Introduction Flashcards
(29 cards)
Dobzhansky’s definition of evolution?
A change in the frequency of an allele within a gene pool
What are the 4 postulates of evolution by natural selection?
- Individuals within a species are variable (mutations and shuffling of alleles)
- Some of the variations are passed on to offspring - inheritance
- In most generations, more offspring are produced than can survive
- Survival and reproduction are not random: individuals with the highest reproductive success are those with the most favourable variations - they are naturally selected
Define variation
All life forms vary genetically within a population
Define inheritance
Genetic traits are inherited from parents and are passed on to offspring
Define selection
Organisms with traits that are favourable to their survival and reproduction are more likely to pass on their genes to the next generation
Define time
Evolutionary change can happen in a few generatios, but major change, such as speciation, often takes many thousands of generations
Describe pre-darwinian evolutionary biology
Classifying the organisms around them. Hunter gatherers for biological diversity. Agriculture requires understanding inheritance
Describe Aristotle
Classified organisms into the Scala naturae (natural ladder)
Species had fixed essences. The world is eternal and unchanging. The earth is young ad species were created recently
Describe compte de Buffon
Calculated the age of the earth based on the cooling time of a ball of similar material to the Earth at 75000 years
Describe James Hutton
- Scottish geologist observed rates of processes such as erosion or sedimentation of rock and concluded that enormous lengths of time were required to account for the thickness of exposed rock layers observed
Describe paleontology
Paleontologists (Georges Cuvier and Mary Annings) were finding animal forms that no longer existed - life forms are not fixed
Describe Jean-Baptise Lamarck
All species, including humans, are derived by gradual evolution from other species.
Process is driven by the inheritance of acquired characteristics and by inherent tendency of organisms to progress from simple to complex form
The new of changed features that an organism acquired during its life would be passed on to its offspring
Describe Lamarck’s theory of organic progression
Over time, species originate by spontaneous generation and each evolves up the scale of organisation
In this theory, species do not originate from a common ancestor
Describe Charles Darwin
Darwin’s insights into the nature and mechanisms of evolutionary processes were built on observation on the patterns of variation across the natural world
Was influencedby observations made
- 1838, formulates theory of natural selection. 1854, starts writing
Describe Alfred Russel Wallace
Independently thought out the idea of natural selection as the method for evolution.
Idea was openly acknowledged by Darwin
What did Darwin postulate?
Variation exists in populations, some of this variation must be inherited from parent to offspring, individuals vary in their ability to survive and reproduce and in most generations, more offspring are produced than can survive, survival is non-random
What didn’t Darwin know?
How inheritance works
Assumed blending: if individual inherited an A and an a gene, the two would physically blend in some way to form a new sort of gene
Doesn’t explain traits that disappear and reappear. Each generation would become more uniform
Descrbe mendel
Theory of inheritance in 1865. Segregation of traits in the garden pea
What did Mendel’s work show?
Inheritance is particulate. Genes are passed from parents to offspring. They are discrete and preserved during development and passed on unaltered to the next generation. Genotypes to not blend, but phenotypes can
What is the evidence for evolution?
- species change over time (microevolution)
- lineages split and diverge (speciation)
- new-life forms derive from older forms
- all life forms are related
- earth and life are old
Describe vestigial structures
A useless or rudimentary version of a body part that has an important fuction in other closely allied species (e.g. hair/fur on humans, reduced armour in freshwater sticklebacks)
Describe homology
The same organ in different animals under every variety of form and function.
A characteristic shared between two taxa that is similar because of common ancestry.
Describe phylogeny
Descent from a common ancestor entails a process of branching and divergence. Similar species have a common ancestor, and can be grouped on the basis of common features
Fossil record
Extinction, law of succession (fossils and organims in same geographic region are related to each other) and transitional forms (fossils display intermediate forms)
