Recap: Ecological SuccessionRecap: Ecological Succession

Succession concepts, Succession concepts, type of successiontype of successionMechanisms of successionMechanisms of successionClimax communityClimax community

16.3 Succession becomes self-limiting as it approaches the climax

Succession continues until the addition of new species to the sere and the exclusion of established species no longer change the environment of the developing community.

The progression from small to large growth form modifies the conditions of light, temperature, moisture and soil nutrients.

Conditions change slowly after the vegetations achieves the largest growth form that the environment can support.

Final dimensions of a climax community are limited by climate independently of events during succession.

Succession becomes self-limiting as it approaches the climax

Time required for succession from a new or disturbed habitat to a climax community depends on nature of climax and initial quality of habitat

Mature oak-hickory climax forest from old field in North Carolina: 150 yrs

Climax stage of grasslands in western North America: 20-40 years

Humid tropics, reach climax within 100 years from clear cut, but may take a few more centuries to achieves a fully mature structure and species composition.

Sand dune beech-maple climax, up to 1,000 years

Climax is an elusive concept:Communities also change in response to climate change, hunting, fire, and logging, disappearance of keystone consumers (wolf, passenger pigeon) and trees (chestnuts, eastern hemlock)

Climax communities under extreme environmental conditions

Fire is an important feature of many climax communities, favoring fire-resistant species and excluding species that would otherwise dominate.

Longleaf pine after a fire

Seedling may be badly burned, but the growing shoot is protected by the long, dense needles.

Grazing pressure also modify a climax community

Grassland can be turned into shrubland by intense grazing

Herbivivores may kill or severely damage perennial grasses and allow shrubs and cacti that are unsuitable for forage to invade.

Selective grazing

Some species prefer to feed on areas previously grazed by others. Both zebras and Thompson’s gazelles feed on Serengeti ecosystem of east Africa, but eating different plants.

In North America, cattle grazing may lead to invasion by alien cheatgrass, which promote fire.

Transient and cyclic climaxes

Succession is a series of changes leading to a stable climax, whose character is determined by local environment. Once established, a beech-maple forest perpetuates itself, and its general appearance changes little despite constant replacement of individuals within the community. Transient climaxes: such

as communities in seasonal ponds – small bodies of water that either dry up in summer, or freeze solid in winter.

The extreme seasonal changes regularly destroy the communities that become established in the ponds each year.

On African savannas, carcasses of large mammals are devoured by a succession of vultures including: large, aggressive species smaller species that glen smaller bits of meat from bone species that cracks open bone to feed on marrow.

Cyclic climax:

Suppose, for example, species A can only germinate under species B, B only under C, and C only under A. The relationships create a regular cycle of species dominance in the order of A, C, B, A, C, B, A, …, in which the length of each stage is determined by the life span of the dominant species.

Cyclic succession is usually driven by stressful environmental conditions.

When high winds damage heaths and other types of vegetation in northern Scotland, shredded foliage and broken twigs create openings for further damage, and soon a wide swath is opened in the vegetation.

Regeneration occurs on the protected side of damaged area while wind damage further encroaches on exposed vegetation.

Temporal: wind damage and regenerate, cycling

Spatial: mosaic patches

BIOL 4120: Principles of EcologyBIOL 4120: Principles of Ecology

Lecture 17: Biodiversity Lecture 17: Biodiversity

Dafeng HuiDafeng Hui

Office: Harned Hall 320Office: Harned Hall 320

Phone: 963-5777Phone: 963-5777

Email: dhui@tnstate.eduEmail: dhui@tnstate.edu

Species richness varies over the surface of the earth

Why so may species in tropics and few toward the poles?

1 hectare of forest

Boreal: <5 Temperate : 10-30Tropical: 100-300

Outline (Chapter 20)Outline (Chapter 20)

17.1 Variation in the relative abundance of species influences 17.1 Variation in the relative abundance of species influences concepts of biodiversityconcepts of biodiversity

