Interaction in EcosystemsInteraction in Ecosystems1.1. Biotic InteractionsBiotic Interactions

2.2. Symbiotic RelationshipsSymbiotic Relationships

3.3. The costs, benefits and The costs, benefits and consequences of interactionsconsequences of interactions

Interactions between speciesInteractions between species

Type of InteractionType of Interaction Effect on population Effect on population densitydensity

ParasitismParasitism

CommensalismCommensalism

MutualismMutualism

PredationPredation

CompetitionCompetition

+ / -

+ / 0

+ / +

+ / -

- / -

Maintaining symbiotic relationshipsMaintaining symbiotic relationships

Symbiotic relationships are affected by both Symbiotic relationships are affected by both Biotic factors e.g. host healthBiotic factors e.g. host health External factors e.g. environmental conditionsExternal factors e.g. environmental conditions

Both must be suitable to maintain the Both must be suitable to maintain the symbiotic relationship, if one is changed the symbiotic relationship, if one is changed the balance of the relationship may changebalance of the relationship may change

E.g. ….E.g. ….

Managing symbiotic relationshipsManaging symbiotic relationships

Humans can manage their symbiotic Humans can manage their symbiotic relationships with other speciesrelationships with other species E.g.E.g.

Humans can manage symbiotic relationships Humans can manage symbiotic relationships between other speciesbetween other species E.g.E.g.

Interactions with the environmentInteractions with the environment

Organisms respond to changes in the Organisms respond to changes in the environment in 2 main waysenvironment in 2 main ways Conformation Conformation RegulationRegulation

ConformationConformation

Conformers internal body conditions change with Conformers internal body conditions change with environmental changesenvironmental changes

Conformers may have strategies that lead to tolerance Conformers may have strategies that lead to tolerance and resistance to the environmental changesand resistance to the environmental changes

Tolerance is the ability of an organism to withstand Tolerance is the ability of an organism to withstand variations in environmental conditionsvariations in environmental conditions This usually involves physiological changesThis usually involves physiological changes

E.g. Changes in the production rate of glomerular filtrateE.g. Changes in the production rate of glomerular filtrate

Tends to be a temporary adaptationTends to be a temporary adaptation

Conformation cont…Conformation cont…

Resistance to environmental changes results Resistance to environmental changes results from more overt strategies. In addition to from more overt strategies. In addition to physiological changes, it involves physiological changes, it involves morphological and behavioural changes, that morphological and behavioural changes, that may be longer term may be longer term E.g.E.g.

growth of winter coat (morphological)growth of winter coat (morphological) Active only at night (behavioural)Active only at night (behavioural)

Conformation cont…Conformation cont…

Conformers are restricted in the habitats that Conformers are restricted in the habitats that they are able to survive inthey are able to survive in

These tend to be habitats where any These tend to be habitats where any environmental changes are small, occur over environmental changes are small, occur over long times or are regularlong times or are regular

Conformation cont…Conformation cont…

Example 1 – osmoconformersExample 1 – osmoconformers These organisms have the same osmotic potential as their These organisms have the same osmotic potential as their

surrounding environmentsurrounding environment The concentration of jellyfish body fluids changes with the The concentration of jellyfish body fluids changes with the

salinity of the seawater.salinity of the seawater. Note salt concentration of seawater does not vary much Note salt concentration of seawater does not vary much

over a short period of timeover a short period of time Example 2 – poikilothermsExample 2 – poikilotherms

Have a body temperature that fluctuates with the Have a body temperature that fluctuates with the environment (cold-blooded organisms or ectotherms)environment (cold-blooded organisms or ectotherms)

ReptilesReptiles

DormancyDormancy

Dormancy is a means of resisting or tolerating Dormancy is a means of resisting or tolerating environmental diversityenvironmental diversity

Dormancy is an inactive period in the life of Dormancy is an inactive period in the life of an organism during which growth slows or an organism during which growth slows or decreases.decreases.

Dormancy can beDormancy can be Predictive dormancy – occurs in advance of the Predictive dormancy – occurs in advance of the

adverse conditions (therefore is genetically adverse conditions (therefore is genetically programmed)programmed)

Consequential – occurs in response to conditionsConsequential – occurs in response to conditions

Dormancy cont…Dormancy cont…

Forms of dormancyForms of dormancy Resting sporesResting spores

Examples – bacterial spores, fungal spores, seedsExamples – bacterial spores, fungal spores, seeds Brought on by drought or temperature extremesBrought on by drought or temperature extremes

DiapauseDiapause Most common in insects or earthwormsMost common in insects or earthworms Stage in the life cycle where metabolism is suspendedStage in the life cycle where metabolism is suspended Brought on by drought or low temperatureBrought on by drought or low temperature

Dormancy cont…Dormancy cont…

HibernationHibernation Inactivity in mammalsInactivity in mammals Lowered metabolic rate to conserve energyLowered metabolic rate to conserve energy Brought on by periods of food shortage (usually in Brought on by periods of food shortage (usually in

association with cold temperatures)association with cold temperatures) AestivationAestivation

Common in lungfish and amphibiansCommon in lungfish and amphibians Lowering of metabolic rate (said to induce a state of Lowering of metabolic rate (said to induce a state of

torpor) torpor) Brought on by hot, dry conditionsBrought on by hot, dry conditions

RegulationRegulation

Regulators internal body conditions remain Regulators internal body conditions remain constant despite environmental changesconstant despite environmental changes

Regulators can occupy a wide range of Regulators can occupy a wide range of habitatshabitats

Homeostasis (the process of regulating body Homeostasis (the process of regulating body conditions) requires energyconditions) requires energy

Regulation cont….Regulation cont….

Example 1 – osmoregulationExample 1 – osmoregulation The ability of an organism to maintain a constant The ability of an organism to maintain a constant

internal water and salt concentrationinternal water and salt concentration

Example 2 – homeothermsExample 2 – homeotherms Maintain a constant body temperatureMaintain a constant body temperature AKA – warm-blooded organisms or endothermsAKA – warm-blooded organisms or endotherms