Chapter 6: Evolution of the Nervous System Flashcards
What contains all the genetic information of an organism?
The genome/genotype
What is the difference between a genotype and a phenotype?
An organism’s observable characteristics make up its phenotype, while its genetic information that codes for that characteristic is a genotype.
What influences a phenotype?
One’s genotype and environment through epigenetic influences.
What are 2 steps of epigenetic changes we studied?
1) DNA Methylation
2) Histone modification
Explain DNA Methylation and Histone Modification in Epigenetics
1) Methyl group, found in diet sometimes, tags DNA for gene activation or repression.
2) This then leads to Histone modification - it affects how tightly the DNA is wrapped around the histone. If it’s wrapped tightly, its harder to express the gene and if it’s not it’s easier.
Human brains are the product of natural selection. true or false?
True
What is Directional selection? (graph)
Selection that favors a shift in a characteristic within a population. (prefer brown over blue eyes)
What is Stabilizing selection? (graph)
Selection that favors reduced variation in a characteristic within a population. (prefer only brown eyes)
What is Disrruptive selection? (graph)
Selection that favors a divergence in a characteristic within a population. (prefer both brown and blue)
Describe the 3 myths of evolution.
1) Naturalistic fallacy: the assumption that what ‘is’ is what is ‘good’
2) Nature vs Nurture: that theres competition between the two when in reality it’s a mixed influence.
3) Determinism fallacy: the assumption that what is rooted in genetics is unchangeable.
What is Adaptive flexibility?
It’s a term that claims the brain is a physical system designed to adapt and change according to the environment.
What are Spandrels in evolution?
A behavior/structure that is a by-product of an adaptive behavior/structure but is of no use now.
What is an example of a Spandrel?
The belly button - from the umbilical chord.
What do you call features that have adapted to perform a function that is not what it originally was supposed to adapt for?
Exaptations
What is an example of an Exaptation?
Feathers - they were meant to retain body heat but instead birds use them to fly.
What are Analogous features?
Structures between species that LOOK like they have common evolutionary origins but they DO NOT. (e.g. bee wing and bird wings)
How do analogous features come about?
Through Convergent evolution.
What is convergent evolution?
The evolution of a shape/structure in DIFFERENT ways to serve the SAME function.
What are Homologous features?
Structures that ARE SIMILAR because they have COMMON evolutionary origin.
What is divergent evolution?
the evolutionary pattern in which species sharing a common ancestry become more distinct due to differential selection pressure
Identify 6 shared features among vertebrates.
1) Development from a Hollow Dorsal Neural Tube: The head of the embryonic neural tube goes on to form the major subdivisions of the brain, but a fluid series of hollow spaces within the brain—the ventricular system—persists into adulthood.
2) Bilateral symmetry
3) Segmentation of Spinal Nerves
4) Hierarchical control: Higher levels of the nervous system tend to control or modulate lower levels.
5) CNS and PNS separation
6) Functional specialization: Certain physiological and behavioral processes are controlled by specific neural mechanisms, often consisting of specific networks of brain regions operating together.
Identify 3 evolutionary changes to the human brain.
1) Increase in size.
2) Increase in size mostly in Cerebrum
3) Increase in brain convolutions (gyri and sulci)
What is the term used to describe when once evolved traits are no longer useful or are maladaptive due to changes in environment?
Evolutionary mismatch.
