t21 communities wrksht.ppt - clark university

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Topic 21: Communities

� What is a community?

� What are some examples?

� What are some measures of community structure?

� What forces shape community structure?

What is a community?

� The group of all species living at a ________________ and potentially _________________ with one another

� Defined by its _______________ features

� Includes all species, including plants and animals

www.stoys.com

� Includes more

than can be

studied

� Considers

processes and patterns above

the __________

__________

What is a community?

� ____________________

� The species that are studied

� A subset of a community

� Often restricted in terms of:

� ___________ of species

� ___________ of species

� Gives a partial picture of

what is going on

� Our focus here will be community-level processes with herp examples

� Consider the herps that live in a given locality

Haekel, Batrachia

What are some examples of

a herp species assemblage?

� Area just east of Tucson, Aizona� A diverse herp community

� Species (partial list)� Urosaurus ornatus

� Uta stansburiana

� Sceloporus clarkii

� Sceloporus magister

� Sceloporus undulatus

� Cophosaurus texanus

� Phrynosoma solare

� Aspidoscelis sonorense

� Elgaria kingi?

� Crotalus atrox

� Crotalus molossus

� Pituophis catenifer

� Masticophis bilineatus

Photos PJB

Phrynosomatinae

Serpentes

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� Yuma, SW Arizona

� Hotter, drier, lower than

Tucson

� Species (partial list)



� Callisaurus draconoides

� Uma notata

� Phrynosoma mcallii

� Phrynosoma platyrhinos

� Dipsosaurus dorsalis

� Gambelia wislizeni

� Coleonyx variegatus

� Crotalus atrox

� Crotalus cerastes

� Chionactis occipitalis

� Masticophis flagellumPhotos PJB



Phrynosomatinae

Serpentes

� Osa Peninsula, Costa Rica

� Anolis polylepis

� Anolis capito

� Basiliscus basiliscus

� Ctenosaura similis

� Coniophanes fissidens

� Ameiva quadrilineata

� Sphenomorphus cherriei

� Immantodes inornatus

� Bothriechis schlageli

� Leptodactylus pentadactylus

� Eleutherodactylus spp.

� Agalychnis callidryas

� Phrynohyas venulosa

� Hyla rosenbergi

Photos: KP Bergmann; M Fogden; K Warkentin

Anura

Squamata



� Communities can differ between localities in a region

� Different species ________________________________

� Example below: Local snakes

Valley bottom riparian(mesquite dominant)

Mountain canyon riparian(ash dominant)

Thamnophis marcianus Thamnophis cyrtopsisMasticophis flagellum Masticophis bilineatusCrotalus scutulatus Crotalus molossus

Photos: PJB; W Wells; T Brennan;

What are some examples of a herp

species assemblage? How do we measure community structure?

� _____________________

� Number of species in a

community

� One measure of diversity

� Also consider morphological,

functional & ecological

diversity

Lanier et al. 2013

� ______________________

� Which species are at a

locality

� How do they differ from another locality?

� How closely related to one

another are they

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� ____________________

� Relative abundance

� Also called species evenness

� Which species are dominant in a community?

� Which species are rare?

� ____________________

� Which niches do the different species fill?

� What are they doing in the community?

Haekel, Lacertilia

How do we measure community structure?

What forces shape community structure?

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0 10 20 30 40 50

Latitude

# of Species

0

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Anura

Gymnophiona

Urodela

Testudines

Lizards

Serpentes

# of Species

MI, USA (42)

GA, USA (32)

Guatemala (16)

Costa Rica (10)

Ecuador (0)

What forces shape community structure?

� _____________________ __________ of the species

� Environmental gradients often determine factors like ______________________� Latitudinal gradients

correlate with both

� Lower ______________

� Warmer

� More humid

� Greater species richness

� Other factors, such as biome type also play a role

Modified from Pough et al. 2004, Table 16-1

Climate & physiological tolerance

� ___________________ is important

� Higher elevations are colder

� Simulate changes in latitude

Pough et al. 2004, Fig 5-20, 16-1

� Important climatic factors for amphibians and “reptiles”� Amount of ______________

� Amount of ______________

� _________________

� Different clades like different things (Anura vs. Squamata)� This will influence

� Species richness

� Species evenness

� Species composition

Modified from Pough et al. 2004, Table 16-2

TaxonHours Sun

Precip Temp

Anura

Testudines

Lizards

Serpentes

Correlations with species richness – US & Australia

Climate & physiological tolerance Interspecific interactions

Pough et al. 2004, Fig 16-10

� What kinds of interspecific interactions are there?

� ________________

� ________________

� ________________

� How would you expect each one to influence a species or a community?� (Species richness, occurrence, abundance, niche)

� _________________

� _________________

� _________________

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Interspecific interactions

� ________________� Some species are better

competitors than others

� ___________________

� ___________________

� Thai tadpole assemblage� Different species inhabit

different parts of water column

� Forage for different things

� Can coexist

� Also temporal partitioning: some species hatch earlier than others


Interspecific

interactions

� _________________ complexity

� Anolis lizards partition their habitat in various ways

� _____________________ occurs on the tiny Lesser Antilles

� Some islands have 1 species

� Intermediate body size

� Larger islands have 2 species

� One species is small

� One species is large

� The species fill different niches

� There are strong phylogenetic effects

Butler and Losos 1997


� Anolis habitat use changes with increased _________________

� ___________________ changes with number of species

� Anolis sagrei

� Perch diversity decreases with increasing number of sympatric species

Males

Females

Photo © I Sevi

Interspecific

interactions

� ___________ can influence

� ___________

� ___________

� Changes selective pressures

� Anolis sagrei on islands with Leiocephalus carinatus

� L. c. is a terrestrial predator

� Influences habitat use and selection

Losos et al. 2006


� _______________

� Can decrease interspecific ______________

� Can lead to some species thriving

� Newt (Notophthalmus) is a predator of various frog tadpoles

� When predation is high, the Pseudacris crucifer tadpoles are significantly larger

� Less competition for food

with other species

� May also be more resistant to predation




� Continuing with Pseudacris example

� When newts are absent, Pseudacris is outcompeted by other species

� When newts are in high density, Pseudacris dominate the assemblage


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History

� __________________

� Is a clade species rich or not?

� Closely related species often are more similar ecologically

� May not live in the same community due to competition

� __________________

� Are species from a clade present in the area?

� How many species from the clade?

� Which clade got there first?

Noonan & Chippindale 2006; Duellman & Pianka, 1990

Anthropogenic Effects

� Our activities __________________________

� Some species do well in anthropogenic ecosystems, others do not

Photo © S Renzl

� Urban Arizona Species� Hemidactylus turcicus

� Callisaurus draconoides


� Urosaurus ornatus


� Aspidoscelis sp.

� Crotalus atrox

� Rural Arizona Species

� NOT Hemidactylus turcicus

� Also Holbrookia maculata

� Sceloporus clarkii

� Masticophis spp.

� Other Crotalus

� Gopherus agassizii

� Etc.


� Introduced species act as ____________ and __________ to native species

� Mongoose, goats, cats, rats, cane toad, etc.

� Islands are highly affected/vulnerable

Photos: wikipedia; Australian Gov’t

� Bufo marinus

� Introduced to E Australia ~1940

� Biological control of Cane Beetle

� Spread rapidly

� Impacts of Bufo marinus

� _________________

� Competitor

� Predator

� _________________

� Poisons native predators

� Incl. Crocodylus johnstoni

� High native anuran tadpole mortality with Bufo marinuseggs and tadpoles

Photo: M Letnic; Fig: Crossland 2000


t21 communities wrksht.ppt - clark university

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