7.1 adaptation and variation SBI3U

Only the fittest survive… What does the saying: « Only the fittest survive » mean to you?

Adaptation and variation Organisms that survive environmental challenges are able to pass on their genetic information to offspring. By passing on the genetic information, their species survive. The varying interactions between species and the envrionmental changes causes some species to go extinct while others thrive.

Adaptations and survival Organisms undergo a variety of adaptations that enable them to survive and escape predators. Adaptation: a structure, behaviour or physiological process that helps an organism survive and reproduce in a particular environment.

adaptations Adaptations can by structural, behavioural or phsyiological. Structural Adaptation: physical features of an organism like the beak on a bird or the fur on a bear. Behavioral Adaptation: Things organisms do to survive such as migration Physiological Adaptation: changes or chemical reactions that occur within an organism ( snake venom, hibernation)

camouflage Many organisms are able to camouflage and blend in with their environment which enables them to escape predators.

Hibernation Hibernation is a physiological adaptation involving changes in metabolic rate. It allows organisms to survive in harsh conditions by keeping warm and preserving their energy

mimicry Mimicry is a form of structural adaptation, where the animal is able to imitate something other than what it is. Butterflies use it as a protection mechanism to trick predators into thinking they are an inedible species.

Mimicry The intention of mimicry is to draw attention to yourself. This is usually achieved through the presence of bright colours.

Check point!!! Clicker questions 1-2

Development of adaptation Adaptation is due to gradual , accumulative changes that helps an organism survive and reproduce. Adaptations are a result of genetic mutations in an organisms’ DNA. These mutations must be heritable in order for the adaptation to persist.

Development of adapations As a result of the mutations, there are many variations that appear in the population. Although a mutation may lead to variation, not all variations become an adaptation. Variations: differences between individuals which may be structural, functional or physiological.

Development of adaptation Depending on the environment, certain variations will persist while others do not. If the variation enables an organism to survive in an environment, the organism will pass on the genetic mutation to their offspring. Those who survive have a greater chance of passing on their genetic information,i.e. greater fitness.

Development of adaptations Although variations may not play a big role at one point in time, as the environment changes, that variation may become useful to an organism’s survival. If that organism survives, it is able to pass on that trait to the offpsring allowing them in turn to survive in such an environment.This trait becomes more common in the population and leads to adaptation.

Variations within species Although organisms are part of the same species, there may be alot of variation. Humans have a great deal of variation due to the random combinations of alleles that we inherit from our parents. The different combinations of alleles contribute to the variation in phenotypes of many species.

Mutations leading to genetic variation Mutations : changes in the genetic material (i.e. DNA) of an organism The mutation in the nucleotide sequence creates new versions of alleles. All mutations happen spontaneously when DNA is copied in the S phase.

CGA-CCA-ACG-GCG... Amino Acids Produced: Arginine - Proline - Threonine - Alanine ... CGA-CCA-GAA-CGG-CG... Amino Acids Produced: Arginine - Proline - Glutamic Acid - Arginine ... Mutations may be silent, harmful or beneficial **only the beneficial mutations are relevant to evolution.

Mutations leading to variation Some mutations can alter the shape and function of a cell. The organism has mechanisms that are able to get rid of these malfunctioning cells. If the malfunctioning cell is able to bypass this checkpoint, it proliferates and accumulated into a tumor.

Check point!!! Clicker question 3

MUTATIONS AND SELECTIVE ADAVANTAGE When the environment changes, certain mutations that were once unfavorable can now be favourable. Selective advantage: a genetic advantage that improves an organisms’ chance of survival, usually in a changing environment. When an organism has a mutation that has a selective advantage, that orgnaism is favored in terms of survival and reproduction.

Check point!!! Clicker question 4

Rapid reproduction and selective advantage Bacteria and viruses tend to have a rapid rate of reproduction. Due to the rapid reproduction, a mutation that has a selective advantage can be spread into a population quickly Thus, when there is a selective pressure applied to the environment, a whole population of bacteria may develop. This may result in antibiotic resistance.

Antibacterial resistance If a bacteria undergoes a mutation that allows it to have higher than normal resistance to antibacterial drugs, it may survive and pass this trait on to the next generation….. ( directional selection) New populations of bateria will grow and be resistant to the medication. « superbugs »