Evolution 1
Adaptations
Adaptations- are biological traits that help an individual to survive and reproduce in its habitat
Adaptations perform a specific function that make an organism better suited to its environment
They are used during tasks organisms face when interacting with the physical world.
Example: your eyes enable you to recognize and respond effectively to things around you by detecting
and analyzing the reflected light.
Perceptual processes and behaviours are also biological adaptations.
Psychological Adaptations
“Higher” mental processes- Selective attention, memory encoding, memory retrieval and word
recognition; these all refer to tasks that the mind needs to accomplish to do its job= the adaptive
functions of the mind.
The adaptive functions that are served by our minds evolved like all other adaptations- through natural
selection.
Evolution by Natural Selection
Adaptations emerge in development as a result of the activation of relevant genes in interaction with
relevant aspects of the environment.
Natural Selection- differential survival and reproduction of organisms as a result of the heritable
differences between them.
Natural Selection was discovered by Charles Darwin and Alfred Russel Wallace and is one of the 4 basic
mechanisms of evolution; the others being mutation, genetic drift and migration.
Three Essential Components:
1. Individual differences- within any population, there is variation among individuals for any given
characteristic, and these differences affect individuals’ chances of surviving and reproducing, causing
differential reproduction.
2. Differential reproduction- some individuals will have more offspring than others. The traits that give rise
to differential reproduction have a genetic basis, meaning they are heritable.
3. Heritable- the offspring of successful reproducers will resemble their parents with respect to these
variable characteristics.
Selective Transmission
Over a successive generation of a species with a specific trait, there will be selective transmission of the
heritable parental traits.
This is because of the specific characteristics that are best adapted for survival and reproduction are
going to be reproduced at higher rates.
Eventually the entire population of that species, in that area, will have that trait.
Natural Selection in the Wild
Stabilizing Selection- selection against any sort of departure from the species-typical adaptive design.
This type of selection is usually what researchers observe in the wild; this sort of selection tends to keep
traits stable over generations.
In some cases where there has been a significant change in the environment, then selection favours traits
that are not typical, and evolutionary change can be observed, sometimes quite rapidly.
Example: the evolution of beak shape and size in one particular species of Darwin’s finches, the Medium
Ground- Finch which lives on Daphne Island in the Galapagos. In 1977, a severe drought hit the island and
decimated the vegetation; the small seeds were quickly eaten up , leaving only large, tough seeds that the
finches usually didn’t
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