17.2 The number of species increase with the area sampled17.2 The number of species increase with the area sampled17.3 Large-scale patterns of diversity reflect latitude, 17.3 Large-scale patterns of diversity reflect latitude,

environmental heterogeneity, and productivityenvironmental heterogeneity, and productivity17.4 Diversity has both regional and local components17.4 Diversity has both regional and local components17.5 Diversity can be understood in terms of niche relationships17.5 Diversity can be understood in terms of niche relationships17.6 Equilibrium theories of diversity balance factors that add and 17.6 Equilibrium theories of diversity balance factors that add and

remove speciesremove species17.7 Explanations for high tree species richness in the tropics 17.7 Explanations for high tree species richness in the tropics

focus on forest dynamicsfocus on forest dynamics

17.1 Variation in the relative abundance of 17.1 Variation in the relative abundance of species influences concepts of biodiversityspecies influences concepts of biodiversity

Biodiversity: variation among organisms and ecological systems Biodiversity: variation among organisms and ecological systems at all levels, including genetic variation within populations, at all levels, including genetic variation within populations, morphological and functional differences between species, and morphological and functional differences between species, and variation in biome structure and ecosystem process in both variation in biome structure and ecosystem process in both terrestrial and aquatic systems.terrestrial and aquatic systems.

Indices of biodiversityIndices of biodiversity1.1. Species richness: number of species that occur within the Species richness: number of species that occur within the

community (simple and most general one).community (simple and most general one).2.2. Relative abundance: counting all individuals of each species in Relative abundance: counting all individuals of each species in

a number of sample plots within a community and determining a number of sample plots within a community and determining what percentage each contributes to the total number of what percentage each contributes to the total number of individual of all species.individual of all species.

Can also be quantified by density, or biomass of individuals Can also be quantified by density, or biomass of individuals within a sample area, by the frequency of sample plots in within a sample area, by the frequency of sample plots in which a specific species is recorded, or by the cover which a specific species is recorded, or by the cover (proportion of the area of habitat covered by a species)(proportion of the area of habitat covered by a species)

24 species, 256 trees

Compared to 1st forest stand, this stand has less species. Also, two species make up 83.5% of the total tree density.

10 species

Species diversitySpecies diversity

Graphical display of attributes of community structureGraphical display of attributes of community structure1.1. Rank-abundance diagram: graphical way to show relative Rank-abundance diagram: graphical way to show relative

abundanceabundance2.2. Species evenness: equitable distribution of individuals among Species evenness: equitable distribution of individuals among

speciesspeciesGradual slope in the rank-abundance diagram Gradual slope in the rank-abundance diagram

Length shows species richness, slope shows species eveness.

Rank-abundance plot

Birds in a deciduous forest in W. Virginia; vascular plants in a subalpine fir forest in Great Smoky Mountains, TN; and vascular plants in a deciduous cove forest in Great Smoky Mountains.

Abundance is represented by number of species for birds and by NPP for plants (Whittaker 1975).

Diversity indexes: an index considering only species Diversity indexes: an index considering only species richnessrichness

Margalef’s indexMargalef’s indexD=(S-1)/ln(N)D=(S-1)/ln(N)S is species richness, N is sample sizeS is species richness, N is sample size

Menhinick’s indexMenhinick’s indexD=S/Sqrt(N)D=S/Sqrt(N)

Both indexes normalize species richness in relation Both indexes normalize species richness in relation to the size of the sample.to the size of the sample.

Species diversitySpecies diversity

Simpson’s Species diversitySimpson’s Species diversity

Diversity indexes: an index considering both the number and Diversity indexes: an index considering both the number and relative abundance of species within the community.relative abundance of species within the community.

Simpson’s index (D): three definitionsSimpson’s index (D): three definitionsDefinition: Definition:

Where ni is the number of individuals in species i; n is the total Where ni is the number of individuals in species i; n is the total number of individuals of all speciesnumber of individuals of all species

D measures the probability that two individuals randomly D measures the probability that two individuals randomly selected from a sample will belong to the same speciesselected from a sample will belong to the same species

Range of D: 0 to 1 (1 is no diversity)Range of D: 0 to 1 (1 is no diversity)

Species diversitySpecies diversity

Simpson’s index of diversity=1-DSimpson’s index of diversity=1-D

Simpson’s reciprocal index =1/DSimpson’s reciprocal index =1/Dalso called Simpson’s diversity indexalso called Simpson’s diversity index

Calculate Simpson’s Index using Tables 16.1 and 16.2Calculate Simpson’s Index using Tables 16.1 and 16.2

Stand 1: D=0.13 , index of diversity 0.87, diversity index 7.7 Stand 1: D=0.13 , index of diversity 0.87, diversity index 7.7

Stand 2: D=0.36 0.64 2.8Stand 2: D=0.36 0.64 2.8

Shannon's diversity indexShannon's diversity indexintroduced by Claude Shannon:

pi is the fraction of individuals belonging to the i-th species, relative abundance.The most widely used

17.2 The number of species increases with the area sampled

Species-area relationshipOlaf Arrhenius, 1921

S=cA^z

Power function

log (S) = log(c) + z log (A)

Z=0.20-0.35

The number of species increase with the area sampled

More species are found within large areas than within small areas.

