Chapter 18: Evolution and the origin of species

Evolution

The change in organisms throughout earths history

• “descent with modification”

How does evolution happen

Descent with modification

Who originally proposed decent with modification

Charles Darwin

How do organisms evolve from common ancestors

• Change in genetic makeup of organism leads to new trait potentially becoming prevalent

• Many organisms descend from this point and have this trait

• New variations continue to arise some adaptive and persist, leading to new traits

• With new traits, a new Claude is determined

What was the ancient philosophy in western thoughts

Ideas about nature and life from Greek and Roman times through the Middle Ages

What was the ancient philosophy in non-western cultures

Spiritual and philosophical traditions like Hinduism, Buddhism, Chinese philosophy, and Islamic thoughts contributed diverse understanding of life

What was the age of reason (1700-1800)

• Rise of scientific inquiry and the use of reason

• Emphasis on observation, experimentation, and challenging established doctrines

What did Aristotle contribute

• foxed ideal species

• Scala naturae “ladder of nature”

  • Ranking of complexity

What did Linnaeus do

• orderly, nested classification system

• Binomial naming

• Grouping based in similarity

What did James Hutton do

• slow continuous processes → geological features

• Gradualism

What did Charles Lyell do

• Uniformitarianism expanded Hutton’s ideas

  • Same geological processes in past as today, same rate as today

  • I spired Darwins theories

What did Lamarck do

linked evolution to adaptation

• extinct species replaced by descendants with new features

• These adaptations helped the, survive in environment

• Darwin agreed with these ideas

• Proposed inheritance of acquired characteristics but it’s wrong and Darwin rejected ideas

  • “Lamarckism”

What were Darwins two main ideas

• Descent with modification

• Natural selection

How did Darwin get his theory

• Traveled mostly to South American including the Galapagos

• Collected plants, wildlife, fossils

• Observed species’ geographic locales and adaptions

  • Beak shape of finches

Who was Wallace

Gave letter to Darwin with similar ideas to him and helped contribute ideas of natural selection

What is the definition of Darwins idea of descent with modification

All present life is related through “decent with modification” from a common ancestor in the past

• Extinction is common

What is the dentition of Darwin’s Henry of natural selection

• Natural selection is the mechanism for evolution

What did Darwin observe to help with his natural selection theory

• heritable variation exists in most species

  • Characteristics of offspring vary and these variation are variable

  • Farmers can enhance small heritable variation by artificial selection (breeding)

• More offspring are produced that can survive; there is competition for resources

What are the misconceptions of evolution

• Evolution is just a theory

• Individuals evolve

• Evolution explains the origin of life

• Organisms evolve on purpose

• Species are always evolving into “higher” or “better” beings

• Evolution creates new forms of life by dramatic mutations

• Evolution is a completely random process

What is the therapy of evolution by natural selection

• explains both diversity and unity of life

• accounts for much of form and function

• can predict outcome of environmental change

Can individuals evolve

No, populations evolve

What is not explained in Darwins theory

• Origin of life

• How variation arises

• How inheritance works

• Why variation still exists

• “Sudden” changes in fossil records

• Source of totally “new” characters

What is an example of evolution not leading to perfection

Octopus vs human eye

Is evolution a completely random process?

No, species adapt to environment and pass traits on

What evidence shows evolution

• Direct observation

• Fossil record

• Homologous structures and vestigial structures

• Convergence

• Biogeography

• Molecular biology

What is an example of direct observation of evolution

Soapberry bugs adapt to new food source, smaller beaks

Example of fossil records showing evolution

Extinct species showing transition of adaptive from over time; whales

Homologous structures

Forms related by common ancestry

• human, dog, bird, and whale limbs have similar construction but different functions

• Embryos

• Shared homologous build evolutionary trees

Vestigial structures

Remnants of ancestral (homologous) structures with no present adaptive function

• blind cave salamanders have eyes

• Descended from species that could see

• Legs on snakes are used somewhere else or hidden

Convergence

Unrelated species have similar adaptions (analogous structures) under similar environmental conditions

• natural selection acted in the same way under the same conditions

• Torpedo shaped for swimming; white colored in snow

Biogeography

Distribution of species corresponds to geographic history; development and presence of species based on location

• groups evolving before Pangea broke up

• Marine vs tree dwelling iguanas

Molecular biology

• DNA analysis supports evolution

• Closely related organisms have similar DNA

• Evolution of new functions for pretend after mutations

Cellular and molecular homologies

• similarity of cell structures, proteins, and DNA corresponds to relatedness

• Genetic code is universal

What are species

Taxonomic term for a group of organisms; basic unit of biological classification

Morphological species

Based. on physical similarities and differences; smallest set of organisms that look alike

Ecological species

A set of organisms adapted to a specific set of resources; defined by an ecological niche

Phylogenic species

Smallest distinct set of organisms that share a common ancestor

Biological species

Set of populations whose members potentially interbreed in nature to produce fertile, viable young and do not successfully interbreed with other such groups

Pre-zygotic barriers

Prevents fertilization

• temporal isolation

• Habitat isolation

• Behavioral isolation

• Gametic isolation

• Mechanical isolation

Temporal isolation

Species have different breeding schedules

Habitat isolation

Members of species move or are otherwise separated

Behavioral isolation

Certain actions or behaviors (or the lack of them) impacts reproduction

Mechanical isolation

Shape of the male reproductive organ varies among male damselfly species and is only compatible with the female of that species, keeping species reproductively isolated

Gametic isolation

Sperm of one species may not be able to fertilize eggs of another species

Post-zygotic barriers

Act after a hybrid zygote is formed

• reduced hybrid viability, fertility, and hybrid breakdown

Reduced hybrid viability

Embryo fails to develop or is weak

Reduced hybrid fertility

Hybrid survives but is sterile or almost so

Hybrid breakdown

Second generation hybrids are feeble or sterile

Micro evolution

Population changes over time

Macro evolution

The process that gave rise to her species and higher taxonomic groups with widely divergent characters

Allopathic speciation

Involves geographic isolation

• dispersal

• Vicariance

• Adaptive radiation

Sympatric speciation

Occurs in the same geographical area; chromosomal errors in cell division

• mating behavior

• Habitat differentiation

• Chromosomal errors in cell division

  • Aneuploidy

  • Autopolyploidy

  • Allopolyploidy

Aneuploidy

too many or too few chromosomes

Autopolyploidy

Two or more complete sets of chromosomes after division, results from errors in meiosis

Allopolyploid

Gametes from two different species combine

Hybrid zones

Reconnection area where two closely related species interact and interbreed

Gradual speciation

species diverge gradually through time with small steps

Punctuated equilibrium

species exhibit a large change in relatively short period of time followed by long periods of stasis