Evolution Flashcards
What is biological evolution?
A genetic change in a population over generations
What is fitness?
How well an individual is able to reproduce within its environment
What are the components of fitness?
Survival + reproductive success
What is sexual selection?
Selection of traits that give an individual an advantage in attracting mates, even if these traits are neutral or harmful for survival
What are they types of sexual selection?
Intrasexual selection and intersexual selection
What are selection pressures?
External agents which affect an individual’s ability to survive and reproduce within an environment
What are biotic selection pressures?
Living organisms within the same ecosystem that interact with the affected individual and affect fitness
What are abiotic selection pressures?
Non-living factors within an individual’s environment that affects fitness
What are the characteristics of a selection pressure?
- act on all stages of the life cycle
- may act for many generations
- act on the phenotype
What is essential for natural selection to occur?
- system of reproduction
- inherited variation
- differential reproductive success
- changing environment
- selection pressures
What were Darwin’s observations?
- Organisms have great potential fertility which enables populations to grow exponentially
- Natural populations normally do not increase exponentially but remain fairly constant in size
- Natural resources are limited
- Variation occurs among organisms within a population
- Variation is heritable (offspring look like their parents)
What were Darwin’s inferences?
- A struggle for existence occurs among organisms within populations
- Individuals show differential survival and reproduction, favouring advantageous traits (natural selection)
- Natural selection, acting over many generations gradually produces new adaptions and new species
When may vestigial organs arise?
When a species changes its lifestyle
What are species found in the fossil record known as?
Chronospecies (paleospecies)
What is punctuated equilibrium?
Evolution consisting of period of no or very little change followed by relatively large changes in a relatively short space of time
What is an example of punctuated equilibrium?
Horseshoe crabs have existed unchanged for approximately 250 million years
What were key concepts when Darwin was developing his ideas about evolution?
Hutton and Lyde’s ideas that the earth was old and continually changing
How did Darwin describe evolution?
“Descent with modification”
What book presented a mechanism for natural selection?
The Origin of Species
What is macroevolution?
The descent of different species from a common anscestor over many generations
What is micro evolution?
Changes in gene frequency in a population from one generation to the next
The genetic code is an example of a ________
Homology
What are some examples of biotic selection pressures?
- predation
- competition
- disease
What are some examples of abiotic selection pressures?
- climate
- topography
- habitat