The slope of S-A relationship is influenced by different processes on different scales

Three grasslands in North Carolina, USA, the Netherlands, and Sweden

Small sample: 10 cm2

Specie richness increase with sample size over small areas.

S-As are nearly superimposable.

Species richness-area relationships on islands

The fourth process: extinction

Slope of S-A is higher when islands of different sizes are compared than it is across continental areas over a comparable size range.

1. The range of endemic island species (a species found only on that island and nowhere else) can be no larger than the island, but the range of continental species generally exceeds the particular sampling area.

2. Dispersal in island is limited and easily to go extinction, thus smaller and larger areas within continents have more similar complements of species than do smaller and larger islands, and the slope of S-A is consequently lower.

3. Habitat diversity also influence S-A relationship:Large island has more diverse habitats

Recap: Recap: BiodiversityBiodiversity

BiodiversityBiodiversity ConceptConcept Components of biodiversityComponents of biodiversity

Species richness and relative Species richness and relative abundanceabundance

Different species diversity indicesDifferent species diversity indices Margalef’s indexMargalef’s index

Menhinick’s indexMenhinick’s index Simpson’s indicesSimpson’s indices

Species and area (S-A) relationshipSpecies and area (S-A) relationship

17.3 Large-scale patterns of diversity reflect latitude, environmental heterogeneity, and

productivitySpecies richness increases from north to south in the Northern Hemisphere

Mammal species richness increases toward the equator and in regions of high habitat diversity

Numbers are species richness in sample blocks 150 miles on a side

Simpson 1964.

Land birds show similar pattern, but trees and reptiles, and amphibians present strikingly different patterns.

Land birds show similar pattern, but trees and reptiles, and amphibians present strikingly different patterns.

Ecological heterogeneity and habitat productivity

Diversity is higher in structurally complex habitats. Among several habitats in temperate regions, the average of bird species tends to increase with habitat productivity (Whittaker 1975)

Vegetation structure may be more important than productivity in determining diversitySonoran Desert, CA

and salt marsh, MIVery productive, but structure simple salt marsh has fewer plant species than the desert.

Bird species diversity is correlated with foliage height diversity

Robert and John MacArthus, 1981

13 communities in northeastern US

Deciduous forest, old fields, and regenerating forest habitats in eastern North America

Solar energy input and precipitation

Two factors predict species richness well:Energy input from the sun and water input from precipitation

Brad Hawkins, UC Irvine, 2003

Published data

Bars indicate number of studies show significant influences

Precipitation is more important in tropics and south-temperate regions

Species richness is correlated with energy input into the environment

PET: potential evapotranspiration, amount of water that could be evaporated from the soil and transpired by plants, given the average T and humidity.

The relationship leads to energy-diversity hypothesisLarge amount of energy in an ecosystem can be shared by a large number of species. Great input also support higher productivity, support large population size, reduce extinction.High energy increase rate of speciation.

17.5 Diversity has both regional and local components

Local diversity (alpha)Number of species in a small area of homogeneous habitat

Regional diversity ( gamma)Total number of species observed in all habitats within a geographic area that includes no significant barriers to the dispersal of organisms.

Gamma diversity=alpha (each habit has all) or sum of alpha diversity (no overlap of species)

Beta diversity: difference (or turn over) in species from one habitat to another.

Beta diversitySorensen’s similarity (or coefficient of community)

Based on the species presence or absence

An Example: s1=24, s2=10, c=9; CC=2*9/(24+10)= 0.529

CC ranges from 0 to 1, (Jaccard Similarity J= C/(C+U1+U2)

Change of beta diversity

Rate of similarity decreases with the distance between two samples

Beta diversity is high in Asia with respect to both latitude and longitude.

Regional diversity in also higher in Asia.

