ECOLOGY

ZENAIDA M. AGNGARAYNGAY, Ph.D.

Ecology = interdisciplinary scientific study of the distribution and abundance of organisms and their interactions with their environment

The environment of an organism includes all external factors, including

• abiotic ones such as climate and geology, and • biotic factors, including members of the same

species (conspecifics) and other species that share a habitat

Examples of objects of ecological study include:

• Population processes, including reproductive behavior, mortality, bioenergetics and migrations,

• interspecific interactions such as predation, competition, parasitism and mutualism,

• plant and animal community structures and their function and resilience, &

• biogeochemical cycling.

Ecological Science is often closely related toother disciplines. Thus,

• molecular ecology addresses ecological questions using tools from genetics,

• paleoecology uses tools from archeology • theoretical ecologists use often highly

complex mathematical models to explore how ecosystems and their elements function.

History

1850: Wallace & Darwin Theory of Natural Selectionconcepts that is how living systems relate with their environemnt

1859: Haekel first formally define Ecologytransform to some dynamic term

that is environment

Ecology

Ernst Haekel German biologist Oekologie

"the comprehensive science of the relationship of the organism to the environment."

oikos = houselogia = logia

Ernst Haeckel and Eugenius Warmingtwo early founders of Ecology

Several notable 19th century scientists such as Alexander Humboldt (1769 – 1859)Charles Darwin (1809 – 1882)

Alfred Russel Wallace(1823 – 1913) Karl Mobius (1825 – 1908)

made many important contributions, from laying down the foundation of biogeography to identifying an interacting groups of organisms as a functionally connected community (biocoenosis)

Eugenius Warming Danish botanist first significant textbook of ecology

For this early work, he is sometimes identified as the founder of ecology

Alexander von Humboldt, German explorer often considered as father of ecology. first to take on the study of the relationship between organisms and their environmentexposed the existing relationships between observed plant species and climate and described vegetation zones using latitude and altitude, a discipline now known as geobotanyone of his famous works was (1805) "Idea for a Plant Geography"

Alfred Russel Wallace contemporary and competitor to Darwinwas first to propose a "geography" of animal

species. Several authors recognized at the time that species were not independent of each other, and grouped them into plant species, animal species, and later into communities of living beings or biocoenosis

Karl Mobius(1877) first use of biocoenosis

Adolphe Dureau de la Malle(1825) French naturalist used the term societé about an assemblage of plant individuals of different species.

Darwin focused exclusively on competition as a selective force

Eugen Warming devised a new discipline that took abiotic factors, that is drought, fire, salt, cold etc., as seriously as biotic factors in the assembly of biotic communities.

Eduard Suessthe Austrian geologist proposed the

term biosphere in 1875Suess proposed the name biosphere for the conditions promoting life, such as

those found on Earth which includes:flora faunamineralsmatter cycles

Biogeography before Warming was largely of descriptive nature - faunistic or floristic.

Warming’s aim was, through the study of organism (plant) morphology and anatomy,

i.e. adaptation – to explain why a species occurred under a certain set of environmental

conditions Moreover, the goal of the new discipline was to explain why species occupying similar habitats, experiencing similar hazards, would solve problems in similar ways, despite often being of widely different phylogenetic descent.

1890:viewed ecology only as “interrelationship” :scientific study of interrelations between

organism and its environmentBeyond : Aristotle “Balance of Nature”

: species as constant and mutable and had its place in nature

:followed by birth of Natural HistoryDarwin, natural historian

called the discovery of “new world”: associate existence with certain

living systeme.g. forest grass with climate

Darwin’s concept of natural selection focused primarily on competition

• all his life a man nearly obsessed with the ideas of competition, struggle and conquest – with all forms of human contact as confrontation

Lavoisier and de Saussure (19th century) ecology blossomed due to new discoveries in chemistry by notably the nitrogen cycle

• That life developed only within strict limits of each compartment that makes up the atmosphere

hydrospherelithosphere

Vladimir I. Vernadsky (1920) a Russian geologist who had defected to France, detailed the idea of the biosphere in his work

• "The biosphere" (1926), and described the fundamental principles of the biogeochemical cycles

• He thus redefined the biosphere as the sum of all ecosystems

• First ecological damages were reported in the 18th century as the multiplication of colonies caused deforestration

• Since the 19th century with the industrial revolution, more and more pressing concerns have grown about the impact of human activity on the environment

• The term ecologist has been in use since the end of the 19th century

ArthurTansley (1935)• the British ecologist, coined the term ecosystem, the

interactive system established between the biocoenosis (the group of living creatures), and their biotope, the environment in which they live.

