13. Coexistence

Who are our friends?

Species

http://neatorama.cachefly.net/images/2008-12/species-population-size.jpg

About 1,500,000 species identified

Insects – 750,000

Other Arthropods – 123,000

ArthropodsMeans Jointed appendages

First repetitive body segments (adaptation)

Dominant life on Earth based on species

Exoskeleton (molt to get larger)

Live in all habitats

Arthropod Classes

Trilobites:

extinct

Crustaceans

Chelicerates

Myriapods

Hexapods (insects)

65% (1.5 million species)

crabs, shrimp, lobsters

spiders, scorpions, ticks, mites

centipedes, millipedes

Hexapoda: Insect Species

Beetles: 300,000

1of 5 species on Earth!

Butterflies & Moths: 170,000

Flies: 120,000

Bees, Wasps, & Ants: 110,000

Grasshoppers: 20,000

Dragonflies: 5,000

Preying mantis: 2,000

Insect Body Plan

Body Segments

Head: senses

Thorax: movement

Abdomen: organs,

reproduction

Appendages

Antennae

Legs

Wings

Adaptation of these structures has led to the

diversity of insect forms

Insect importanceDecomposition of dead organic material

Products

silkhoney shellac

http://www.radiomuseum.org

/forumdata/upload/FlakeShell

ac_Finish.jpg

Food source for animals

birds

reptiles

arthropods (spiders)

mammals (humans)

Pollinators

Pests and disease

Co-evolution of plants and insects

Coevolution:

adaptation of two

species to each

other for their

mutual survival

Certain flowers and

insects have co-

evolved

Explains the

diversity of forms

plants and insects

Darwin’s Hawkmoth

Charles Darwin (in 1822)

Comet orchid with 12” nectar

tube

Predicted there must be an

insect with a 12” tongue

http://faculty.washingt

on.edu/jrw/110/darorc

h.JPG

Darwin’s Hawkmoth

Co-evolution

Orchid tube is too long:

moth starves

orchid dies off

Orchid tube is too short:

moth does not pollinate

orchid dies off

Balance for the mutual benefit

Honey BeesColony Collapse Disorder (CCD)

Death of hives in a matter of days

2006 and 2007: 30% of U.S. hives

2008: lost 35% of 2.5 million hives

Severe consequences to human agriculture

Cause of CCD?

GM crops

use of monocultures

insecticides and herbicides

diseases/pests

unknown

multiple causes

Importance of insects:

Honey Bees

Pollinators of agriculture (30%)

- fruit trees, vegetables, berries

Bees for hire!

Very successful

High organized society (Eusocial):

Queen, Drone (reproductives)

Workers (sterile daughters, specific tasks),

General pollinators (variety of flowers)

Intelligent (memory, complex maps,

communication)

Leaf cutter ants39 species

Eusocial society: different castes

Soldiers, workers

Cut, move leaves back to nest

Chew and feed the leaves to fungi

Eat the fungi (species specific)

Leaf cutter and foreign fungiCarry around bacteria (antibiotics!)

Ant, fungi, bacteria relationship

Normal human fauna

>1,000 species

Bacteria (100,000 billion)

Fungi

Protozoans

Multicellular organisms

follicle mites

parasites

Humans as an ecosystem

Humans as an ecosystem

How did you get them?

Infants born without

Sources: air, mothers milk, food, environment

Benefits:

Digestion (e.g., plant material)

Clean-up of your waste (e.g., dead skin cells)

Cost:

Cause disease if not kept in checkWhere did they come from?

Invaders that stayed

Humans evolved defenses to control them

Microbes evolved to be less virulent

Provide

habitat for diversity of animals (100,000 species)

“Rain forests” of the ocean

tourism

medical products

food

shoreline protection

Coral reefs

http://batchisthenewshit.files.wordpress.com/2007/

06/coral_reef.jpg

Corals provide algae with nitrogen & CO2

Algae provide food for coral (photosynthesis)

Mutualism!

Algae may be 50% of the coral biomass

Coral and algae

Problems:

Coral bleaching

Loss of algae

Coral dies

Why?

Climate change

in warmer water corals expel algae

coral also are more prone to disease

Types of InteractionsType of relationship varies between species

Mutualism (+,+): mutually beneficial

Leaf cutter ant – fungus

Corals - algae

Parasitism (-, +): one hurt, one helped

broadly can define predator-prey

Cheetah (+), Gazelle (-)

Gazelle (+), Grass (-)

Commensalism (+, 0): one helped, one unaffected

Barnacles (+), Whale (0)

Relationships can vary with circumstances!

Summary:

Arthropods are the most successful phylum on Earth

Insects are the most dominant class of arthropods

Their diversity is explained by co-evolution with plants and their “tool kit” of appendages

Diversity of forms also stems from cooperation

among species

Humans are part of this system too!

Ends Organism section

next: Unique

Next time: Variation

Read: Ch. 10.1-10.4, 11.1-11.5