Evolution

Sexual selection

mates looking for signs in other mates for the best possibilities for gene reproduction

Natural selection

 traits that allow us to survive and reproduce in our environment

Adaptations

biological traits that help an individual to survive and reproduce in its habitat

Examples of Adaptations

• Performs certain functions that make an organism better suited for its environment

• Selective attention, memory encoding, and memory retrieval are all mental forms of adaptations

• Ex. racoons have adapted to have specific receptors on their paws that help them differentiate food and non food items

Creators of Natural Selection

• Charles Darwin and Alfred Russell Wallace

  • Focused on the 4 units of evolution including adaptations, mutations, genetic drift and migrations

4 Units of Evolution

1. adaptations

2. mutations

3. genetic drift

4. migrations

Natural Selection

differential survival and reproduction of organisms as a result of the heritable differences between them

Significance of individual differences

within any population there are variation of individuals for any given characteristic

Differential reproduction

affect individuals chances of surviving and reproducing, leading some individuals to have more offspring than others

Heritability

the offspring of successful reproducers will resemble their parents in respect to these variable characteristics

Stabilizing selection

selection against any sort of departure from the species-typical adaptive design

Fitness

label for the abstract property that natural selection tries to maximize

Darwinian Fitness

average reproductive success of a genotype relative to alternative genotypes

Evolution

change in gene frequencies over generations, in part due to the introduction of new gene variants via mutations

Sexual Selection

the component of natural selection that acts on traits that influence an organism's ability to obtain a mate, resulting in differential reproductive success

Examples of Physical survival

• Energetically expensive to produce

• More conspicuous to predators

• Harder to get away from predators

• Increases the males risk of dying

Example of Fitness

Increased chance of mating

Intersexual selection

• involves an interaction between males and females

Intrasexual selection

competition with other males

Mate choice preferences

 female choice picks out males with the best resistance to diseases (best genes available)

Species typical behaviour

allow one to identify a species by observing certain behaviours

4 Types of Species Typical Behaviour

1. Topography - physical form, how they move

2. Habitat Preference - where they go, what they choose to eat, how they pursue and capture food

3. Group Size - whether a species like to be alone vs in a flock

4. Social System - keep animals in captivity and selectively breed those who are more or less aggressive or whatever trait you like

Selfish gene

Genes that contribute to an individual's fitness will consequently get replicated more often increasing in frequency in successive generation

• Natural selection will favour the gene that best serve their own wellbeing

Cooperation

if the actor does something that helps both themself and the recipient

Selfish

f the actor does something that helps themself but hurts the recipient

• Individual who behaves selfishly does not decrease fitness

Group selection

the increase of group success translated into better success for the metaphorical helping gene

• Favours the good of the group only as a side effect of favouring the good of the individual

Forging

finding food

Scanning

keeping lookout for potential predators or other environmental factors

Altruism

behaviour in which the actor incurs a cost to provide a benefit to a recipient

• Individual that behaves altruistically decreases direct fitness by definition

Not altruism

forging/vigilance in groups as the actor gains directly from the behaviour

Eusocial Hymenoptra

in this level of social organization, most individuals spend their lives serving the colony without reproducing

• Includes all ants, some bees and some wasps

• Do not reproduce because of relatedness, colonies are often founded by small number of individuals so they are made up of very close relatives, meaning that it pays to help your colonies

W.D Hamilton Realization

genes for altruism could be successful if they helped identical copies of themselves

Direct Fitness

individuals genetic contribution through its personal reproduction

Indirect fitness

individuals genetic contribution through the reproduction o close genetic relatives

• You can increase your fitness by helping kin to successfully raise their offspring

Inclusive fitness

Direct fitness and Indirect fitness

• Natural selection can favour not only behaviours that increase an individual's own reproductive success but also behaviours that increase the reproductive success of close genetic kin

• Shared genes between relatives can drive the evolution of altruism

Hamilton's rule

• summarized the rule of inclusive fitness with an inequality that predicts when altruistic behaviours will be favoured 

  • Provides a mathematical model to provide predictions about behavioural tendencies (rB>C)

Hamiltons Rule Formula

• r B > C

  • C - the reproductive cost to the actor

  • B - the reproductive benefit to the recipients 

  • r - degree of relatedness between the two individuals, multiplied by the probability that the recipients actually have identical copies of the same gene, or coefficient of relatedness 

Relatedness

• probability that actor and recipient share gene in question

Probability of inheriting genes from parent

50%

Probability of having same gene as sibling

25% from each parent leading to 50% chance

Probability of having same gene as half sibling

25%

Probability of having same gene as first cousin

12.5%

Close kin

individuals in close proximity with you (neighbours, family, etc.)

Cues of kinship

• Mothers association

• Co residence with other children

Signs of altruism

• Alarm calls - altruistic warning of approaching predators

  • Females give alarm calls more often when they live near kin

  • Males leave kin early and almost never give alarm call

Phenotype matching

an evaluation of relatedness between individuals based on an assessment of phenotypic similarity

Direct reciprocity

when individuals help each other and both benefit

Indirect reciprocity

occurs when others help others who have helped others

• By helping another, you establish a good reputation for yourself and overall will be helped by others