Community Interactions

Symbiosis, predator/prey, and coevolution

Objectives

• To be able to differentiate between the concepts of habitat and niche

• To be able to describe symbiosis and identify a symbiotic relationship.

• To be able to synthesize the concepts of habitat and niche with coevolution and evolutionary arms race.

Vocabulary

• Competition• Predation• Symbiosis• Mutualism• Commensalism • Parasitism • Evolutionary Arms Race• Coevolution

Concept Recapitulation - Habitat

• Habitat – all of the biotic and abiotic factors in the area where the organism lives.– You can think of habitat as the organism’s address

(a bison’s address is the prairie ecosystem).

Concept Recapitulation - Niche

• Ecological Niche – we simplified this concepts earlier as a species’ job (it is more complex). – To be more precise, a species’ niche is all of the

physical, chemical, and biological factors needed to survive, stay healthy, and reproduce.

– This is made up of:• food (what the species eats), • behavior (including food gathering and reproductive), • and abiotic conditions (conditions like temperature and

amount of water that a species can tolerate).

When your habitat changes and your ecological niche is threatened

• http://iowapublicradio.org/post/algae-bloom-kills-record-number-florida-manatees

• As you listen, jot down (as much as you can) what the manatees habitat and ecological niche are.

Community Interactions

• Symbiosis – a close ecological relationship between two or more organisms of different species that live in direct contact with one another.

• Mutualism – an interspecies interaction in which both species benefit from one another.– Ex. The leaf cutter ants and the fungus they

cultivate and harvest (we will see a video on this). They depend completely on one another.

Leaf Cutter Ants

• https://www.youtube.com/watch?v=dOV0E5FaKoQ. Ancient Amazonian Farmers.

Mutualism between lesser long-nosed bat and saguaro cactus

• The cactus blooms just one evening in spring to attract the lesser long-nosed bat.

http://www.fs.fed.us/wildflowers/pollinators/pollinator-of-the-month/lesser_long-nosed_bat.shtml

Quick Question

• What is the lesser long-nose bat’s habitat and niche?

Commensalism

An association between two organisms in which one benefits and the other derives neither benefit nor harm.

Human Commensalists

• At least two species of mites live commensalistically on the foreheads of humans.

• Demodex folliculorum lives in hair follicles, whereas Demodex brevis inhabits the sebaceous glands.

• The mites spend the day in the protected confines of their respective hiding places; however, at night, they typically move from one place to another - unnoticed by you, their host

Parasitism

• A non-mutual symbiotic relationship between species, where one species, the parasite, benefits at the expense of the other, the host

Lung parasite on lung of a cane toad.

Deer liver fluke

Can you identify this?

Human Parasites

Chagas disease – caused by a tropical protozoan carried by insects called kissing bugs, which are blood parasites (they suck their hosts’ blood). The picture below is of a child in the acute stage of Chagas disease.

Concepts Continued

• Coevolution – the process in which two or more species evolve in response to changes in each other.

• Evolutionary arms race – a type of coevolution in which each species responds to pressure (often a predator/prey relationship) from the other through better adaptations over many generations. – Greatly speeds up evolution – newts and garter snakes (

https://www.youtube.com/watch?v=9CuhqQzBACQ)

Fun Question

• What do sea otters and striped skunks have in common?