon?

A
  • 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
Q

Is biodiversity worth preserving?

A
  • 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)

Organisms 2 (23 decks)

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