240 6 Competition

8/19/2019 240 6 Competition

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Volunteer with Habitat Acquisition Trust!

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"#$% %& '( )&*( +$,&-,(./ 0)#+- ,&-1$%((*234#%5'656#


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Competition


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Predator

Prey

C o m p e t i t o r

C om

p e t i t or


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What is

exponentialgrowth?

Exponential growth (and decay) occurs when growth rate isproportional to the current value. Contrast with linear growth

where the rate of change is constant.


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Linear

Exponential


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Compound Interest


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Gossip


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Rate at which

a hot drink cools

(example of exponential decay)


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Fashions

(growth &decay)


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Atmospheric pressure

at rising altitudes


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Radioactive

Decay


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Populations in resourcerich environments

Making beer - yeast is the population of interest here.


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TIME

P o p u l a t i o n A

b u n d a n c e Exponential Growth


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Thomas Robert Malthus

(1766 –1834)

Populations increases

exponentially when food

(and other factors i.e.

space) are not limiting.


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MalthusEssay

on Population

Argues EnglishPoor Law is too

liberal and

undermines good

governance. Poor

should not beallowed to

breed as inevitable

overpopulation

leads to socialunrest

Malthus + Darwin

= inhumane

Victorian classism


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Darwin adaptsMalthus’ ideas

into hisstruggle for

existencearguments


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Reproduction produces slight variations in individuals

Variants in a population possessing characters that

enhance resource acquisition will be more numerous

in subsequent generation!evolution


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Darwin recognized that a “struggle for existence”

is exerted on a population that, over generations,can lead to change.

This descent with modification is also

known as “natural selection”

The differential survival and reproduction of

organisms because of differences in

their ability to utilize environmental resources

Leading to differential reproductive output

(aka “fitness”)


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Competition

(K)


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Thingvallavatn, IcelandLandlocked for 10,000 yrs (brief evolutionary time). Did the

morphs evolve together (sympatrically) or apart (allopatrically)?


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Small Benthivore

Large Benthivore

Planktivore

3

Piscivore


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http://www.slowleadership.org/2006_07_01_slowleadership_archive.html


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Charles Elton(1900-1991)

1958

The ecological function of a species is itsecological niche – more commonly known

today as the functional niche

When an ecologist says 'there goes a

badger,' he should include in his thoughtssome definite idea of the animal's place

in the community to which it belongs, just

as if he had said, 'there goes the vicar.'"


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Little brown bat

Mexican free-tailed bat

Both

nocturnalinsectivores

Therefore,

similar niches


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Deciduous forest

Desert

Habitat " Niche


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Elton’s Functional niche is obviously usefulbut also has significant limitations. What are they?

i)

Too broad – particular interactionsare not clearly stated

ii) Not amenable to quantification,

can not be analyzed mathematically

Hutchinson (1957): For any species we can identify a tolerance

range of conditions and exploitable range of resources.

n biotic & abiotic resource axes are combined to yield

n – dimensional hypervolumes


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George Evelyn Hutchinson

(1903 – 1991)

Popularized the niche

concept by visualizing the niche

as theecological spaceof

of the species

What determines the

number of organisms

in any one habitat?


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Prey size + [O2] =Two dimensions of

resource use

Prey size =One dimension of

resource use

FISH


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Prey size x [O2] x [salinity] = Three dimensional resource use

Other critical factors for fish?

Water temp., Depth, pH, etc!.. “hypervolume inmultidimensional space”


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Consider the resource use curves for two species

Typically single resource use curves are normal (aka bell) shaped.

Niche breadth: tolerance end points for a single species

Niche separation: distance separating the means of two resource

use curvesNiche overlap: area of overlap of two or more resource use curves

- where competition is expected

Impossible to accurately quantifyall resources used by a species

Competition = resource must

be limiting

(demand>availability)

(Prey Size)


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Aerial Nectavores


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World map of color coded by diversity of

vertebrate species


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Birds Mammals Amphibians


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Endemic

Birds


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Competitive

Exclusion

hich cases reflectintraspecific

competition and

hich interspecific

com etition?


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H>'$*/%'"*5 N9,-%J


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10.1

Greater range ofresources

Increased degree of

specialization

More overlap

Full exploitation(saturation)

How to get more

species into a

Community?


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( T e m p e r a

t u r e )

(Prey Size)

Niche overlap ofprey size in

species E & F

suggest intense

competition !.

until the

temperature axis is

taken into

consideration

resulting minimal

realized

competition

between E & F.


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MacArthur (1958) Each species forage

in slightly different habitat within atree – thus the five species do not

occupy the same niche


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Greater

Connectance

Resolving the role of competition

Competition drives community evolutionwhich sorts those species that can

coexist over time from those that cannot

Over time older community members become tightly packed in centre

Exclusion thins

species numbers and

character displacement

narrows nichebreadth and shifts

niche centroids

New species are

added at the

periphery, andlikewise have broad

niche breadth


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Trophic Resource Use E n e r g y e x

p e n d e d i n s e a r

c h

Niche breadth determines speciesgeneralist / specialist status

Who is the specialist?

Is there trophic competitionbetween the species?


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Competition: Two species use thesame limited resource, or seek that

resource to the detriment of both

Limited resource: a critical resource for whose availability doesnot meet demand. If the resource is critical to # 2 species,

competition between species ensues and potential

population growth of both species is affected.

There are numerous types of competition!!!


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Mate

Competition


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Who does the competing,males or females? Why


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Exploitative

Competition

What kind of

competition isthis?


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!.can be intraspecific


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! or interspecific


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Preemptive Competition


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PreemptiveCompetition


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Both EXPLOITATIVE and PREEMPTIVE competition arecharacterized by one group “using up” a resource to the

detriment of others.

But, when one individual (not necessarily a species)

interferes with the ability of another to access the resourceis called:

Interference competition

Interference competition: When organisms seeking a

common resource directly interfere with one another.Can occur even if the shared resource is not limiting .

Examples of interference competition?


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Allelopathy

Black walnut

( Juglans nigra)


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Territoriality


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“Darwin’s Finches”

an example of Adaptive Radiation


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Hawaiian Honeycreepers


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Among the most prevalent evidence

of competition in our society is!

Branding

240 6 Competition

Documents

Transcript of 240 6 Competition