Chapter 4 evolution biological communities and species interactions
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Chapter 4 Evolution, Biological Communities, and Species Interactions. “Of course, long before you mature, most of you will be eaten.”. “The picture’s pretty bleak, gentlemen. The earth’s climate is changing, the mammals are taking over, and we all have brains the size of a walnut.”.

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Chapter 4 evolution biological communities and species interactions

Chapter 4 Evolution, BiologicalCommunities, and Species Interactions



“The picture’s pretty bleak, gentlemen. The earth’s climate is changing, the mammals are taking over, and we all have brains the size of a walnut.”




Evolution produces species diversity
Evolution Produces Species Diversity Thag Simmons.”

  • Natural Selection Leads to Evolution

  • All Species Live Within Limits

  • The Ecological Niche is a Species’ Role and Environment

    • Large Grassland Herbivore

      • North America: Pronghorn

      • Africa: Antelope

      • Australia: Large Kangaroos

  • Speciation Maintains Species Diversity


Exaptation
Exaptation Thag Simmons.”


There are no half evolved organisms
There Are No Half-Evolved Organisms Thag Simmons.”

  • Every organism is adapted to its environment all the time

  • Change happens when the environment changes

    • Mass Extinctions

    • Exotic Species Invasions

    • Climate Change


What good is half an eye
What Good is Half an Eye? Thag Simmons.”


What does a bug see
What Does a Bug See? Thag Simmons.”


What does a bug see1
What Does a Bug See? Thag Simmons.”


What good is half a wing
What Good is Half a Wing? Thag Simmons.”

  • It’s about Terminal Velocity

    • Humans: 50m/sec (Really terminal)

    • Mice: 5 m/sec (Generally not terminal)

  • True Powered Flight

    • Birds

    • Bats

    • Insects

    • Flying Reptiles (Maybe)


What good is half a wing1
What Good is Half a Wing? Thag Simmons.”

  • Critters that Glide

    • Squirrels

    • Marsupials

    • Lemurs

    • Fish

    • Squid

    • Lizards

    • Snakes

    • Frogs


What good is half a wing2
What Good is Half a Wing? Thag Simmons.”

  • Critters that Glide are all Small

    • Low Terminal Velocity

    • Falls usually not fatal

    • Selection favors duration and control

  • Pre-Flight Uses for Wings

    • Catching prey

    • Mating displays

    • Fighting

    • Ground maneuverability


The bumblebee myth
The Bumblebee Myth Thag Simmons.”

  • Bumblebees, theoretically, can’t fly

    • They can’t glide. Neither can an F-16

  • Bumblebees can carry more than their own weight, something no aircraft can do

    • C-130 transport: empty weight of 76,780 pounds and a maximum takeoff weight of 175,000 pounds

    • A C-5 Galaxy: empty weight of 238,000 pounds and a maximum takeoff weight in wartime of 840,000 pounds


Species interactions shape biological communities
Species Interactions Shape Biological Communities Thag Simmons.”

  • Competition Leads to Resource Allocation

  • Predation Affects Species Relationships

  • Some adaptations help avoid predation

  • Symbiosis involves intimate relations among species

  • Keystone species have disproportionate influence


Community properties affect species and populations
Community Properties Affect Species And Populations Thag Simmons.”

  • Productivity is a measure of biological activity

  • Abundance and diversity measure the number and variety of organisms

  • Cormnunity structure describes spatial distribution of organisms

  • Complexity and connectedness are important ecological indicators

  • Resilience and stability make communities resistant to disturbance

  • Edges and boundaries are the interfaces between adjacent communities


Communities are dynamic and change over time
Communities Are Dynamic And Change Over Time Thag Simmons.”

  • The nature of communities is debated

  • Ecological succession describes a history of community development

  • Appropriate disturbances can benefit communities

  • Introduced species can cause profound community change


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