Patterns of Life Flashcards
What is biogeography?
occupies a space between several fields of research within biology (ecology, systematics, taxonomy, palaeobiology) and draws from environmental geography and geology- oldest discipline in biology
What made comparitive assessments of patterns of life across the globe possible?
Trade and the invasion of new territories by military forces
Name 2 of the 1st pioneers to notice the different patterns of life across the globe + what did they discover?
Comte du Buffon- noticed large animals of the old and new world were different
- Buffons law stating that different regions of the world were home to different species = principles of biogeography
Alexander von Humboldt- Travelled extensively and noticed the same thing applied to other animals and plants
OVERALL PATTERN = role a species plays in the environment is selected by the environment
What was the reason behind those observations?
Continental drift in 1915
What is convergent evolution?
the process whereby organisms not closely related (not monophyletic), independentlyevolvesimilar traits as a result of having to adapt to similar environments or ecological niches
Describe the process of continental drift
- Permian (300mya)- continents were combined into a single landmass called Pangaea
- Triassic (200mya)- split into 2 sections known as Northern Laurasia and Southern Gondwana caused by radioactive heating
- 120mya- a complete split had formed and the land masses started to move away
What did Alfred Russel Wallace develop?
A map of faunal kingdoms across the globe, based on changes in the distribution of mammals- has been updated but lines drawn still correspond to major continents
What are faunal kingdoms known as today?
Biomes
What are biomes and what is the pattern of distribution?
= correspond to different habitat types across the planet
- Warm + wet biomes run across equator
- Cold + dry biomes found closer to the poles
What 2 factors can be used to predict the distribution of biomes?
annual temp + rainfall
What was the trend identified by Humboldt?
altitude mirrors latitude- as you ascend a mountain in the tropics, you will pass through a similar sequence of biomes as if you were moving from the equator to the poles
Name all the different biomes and their chacteristics
Tropical rainforests
Savanna
Temperate forest
Temperate grasslands
Boreal forest
Tundra
Deserts
Describe the characteristics of a tropical rainforest.
- Highest species richness
- Predictable climate
- infertile soils- all nutrients are locked up in biomass
- layered- 1-2% of light reaches forest floor = increased competition for light and nutrients
- Average of 80mm of rain per month
Describe the characteristics of a Savannah
= recent biome, owning existence to evolution of C4 grasses
- C4 grasses + scattered trees = supports large herds of migratory herbivores
- Tree cover declines with rainfall until eventually leading to grasslands
- Hot seasonal climate- long dry period + occasional large fires, consequently = zone of feast and famine between wet and dry seasons
- Humans 1st evolved here
Twilight- Forks
Describe the characteristics of a temperate forest
- Located towards the poles
- Wild climatic range
- cooler climates = seasonal stress of winter = frosts
- deciduous trees lose leaves to reduce dehydration as growth is limited by low light + temp
- Inhabiting organisms must tolerate winter by hibernation/migration
- Rapid life cycles- due to short summers
- Many generalists feeders