Chapter 3 - Descent with Modifications Flashcards
Aristotle (384-322 BC)
- Species fixed, unchanging
- Scala naturae
Linnaeus (1707-78)
- Hierarchical classification
- Binomial nomenclature
- Species fixed, unchanging
Biogeography
the distribution of species around the world
Fossil record (Cuvier)
evidence of extinction of species and change through time
(Hutton & Lyell)
Gradual geological change through time
Therefore, earth very old!
(Malthus)
- Concept of population pressure
Lamarck (1744-1829)
o Theory of inheritance of acquired characteristics
holds that an organism experiencing such a modification can transmit such a character to its offspring.
Darwin’s voyage
1831-1836
Galapagos finches
o Studied 14 species
o Hypothesized that they evolved from common ancestor from mainland
o “One might really fancy that, from an original paucity of birds in this archipelago, one species had been taken and modified for different ends.”
Alfred Wallace
-1823—1913
- Naturalist
- Studied biodiversity of Southeast Asia
- Published a paper on evolution by natural selection alongside Darwin’s first published paper in 1958.
The Darwin-Wallace Principle of Natural selection
- Individuals within a population vary for one or more characteristics (traits)
- Traits are (to some extent) inherited by offspring from their parents
- More offspring are produced than can survive
those with traits that improve survival/reproduction leave more offspring
these favorable traits will accumulate in the population over generations
Evolution
a change in the genetic makeup of a population over time (microevolution)
Frequency of Alleles
Change in the genetic makeup refers to a change in the frequency of alleles in a population
Allele Frequency
the relative abundance of an allele in a population
Adaptation
- In evolutionary terms, an adaptation is some heritable trait that improves the odds for surviving and reproducing in a given environment.
- It is the outcome of natural selection.
- Natural selection can only increase or decrease the frequency of an adaptation in a population
Fitness
- A way of quantifying an organism’s reproductive success
- 3 components:
Survival
Mating success
Number of offspring per mating
POPULATIONS Evolve
- Individuals do not evolve!
- Natural selection acts on populations over many generations
- When the allele frequency in a population has changed, we say that the population has evolved.
Evidence For Evolution
Four types of data:
- Direct observations
- Homology
- Fossil record
- Biogeography
Artificial Selection
man, artificially selects for desirable or beneficial characteristics
Convergent Evolution
- Organisms evolving under similar environments will evolve similar characteristics.
- Results in evolution of analogous traits in different species
- Occurs when they face similar selection pressures due to similarities in their environments
- Evidence of how natural selection leads to adaptations
- Classic example is convergent evolution of placental and marsupial mammals
Australian marsupials closely resemble placental mammals on other continents
Homology
- Homologous structures - inherited from a common ancestor
- structures that have the same embryonic origin but may have a different function.
- May have different functions in different species
- Provide evidence that organisms are related/descended from a common ancestor
Vestigial Structures
- structures with no apparent function. Certain organisms have lost need of appendages, they become useless, and appear to have no function
- Evidence of descent with modification
Fossil Record
- shows changes in organisms over time.
- Evidence that organisms have changed over time
- Evidence that organisms we see today evolved from pre-existing species
- Fossil Record provides evidence of transitional species
