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Ecology - Dynamics > Population - Community Composition Patterns > Flashcards

Population - Community Composition Patterns Flashcards

1
Q

What are populations influenced by?

A

Space and time by biotic and abiotic factors

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2
Q

What does community assembly derive rom?

A

Dispersal Contraints
Envrionmental Constraints
Internal dynamics(Competition, predation, facilitation)

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3
Q

Two classes of internal dynamics…

A

Selection is the determinsitc interactions between competitors or predators and prey
Drift is the random changes in species relative to abundances

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4
Q

What are the four classes of community assembly described by Vellend?

A

Ecological Drift
Selection
Speciation
Dispersal

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5
Q

Communities on the macro scale…

A

Biomes with broad patterns by climate, like temperatre forests

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6
Q

Communities on the micro scale?

A

Communities of species, like beech and maple, or gut biome of species.

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7
Q

Hypervolume

A

Space in more than three dimensions.

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8
Q

What is a hypervolume in ecology?

A

Multi-dimensional resource space avaiable to and used by organisms

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9
Q

Most basic way of characterising communties?

A

Counting species present, allowing comparison by richness.

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10
Q

Sampling in comparing seperate communities…

A

If multiple sample taken, variable should be the same

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11
Q

Rarefaction

A

The reduction in the density of something.

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12
Q

How can richness be worked out?

A

Comparing number of species to number of individuals in a sample

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13
Q

Simpsons Diversity Index

A

A measure of diversity taking into account number of species present, as well as relativev abundance of each species.

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14
Q

Why is it important to take into acount rarity and commonness of species?

A

A population dominant in one species may have same richness as another if both have 10 total species.

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15
Q

What does simpsons index account for?

A

Abundance and species richness.

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16
Q

What does simpsons index measure?

A

Proportion of individuals contributing to the total in the sample

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17
Q

Hill Numbers

A

Describe the effective number of species or species equivalents

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18
Q

What three functions can be used to measure species richness

A

Alpha Diversity
Beta Diversity
Gamma Diversity

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19
Q

Alpha Diversity

A

Describes species richness occuring within a given area within a region, smaller than the entire distribution of the species

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20
Q

Beta Diversity

A

Rate at which species richnesss increases as one moves in a straight line across a region from one habitat to another habitat

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21
Q

Gamma Diversity

A

Describes the species richness within an entire region.

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22
Q

Mathematically describe a,b,g diversity…

A

G is sum of B and A, if each patch has identical species list then B=0 and A=G, and B contributes to G when heterogeneity arises.

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23
Q

Rank Abundance Diagrams

A

These display relative species abundance of a variety of P1, from an abundance rank 1 to however many species there are.

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24
Q

Down side of RAD?

A

Do not account for HOW species interact with one another

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25
Q

Niche Orientated Models

A

Help in understanding of mechanisms of community organisation.

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26
Q

Types of Niche-Orientated Models

A

Dominance Pre-emption model
Random Fraction Model
Dominance Decay Model

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27
Q

Dominance Premption Model

A

Describes situations where after intial colonisation, each new species preempts more than 50% of the smallest remaining niche.

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28
Q

Random Fraction Model

A

A situation where abundances of different species are not mutually related at all

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29
Q

Dominance Decay Model

A

Where invading species occupy the niche spaces of the current most abundant species.

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30
Q

What do niche-orientated models provide?

A

Abstract on commmunity structure of a given indicie(diversity, richness, equitability)

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31
Q

Community Size Spectra

A

This represents a specific function(BMR, reproduction, specialisaiton, tolerance, diet) relative to abundance.

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32
Q

Why is community size spectra good?

A

Relative size of individuals indicates many functional traits and ecological processes.(competitiveness, vulnerability and reproduction)

33
Q

Monotonic

A

Variable in such aa way that it never increases nor decreases

34
Q

Gradient Analysis

A

Technique analysing dynamic, structure of functional change in ecosystems

35
Q

Whittaker Gradient Analysis…

A

Great smokey mountains of changes of vegetation with varying altitude gradients.

36
Q

A criticisms of gradient analysis…

A

Bias in detecting patterns and subjectiveness of gradient chosen, most approparatie to a particular species not necesserality appropriate ubiquitously.

37
Q

Ordination

A

This is a mathematical treatment allowing community organising in a graph so those most similar in species composition and relative abundance appear closer together

38
Q

How can bias in Gradient Analysis be avoided?

A

Using CCA

39
Q

Canonical Correspondence Analysis

A

Ordination technique determining axis from the response data as a linear comibnaiton of measured predictors

40
Q

Use of CCA in ecology?

A

Extracts gradients deriving composition of ecological communities.

41
Q

Example of CCA?