• Biogeography (19th century) Botanical geography and zoogeography combined

• This science, which deals with habitats of species, seeks to explain the reasons for the presence of certain species in a given location.

• Ecology thus became the science of ecosystems.

• Tansley's concept of the ecosystem was adopted by the energetic and influential biology educator Eugene Odum

• Along with his brother, Howard Odum, Eugene P. Odum wrote a textbook which (starting in 1953) educated more than one generation of biologists and ecologists in North America.

• Human ecology began in the 1920s, through the study of changes in vegetation succession

• It became a distinct field of study in the 1970s • This marked the first recognition that humans,

who had colonized all of the Earth's continents, were a major ecological factor.

• Humans greatly modify the environment through the development of the habitat, (n particular urban planning by intensive exploitation activities such as:

logging fishing and as side effects of:

agricultureminingindustry

• 1960: direction in Ecology took turn, the trust is on “human”

e.g. Silent Spring *focus on how organisms and environment is

interrupted by man - introduction of pesticide

* was also the impetus for the environmental protection programs that were started

in the Kennedy and Johnson administrations and passed into law just before the first Earth Day.

In 1972, the United Nations held • The First International Conference on the

Human Environment in Stockholm, prepared by Rene Dubos and other experts

- This conference was the origin of the phrase “Think Globally, Act Locally”

The next major events in ecology (1980s)-were the development of the concept

of biosphere and the appearance of terms "biological diversity” or now more

commonly biodiversity

In 1992, during the Earth Summit inRio de Janeiro

these terms were developed where the concept of the biosphere was recognized by the major international organizations, and risks associated with reductions in biodiversity were publicly acknowledged.

In 1997, at the conference leading to the kyoto Protocol -the dangers the biosphere was facing were recognized from an international point of view-In particular, this conference highlighted the increasing dangers of the greenhouse effect -- related to the increasing concentration of greenhouse gases in the atmosphere, leading to global changes in climate-In Kyoto, most of the world's nations recognized the importance of looking at ecology from a global point of view, on a worldwide scale, and to take into account the impact of humans on the Earth's environment

ScopeEcology • usually considered as a branch of

biology, the general science that studies living organisms

• associated with the highest levels of biological organization, including the individual organism, the population, the ecological community, the ecosystem and the biosphere as a whole.

.

Ecology is a multidisciplinary science that draws on many other branches, including geology and geography, meteorology, soil science, genetics, chemistry, physics, mathematics and statistics, because of its focus on the interrelations between organisms and their environment,

Ecology is considered by some to be a holistic science, one that over-arches older disciplines such as biology which in this view become sub-disciplines contributing to ecological knowledge due to its breadth of scope,

• Applied Ecology with respect to issues of natural resource management:

*wildlife conservation *habitat management

*mitigation of ecological impacts of environmental pollution*ecosystem restoration*species reintroductions, fisheries, forestry and game management*Urban development, agricultural and public

health issues

Disciplines• Ecophysiology examines how the

physiological functions of organisms influence the way they interact with the environment, both biotic and abiotic.

• Behavioral ecology examines the roles of behavior in enabling an animal to adapt to its environment.

• Population ecology studies the dynamics of populations of a single species.

• Community ecology (or synecology) focuses on the interactions between species within an ecological community.

• Ecosystem ecology studies the flows of energy and matter through the biotic and abiotic components of ecosystems.

• Systems ecology is an interdisciplinary field focusing on the study, development, and organization of ecological systems from a holistic perspective.

• Landscape ecology examines processes and relationship in a spatially explicit manner, often across multiple ecosystems or very large geographic areas.

• Evolutionary ecology studies ecology in a way that explicitly considers the evolutionary histories of species and their interactions.

• Political ecology connects politics and economy to problems of environmental control and ecological change.

