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Module 3: Biological Diversity (Selection Pressures (Biotic Factors…
Module 3: Biological Diversity
Adaptations
Physiological: relates to the way the organism functions, how it's body works
Examples - human sweating which assist with heat loss, salt exclusion/ avoidance in plants - when the excess sodium and chloride ions are transported into bladder cells on tips of hair on leaves, when reach full capacity, they burst releasing slat into environment. Salt accumulation . tolerant - increase water content in large vacuoles
Behavioural
Structural: shape and size of an organism and it's various body parts
Examples - kangaroo's powerful leg muscles assist it hopping at high speeds, fleshy stems and leaves of succulents makes them able to swell up and retain moisture, thorny devil has large prickly spikes makes it look hard to swallow, scales on body collect water
Definition: (noun) A feature (not something it does) of an organism that makes it well suited to its environment and lifestyle
Adaptations helps the organism survive and reproduce in an ecosystem and are inherited from one generation to another through DNA
Selection Pressures
Abiotic Factors
Non - living factors
E.g. Temperature, soil type, exposure to natural forces (waves, wind, tides,) light availability, water, climate, availability of gases (oxygen and CO2) - in aquatic environments
Biotic Factors
Sampling Techniques
Transects - measure distribution
Quadrats - measure the abundance
Symbiotic Relationships
Mutualism
Benefits both organisms - neither could survive without the other
Examples - clownfish and sea anemone - the clownfish is protected by the sea anemone from predators and the anemone gets a lot of prey who come near it
Terrestrial - oxpeckers and rhinos - the oxpecker gets food from ticks and parasites and rhino has protection from ticks and parasites
Commenalism
One organism is benefited and the other is not harmed
Examples - Barnacles and whales - barnacles attach themselves to whales and are exposed to more food sources the whales are not harmed
Epiphytes are plants that grow up high on tree trunks of other trees so they gain more exposure to light for photosynthesis and the other trees are not harmed
Parasitism
One organism feeds on the host - one is benefited - the other is harmed
Examples - head lice - head lice feed off humans taking their nutrients to grow
Glossary
Autotroph - (self- feeding) organisms that produce own nutrients through photosynthesis (plant) or chemosynthesis (bacteria)
Heterotroph - (different feeding) organisms that can't produce own food and eats other organisms e.g. animals
Producer - an autotroph
Consumer - heterotrophic organism that eats/consumes others
Carnivore - an organism that eats meat
Herbivore - an organism that eats plants
Omnivore - an organism that eats plants and meat
Scavenger - an animal that feeds on dead organisms
Decomposer - an organism that breaks down dead plants and animals and returns nutrients to the soil to be resused by producers
Food chains - shows the sequence of energy through organisms from producers to consumers
Arrows show the thing that is eaten
Food web - shows a number of interacting food chains with producers on the bottom and consumers on the top
Predator - prey
The number of prey will peak before number of predators - number of prey dictates number of predators
Prey - the thing that gets eaten
Predator - the thing thats eats organism
As prey population increases --> predator population increases
Direct relationship
As prey population decreases --> predator population decreases as they don't have enough food/ prey
Number of predators can't increase indefinitely as they eventually would run out food
Competition
The struggle between organisms for the same resource - usually limited in supply but vital to survival e.g. food, shelter, mates,
Survival of the fittest
Short term consequences - decrease in population of both species - can cause a decrease in food source for other animals
Competing species is often related to food availability
Intraspecific - same species
Interspecific - different species
Allelopathy
When one organism produces a substance which prevents the abundance of another organism from a different species
Examples - The camphor laurel tree produces camphor which prevents the growth of seedlings around the base of the tree in the zone of inhibition
This relationship helps the camphor laurel tree as they are the only tree in the area and therefore have access to all nutrients in the area
Symbiosis
A type of interaction between organisms where two different species live together in close association, this association benefits at least one of them - there are 3 types - mutualism, commensalism, parasitism
Living factors
E.g. seasonal availability and abundance of food, number of competitors, number of mates available, number of predators, number and variety of disease causing organisms
Individual -
Population -
Community - a group of different species living together and interacting in a particular habitat
Ecosystem - combination of all biotic factors and abiotic factors that interact
Biome -
Biosphere - all living organisms on Earth
Provides organism with nutrients, water, shelter and opportunities to mate
Factors often in the environment, that affect the survival of an individual within a population. Selection pressures therefore drive natural selection
They also affect distribution and abundance
Distribution - where a species is found in an ecosystem
Can be clumped (elephants,) uniform/evenly spread (creosote bush,) or random (dandelions
Abundance - how many individuals of that species live throughout the ecosystem
Ecology - is the study of interrelationships between different types of organisms and their environment - these interrelationships between abiotic factors and biotic determine distribution and abundance
Scenarios
Selection pressure - trees being culled - this is abiotic - trees are biotic but it is a habitat which is abiotic - this selection pressure will cause a decrease in the number of barn owls as they will lose their habitat
Selection pressure - food supply only in trees - biotic - the coconut crab has to climb up trees to get access to food - those with this ability survived and reproduced those who didn't - died
*If the selection pressures change - the population will change to be better adapted to it
Case Study - cane toads
*
Ecological niches -
Evolution
Evidence for evolution
Amino acid sequencing
DNA - DNA hybridisation
Fossils
Comparative anatomy
Comparative embryology
Rates of evolution
Punctuated Equilibrium
Gradualism
Types of evolution
Divergent evolution
Convergent evolution
Macro and micro evolution
Natural Selection
In any population there are variations between the individuals. More offspring are produced than are needed and there is a constant struggle for survival
Those individuals with favourable characteristics (adaptations) are selected by the environment to survive and reproduce. Those without favourable characteristics are removed from the population
The individuals with favourable characteristics reproduce and pass on these favourable characteristics to their offspring
Over time these favourable characteristics become more common in a population
Darwin and Galapagos Islands
Modern Examples