LIFESCI 3C03 Chapter Notes - Chapter 1: Melanin, Group Selection, Melanocortin 1 Receptor

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Ecology Textbook Reading Chapter 1
Natural Selection, Ecology, and Behaviour
Watching and Wondering
Tinbegen’s fou why uestions
Proximate explanations: explain how an individual comes to behave in a particular way
during its lifetime
1. Causation: mechanisms by which behaviours are expressed, e.g. sensory and nervous
systems, hormonal mechanisms, skeletal-muscle control
2. Ontogeny (development): how and when the behaviour develops in the individual, e.g.
genetic and developmental mechanisms
Ultimate explanations: explain why and how the individual evolved a behaviour
3. Function: adaptive advantage, why the behaviour provides an adaptive benefit
4. Phylogeny: evolutionary history of the behaviour in the species (ultimate)
Natural Selection: changes in gene frequency that rely on variation within traits to give
advantages to certain individuals that possess them under specific environmental conditions
and heritability that allows passing of these gene variants from parent to offspring
1. Variation: individuals within a species differ in morphology, physiology, and behaviour
2. Heritability: traits are passed from parent to offspring via genes
3. Competition: between individuals for resources
4. Adaptation: selection of beneficial variants
5. Evolutionary change: under environmental change
Genes and Behaviour
- For behaviour to evolve:
There must be behavioural alternatives in the population
The differences must be heritable (or some proportion)
Some behavioural alternatives must confer greater reproductive success
- Gene differences can bring about differences in behaviour
Drosophila and honeybees: foraging, learning, and singing
- Rovers: wander in search of food (heterozygous in foraging gene), better at short-term
memory of olfactory cues, do best under patchy food and high larval densities
- Sitters: remain in one small area to feed (homozygous for sitter allele in foraging gene),
better at long-term memory of olfactory cues, do best when food is uniformly
distributed and larval density is low
- In the absence of food, rovers and sitters do not differ in general activity.
- In honeybees, changes occur to the foraging gene expression at age three weeks and
when older bees are not present in the hive that cause worker bees who do not leave
the hive to do so in search of pollen
MC1R: mate choice and camouflage
- MCR1: melanocortin-1 receptor, expressed in melanocytes that produce melanin
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