Genetics, Hormones & Senses: Natural Selection

  • Created by: Kate Fish
  • Created on: 17-05-17 15:02
What is Natural Selection?
A complex process in which the total environment determines which members of the species survive to reproduce and so pass on their genes to the next generation. Theories of natural selection - Darwin. Laws of Inheritance - Mendal.
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Genetic Variation
Preservation of genetic diversity. Influenced by: new combination of genes, genetic drift, random variation.
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Flow of Material
(Draw flow of material)
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Behavioural Control
Behavioural traits can be under control of one gene. Rothenbuhler (1964) - hygeinic & unhygenic honey bees. Now an important characteristic.
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Behavioural Control 2
Most behavioural traits involve a large number of genes. A facet of developmental biology. E.g Song in male crickets
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Genetic (instinctive) Behaviours
Innate actions (via natural selection). Lorenz & herring gulls. Simple reflex behaviours - knee jerk, fixed action pattern.
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Experimental analysis
Difficult area to investigate. Incomplete information on how genes regulate behaviour patterns. Controls; consider what controls would be required.
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Genes also...
Genes influence processes of development: Nervous system, Sensory perecption. Influences how animals interpret and process information. Interaction of genes and the enviornment. Nature vs Nurture - instinct and learning.
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Natural Selection in Practice
Natural selection remains the single primary explanation for adaptive evolution. Works in conjunction with heritable traits and environmental pressures to act on the entire phenotype of the animal.
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What is stablising selection?
None of the extremes are favoured (not too small or too big) e.g human baby don't want it to be too big or too small
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What is disruptive selection?
Extremes are favoured at both ends
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What is directional selection?
Exteremes are favoured at one end
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Natural selection works with?
1. Genes 2. Hormones 3. Immune system 4. Behaviour
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Adaptive Radiation
Group of organisms diverge into forms filling different ecological niches.
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Convergent Evolution
Organisms have two different ancetrial routes. But because they live in the same enviornment, they develop similar characteristics.
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Divergent Evolution
Organisms have similar ancestrial route but due to different habitats they develop different characteristics
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Parallel Evoluton
Same ancestrial routes and have similar traits but are different due to environmental factors. e.g monkeys and lemurs
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Card 2


Genetic Variation


Preservation of genetic diversity. Influenced by: new combination of genes, genetic drift, random variation.

Card 3


Flow of Material


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Card 4


Behavioural Control


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Card 5


Behavioural Control 2


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