State level flora species

Beta diversity of plants decrease from south to north in North America

Whittaker’s beta diversity index: beta=S_total/mean(alpha)S_total: regional species richness; alpha is alpha diversity: r=alpha_bar*beta.

Beta diversity decreases from south to north in North America

Local communities and regional species pool

Species pool: species occur within a region.

Whether a species occurs in a local community depends both on its adaptations to local conditions and on its interactions with other species

Species sorting: Species present within the regional species pool are sorted into different communities based on their adaptations and interactions.

Species sorting

8 5 12

Local communities and regional species pool

Species pool: mussels, algae speciesSpecies sorting: exposed area, mussels; protected area, algae or mussels.

Mark Bertness, Brown 2006

Species interactions and ecological release

Competitive interactions between species also play an important role in species sorting

Species sorting should be greatest where the regional pool contains the most species.

In such a situation, each species should be able to maintain itself over only a narrow range of habitats – those to which it is best adapted – and beta diversity should be high.

Species interactions and ecological release

Island and neighboring continental regions.

Comparing species richness among regions with similar climate and range of habitats, but different degrees of geographic isolation.

Island usually have few species than comparable mainland areas, but island species often attain greater densities than their mainland counterparts. In addition, they expand into habitats that would be filled by other species on the mainland: Collectively, these phenomena are referred to as ecological release.

Example of bird communities in two continental regions and five islands of various sizes within the Caribbean basin

Panama: a large region with a large species pool

St. Kitts: a small region with a small species pool

When few species occur, each is likely to be more abundant and to live in more habitats

Thus, as the size of regional species pool decrease, the realized niche of each species becomes broader.

Fundamental nicheFundamental niche Boundaries of a particular species’s niche might extend Boundaries of a particular species’s niche might extend

between T of 10oC and 30oC, prey sizes of 4 and 12 between T of 10oC and 30oC, prey sizes of 4 and 12 mm, perches on branches with diameters between 5 mm, perches on branches with diameters between 5 and 20cm, or day-time light levels between 10 and 50 and 20cm, or day-time light levels between 10 and 50 W m-2W m-2

Niche overlap means competition Niche overlap means competition Niche relationships of species provide informative Niche relationships of species provide informative

measure of community structuremeasure of community structure Three factors: total community niche space, niche Three factors: total community niche space, niche

overlap among species, and niche breadth of individual overlap among species, and niche breadth of individual speciesspecies

17.4 Diversity can be understood in terms of niche relationships

Variation in local specie richness represent Variation in local specie richness represent difference in total niche spacedifference in total niche space

In a particular location with a fixed volume of In a particular location with a fixed volume of total niche space, species can be added only by total niche space, species can be added only by increasing niche overlap (sharing of niche increasing niche overlap (sharing of niche space) or by decreasing niche breadth space) or by decreasing niche breadth (partitioning total niche space more finely).(partitioning total niche space more finely).

Competition, diversity and niche

Intensive competition Intensive competition species exclusion species exclusion High diversity is associated with weaker competition High diversity is associated with weaker competition

between speciesbetween species Mechanisms: competitors have to either avoid competition Mechanisms: competitors have to either avoid competition

through ecological specialization or be limited by predators through ecological specialization or be limited by predators rather than by resourcesrather than by resources

High species richness in tropics results at least in part from High species richness in tropics results at least in part from the presence of a great variety of ecological resourcesthe presence of a great variety of ecological resources More fruit eating bird species, nectar-feeding, and insectivorous More fruit eating bird species, nectar-feeding, and insectivorous

speciesspecies More mammals (bat) feed on fruit, nectar and night-flying insects More mammals (bat) feed on fruit, nectar and night-flying insects

(non-flying mammal species are similar to temperate)(non-flying mammal species are similar to temperate) Herbivorous insects diversified to take advantage of immense Herbivorous insects diversified to take advantage of immense

variety of plant species variety of plant species

Competition, diversity and niche

Species diversity is paralleled by the functional Species diversity is paralleled by the functional diversity or niche diversity of the species in a diversity or niche diversity of the species in a communitycommunity

Species diversity and niche diversity

Niche breadths /species are the same:

Morphological analyses have revealed that number of species packed into a certain amount of morphologically defined niche space is relatively constant – average niche breadth remains the same in communities with different number of species. Therefore, as species diversity increases, so does the niche diversity.

