Natural Selection

Evolution

Evolution

Small changes over long periods

Historical phenomenon

Phenotypic

Appearance of the genes

Lamarck's Theory

Theory of inheritance of acquired characteristics

During your life, you experience new changes and then pass it onto your offspring

Example of Lamarck’s Theory

Inheritance of acquired characteristics

Giraffe passed the traits of having long necks because their ancestors kept stretching their neck to eat the leaves to tall trees and grew their neck over time

Natural Selection

The mechanism of evolution, how it happened

Other people who made theories about how evolution works

Erasmus Darwin, Jean Baptistery Lamarck

William Paley

Natural theology

Charles Darwin

Rich guy who when on a long voyage learning about how organisms were different from place to place

Collected a lot of evidence and studied finches

When did Darwin go on the Beagle voyage

1931 - 1936

How long did Darwin take to develop his theory?

1937 - 1959

Alfred Russel Wallace

Sent Darwin a letter that he had the same idea

Wasn’t rich and collected samples of orangutang for museums (by killing them)

Believe life/resources was unlimited at the time

When did Wallace send a letter to Darwin?

1958

Competition

Out compete the others

Since resources are limited, not everyone will have the resources to survive and some will have more than others

Who came up with the idea of Competition?

Malthus (based on the course of human population)

Variation

There were variations between individuals

Such as teeth to eat better fruit to allow more energy for reproduction

Affects ones ability to survive and reproduce

Reproduction

Maximizing reproduction to pass down your genetics

Inheritance

Passing down genetics to offspring

Finches

Studied by Darwin

They have different beak sizes based on their diet

Adaptation

A feature shaped by natural selection, promoting survival and reproduction

Fitness

The relative ability of an organism to survive and transmit its ends to the next generation

Be better than other animals to have success

There is not global fitness, just the local fitness of the area

Direct fitness

Number of your genome copies you pass directly to the next generation

Counting babies

Indirect fitness

Number of your genome copies passed indirectly to the next generation via kin

Inclusive fitness

Number of genome copies that are passed in total to the next generation

Direct + indirect fitness

Inclusive fitness theory (kin selection)

Natural selection favours traits that maximize inclusive fitness

Both the genes are spread through both direct and indirect fitness

Hamilton's Rule

c < b * r

You are less likely to go out of the way to save someone who isn’t related to you

The more closely related you are, the higher than chance

2 brothers = 8 cousins in terms of genetics

Humans are special as we also help non kin

Typological thinking

Species are unvarying

There was always a dog, wolf, elephant

They just evolved into their best form (ideal types/essences)

No variation

Evolutionary thinking

Variation within species is the essence

Why some primates do certain things, when some are better than others

Individual = samples of population

Based on probabilities, not certainties

Tree thinking (phylogenetic)

Variation between species from LCA

Examine when traits arose and why (what pressures occurred at that time)

What was the massive shit in thinking towards evolution?

Humans are the most evolved species and all species are evolving to be like humans

Not directional

Selection imparts an advantage to certain individuals in a particular environment at the particular moment

Mutations

Drives evolution and creates variation

Is quite rarely and usually doesn’t work

Genetic drift (Neutral Theory of evolution)

Random fluctuations in allele frequencies

Population bottleneck

Contraction of population size due to evironmental events/ecological factors

Finches: Drought, reducing genetic diversity (small beak ones die while bigger beaks lived)

Founder effect

Founding of a new population by a non representative sample

Finches: A group of finches moved to another island, limiting genetics to only the finishes within that group

Incidental by product

Something that is trivially adapted

Bones: Contain calcium for structural integrity thus are white and is not something evolution is selecting for or against

Phenotype

A description of your physical traits

What you see and its behaviour

Genotype

Your habitable genetic identity

Phenotypic plasticity

The ability of one genotype to produce more than on phenotype when exposed to different environments

Milk: Drink more milk = taller, drinking less milk = shorter

Behaviour

How animals interact with the environment and each other

Their response is carried out by musculoskeletal system

Relies on genetics, neurobiology, endocrinology, physiology, evolution and ecology

Fox domestication

Only foxes that reacted nicely to being pet were allowed to breed

After a few generations certain traits such as spotted coats started to show which is also common to other domesticated animals

Pleiotropy

One gene affecting other phenotypic traits

Behavioural ecology

Evolutionary theory applied to behaviour

Same conditions apply

• Competition

• Variation

• Reproduction

• Inheritance

Sociobiology

Applying evolutionary principles, specifically natural selection to behaviour

Tinbergen's 4 Questions and Levels of Analysis

Adaptive value, phylogeny, mechanism, and ontogeny

Adaptive value (function)

How does the behaviour contribute to survival and reproduction (fitness)?

Evolutionary history (phylogeny)

What is the evolutionary history of the behaviour?

Causation (mechanism)

What is the mechanistic basis of the behaviour, including chemical, anatomical and physiological mechanisms?

Development (ontogeny)

How does development of the animal, from zygote to mature individual, influence the behaviour?