Earth Diversity

Question 1

What is a community?

Answer 1

an assemblage of many interacting populations of different species occurring together in space and time

Question 2

how are communities established?

Answer 2

The presence of species in the community depends on abiotic factors.

Question 3

What is community ecology?

Answer 3

study of members of a multispecies assemblage interacting with each other and their surroundings; the ecology of
biodiversity.

Why are some species associated with some communities and not others? - turn over

Question 4

Interaction networks

Answer 4

Tell us how strongly species interact with each other.
Gives you some idea of the richness of the population in the community.

Question 5

How many species are there on Earth?

Answer 5

1.5Mil species catelogued.
but around a 10% error due to taxonomic uncertainty.
Diversity in unevenly distributed between phyla.

Question 6

HOw do determine the estimate total species diversity?

Question 7

What is species diversity?

Question 8

WHat is species richness?

Answer 8

the number of species in a community.
The relative abundance of species in the community.

Question 9

Who came up with the relative abundance?

Answer 9

Robert whitaker.
Lognormal distribution
Low evenness

Question 10

Why do we care about the relative abundance?

Answer 10

1. Population density
2. Habitat specificty
3. Range size.

Question 11

Species richness (S)

Answer 11

After you have sampled, you can draw curves.
Rarefaction curve (grey one) - shows the individual based
Species accumulation curve (black one)

old growth vs secondary growth example. Slide 10 lecture 2.

when we try to compare species richness confidence to the … that’s why we use a rarefaction curve.

Question 12

Chao1 asymptotic species richness estimator.

Answer 12

Sest=Sobs+a2/2b
a=number of species that only occur once in the sample,
b=species that occur twice

need to be thinking about the fact that species are always unevenly distributed and how that affects our ability to estimate them.

Question 13

Species diversity/ evenness component.

Answer 13

Metric combining species richness and relative abundance.

2 communities with the same amount of species - one with low evenness and one with high evenness.
High evenness have more communities of higher diversity.

Question 14

Species diversity indicies

Answer 14

Diversity metrics are not linearly scales
NB - give priority to the dominant species in the community.

Question 15

What is true diversity?

Answer 15

Effective number of species.
NUmber of equally abundant species that would give the observed diversity metric .
True diversity = 2^H

Question 16

Spatial organization of biodiversity.

Answer 16

species-area relationship

(i) sampling of more individuals,
(ii) spatial habitat heterogeneity,
(iii) immigration-extinction dynamics
(iv) Evolutionary effects

Question 17

Dimensions of diversity

Answer 17

a diversity - local diversity
β diversity - turnover between communities (like different landscapes/habitats)
y diversity - regional diversity

β diversity = γ diversity / α diversity
The effective number of unique communities in the region

Question 18

Spatial organization of biodiversity

Answer 18

β diversity = species compositional turnover
between communities

community similarity coefficients:
Based on the similarity of species composition between the two communities:
Jaccard coefficient
Sorenson coefficient
= These coefficients do not take relative abundance into account.
Horn index
Morisita-Horn indices
= These account for relative abundance

Question 19

Global diversity of distribution?

Answer 19

Correlations around the poles.
Species near the poles

Question 20

What are deterministic explanations of the land-sea diversity rule?

Answer 20

• Land is more productive - can sustain more species, but that is not always the case. The ocean can be more productive.
• More difficult movement in the water - water is not an easy medium to move through, higher species abundances in the ocean.
• Greater habitat heterogeneity on land - not necessarily that marine systems are less heterogeneous.

Question 21

What are the evolutionary explanations of the land-sea diversity rule?

Answer 21

• More geographic isolation on land
• Reduced dispersal on land
• speciation/extinction
• Time - the more time the system has been stable, the more likely new species will arise in the system
• Rates of transition between habitats
• Diversification within habitats - increased geographic isolation between terrestrial environments and reduced dispersal ability, but the ocean is also separated by landmasses. Species disperse over longer distances in the ocean.

Question 22

What is a global diversity hotspot

Answer 22

High richness and relatively high evenness..

Question 23

What is the latitudinal gradient of diversity?

Lecture 3 sllide 10

Answer 23

Latitudinal gradients of species diversity in deep-sea isopods, gastropods,
and bivalves from the North Atlantic and Norwegian Sea
Holds for virtually all taxonomic groups
(except aquatic macrophytes, parasites)
Has existed for 250 my at least

graphs

2 kinds of explanations:
1. Local determinism = how many species you can pack into a community
2. Evolutionary explanations

Question 24

What is the mid-domain effect?

Answer 24

no underlying biology, more likely to have more than 1 species overlap in the middle if there is a start and end point. But its unrealistic.

Question 25

What is the area theory ?

Answer 25

The relationship between climate area and species richness

Question 26

What is the species-energy theory?

Answer 26

develop predictions of species’ abundances and probabilities of occurrence on an island.

Question 27

What is the Physiological tolerance
hypothesis?

Answer 27

higher regions provide climates that are extreme, so only a few species have adaptions and restrict the number of species that can exist there. more tropic climates, organisms don’t have many adaptions.

Question 28

What is the spatial heterogeneity theory?

Answer 28

the uneven distribution of various concentrations of each species within an area.

Question 29

What is the competition theory?

Answer 29

declining inequality among regions (or groups) promotes competitive conflict among race and ethnic groups

Question 30

What is the enemies theory?

Question 31

What is the time/stability theory?

Answer 31

Tropics have more stable environments than in the polar areas = more stable species in the tropic areas.

Question 32

What is the tropical conservatism hypothesis?

Answer 32

Most species have come out of the tropics and colonized more temperate areas. evolving adaptations necessary to survive more temperate environments. temperate adaptions are derived.

Question 33

What is the evolutionary speed theory?

Answer 33

speed up the evolutionary process over latitudes due to change in temperatures.

Question 34

lecutre 3 slide 22 nb