A

Rotifer assessed by eutrophication(CP levels, P conc and phytoplankton cell transparency)

42
Q

CCA allows for…

A

Measure of species compositon against a variety of envrionmental factors.

43
Q

Correlation does not imply causation in CCA…

A

Dissolved oxygen and community composition may vary together by a common response to other envrionmental factors.

44
Q

Temporal community structure change analysis…

A

Fire prone trees where composition relfective of time since a fire was prominent.

45
Q

Clements view on population…

A

Superorganism like tissues

46
Q

Modern view of populations…

A

A gradient analysis and ordination indicating physical characteristics of a given location will unlikely occur with another group of species under different conditons elsehwere…

47
Q

How may species vary temporally?

A

Incapable of reaching a location.

48
Q

How may species vary temporally?

A

Incapable of reaching a location.
Inapproprate resource and conditions
Preclusion of competitors, predators and parasites

49
Q

Example of common temporal change?

A

Life cycles with seasonal changes, with changes in ecosystem structure.

50
Q

What are vellends four class of community assembly?

A

Dispersal
Niche Assembly
Neutral Assembly
Historical Assembly

51
Q

Neutral Assembly

A

This describes stochastic processes like birth, death and dispersal, without paritcular environmental factors influencing species co-existence.

52
Q

Hypervolumes

A

These are multi-dimensional shapes with each axis being some environmental variable: temperature, precipiration or soil nutrients.

53
Q

What does space occupied by a species represent in a hypervolume?

A

Conditions they can persists for ecological niche determination and what limits distribition/abundance.

54
Q

How might Hypervolumes be simplified?

A

Principal Component Analysis and Non-metric Multidimensional Scaling.

55
Q

What is a reduced hypervolume analysed by?

A

Convex hulls

56
Q

Convex Hulls

A

This is the minium convex set enclosing them all, yielding a polygon connecting the outermost points in the sample and all whose inner angle are less than 180 degrees.

57
Q

What is an example of using Convex Hulls in ecology?

A

Quantifying functional traits of plants and how they relate to envrionmental conditions, like leaf area and specific leaf area across different environmental gradients.

58
Q

What can Artifical Neural Networks be used for?

A

Prediction of new data it hasnt seen before by training, like on environmental variable relation to species occurence

59
Q

Artifical Neural Networks

A

This simulates biological nervous systems where information is sent via input signals to a processor resulting in output signals.

60
Q

What is an example of functional application of ANN?

A

Analysis of 66 bird species in Switzerland with envrionmental variables like previous bird occurence data, trained ANN to predict probabilty of occurence in new area.

61
Q

Simpsons Diversity Index

A

This index is a biodiversity measured based on richness and eveness of a community.

62
Q

How is the SDI calculated?

A

Proportions of each species are squared then summed, then subtracting that sum from 1.

63
Q

What does a high SDI indicate?

A

Greater dominane of one or a few species.

64
Q

Why is SDI useful?

A

Takes into account number of species present in a community and relative abundance of each species.

65
Q

What is a downside of SDI?

A

It is influenced heavily by rare species.

66
Q

How can the simpsons diversity index be applied to conservation?

A

Before and after restoration efforts to assess effects of restoration.

67
Q

Rarefaction

A

This is a species richness estimation based on number of individuals or samples collected from the community.

68
Q

What is the process of rarefaction?

A

Random sub-sampling of a given number of samples is taken, where unique species in that subsample are taken.
This is repeated, each subsample being a different set of samples, until maximum unique species observed is reached

69
Q

Hill Numbers

A

These quantify number of species and their relative abundances.

70
Q

What are hill numbers based on?

A

More even species distribution in the community is the more diverse the community.

71
Q

First-order Hill Number

A

This measures species richness by counting number of species in the ocmmunity.

72
Q

Second-order Hill number

A

This is the same as the Shannon index.

73
Q

Shannon Index

A

This is a measure of the information content(like relative abundance) of a communtiy rather than of the paritcular species that is present.

74
Q

What is a disadvantage of first-order hill numbers?

A

Do not take into account abundance, thus two communities with same species number might have different overall diversity.

75
Q

How do A, B and G mathematically relate?

A

G = A x B, meaning low beta means gamma and alpha are more equal, or where high beta means gamma greater than alpha.

76
Q

How is Beta Diversity measured?

A

Jaccards Index
Bray-Curtis Dissimilarity.

77
Q

Jaccards Index

A

This gauges similarity and diversity of sample sets (J = a/ (a+b+c)

78
Q

What do rank abundance diagrams do?

A

Quantify relative abundaces of different species within a community.

79
Q

How are RAD graphs read?

A

If curve is steep, community dominated by few highly abundant species.

Ecology - Dynamics (9 decks)

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