Ecological Niche Modeling: Ecological Niche Modeling: Concepts and ApplicationsConcepts and Applications

A. Townsend PetersonA. Townsend Peterson

University of Kansas Natural History MuseumUniversity of Kansas Natural History Museum

Niche ConceptsNiche Concepts

Many definitions exist for Many definitions exist for ‘‘nicheniche’’ ……�� I avoid those that are processI avoid those that are process--oriented (e.g., oriented (e.g., ““the the

role of species X in its communityrole of species X in its community””))�� Focus on a more workable definition: Focus on a more workable definition: ““the set of the set of

environmental conditions within which a species environmental conditions within which a species can maintain populations without immigrational can maintain populations without immigrational subsidysubsidy”” (J. Grinnell)(J. Grinnell)

Grinnellian concept has the advantage of a Grinnellian concept has the advantage of a single focus (environmental conditions)single focus (environmental conditions)Interactive (Eltonian) processes probably act Interactive (Eltonian) processes probably act chiefly on finer spatial scales and are not chiefly on finer spatial scales and are not commonly discernable on coarse scalescommonly discernable on coarse scales

Abiotic niche

Biotic interactionsAccessibility

Area presenting appropriate combinations of abiotic and biotic conditions (= potentialdistribution)

Actual geographic distribution(abiotic and biotic conditions fulfilled,accessible to dispersers)

The BAM DiagramThe BAM Diagram

Abiotic niche

Biotic interactionsAccessibility

Species Interactions Important

Abiotic niche

Biotic interactions

Accessibility

Species Interactions Unimportant

Niche ModelingNiche Modeling

Physiological constraints Physiological constraints �� Ecological Ecological processes processes �� Geographic phenomenonGeographic phenomenon

As such, geographic phenomena of As such, geographic phenomena of distributions should be reconstructed in distributions should be reconstructed in ecological spacesecological spaces

Linked spaces, in which there is a oneLinked spaces, in which there is a one--toto--one mapping between elements in G and one mapping between elements in G and elements in Eelements in E

Modeling best carried out in EModeling best carried out in E

Easy-to-measurevariables

(scenopoetic)

S1

S2

S3

S4

S5

S6

Proximate variables

(scenopoetic and/or

bionomic)

P1

P2

P3

P4

Presence or absence of suitable conditions

for the species in question

““PresencePresence””

Absence DataAbsence Data

Abiotic niche

Biotic interactionsAccessibility

Niche Modeling ConsiderationsNiche Modeling ConsiderationsInput DataInput Data

Presence data should be Presence data should be unbiased in sampling unbiased in sampling environmentsenvironments

OR interpretation limited to OR interpretation limited to environments sampledenvironments sampled

Absence data are of Absence data are of dubious utilitydubious utility

Environmental data must be Environmental data must be proximate proximate …… i.e., as close i.e., as close to causal as can beto causal as can be

Occurrence data and Occurrence data and environmental data must be environmental data must be of comparable resolution of comparable resolution spatially and temporallyspatially and temporally

Modeling ConsiderationsModeling Considerations

Enough complexity to Enough complexity to capture details of nichescapture details of niches

Not Not too muchtoo much complexity to complexity to avoid overfittingavoid overfitting

Model response types must Model response types must be appropriate to the be appropriate to the complexity of ecological complexity of ecological nichesniches

Appropriate regions for Appropriate regions for training and testing models training and testing models must be chosen based on must be chosen based on M (accessibility)M (accessibility)

Model validation is not Model validation is not simplesimple

Major FindingsMajor FindingsENM offers a means of identifying nonrandom ENM offers a means of identifying nonrandom associations between speciesassociations between species’’ occurrences occurrences and ecological features (= niche)and ecological features (= niche)

Niches are conserved over ecologicalNiches are conserved over ecological--evolutionary time periodsevolutionary time periods

Niches are conserved even in novel Niches are conserved even in novel community contextscommunity contexts

ENM offers excellent predictivity of geographic ENM offers excellent predictivity of geographic phenomena related to biodiversity phenomena related to biodiversity ……

Niche Conservatism I: Niche Conservatism I: Invasions are PredictableInvasions are Predictable

Aedes albopictusAedes albopictus

Aedes albopictus Aedes albopictus Known as the Known as the ““Asian Asian Tiger MosquitoTiger Mosquito””

