Lecture XIII: Evolution Flashcards
Vertical descent with modification (mutation)
Evolution is the process by which populations of species become better adapted to their environment over time through the accumulation of beneficial genetic mutations (many generations).
Darwin’s proposed mechanism for evolution: Natural selection
Natural selection is the process in which individuals that have advantageous genetic variations in a heritable characteristic will survive and reproduce at higher rates than other individuals.
Microevolution
Small changes in the genetic makeup of populations may occur between generations This is called microevolution.
Macroevolution
Over a long period of time, if a population accumulates enough genetic changes it may become a new species. This is called macroevolution.
What was Aristotle’s theory?
Scala Naturae:
Nature exhibits levels of complexity from simple (air) to most complex (humans)
What is Carolus Linnaeus
Swedish physician and botanist
Believed all species were created for a particular purpose.
Proof was how well-adapted species are to their environments.
He also developed the binomial name system
Unlike Darwin, he thought that Nested hierarchical classification of living things instead of the previous linear classification (scala naturae).
What is George’s Cuvier theory?
Studied fossils found in different sedimentary layers (strata).
Observations:
Older strata have fewer organisms in common with ones alive today than younger strata.
Some species appear and others disappear between strata.
His hypothesis: Catastrophism
Each new strata started after a catastrophy (e.g. flood). Old species went extinct and were replaced with new species moving into the area.
James Hutton and Charles Lyell Theories?
Didn’t believe in catastrophism
Hypothesized that geological strata were deposited gradually and slowly over time at a similar rate that sedimentation occurs today.
Hutton & Lyell’s Hypothesis: Uniformitarianism
This influenced Darwin to extend uniformitarianism (slow change over time) to living organisms.
Jean-Baptiste de Lamark Theories
2 principles:
- Use and Disuse
Body parts that are especially needed for survival get bigger and stronger within an individual while others not needed deteriorate. - Inheritance of acquired characteristics
Traits can be passed to the next generation.
Lamarck’s Hypothesis: Use and Disuse
A giraffe stretches it’s neck to reach food. Neck gets longer over the lifetime of the animal and it is passed on to it’s offspring.
Charles Darwin Theories
Darwin focused on:
Adaptations = Inherited characteristics of organisms that enhance their survival and reproductive success in specific environments.
Adaptive Radiation?
Adaptive Radiation:
Birds beaks over many generations became better suited to the food source available on the island that they lived.
Natural Selection?
Darwin proposed the following mechanism:
Natural Selection
A process by which individuals that have a certain inherited characteristic tend to survive and reproduce at higher rates than other individuals because of that characteristic. These individuals contribute more genetic descendants carrying that heritable trait.
Define Darwin’s Interference
Darwin’s inference:
Individuals with a variation of an inherited character that increases their chances of reproduction and/or survival tend to leave more offspring than other individuals.
What is a Phylogenetic Tree?
A tool still used today to better understand the evolutionary relationship between organisms.
Based on number of shared characteristics (anatomical, genetic, fossil record)
How natural selection works?
The environment in which an organism lives puts certain pressures on them for survival.
Exerted by:
1. The physical environment (weather conditions, availability of ressources)
2. The living organisms they interact with.
Interactions same species:
competition for mates and territories
Different Species: Predator/pray
Competition for resources.
