AANT 211 Chapters 1-2: Concepts of Evolution; Tinbergens; Genetics and Microevolution

Early Notions of Evolution are shaped by

(1) Ideas about time

(2) Ideas about creation/the creator

Time as a Cycle

Proceeds in Phases with multiple destructions and creations

Phases for Time as a Cycle

(1) Golden Age

(2) Phase of Degeneration

(3) Cataclysm/Destruction

(4) Divine Intervention & Start of Next Cycle

Judeo-Christian Tradition

Single Creation, so no more cycling; Retained Similar Ideas of Time as a Cycle; believes Decline is inevitable

Phases for Judeo-Christian Tradition

(1) Golden Age - Garden of Eden

(2) Degeneration

(3) Cataclysm (Apocalypse)

(4) Intervention

Modern Ideas - Deep Time

Big Bang to Now

- Space and Time begins at a signle point

- Billions of years

- Linear, Asymmetric

Modern Ideas - Progress

World Improves Over Time

- Renaissance (14th-17th c.)

- Enlightenment (18th c.)

- Scientific Revolution (16th-17th c.)

Greek Philosophy - Plato

(~428-348 BCE)

Believes the creator is perfect and that creation is perfect

Greek Philosophy - Aristotle

(~384-322 BCE)

Believes in the continuity in nature. The inanimate to animate. Believes in Scala naturae.

What does 'Scala naturae' mean?

Scale of Nature

Who originated the concept of Scala naturae?

Aristotle

What is the Great Chain of Being?

A hierarchical structure that arranges all beings from lower to higher forms of existence.

Where are humans typically placed in the Scala naturae?

Near the top

Great Chain of Being is considered ________________________

- Linear

- Gradation/Hierarchy that is divinely ordained.

- Permanent

- No "missing links"

- FIXED, unchanging

Who was Jean-Baptiste de Lamarck?

A French naturalist known for his early 19th-century theories on evolution.

What concept did Lamarck combine with the Great Chain of Being?

The concept of progress.

What did Lamarck believe about organisms over generations?

He believed that organisms progress up the chain over generations.

What was Lamarck's belief about the origin of new organisms?

He believed new organisms appeared on lower rungs via spontaneous generation.

What did Lamarck propose about inanimate and animate matter?

He proposed that inanimate matter could become animate through spontaneous generation, a belief that was later proven false.

Lamarack's Ideas

(1) All Organisms have needs

(2) Needs lead to different habitual behaviors

(3) Differential use of body parts

(4) Theory of Use and Disuse

(5) Inheritance of acquired traits

Which of Lamarack's Ideas are true?

(1) All Organisms have needs

(2) Needs lead to different habitual behaviors

(3) Differential use of body parts

Which of Lamarack's Ideas were not true?

(4) Theory of Use and Disuse

(5) Inheritance of acquired traits

In which century did Charles Darwin develop his theories?

Mid 19th century

Who had similar ideas to Charles Darwin?

Alfred Russel Wallace

What did Charles Darwin base his evidence on?

Extensive observations

What mechanism of evolution did Charles Darwin propose?

Natural Selection

Darwin's 1st Observation

Populations can increase exponentially

Darwin's 2nd Observation

Populations tend to remain stable

Some exceptions to Darwin's 2nd Observation

Seasonal Variation and Occasuonal increases/decreases also knwon as "boom" or "bust" cycles

Darwin's 3rd Observation

Natural Resources are limited

Darwin's 1st Inference

There is a struggle for existence

Why is there a struggle for existence?

More individuals are produced than the environment can support resulting in only a fraction of offspring born each generation survives

Darwin's 4th Observation

Variation; characteristics vary so no 2 individuals are exactly alike

Darwin's 5th Observation

Much of variation is HERITABLE, that is passed down from the parents to their offspring

Darwin's 2nd Inference

Survival and reproduction are not random; they depend on traits.

What determines who is more likely to survive and reproduce according to Darwin's 2nd Inference?

The traits that are best fit for the environment.

What is differential fitness?

It refers to the concept that individuals with traits better suited to the environment are more likely to survive and leave offspring.

Darwin's 3rd Inference

Unequal survival and reproduction leads to change over time.

What does Darwin's 3rd Inference imply about population change?

The change in population is with respect to those traits.

Darwin's 1st Observation talks mainly of

Overpopulation

Darwin's 3rd Observation and 1st Inference talks mainly of

Competition

Darwin's 2nd and 3rd Inferences talks mainly of

Natural Selection

Gregor Mendel

- Mid 19th c. to Early 20th c.

- Modern Sunthesis ("Neo-Darwinism)

- 1930s-1940s

Darwin (1859) vs Modern Synthesis (1942): Variation

Darwin: Unknown

Modern Synthesis: Changes in "genes; Random mutations due to copy errors and damage

Darwin (1859) vs Modern Synthesis (1942): Inheritance

Darwin: Vertical

Modern Synthesis: Vertical

Darwin (1859) vs Modern Synthesis (1942): Selection

Darwin: Natural, Artificial, Sexual

Modern Synthesis: Natural, Artificial, Sexual, Genetic Drift

Darwin (1859) vs Modern Synthesis (1942): Time

Darwin: ~500 million yrs

Modern Synthesis: ~2 billion yrs

Evolution

Descent with modification, or genetic change in a population through time

Forces of Evolution

- Natural Selection

- Genetic Drift

- Gene Flow

- Mutation

Genetic Drift

Change in genetic composition due to sampling (random event)

Gene Flow

Movement of genetic material between populations

Microevolution

Species and allele frequencies change over time

Speciation

Lineages split and diverage

Macroevolution

New Life-forms derive from older forms

Common Ancestry

All life-forms are related

Evidence for Selection

(1) Adaptation

(2) Paleontology

(3) Comparative Anatomy

(4) Comparative Embryology

(5) Artificial Selection

Adaptation Process

a trait; a process by which heritable features, anatomical or behavioral, that enhance the fitness of an organism relative to its peers, increase in frequency in the population in succeeding generations

What is one way fitness can be measured?