Invader; fastest Invader; fastest spreading mosquito in spreading mosquito in the world the world

Aggressive daytime Aggressive daytime biter and pestbiter and pest

Known to transmit Known to transmit Dengue, La Crosse, St. Dengue, La Crosse, St. Louis, Eastern Equine, Louis, Eastern Equine, Ross River, Rift Valley, Ross River, Rift Valley, and West Nile Virusesand West Nile Viruses

Abiotic niche

Biotic interactionsAccessibility

Area presenting appropriate combinations of abiotic and biotic conditions (= potentialdistribution)

Actual geographic distribution(abiotic and biotic conditions fulfilled,accessible to dispersers)

Abiotic niche

Biotic interactionsAccessibility

Area presenting appropriate combinations of abiotic and biotic conditions (= potentialdistribution)

Actual geographic distribution(abiotic and biotic conditions fulfilled,accessible to dispersers)

Accessibility

Aedes albopictusAedes albopictus

Present predicted distribution, native range in Asia

Aedes albopictusAedes albopictus::USA invasionUSA invasion

Projected Asian niche into USA present to create invasion risk-map. How well did GARP perform...

Aedes albopictusAedes albopictus: : USA invasionUSA invasion

Aedes albopictusAedes albopictus: : world riskworld risk--mapmap

Conservatism IIConservatism IIPredictivity Across the End of the Predictivity Across the End of the

PleistocenePleistocene

PollenPollen--based Analysesbased Analyses

Picea Picea sp.sp.

Brasenia schreberiBrasenia schreberi

Acer saccharumAcer saccharum

Niche Conservatism EvidenceNiche Conservatism Evidence

Short term Short term –– invasions are predictable in invasions are predictable in terms of potential geographyterms of potential geography

Middle termMiddle term –– longitudinal studies longitudinal studies Pleistocene to Present are successfulPleistocene to Present are successful

MiddleMiddle--toto--Long term Long term –– sister species tend sister species tend to be very similarto be very similar

Long term Long term –– tracing over phylogeny often tracing over phylogeny often (but not always) shows conservative (but not always) shows conservative evolutionary patternsevolutionary patterns

Applications II: Applications II: Marine Intrusion and Marine Intrusion and Climate Change Effects on BiodiversityClimate Change Effects on Biodiversity

Coastline Topography and Marine Coastline Topography and Marine Intrusion Intrusion

New Zealand New Zealand -- Coromandel CoastCoromandel Coast

South Coast New GuineaSouth Coast New Guinea

The AmericasThe Americas

Global Projected Extinctions from Global Projected Extinctions from Marine IntrusionMarine Intrusion

Global Species Losses: � 181 species under the 1 m scenario � 337 species under the 6 m scenario� out of 18,628 current species considered

Mexican Sheartail Mexican Sheartail Doricha elizaDoricha eliza

Joint EffectsJoint Effects

Double whammy More species affected

Joint EffectsJoint Effects

0

20

40

60

0 20 40 60 80

Per

cen

t los

s ow

ing

to in

un

datio

n

Percent loss owing to climate change

APPLICATIONS III: APPLICATIONS III: BIODIVERSITY LOSS IN MEXICOBIODIVERSITY LOSS IN MEXICO

Biodiversity Loss in MexicoBiodiversity Loss in Mexico

Loss of Evergreen Tropical ForestLoss of Evergreen Tropical Forest

Black – area lost; lightest gray – area remaining

Jay Species Jay Species –– Distributional LossDistributional Loss

Map of Distributional Loss Map of Distributional Loss -- CorvidsCorvids

APPLICATIONS IV: MALARIA APPLICATIONS IV: MALARIA IN AFRICAIN AFRICA

Anopheles gambiaeAnopheles gambiae

Forecasting Dengue Vector Forecasting Dengue Vector Activity Using TimeActivity Using Time--specific specific Ecological Niche ModelingEcological Niche Modeling

A. T. Peterson, Y. Nakazawa, and E. MartinezA. T. Peterson, Y. Nakazawa, and E. Martinez--MeyerMeyerInstituto de Biologia and Facultad de Ciencias, Universidad Instituto de Biologia and Facultad de Ciencias, Universidad