• Ecology can also be sub-divided according to the species of interest into fields such as:

-animal ecology-plant ecology, -insect ecology

• Another frequent method of subdivision is by biome studied, e.g., Arctic ecology (or polar)

tropical ecologydesert ecologymarine ecology

The primary technique used for investigation is often used to subdivide the discipline into groups such as:

chemical ecology molecular ecologyfield ecology quantitative ecologytheoretical ecology

• LEVELS OF ORGANIZATIONbiomolecules

organelles organisms

cells population

tissues communities

organs ecosystem

organ system biomes (major habitat)

• Operational environment:– Exchange of matter– Source of energy

Flow of energy– Vital essential material– Source of energy

LIVING ENVIRONMENT (OPERATIONAL)

Odum: Ecology is basically……..• the study of structures and functions in nature• When particular structures interact they exhibit specific

functions• Functions are also interrelated to be capable of interaction• Thus, the structural framework of ecosystem when viewed

as Systems Analysis

STRUCTURES FUNCTIONS

STRUCTURES FUNCTIONS1. Inorganic 1. energy flows/transformation2. Organic 2. trophic organization (food chain) 3. Climate 3. biogeochemical cycles4. Producer 4. diversity pattern5. Consumer 5. development6. Decomposer 6. homeostasis

Structures1.Inorganic – non carbon compounds which

play a vital speciific function in the production of sugar

i.e. in order for the leaf to capture light for the manufacture of sugar, it must be provided with necessary nutrient to trigger the process

2. Organic – fatty acids, sugars, carbon, protein, lipids, organic acids

3. Climate – physical profile It is categorized into 3 based on diurnal factors

a. photoperiod-duration of lightb. temperature-ambient temp.c. humidity - transpiration

Climate further characterized bya. Precipitation- amount of rainfall in the system

classify plants into- Hydrophytes- water Hygrophytes – damp areaMesophytes – dry/wet area Xerophytes- dry areab. pH –the 10 importance of which is the availability of

nutrients in available formc. Salinity – salt concentrationd. Seasons – dry/wet

4. Producers• green plants with light energy - to produce

organic matter from the inorganic (abiotic) nutrients in the environment

• Categorize into 2 according to sizea. microphytes: photosynthetic bacteria

blue green algaephytoplanktonsnanoplanktonsflagellates

b. macrophytesalgaemossesfernsfern alliesgymnospermsangiosperms

5. Consumers• All the animals which feed directly or indirectly

through food chains on the green plants• They are highly diverse group of organisms with

many complex relationships among them• Therefore consumers are placed in many categories

microconsumers- parasitesmacroconsumers- herbivores-10 consumers

carnivores-20 consumersomnivores- animals that

feed on both

6. DecomposersMicrobes and fungi that rot decompose or

otherwise break down organic wastes and return the nutrients to the environment

2 classes: 1. fungi } both feed 2. bacteria } on organic matter

Consumers and Decomposers contribute to the stability of the ecosystem

Functions1.Energy flows laws of thermodynamics an important aspect of ecology is to try to measure

the pathways and efficiencies of energy transfer Questions central to understanding the structure

and function of ecological systems1. How does energy enter & pass through an ecosystem2. How much eenergy is lost when solar energy is transformed

into the chemical energy of plant protoplasm through photosynthesis

3. How much is lost when plants are consumed by animals4. How can man best utilize energy flow patterns to improve

the quantity and quality of his own food supply.

Energy flow

sunlight

photons

wavelength

short

long

visible light

Invisible light

IR

UV

2.Trophic organization

a. Food chain after the initial production of organic matter

by the producer, the nutrients & energy incorporated in the producer are passed through the rest of the system by consumers feeding upon producers and upon one another

In all food chains the ultimate beneficiaries are the decomposers

b. Food pyramidDiagram of data representing the standing

crops of each trophic levelStructured according to members of

organisms, total biomass or total energy flow at each trophic level

reflects the relative size of the participation in the food chain & food web

c. Food webPut together all the food chains in any

community or ecosystemIt gives no indication of the importance of

each link in terms of energiesIt is a useful devise for expressing trophic

relationships in a qualitative way but it can tell us little or nothing about quantitative energy relationships

3. Geochemical cycleBasically corollary to energy flows & trophic

organizationThe structures interact with each other and

some of the functions interlay e.g. nutrient K+ which is part of the substrate

or the so called geological substrate is absorbed by the root to stem finally to the leaf………..matures….falls….in the process K+ is released & becomes again part of the substrate

• The importance of geochemical cycle is that…the cycles are moved by living protoplasm that is living things capable of extracting materials

• So with refernce to the example it would be the movement of K+ to the protoplasm of the root to the stem to the leaf to the monkey to the lion back to the origin of K+ throughwaste materials which undergo sedimentary cycle or gaseous cycle

• Practically, all essential materials in the ecosystem are constantly in cycle hnece termed “biocoenosis” that means lot of life processes are open ended i.e. no wall separating each & everyone, hence, capabnle of interacting with each other