Genetic contribution of a genotype to the next generation

What is another way fitness can be measured?

Proportion of individuals of a given genotype who survive and reproduce

What is evidence that adaptation is one result of selection?

- Camouflage/Concealment (for safety and stealth)

- Mimicry (predator avoidance)

- Imperfect Adaptations

Example of Comouflage/Concealment

Peppered Moth

Most were light before the Industrial Revolution

Most were dark during the Industrial Revolution

Now, because of anti-pollution laws, most are light

Examples of Imperfect Adaptations

Panda False Thumb

Red Panda False Thumb

Eye

Back and Feet

What are Imperfect Adaptations?

Makeshift traits; "jury-rigged" or "good enough"

Panda False Thumb

Developed from a wrist bone (radial sesamoid) over millions of yrs

Red Panda False Thumb

Not as effective as true opposable thumb; good enough to grab bamboo but can't rotate it, and if its too long then it impedes on their walking

Vertebrate Eye

Since the optic nerve cuts thru the photoreceptors, it means there's a blind spot

Cephalopod Eye

Don't have optic nerve thta goes straight back, but this means they don't have a big field of image bc the eyes are not as mobile as the vertebrate eye

Diabetic Retinopathy

high blood sugar contributes to damage to small blood vessels, and these blood vessels get in the way and block vision

Back and Feet

Human bodies weren't originally designed for upright walking. Instead of a full redesign, evolution modified structures from four-legged ancestors, leaving "good enough" solutions with flaws.

Spine: Evolved from horizontal to vertical, forcing it to bear the body's weight on a single axis. An S-shaped curve helps balance but creates weak points prone to back problems.

Feet: Changed from grasping to weight-bearing. The big toe aligned with the others and arches formed for shock absorption, but the foot must be both flexible (for uneven ground) and rigid (for push-off), creating ongoing stress and injuries.

Paleotology

Continous change over time; Newer fossils more likely to resemble living forms than older fossils

What are homologous structures?

Structures that share a common ancestry.

What is the significance of shared ancestry in homologous structures?

It indicates inheritance from a recent common ancestor.

Divergent Evolution

When species with a shared common ancestor become more different over time, developing unique traits and forming new species to adapt to different environments or lifestyles; associated with homologous structures

Give an example of homologous structures.

Vertebrate forelimbs

What is a key characteristic of Vertebrate forelimbs in terms of form and function?

They have similarity in form but not necessarily in function.

Analogous Strucutures

Similar function; Independent function; Convergent Evolution; Adaptation to similar needs, but in very distantly related species

Convergent Evolution

When unrelated species independently develop similar traits or characteristics because they face similar environmental pressures or live in similar ecological niches

Vestigal Structures

"evolutionary baggage" basically features that has lost most or all of its original function over the course of evolution

Examples of Vestigial Structures in Humans

Appendix, tailbone, wisdom teeth, rudimentary ear muscle, goosebumps, nictitating membrane

Example of Vestigial Structure

Whales has a pelvis and femur

Comparative Embryology

the study of the formation, early growth, and development of different organisms

Artificial Selection

Human Intervention and "Selective Breeding"

Ethology

Study of animal behavior with emphasis on behavioral patterns that occur in natural environments

Niko Tinbergen's 4 questions

Asked about any product of evolution including behavioral traits

Tinbergen's Question on Adaptation

What is its FUNCTION? What is the trait there to do?

Tinbergen's Question on Mechanism

What is its MECHANISM? How does the trait work?

Tinbergen's Question on Ontogeny

What is its DEVELOPMENT? How did the trait come to be?

Tinbergen's Question on Phylogeny

What is its EVOLUTION? What is the trait's phylogenetic history?

Tinbergen's Question on Culture

What role does CULTURE play? How did culture help to develop the trait and variation of the trait?

Ontogeny Explanation

Description of an organism's development from DNA code to the forms of different life stages

Mechanism Explanation

Description of an organism's structure and how its mechanisms work

Phylogeny Explanation

Description of the hisotry of a species as reconstructed from its fossil precursors and DNA evidence

Adaptation Explanation

Explanation for the characteristics of a species based on how they give a selective advantage

Proximate Questions

Address mechanisms that produce behavior/trait

Ultimate questions

Address evolutionary significance of behavior/trait

Evolutionary Biologists

focus strongly on ultimate causation (Phylogeny and Adaptation)

Molecular Biologists

focus strongly on proximate causation (ontogeny and mechanism)

Protein Structure

(20 kinds) amino acids and peptides

Function of a Protein

Highly variable! When brooken down, can be used as building blocks, can be used as enzymes and hormones. Depends on its structure

DNA are in the

nuclei (chromosome)