Bat’s communities in temperate and tropical localities

Morphological space: two axes, ratio of ear-forearm and ratio of digit length

First: relate to type of prey can locateSecond: flies ability to purse and capture prey

Ontario, Canada and Cameroon, West Africa

A tropical bat fauna occupies more morphologically defined niche space than a temperate bat fauna

Fish exhibit more ecological roles in more diverse communities

Fish are sampled at four locations, Mexico

From headwater spring to a downstream community at river mouth

RecapRecapDiversity patternsDiversity patterns

Latitude, habitat heterogeneity, productivityLatitude, habitat heterogeneity, productivity

Local and regional diversity, beta diversityLocal and regional diversity, beta diversity

Species interaction and ecological releaseSpecies interaction and ecological releaseSpecies pool and species sortingSpecies pool and species sorting

Species diversity and niche diversitySpecies diversity and niche diversity

Diversity patters:Diversity patters: At global scale, species richness increases from high latitude At global scale, species richness increases from high latitude

toward equatortoward equator Within latitude belts, diversity appears to be correlated with Within latitude belts, diversity appears to be correlated with

temperature, productivity, topographic heterogeneity within a temperature, productivity, topographic heterogeneity within a region and structure complexity of local habitatsregion and structure complexity of local habitats

Isolated islands exhibit species impoverishmentIsolated islands exhibit species impoverishment High diversity is associated with greater ecological varietyHigh diversity is associated with greater ecological variety

The ultimate source of diversity is speciation. Change in species The ultimate source of diversity is speciation. Change in species diversity is determined by speciation and extinction.diversity is determined by speciation and extinction.

17.5 Equilibrium theories of diversity balance factors that add and remove

species

Similar to density-dependent regulation of Similar to density-dependent regulation of population sizepopulation size

Births – formation of new species or colonization by Births – formation of new species or colonization by species from elsewherespecies from elsewhere

Death – local extinction of speciesDeath – local extinction of species Carrying capacity – steady-state number of speciesCarrying capacity – steady-state number of species

Steady-state (equilibrium) model

Species richness on islands

Robert MarArthur and E.O Wilson, 1960s

Equilibrium theory of island biogeography:The number of species on an island balances regional processes governing immigration against local processes governing extinction.

A small offshore island

Too small, only way to add species is from mainland.

S: stead-state.

The steady-state number of species is determined by the intersection of colonization and extinction curves

Smaller island support few species

Islands close to the mainland support more species because of higher

immigration rates

Disturbance study by Simberloff and Wilson

Red mangrove

Experiment by Daniel Simberloff and E.O. Wilson

Disturbance influence species

If some diseaster exterminated a part of an island’s biota or all of it, new colonists would, over time, restore diversity to its pre-disturbance equilibrium.

Erecting metal scaffolds covered with plastic sheeting over entire red mangrove trees and resampled at regular intervals for a year.

Equilibrium theory in continental community

At the continental scale, new species are added to the regional pool by evolutionary process of speciation as well as immigration from elsewhere (MacArthur 1969)

Why are there so many different kinds of trees in Why are there so many different kinds of trees in the tropics? the tropics?

Plausible mechanisms include:Plausible mechanisms include: 1. Environmental heterogeneity1. Environmental heterogeneity 2. Disturbance such as tree falls2. Disturbance such as tree falls 3. Herbivores and pathogens allow rare species to 3. Herbivores and pathogens allow rare species to

coexistcoexist 4. Tree species are closely matched ecologically, 4. Tree species are closely matched ecologically,

competitive exclusion takes a long time, and the competitive exclusion takes a long time, and the resulting rare species advantage allows many species resulting rare species advantage allows many species to coexist (neutral theory)to coexist (neutral theory)

17.6 Explanations for high tree species richness in the tropics focus on forest

dynamics

Number of tree species varies in proportion to the Number of tree species varies in proportion to the heterogeneity of the environmentheterogeneity of the environment

Soil and climateSoil and climate

Could great variation in the physical environment in the Could great variation in the physical environment in the tropics account for the tenfold (or more) greater tropics account for the tenfold (or more) greater diversity of trees in tropical than in the temperate diversity of trees in tropical than in the temperate forest?forest?

1. Environmental heterogeneity

It seems unlikely, unless trees recognize much It seems unlikely, unless trees recognize much finer habitat differences in the tropics than they finer habitat differences in the tropics than they do in temperate regions, especially considering do in temperate regions, especially considering that temperate regions contain greater that temperate regions contain greater heterogeneity in some climatic factors. heterogeneity in some climatic factors.

