LECLERC DU BUFFON
-French scientist who studied anatomy, examining body structure and function.
-He was puzzled by features which serve no purpose.
-Example: why do pigs have an extra toe that doesn’t even touch the ground,
-Species had been created in a perfect form but changed overtime.
Charles Linnaeus
suggested life changed overtime.
Erasmus Darwin (grandfather of Charles Darwin)
thought that all life evolved from a original source.
There was no explanation around this time since there were no mechanisms.
CHEVALIER DE LAMARCK
Proposed a mechanism for evolution of species through 2 principles
Use and Disuse
structures that an Individual used, became larger and stronger and structures which weren’t used got smaller and weaker.
Inheritance of Acquired Characteristics
Individuals could pass characteristics onto their offspring that they had acquired over their lifetime.
Issues with Lamarck’s Theory
traits can change over an individual’s lifetime, but it does not change their DNA or how their traits are passed on.
-For Example: a giraffe cannot “stretch” its neck over its life and pass on the trait of a longer neck to its offspring.
ORIGIN OF SPECIES
- Charles Darwin made a book for species evolution.
-He was worried he would get backlash so he prepared outline of his book and when he died he instructed his wife to publish it.
-He was aware that his ideas could be controversial. so he continued to gather evidence and revise his work, he collected more evidence overtime.
Alfred Russell
received a letter from a biologist named Alfred Russell outlining a similar theory, so Darwin felt nervous.
- He later published his book and it sold out on the first day.
THE THEORY OF EVOLUTION BY NATURAL SELECTION TESTBOOK
- overtime population changes as advantageous characteristics become more common
therory of natural selection infernces
textbook
- Individuals of certain populations compete for resources
- some individuals will inherit charteristics that give them a better chance of surviving and reproducing
therory of natural selection obsrvations textbook
- in each gen, individual produces more offsrpint than there are adults
- population dont continue to grow in size
- food and many reosurses are limited
- indiudals within all populations vary
- many varations are heritable
THE THEORY OF EVOLUTION BY NATURAL SELECTION
- the way in which the environment, or nature, favours the reproductive
success of certain individuals over others
-Evolution was just a result of natural selection occurring overtime.
darwins theroy key observations
All healthy populations produce far more offspring than can survive
All individuals exhibited heritable variability
darwins theroy conclusions
Some individuals will have better change of success than others
Their traits are therefore more likely to be passed onto the next generation
“Survival of the Fittest”
- Herbert Spencer used the phrase “survival of the fittest” to describe the process of evolution
- misleading as it does not mean survival of the largest or strongest (fit) organism!
-Its more based on reproductive success, the most fit organisms are the ones who have the most reproductive success.
-You have a lot of offspring, and they survive and thrive.
-The species that are able to adapt to change can survive!