Nacional Autonoma de MexicoNacional Autonoma de Mexico

Satellite ImagerySatellite Imagery

Advanced Very High Resolution Radiometer Advanced Very High Resolution Radiometer (AVHRR) passes over all points on Earth(AVHRR) passes over all points on Earth’’s s surface each daysurface each day

Raw data include reflectance in different parts of Raw data include reflectance in different parts of the electromagnetic spectrumthe electromagnetic spectrum

Normalized Difference Vegetation Index (NDVI) Normalized Difference Vegetation Index (NDVI) is a composite of two bands of raw data that is a composite of two bands of raw data that summarizes summarizes ‘‘greennessgreenness’’, and (more precisely) , and (more precisely) volume of photosynthetic vegetationvolume of photosynthetic vegetation

AVHRR NDVI data are available as biweekly or AVHRR NDVI data are available as biweekly or monthly compositesmonthly composites

Potential for ENM and DenguePotential for ENM and Dengue

ENM is presently developed based on static ENM is presently developed based on static environmental data that are not temporally preciseenvironmental data that are not temporally precise

Using occurrence information and ecological data Using occurrence information and ecological data that are precise both in time and space, ENM can that are precise both in time and space, ENM can be made timebe made time--specificspecific

Would provide detailed predictivity on a weekly or Would provide detailed predictivity on a weekly or monthly basis for vector distributions and disease monthly basis for vector distributions and disease transmissiontransmission

Potentially applicable to any ephemeral species of Potentially applicable to any ephemeral species of epidemiological interestepidemiological interest

Distributional Data for Distributional Data for Aedes Aedes aegyptiaegypti, 1995, in Mexico, 1995, in Mexico

TimeTime--ignorant Predictionignorant Prediction

Closer ViewCloser ViewNote broad areas predictedNote broad areas predicted

TimeTime--specific Occurrence Dataspecific Occurrence Data

August 1995August 1995

August 1995 Predicts August 1995 August 1995 Predicts August 1995 (easy)(easy)

Can We Predict August from Can We Predict August from Previous Months?Previous Months?

Example: June 1995 predicts August 1995

Composite Prediction for August 1995: Composite Prediction for August 1995: Two Previous Months AveragedTwo Previous Months Averaged

TimeTime--specific Model Compared specific Model Compared with Timewith Time--ignorant modelignorant model

Closer ViewCloser View

Summary of Prototype TestsSummary of Prototype TestsPercent correctly predicted

Month N Any >50% >80%

June 22 100 72.7 54.5

July 28 100 82.1 67.9

August 40 100 75 35

September 25 100 80 16

October 19 94.7 78.9 21.1

November 25 100 76 52

December 22 100 95.5 81.8

APPLICATIONS: EMERGENCE APPLICATIONS: EMERGENCE OF LEISHMANIASIS IN OF LEISHMANIASIS IN SOUTHERN BRAZILSOUTHERN BRAZIL

Diferencia 1975 Diferencia 1975 –– 2055 2055 -- migoneimigonei

Red areas improve for the species, blue areas get worse for the species

Diferencia 1975 Diferencia 1975 –– 2055 2055 -- intermediaintermedia

Red areas improve for the species, blue areas get worse for the species

Diferencia 1975 Diferencia 1975 –– 2055 2055 -- whitmaniwhitmani

Red areas improve for the species, blue areas get worse for the species

Conclusion: Lutzomyia whitmaniis the sandfly species most likely to be responding to climate change and causing the observed re-emergence

Niche Modeling SummaryNiche Modeling SummaryNiches evolve slowlyNiches evolve slowly

Conserved niches allow many fascinating Conserved niches allow many fascinating insightsinsights�� Characterize ecology and distributionsCharacterize ecology and distributions

�� Predict unknown and undescribed populationsPredict unknown and undescribed populations

�� Predict geography of speciesPredict geography of species’’ invasionsinvasions

�� Predict shifts in speciesPredict shifts in species’’ distributions in distributions in response to climate change and land use response to climate change and land use changechange

�� Detect effects of interactions with other speciesDetect effects of interactions with other species

�� Improve conservation planning based on Improve conservation planning based on speciesspecies’’ distributionsdistributions

PLEASE, nowPLEASE, nowassemble, organize, and prepare assemble, organize, and prepare

your good your good and bad and bad vibrationsvibrations

ThanksThankstown@ku.edutown@ku.edu