Environmental heterogeneity

Joseph Connell, UC Santa Barbara and othersJoseph Connell, UC Santa Barbara and others

High species richness of tropical rain forests is related to High species richness of tropical rain forests is related to habitat diversity created by disturbancehabitat diversity created by disturbance

Disturbances open up space for colonization and initiates a Disturbances open up space for colonization and initiates a cycle of succession by species adapted for colonizing cycle of succession by species adapted for colonizing disturbed sites. disturbed sites.

Intermediate disturbance hypothesis: specie richness is high Intermediate disturbance hypothesis: specie richness is high when the intensity of disturbance is not too high or low. when the intensity of disturbance is not too high or low.

Death rate of trees due to disturbance showed no difference Death rate of trees due to disturbance showed no difference in temperature and tropic regions (0.5-2% died). It is doubt in temperature and tropic regions (0.5-2% died). It is doubt that gap formation could contribute to 10 fold difference in that gap formation could contribute to 10 fold difference in species richness.species richness.

2. Disturbance and gap dynamics

Consumers reduce the competition and promote Consumers reduce the competition and promote coexistence of many resource species (sea star coexistence of many resource species (sea star example)example)

Daniel Janzen, Uni. Penn suggests herbivory could be Daniel Janzen, Uni. Penn suggests herbivory could be responsible for the high species richness in tropical responsible for the high species richness in tropical forests. forests.

Herbivores feed on buds, seeds and seedling of Herbivores feed on buds, seeds and seedling of abundant species and allow others to grow. abundant species and allow others to grow.

3. Herbivore and pathogen pressure

Several evidence support his “pest pressure” Several evidence support his “pest pressure” hypothesishypothesis Monoculture may fail due to infestations of Monoculture may fail due to infestations of

herbivoresherbivores Rubber plantation in Amazon grow poorly and in Rubber plantation in Amazon grow poorly and in

Malaysia (lack specialist herbivores, and grow well)Malaysia (lack specialist herbivores, and grow well)

Prediction: seedlings should be less likely to become Prediction: seedlings should be less likely to become established close to adult of same species than at a established close to adult of same species than at a distance from them (adults have herbivores)distance from them (adults have herbivores)

Herbivore and pathogen pressure

Seedling survival varies with distance from the parent trees

Fungicide treatment improves survival in seedlings of a tropical tree

Thomas Bell, Uni. Of Oxford

0.24 m2 plots

Two treatments

Applied fungicide and control

Thinned half of plots to create low density

4. Random ecological drift

Steve Hubbell: Neutral theory

Under model of specieation, the equilibrium species richness in the metacommunity (regional diversity) would be S=Jm*nu

Jm is the number of individuals in the metacommunity

Nu is the rate of speciation expressed per individual.

THE End

Response of Stipa neomexicana plants

Jessica Gurevitch

University of New York at Stony Brook

Stipa: C3 perennial grass

Semi-arid grassland in Arizona

Competitive releaseCompetitive release occurs when a occurs when a species expands its niche in response species expands its niche in response to the removal of a competitor or to the removal of a competitor or when a species invades an island and when a species invades an island and expands into unoccupied habitatsexpands into unoccupied habitats

Examples of competitive releaseExamples of competitive release• Response of Stipa neomexicana plantsResponse of Stipa neomexicana plants• Decline in baleen whales has allowed for Decline in baleen whales has allowed for

an increase in other krill-dependent an increase in other krill-dependent predators (penguins, seals)predators (penguins, seals)

Competition release

Commercial whaling in Antarctic Ocean

Baleen whales: 1 million a century ago

eat Antarctic krill (4% of body weight)

Now, less than 200,000

Other krill-dependent predators such as seals and penguins have been found greatly increased in abundance Competition release due to the

dramatic decrease in baleen whale population

RecapRecapDiversity and sampling area Diversity and sampling area

S-A relationship, scales and islandS-A relationship, scales and island

Diversity patternsDiversity patternsLatitude, habitat heterogeneity, productivityLatitude, habitat heterogeneity, productivity

Local and regional diversity, beta diversityLocal and regional diversity, beta diversity

Species interaction and ecological releaseSpecies interaction and ecological releaseSpecies pool and species sortingSpecies pool and species sorting