PSYCH 1XX3 Lecture Notes - Lecture 12: Kin Selection, Heritability, Hymenoptera
Psych 1XX3:
Module 3 and 4: Evolution
Introductions to Adaptations:
Adaptations: The functional systems and subsystems, that animals and humans are made up of
Adaptations: Are biological traits that help an individual to survive and reproduce in its habitat
Adaptations perform a specific function, to better suit it to its environment
Ex: Eyes enable you to see danger and food through use of reflective light
Raccoons are nocturnal, and front paws are very sensitive
Bats enables them to navigate through night using sound waves echolocations.
“Higher” mental processes:
Selective attention
Memory encoding
Memory retrieval
Word recognition
Refer to adaptive functions of the brain. Therefore, cognitive psychologists are also
adaptationists. They break down large scale cognitive problems into adaptive problems, and
then look for the adaptations that solve those problems.
Evolution by Natural Selection:
Adaptations result because of relevant genes in interaction with relevant aspects of the
environment
Natural Selection was discovered by Charles Darwin and Alfred Russel Wallace. Natural
Selection is one of 4 basic mechanisms of evolution.
Other three is, mutation, genetic drift and migration.
Natural Selection: Differential survival and reproduction of organisms as a result of heritable
differences between them.
3 essential components of Natural Selection:
1. Individual differences: There is variation between individuals for a characteristic.
2. Differential Reproduction: These differences affect chances of reproducing and surviving.
Some individuals have more offspring than the other.
3. Heritability: The traits that give rise to differential reproduction have a genetic basis. The
offspring of successful reproducers will resemble their parents with respect to these
characteristics.
find more resources at oneclass.com
find more resources at oneclass.com
Ex:
Blue and red fish. Blue fish are camouflaged = good. Over time more blue fish reproduce. This
causes selective transmission (more blue fish being produced because color is a heritable trait).
Over successive trials the characteristics that are best adapted for survival and reproduction are
going to be reproduced at higher rates.
Eventually this will cause the entire fish pop. to be blue if this pattern continues.
Natural Selection in the wild:
Stabilizing Selection: Selection against any sort of departure from the species typical-adaptive
design
Keeps traits stable. But sometimes there is a significant change in the environment that causes
rapid evolutionary change.
Ex: Medium ground finch - Island of the Galapagos. Able to study natural selection within a
single generation.
1977 - Severe drought caused lack of vegetation. Only tough seeds were left to eat, birds that
had big beaks remained and survived. From 1976 population to 1978 population Beak size
increased dramatically. 1978 change persisted, beak size is inheritable.
When drought ended though and vegetation returned the beak size went back to what it was,
but other changes may be permanent.
Reproductive Success = Fitness:
Natural Selection is not only those who are best at surviving but those best at reproducing
Darwinian Fitness: Average reproductive success of a genotype alternative genotypes
To describe how good a genotype is in leaving copies of his genes in the next generation
relative to other genes.
Evolution: A change in gene frequencies over generations
Sexual Selection:
Reproduction through male and female gametes.
Ex: Peacock - male (pursues female with feathers)
Peahen - female (if agrees will lay hens and raise chicks w/o any male help)
Peacocks tail is energetically expensive to produce, more conspicuous to predators, harder to
get away from predators, increases risk of dying. Not very helpful in physical survival.
Therefore he sheds the tail at end of breeding season.
This tail though increases his fitness by increasing his chances of reproduction.
Sexual Selection: The component of natural selection that acts on traits that influences an
organism’s ability to obtain a mate
find more resources at oneclass.com
find more resources at oneclass.com
Elk / Red deer - competing for dominance status (be the stag) to get to monopolize a “harem” of
females.
Stags (one with massive antlers) are more vulnerable than females, do not have much stamina
in running, and is likely to get stuck in snow, Stags shed antlers at end of breeding season.
Peacock and Stag: Both traits have negative effects on survival. For the elk: antlers are used in
combat, for the peacock: tail feathers are used in courtship
Diff is that elk antlers are used as weapons and females don't care about antlers.
Selective force:
Peacock feathers = female choice
Elk antlers = Success in combat
Therefore Sexual Selection: The component of natural selection ( the differential reproduction of
types) that result from differential access to mates
1. Being chosen by opposite sex
2. Defeating same sex rivals in competition
Ex: Peahens like peacocks with more eyespots (pretty circles) even just 1-2% more and like left
and right symmetry.
Male Choice Preferences:
Female choice picks out males with best resistance to disease.
Best genes for being healthy
Species Typical Behavior and the Comparative Approach:
Every species has its own behavior.
Behavior are evolved, species specific adaptations
Test hypothesis about adaptive functions
Ex: Sandpipers: 3 variations: Sanderling, Semipalmated, Dunlin
Look similar but can tell difference by behavior. Their signature way of foraging
Sanderlings run toward waves and pick at the insects and wait for another way. Feet move
rapidly like windup toy
Species Typical Behavior:
Physical form - typography - way species moves and looks
Habitat preference – where they go, what to eat, how to catch
Group size - prefer to be alone or in a flock, when do they fly south
Social system - mate monogamously or polygamously children raised together or other
Sigal Balshine studies this
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Adaptations: the functional systems and subsystems, that animals and humans are made up of. Adaptations: are biological traits that help an individual to survive and reproduce in its habitat. Adaptations perform a specific function, to better suit it to its environment. Ex: eyes enable you to see danger and food through use of reflective light. Raccoons are nocturnal, and front paws are very sensitive. Bats enables them to navigate through night using sound waves echolocations. They break down large scale cognitive problems into adaptive problems, and then look for the adaptations that solve those problems. Adaptations result because of relevant genes in interaction with relevant aspects of the environment. Natural selection was discovered by charles darwin and alfred russel wallace. Selection is one of 4 basic mechanisms of evolution. Other three is, mutation, genetic drift and migration. Natural selection: differential survival and reproduction of organisms as a result of heritable differences between them.
