3.2 Origins of Biodiversity Flashcards
Wallace Line
Named for Alfred Wallace. To the west of the Wallace Line, the islands are characterized by fauna and flora that are predominantly Asian in origin. To the east, the islands host a mixture of Australian-origin species like marsupials.
Landbridge
Areas which at times have been above sea level and navigable by terrestrial fauna.
Endemic/Endemism
Occurring nowhere else on Earth.
The % endemism of a place is the proportion of unique species.
Placental
A class of mammal which give birth to live young (which develop inside the womb and are nourished through a placenta). From an evolutionary standpoint, placentals babies are subject to fewer environmental pressures than marsupials.
Galapagos Finches
The text-book example of adaptive radiation. They evolved different beak shapes and sizes to best match the food resources available on their islands.
Galapagos Islands
A volcanic archipelago in the Pacific Ocean. Often studied for its contribution to evolutionary theory.
Madagascar
An African island on which lemurs undertook evolution to adapt to take advantage of a variety of trophic and habitat niches.
Trophic niche
Where an organism fits in the food chain. Relates to what they eat and what eats them.
Habitat niche
Where an organism lives. For example, can be arboreal (in the trees), or terrestrial (on the ground)
Terrestrial
on the ground
Arboreal
in the trees
Niche
refers to the role or function of an organism or species within an ecosystem, encompassing its relationships with other living organisms and its interactions with the physical environment.
Survival of the fittest
A concept associated with evolutionary biology in which only those organisms best adapted to their environments successfully procreate and pass their genes to successive generations.
Natural Selection
The concept associated with evolutionary biology which explains how traits become more or less common in a population over time based on the reproductive success of organisms with those traits.
More correct to use than “survival of the fittest”
Evolution
How an organism changes over successive generations to adapt to available resources and conditions.
Can occur through mutations or natural selection.
Darwin’s famous book
“On the Origin of Speices” (1859)
Why are many of New Zealand’s birds flightless?
They evolved in the absence of other mammals or reptiles to occupy available niches, including terrestrial ones, and were successful owing to the absence of predators.
Geographic Isolation
A barrier (natural or manmade) which prevents genetic flow between populations and can lead to speciation (development of separate species).
Speciation
The evolution of populations of the same species separated by a physical barrier into two different species that cannot successfully interbreed.
Pangea
The supercontinent. Split into Gondwanaland (South America, Africa, Australia and Antarctica) and Laurasia (North America, Europe and Asia) 175 million years ago.
Gondwanaland
Supercontinent comprising of South America, Africa, Australia, Antarctica and India (separated from Pangea 175 million years ago)
Laurasia
Supercontinent comprising of North America, Europe and Asia (separated from Pangea 175 million years ago)
Continental Drift
The idea that continental and oceanic plates (as part of the Earth’s crust) are drifting around atop the mantle. Similar to plate tectonics (which describes the mechanism for this drifting).
Temporal Isolation
When two organisms or populations are separated due to the time of day they are active. Similar to behavioral isolation.
Inheritance
The passing down of genetic material from one generation to the next.
Extinction
Death of the last individual of a species.
Endangered
A reduction of between 50-70% of a population size within 10 years, or three generations.
Anthropocene Extinction
the ongoing mass extinction primarily due to human activity affecting the planet’s climate and ecosystems.
The “sixth extinction”.
Mass extinction
Rapid and widespread extinction event. 70-96% loss of biodiversity.
There have been five of them in the last 500 million years. We are probably in the midst of a sixth.
Causes of mass extinction events
- Short, severe ice age
- Widespread ocean anoxia
- Massive volcanic eruptions
- Ocean acidification
- Asteroid impact
Factors that can make a species less prone to extinction
- Genetic diversity (resilience)
- Wide geographic range
- High reproductive rate
- Ecological plasticity and flexibility
Background extinction rate
The natural, steady rate of species extinctions occurring as part of Earth’s evolutionary process. Varies between taxa. Measured as # of species/time.
