Lecture 14 diversity

Question 1

What is diversity (3)

Answer 1

Biological Diversity: variability among living organisms above, below, and at the species level
* Variation within species: genetic & population diversity
* Variation among species: local & regional diversity

Question 2

Genetic diversity (2)

Answer 2

Higher genetic diversity leads to better resistance against environmental changes.
E.g. Caribou
– Different populations are adapted to the different extremes of their environment
– Large response diversity for the species

Question 3

Population Diversity (3)

Answer 3

*Populations go extinct much faster than species
*Small range species go extinct faster
* Average of 220 populations per species

Question 4

Landscape Diversity

Answer 4

differences of the various land uses and ecosystems within a larger area

Question 5

Species diversity (2)

Answer 5

Species diversity: number, types, and distribution of organisms in a given area
Greater species diversity is linked to increased productivity and stability of an ecosystem

Question 6

Species diversity math (3)

Answer 6

Local Diversity (α): Community
Regional Diversity (γ): Ecosystem
β Diversity (γ/ α): Species turnover or Habitat Diversity

Question 7

Species diversity 2 key components

Answer 7

1. Richness
2. Evenness

Question 8

Richness and evenness (2)

Answer 8

Species richness, is a count of the total number of different species in an area.
Evenness is How similar abundances of each species are to each other

Question 9

Richness bias (3)

Answer 9

*There is always bias in our estimate of richness
*What is a species? There are so many definitions and none are always correct
*we often ignore small things or less prominent species

Question 10

alpha, beta, and gamma diversity

Answer 10

Alpha diversity: Number of species found at a local scale

Gamma diversity: Number of species found at a regional scale

Beta diversity: measure of the difference in species composition (or turnover) between 2 or more habitats/local sites within a region

Question 11

Why do larger areas have more species (4)

Answer 11

1. Bigger areas are more likely to have a variety of different abiotic conditions
   2.This diversity of abiotic conditions means there are a diversity of habitats
2. Those diverse habitats then support more/different species
3. Bigger areas also support higher population sizes Larger populations are less likely to go extinct than smaller populations

Question 12

Consequences for ecological interaction in the north (2)

Answer 12

1. Low prey diversity promotes unstable population dynamics (cycles)
2. Less species redundancy lower ecosystem resilience

Question 13

Latitudinal gradient hypotheses (Null) (2)

Answer 13

Null: Species on the earth are randomly distributed. Because of this, most species are in /around the middle of the earth.

aka the mid-domain effect

think about it like this: if you had a bunch of different sized pencils in a box, some would be more to the left, some the right but most of the pencils would still reach to the center

Question 14

Latitudinal gradient hypotheses (history)

Answer 14

The land on earth used to be much more central, and tropical. Since colder habitats are younger there is less time for speciation and adaptation compared to the highly diverse tropics

Question 15

Latitudinal gradient hypotheses (spatial heterogeneity) (2)

Answer 15

*higher diversity in tropics due to increase in number of potential habitats
*lower environmental complexity moving away from equator

Question 16

Latitudinal gradient hypotheses (competition)

Answer 16

Since the vast majority of death in the boreal region is due to abiotic factors, competition is not really at play. In the tropics there are no extreme weather conditions, so populations can increase density to the point where competition for resources is necessary = promotes species diversity through specialization

Question 17

Latitudinal gradient hypotheses (predation)

Answer 17

increased species diversity in tropics is function of increased number of predators that regulate the
prey species at low densities . This decreases competition among prey species and allows coexistence of prey species and potential for new additions.

Question 18

Gause’s law

Answer 18

two species competing for the same limiting resource cannot coexist. one will outcompete the other

Question 19

Latitudinal gradient hypotheses (productivity)

Answer 19

tropics support a greater number of species because more resources are available, allowing for more specialization
* larger input of solar energy = more primary production
– in general: increase production = increase diversity

Question 20

Latitudinal gradient hypotheses (Climate)

Answer 20

Tropic climates are much more constant, constant climate = finer specializations and adaptations, shallower niches

Question 21

Latitudinal gradient hypotheses (disturbance)

Answer 21

if community disturbance frequency is very high = local extinction of species = lower species diversity
if community disturbance frequency is very low = competitive exclusion by dominant species = higher species diversity

Question 22

diversity in the arctic (3)

Answer 22

The diversity of animal, plant and microbial species appears to be low in the Arctic
* decreases from the boreal forests to the polar deserts of the extreme North
* but primitive species are particularly abundant.