Lecture 5: Organisms: Convergent environmental adaptation & terrestrial biomes

Question 1

what is a biome

Answer 1

Geographic regions composed of organisms with similar adaptations.

Question 2

how are biomes and convergent evolution connected

Answer 2

-ecosystems in the same biome in different parts of the earth show convergent evolution in animal and plant life
-Adaptation to geographic regions with distinct abiotic conditions drives convergence in biotic composition and ecological interactions

Question 3

how do you define biomes by their charactersitics

Answer 3

they are characterized by the intersection of annual patterns of temperature and precipitation and the associated dominant plant cover

Question 4

why do ecologists care about biomes

Answer 4

-provide large-scale comparisons of ecological processes across the globe
-Replication of organismal adaptation at the global scale

Question 5

tropical rainforest biome - temperature and precipitation

Answer 5

-Temperature: stable, pretty high, never at 0 degrees Celsius (water doesn’t freeze)
-Precipitation: pretty high, some seasonal change (in earlier months of the year), never 0

Question 6

tropical rainforest biome - soil and dominant plants

Answer 6

-Soils are old, shallow, and nutrient poor, due to high decomposition rates, nutrient loss, and nutrient uptake
-Tall forest trees dominate as a plant growth form - high species diversity
-Lianas and epiphytes grow on other plants to reach the canopy.

Question 7

human impacts and the tropical rainforest

Answer 7

when human’s clear rainforests the land conversion exposes the landscape to extreme erosion from water

Question 8

Tropical seasonal forest/savanna biome - temperature and precipitation

Answer 8

-Precipitation: there are months where rainfall is zero (the tropical ‘winter’), when wet – massive amounts of rainfall
-Temperature: high and stable, not as high as tropical rainforest, never freezing

Question 9

tropical seasonal forest/savanna biome - soil and dominant plants

Answer 9

-Nutrient poor soils, similar to other tropical biomes.
-Dominant growth forms are grasses and low, broad trees.

Question 10

tropical seasonal forest/savanna biome - how grasses and trees are balanced

Answer 10

• they are balanced through natural fires and grazing
  -More frequent fires: more open
  -Less fires: more closed, like a dry forest

Question 11

tropical seasonal forest/savanna - what are rhizomes

Answer 11

fire and grazing adapted underground stems that allow rapid re-sprouting after damage

Question 12

human impacts on the tropical seasonal forest/savanna biome

Answer 12

around Brazilian capital - a lot of land conversion for agriculture and settlement

Question 13

Temperate seasonal forest biome - temperature and precipitation

Answer 13

-Precipitation: high in middle months
-Temperature: it is much lower than other forests, goes below zero (water freezes)

Question 14

temperate seasonal forest biome - dominant plants

Answer 14

-North: broad leaf trees
-South: more diverse, more pine trees, soil becomes more sandy and loose
-both lose their leaves
-Understory layer of shrubs and smaller trees.

Question 15

temperate seasonal forest biome - soil

Answer 15

Lower temperatures, and reduced growing season has led to deeper soils with abundant organic material — favors accumulation

Question 16

temperate seasonal forest biome - why are there rivers and streams here

Answer 16

-Precipitation exceeds evaporation and transpiration
-water moves down through soils and drains via groundwater

Question 17

human impacts on the temperate seasonal rainforest biome (UK)

Answer 17

-Europe has almost no old-growth forest left
-bc of hospitable environment there are massive land clearings for agriculture

Question 18

human impacts on the temperate seasonal rainforest biome (US)

Answer 18

-Dramatic loss of old-growth forest cover (1620 - 1990)
- now: old-growth forests are coming back, especially in the Northeast

Question 19

Temperate grassland/cold desert biome - temperature and precipitation

Answer 19

-moderate annual rainfall
-cold temperatures

Question 20

Temperate grassland/cold desert biome - soil and dominant plants

Answer 20

-Grass is the dominant growth form in regions with higher rainfall and cooler summers
- low decomposition rates and nutrient rich soils

Question 21

human impacts and the temperate grassland/cold desert biome

Answer 21

-Massive land conversion for food production, driven by the fertile soil, this effects the prairie environments

Question 22

Subtropical desert biome - temperature and precipitation

Answer 22

-Almost no water. Water mainly comes in underground from nearby biomes
-rainfall is concentrated in the summer
-high summer temps, mild winters

Question 23

subtropical desert biome - soil and dominant plants

Answer 23

-Often very shallow soils with almost no organic material accumulation.
-Creosote bush is the dominant growth form in drier regions of the biome
-Cacti and small trees become dominant in moister regions.

Question 24

Woodland/scrublands - temperature and precipitation

Answer 24

-Temperatures: never freezing, stable (not super hot/cold)
-Precipitation: during warm periods – low water
-Hot, dry, summers and mild, wet winters

Question 25

Woodlands/scrublands - soil and dominant plants

Answer 25

-Dominant vegetation is drought-tolerant grasses and shrubs.
-Deep roots and small durable leaves on the shrubs.

Question 26

Human impact and woodlands/scrublands biome

Answer 26

-Lots of droughts and wildfires
-High human density and natural dry and fire-prone biome characteristics increases the chances of a human initiated wildfire
-Natural wildfire adaptions in plants are suppressed bc of human fire-preventions which then causes more destructive fires