Lecture 21: Microbial Ecology and Symbiosis

Question 1

What is microbial ecology?

Answer 1

study of interactions of microbes with other organisms in its environment

Question 2

What are populations?

Answer 2

Groups of microbes from same species

Question 3

What are communities?

Answer 3

group of microbes from different species

Question 4

How are microbes in nature different than microbes in lab?

Answer 4

• Mixed communities
• Conditions are not ideal
• Environment change over time

Question 5

What are the two components of microbial diversity?

Answer 5

Richness - total number of species

Evenness - number of individuals per species

Question 6

What is phylogenetic diversity?

Answer 6

evolutionary relatedness among species

Question 7

What is rarefaction analysis?

Answer 7

A measure of species richness

Question 8

WHat is the hyperdiversity paradox?

Answer 8

Unlimited diversity

-english channel sample contained 2/3 world’s microbes

Question 9

What is the paradox of plankton and how was it resolved?

Answer 9

How limited number of resources can suppport seemingly limitless diversity of microbial species

Resolved by temporal variation, complex microenvironments, and metabolic specialization

Question 10

WHat are microhabitats?

Answer 10

small environments on microbial scale

Question 11

What are guilds and niches?

Answer 11

Guild - group of microbes that are metabolically similar and use same resources

Niches - habitats shared by microbial guild

Question 12

What are the types of niches?

Answer 12

Prime - ideal habitat

Fundamental - full habitat range

Question 13

How are microbial biofilms related to microhabitats?

Answer 13

used to group microbes that grow on surfaces or in water

Question 14

What is the benefits of biofilms?

Answer 14

Defense, fixed location and close quarters

Question 15

How are biofilms important to society?

Answer 15

Medicine (grow on implants) and industry (ship fouling)

Question 16

What are the types of Symbioses and who benefits?

Answer 16

Mutualism = +/+
Commensalism = +/o
Parasitism = +/-

Question 17

What type of microbe rarely has symbionts?

Answer 17

archaea

Question 18

What are the ecological impacts of symbiosis?

Answer 18

Supplemental nutrition and Increase host fitness

Question 19

What are the different categories of symbioses?

Answer 19

Microbe-Microbe
Plant-Microbe
Animal-Microbe

Question 20

What is an example of microbe-microbe symbiosis?

Answer 20

Lichens (fungus+cyanobacteria)

• mutualistic
• Fungus acts as anchor
• Cyanobacteria acts as food source

Consortia

• mutualistic
• reverse CAC
• motility from symbiosis = stratified water columns

Question 21

What are some plant-microbe symbiosis?

Answer 21

Legumes
-mutualistic w/ Nitrogen fixing bacteria

Mycorrhizae

• mutualistic
• fungus gets more water for plant roots

Question 22

What are some animal-microbe symbioses?

Answer 22

mammal gut microbiota

• cellulose digestion
• foregut + hindgut
• out of whack microbiota = obesity

-examples: termites, fungus ants

Question 23

What are hydrothermal vents?

Answer 23

Discovered in 1977

• Tubeworms discovered w/ no anus or mouth
• Contain sulfur oxidizing symbionts=fix carbon

Question 24

How biodiverse are coral reefs?

Answer 24

25% of marine species live there but make up <1% of the area

Question 25

What causes the formation and maintenance of coral reefs?

Answer 25

Calcium Carbonate = foundation

Algal symbionts maintain it

Question 26

What are Cnidarians and what are their significance?

Answer 26

Reef corals + jellyfish

They contain photosynthetic symbionts (dinoflagellates)

SYmbiont loss = coral bleaching