• Continuous biogeochemical cycles and active protoplasm makes environment stable

e.g. cut all trees in the forest – there would be inefficient energy flows, disorganized trophic & disrupted cycles

4. Diversity patternsIn time (temporal) and space (spatial) has

something contribute much to the stability of the environment

Living things allocate with other members of the area, they take turns in flowering

In natural environment which is highly heterogenous…the structures vary in intensity & in kind…these variations would make an environment stable

5. growth/developmentStructures grow & develop through stages until stability

is reached or the so called climax stateClimax is self perpetuating & in equilibrium with the

physical habitate.g. open ecosystem (pioneer population)- contributes

to changes in the physical structure of the area – this then grow & develop through stages presumably througgh SERE up to the time when the environment can already be considered stable, hence attained its climax

• Stochastic patterns exist due to trigger factors

APPROACHES IN ECOLOGY

1. Descriptive – natural history2. Functional – proximate analysis3. Evolutionary ultimate analysis

3 basic properties of the environment

1. Holism2. Limiting factors3. Trigger factors

1.Holism – dynamic relationship in the environment e.g. heat from the sun

2. Limiting factors – limit the extent of the relationship. In all the relationship something will be limiting. It is then a question of how far living things can relate with its sorroundings e.g. photosynthesis

3. Trigger factors – factors that would cause changes in the system that will eventually interfere or enhance the relationship of living and non living things

Levels of Biological Integration in the Operational Environment

1. Species2. Population3. Community4. Biomes

SpeciesCharacterized by Ecological Gene FlowEcological point of view – species share a common

gene pool, phenotype, nicheIn taxonomy, species refers to individuals possessing

similar morphological and reproductive characteristics

Problem arises due to constant change of genetic pool

Perform a specific role in ecological niche which is described as to Habitat, Function and Hypervolume

Ecological Niche

• Habitat – must establish a home e.g. grassland• Function – must have a role e.g. herbivores• Hypervolume – adaptability or sociability e.g. extension of which, that is, they can move

Species occupying the same niche

1. Allopatric 2. Sympatric

Allopatric

involves character displacement since there is no competition in this group, it tends

to convergence, that is to develop a phenotype which is similar in morphology

It occurs when there is isolation through geographic separation of populations

Descended from common ancestors

Sympatric

Share the same niche, or habitat or hypervolumeThey speciate to lesser competition and finally

become diverge – this involves displacement of character so we expect changes in morphology

And if the species can overcome all this constrains than they result to speciation, that is, the formation of new species and the development of species diversity, when isolation occurs through ecological or genetic means within the same area…..

EcotypesSpecies with wide geographical ranges almost always

develop locally adapted populationsHave optima and limits of tolerances adjusted to

local conditionse.g. McMillan (1956) found that prairie grasses of the

same species transplanted into experimental gardens from different altitudes responded quite differently ……… the reproductive period change

Ecological Niche Concept

It denotes ecological equilibrium, it is regulated by biological clocks(1) Diurnal (2)Lunar(3) Seasonal

Biological clocks function as coordinating mechnism

Also determine species behavior with respect to speciation

species (indv.) – niche – phenotype - speciation

7 Basic Behavioral Patterns –vary in importance - according to the kind of organism

• Tropism• Nasties• Taxis• Relexes• Instinct• Learning• Reasoning

1. Tropism directed movements & orientations found in plants Behavioral responses directed towards sources of

stimulus It has three types-

- geotropism growth response is directed towards source of stimulus which is gravity-heliotropism vertical orientation of leaves of trees on a hot sunny day-phototropism growth response is directed towards the source of light, that is, turning of plant to face the sun

2. Nasties Behavioral responses that enhance survival of individual The response is towards a stimulus but not necessarily

directed towards a source It has four types –

-Myctinasty response to dark, exhibited by lotus flower which opens at day time to attrack pollinators-thigmonasty response for water saving purposes, exhibited by makahiya which closses its leaf when it is windy for water economy-photonasty

-thermonasty

3. Taxis

Avoidance of unfavorable condition in the habitat

Exhibited by slime molds that is placed near a toxic substance – the tendency of the organism is to grow away from the toxin

It has two types –- chemotaxis-hydrotaxis

4.It co9nsist Reflexes – stimulus responses of specific body organs

5. Instinct – innate, consists of encoded sequences of stereotyped behavior such as nest building, food gathering, courtship, mating and maternal instinct

