Fitness Flashcards
What does ‘fitness’ refer to in evolutionary biology?
The relative probability of survival and reproduction of a given genotype
Remarkably difficult to calculate precisely
What is an example of a genetic condition that illustrates the concept of fitness?
Sickle cell disease
Heterozygotes for sickle cell disease are less likely to get malaria, illustrating heterozygote advantage.
What is meant by ‘levels of selection’?
Debate over whether selection operates at the level of species, groups, families, individuals, or genes
What is Hamilton’s rule?
Natural selection of genes that lead to social actions via the sharing of these genes between performer and recipient
Altruism occurs as long as rb > c
Where b is the benefit to the recipient, c is the cost to the performer, and r is the degree of relatedness
What is ‘inclusive fitness’?
Direct fitness plus indirect fitness (fitness of related offspring)
Also known as kin selection.
What is sexual selection?
A mode of natural selection where typically female choice influences the evolution of traits
This can lead to characteristics that appear maladaptive but may indicate ‘good genes’.
True or False: Species are selected in evolution.
False
Evolution operates on individuals within populations, not on species as a whole.
What do social insects exemplify in evolutionary biology?
The complexities of altruism and social behavior
Most social insects are sterile, with only the queen reproducing.
Fill in the blank: Altruism is the behavior of an animal that benefits another at its own _______.
expense
What is the significance of ‘haplodiploidy’ in social insects?
It explains the genetic relatedness of individuals, where females are diploid and males are haploid
In haplodiploidy, a female is more closely related to her sisters than to her own offspring.
What does the term ‘gene’s eye view’ refer to?
An evolutionary perspective focusing on genes as the unit of selection
Popularized by Richard Dawkins, it emphasizes individual advantages rather than species benefits.
What are the two types of fitness described by Bill Hamilton?
- Darwinian or direct fitness
- Inclusive fitness
Direct fitness refers to survival and production of offspring, while inclusive fitness includes the fitness of related individuals.
What is the primary critique of Hamilton’s rule?
- It is highly unlikely that there is a ‘gene for altruism’
- But altruistic effects can be produced by responding to individuals with similar genotype (e.g. detected by smell)
- Particularly likely to occur when ‘r’ (relatedness between individuals) is high e.g. social insects
What does the term ‘runaway sexual selection’ mean?
A process where traits become exaggerated due to female preference
This can occur until the costs of such traits outweigh their benefits.
What is a key example of a maladaptive character in fitness studies?
The peacock’s tail
It may reduce survival but indicate good genes to potential mates.
