Topic 5: Evolution by Natural Selection Flashcards
Natural Selection Summary
- Natural selection is a process in which individuals that have certain heritable traits survive and reproduce at a higher rate than other individuals.
- Natural selection can increase the frequency of adaptations that are favorable in a given environment
- If an environment changes, or if individuals move to a
new environment, natural selection may result in adaptation to these new conditions and give rise to new species
Darwin Made two points in “On the Origin of Species by Means of Natural Selection”
- species show evidence of “descent with modification” from common ancestors (evolution)
- natural selection is the mechanism for “descent with modification”
Three principles of evolution
- There is variation within a population of organisms and this variation can be inherited (passed to the next generation)
- individuals with inherited traits that are better suited for growth and reproduction in a given environment contribute disproportionately to the next generation
- natural selection is the process in which individuals with favourable traits are more likely to surviveand reproduce
Georges Culvier
- Noted that strata were dissimilar to living organisms and that fossils changed between strata (extinction).
- proposed fossil record represented catastrophism (catastrophic events)
- did not believe in evolution
- a succession of life in strata happens because catastrophe leads to local extinction, and different species move into the area
Jean-Baptiste Lamarck
- the apparent disappearance of species was one species changing into another (opposed to extinction)
- hypothesized that species evolved through inheritance of acquired characteristics
inheritance of acquired characteristics
An organism can pass on characteristics that it acquired during its lifetime to its offspring
Darwin’s observations during his voyage
- species traits matched the environment they inhabited
- fossils resembled living species from the same region and that living species resembled other species from nearby regions
- an uplift of rock happens after earthquakes ( influenced principles of geology)
Natural Selection
a process in which individuals with favorable inherited traits are more likely to survive and reproduce
large morphological gaps between
related groups could be explained
by:
branching process of biodiversity, and extinction events
What explains the duality of unity and diversity in living organisms
natural selection
Descent with modification
describes the origin of new species (speciation) form ancestral species
The Galápagos finch species form a
_____ group, because they
descended from a _____________
monophyletic group, single common
ancestor
Darwin’s observations of evolution:
- Members of a population vary in their inherited traits
- populations produce more offsprings than the environment can support, and many offspring fail to survive and reproduce
Darwin’s inference of evolution:
- individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment leave more offspring than other individuals
- the unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations.
Natural selection results in the ______ of populations to their environment
adaptation