6. Learning – charracterized by presence of central nervous system

7. Reasoning – aside from the presence of CNS it consist also of brain spirit

Species behavior is concerned with social behavior and it onvolves interaction of individual

These interactions may be –-beneficial-non-beneficial- harmful

Social behavioris expected to optimize resource utilizationIt is expected to put orders to members of the

society so hierarchial organization is established

So, survival which is attributed by biological clocks & species behavior with the participation of social behavior is enhanced,

Natural SelectionAn individual or singly the product of each genome

and each surrounding environmentAn individual phenotype is best discussed in terms of

its ecology, morphology, physiology as well as its behavior (behavioral pattern)

If you look around certain phenotype are found in special case……. Niche, which is the sum of individual’s morphology, physiology & behavioral pattern, so that if you pick up an organism, it is composed of genome x environment

Process of natural selection

1. Population which have .1. e.g. rabbits are high reproductive capacity very prolific2. Population size remain 2. they don’t constant due to because3. High mortality 3. of production4.Individuals vary with 4. some rabbits respect to – survival run faster5. Trait is passed on to offspring 5. so do their offspring6. Composition of the 6. rabbits run faster population is selected then their

ancestors

Survival of individual is associated with specific traits which pass on to offspring and this is selected….it takes generation for this to happen

How do we demonstrate or what are the evidence

Darwin explained NICHE in terms of natural selection1st evidence –study on how to control pest

Control Pest Program

In a certain citrus plantation was infested with scale insects. The control pest program sprayed the plantation with cyanida(CN) to act as control as far as citrus is concerned.

IN the process of controlling they noted that some pest (scale insect) die but some were resistant

The resistant trait could be inherited – the offspring were also resistant and can pass on to their next offspring

They counter check the presence of resistant insects through collection of scale insects in an environment, that is, unsprayed areas which is not exposed to cyanide

They found out that some insects were resistantSo, they conclude that the cyanide which was sprayed as a

means of controlling peat did not bring about the resistant insects, it has already been there.

2nd evidence thru the phenomenon - MutationMutants involves error in the passing of traits from parents to

offspringPesticide : brought out an important ecological phenomena…it

acts as selective agent and it forms the resistant*If you favor the resistant, then what happen?

They will be reduced because the natural population is also eliminated by the first choice of pesticide so to further eliminate the resistant you look for new pesticide

Cyanbide (CN) was the selecting agent induced by external means

Population

Group of individuals of the same species which are capable of exchanging genetic materials or share common gene pool

e.g. Gene flowDipterocarp in Mt Makiling Dipterocarp in Mt Data

Questions:

a. Would the individuals in Mt. Makiling constitute the same in Mt. Data

b. Would they intervene with each other

c. Will there be an exchange of genetic flow to qualify them to the definition of population

Population from ecological point of interestThere are group attributes or characteristics which are not

restricted to only an individual but all the individuals belonging to the local population

Thus, group attributes of population1. Demographic

-Natality-Mortality-Density

2. Genetic-population growth-movement/dispersal (distribution)-territoriality-population interaction

Demographic is the end product of dynamic interaction If we know natality, mortality and density of a certain

population, then we can predict the “Life table” Population is a reflection of population density or size Density of any given point of time is determined by four basic

population parameters1. Natality - (+) contribution or effect on density2. Mortality - (-) effect3. Immigration - (+) influence on the size of the population4. Emigration - (-) effect

Density is the no. per unit area in a locality

Density

(+)

(+) (-)

(-)

Immigration

Natality Mortality

Emigration

Ecological Density – since area is heterogeneous we expect differences in the distribution of individuals

How do we approximate density…..

1. Total counts – done by census- impractical as far as ecology of

natural population is concerned2. Quadrat – this method is more practical to use in

approximating density - estimate the density based on quadrat

method is basically extrapolation3. Capture method – on time interval to approximate

the size

NatalityNo. of new individuals per unit time (crude)It has two related phenomena:

– fertility; and -- fecundity.

Fertility – indicative of the capability of individuals to interbreed, assumed with respect to fecundity.

Fecundity – refers to the no. of offsprings per individual per unit time

So called-- potential fecundity rates &- realized fecundity rates

Potential Fecundity RatesWhat would be the potential fecundity rate of man based on fertility age group….it would be the no. of births/year coz it will take 9-10 months for a child to be born

Realized Fecundity RatesTake the inset and offset of female reproductive periods. So that’s approximately from 13 years of age to 45 years of age.When we consider the potential which is 1 birth/year, from that limit 13-45, each female can produce 32 children.But in reality the normal no. of children is 4

So to determine the Realized Fecundity Rates:Divide 32 (possible children) by 4 (average no. of children.

