Ch. 3 - Introducing behaviour

Goal of any organism = survive and reproduce to contribute alleles to the gene pool

To survive, the organism must be able to detect and respond to changes in the environment

Responses are adaptations for survival and reproduction through: * finding favourable conditions * ensuring sufficient supply of nutrients and necessary resources * reducing competition * avoiding predation/herbivory * finding mate of same species

Non-living environmental factors * Temperature * Light intensity * Humidity * Wind speed * Salinity * pH * Water * Oxygen * Carbon dioxide * Mineral levels and substrate
Organisms only inhabit areas where abiotic factors within range of physiological tolerance
Physical tolerance: How much an organism can withstand
Many abiotic factors are predictable as they are rhythmical * eg. daily and seasonal changes in day/night cycle

Influence of living organisms * competition (intra and interspecific) * exploitation (predation, herbivory, parasitism) * mutualism

Organisms detect specific environmental stimuli using receptors (can range from simple nerve endings through specialised sensory cells to complex sense organs)
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Structural adaptations: adaptations to the structure of the organisms’ body ie. tail, hand, teeth, that increase its chance of survival and reproduction
Behavioural adaptations: adaptations to the behaviour of the organism that increase its chance of survival and reproduction ie. homing response of domestic pigeons
Physiological adaptations: adaptations to the chemical processes of an organism that increase its chance of survival and reproduction ie. anti-coagulants in the saliva of bloodsucking parasites

Niche: The way an organism has adapted in response to its habitat * Combination of an organism’s habitat (where it lives), how it lives there, and the role of the organism in its biological community
Fundamental niche: The niche an organism would occupy if all necessary environmental conditions are present
Limits of fundamental niche: Set by limits of the organism’s physiological tolerances to abiotic factors
Realised niche: Actual niche that an organism occupies - much less extensive than the fundamental niche
Limits of realised niche: Set by biotic factors such as interspecific competition or predation
Vacant niche: A niche that has not been inhabited or opened up due to the extinction of a species previously occupying the niche.
Overlap of niches between different specie cause interspecific competition
Interspecific competition increases the more niches overlap
Gauses’s competitive exclusion principle: applies when niches are sufficiently similar

> “No two species with identical niches can co-exist long in the same space”

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