Hence, the realized fecundity rates would be 8 years, that is, one birth/8 years

Natality

Fertility Fecundity

Potential Realized

MortalityLook at it in terms of survivalSurvivorshipProfile of natural population with respect to

mortalityA

B

C

young

Age

old

No

Of

Indv.

Mortality rate is high

Mortality rate is low

Mortality rate is equitable at different age group

Population Age Structure – biologicsl natural resource1. Important in the utilization of biological natural resource and

to know the age distribution of the different members of the population

Age

Pyramid

Age

% of Population

young old mature

Post reproduction

reproduction

Pre reproduction

Segment contributing to population density

Stable population – equal no. of Individuals in the different age

*So low reproduction, decrease population size

2. Useful in programming the future sizes of the population

e.g. In the Scandinavian countries, the gov’t noted that populations are getting old. So, they release a policy of “free love”. This encourage love without the bonds of marriageto back this up the gov’t provided: nurseries; orphanages; & home for unwed mothers. This strategy is rejuvinate the population, to increase the pre-reproduction size of the population

Genetic

How population grow in the Natural Habitat

Popoulation profile has two types:1. J type 1. S type

J type

Time

No.

Of

Indv.

asymptote

Drastic decline

Exponentialincrease

Short establishment or adaptation frontReach an optimum or maximum level because of environmental resistanceCharacteristic of lower forms in the biossphereRealized in a short timeIncrease in exponential form e.g. E. coli

S sygmoid type

Time

No.

Of

Indv.

Geometric increase not exponentialAsymtote level after which fluctuation which oscillate around the asymtote – the difference has something to do with the methods of multiplication of reproductionCharacteristic of higher froms – takes longer time before realizing the optimum sizes

In both instances the asymtote is the reflection of the Intrinsic rate of increase and this is usually represented by:

= basically dN/Ndt

Increase in no./unit time

= birth=death

= b- d

So how do you characterize the maintenance of the asymptote?What does b=d represent?

It represent the environment resistance or the carrying capacity of the environment

To maintain this line you need b=d

Resist any departure from the norm b=d b>d b<d

e.g.(1) lower forms – under unfavorable condition they undergo sporulation to maintain

(2) Myxometes – under favorable condition they multiply rapidly - under unfavorable condition where food is depleted they form sporangium also to maintain

After growth the individual try to distribute themselves – association of individuals belonging to the same species. Thus,

distribution –-random-regular-clumped

RegularDistribution of individual of the same

populationWhat condition gives rise to regular

distribution? …..Among individuals that are not sociable, they tend to keep away from one another – situation where there is regular distribution

e.g. individual release toxin, so only species resistant to such toxic substances are allowed, hence, there is regular distribution

AggregationIs the tendency of individuals to clump which

lead to home range i.e. if you have a no. of individuals & decide to

be closer together…..so, what happens is to form a group

This principle is worked out by Allee

ALLEE’s PRINCIPLEThe degree of aggregation as well as the overall

density which results in optimum population growth and survival varies with species and conditions, therefore, undercrowding (or lack of aggregation) as well as overcrowding may be limiting

Degree of clumping

survival

Random it can be any place within the hypervolume niche within areas where we can establish the niche This happens only when we have homogeneous locality, to

anypoint because the physico=chemical condition is practically the same

But if there is geradient, the distribution must be within areas where niches are favorably established

The degree of aggregation to be found in a given species population, therefore, depends on the specific nature of the habitat (whether uniform or discontinuous)

– the weather or other physical factors, the type of reproductive pattern, characteristic of the species and the degree or sociability

TERRITORIALITYRefers to the establishment of an area which

involves defense of the habitat or the niche of the population

Widely observed in fishes, birds & mammalsIn birds they establish their territory and then

bird “calls” detect the incoming population

GROWTHDISPERSALTERRITORY

-Give rise to POPULATION STRUCTURE

-determine how population is structured

-determine how individual fits itself to the locality

Interactions among populations are basically of two types

1. Symbiosis = positive mutualism = both benefited commensalism = one is benefited2. Competition = negative arise from niche – overlaps where

competition arises When competition is so severe, the needs are so

narrow so one has to give way If hypervolume is wide enough, one species have

to change “Speciation” to avoid severe competition