Unit 7

Charles Darwin 1831 – Unpaid naturalist - HMS Beagle Explored coastlines for ~5 years Noticed that many plants & animals on the Galapagos Islands looked like those on the South American coast Also noticed finches in different areas with different beaks

Malthus Every organism has the potential to produce many offspring Only a limited number of offspring survive and reproduce Population – interbreeding individuals of a species that live in the same geographical area

Darwin Individuals with traits better suited to ENVIRONMENT more likely to survive and reproduce When they reproduce, the number of individuals in the population with this trait will increase This is evolution by natural selection

UNDERSTANDING CHECK

More of Darwin’s Conclusions Organisms differ from place to place because habitats present different challenges ENVIRONMENT is the driving force behind evolution

1859 – On the Origin of Species… Controversial because… Species change  new species Apes are close relatives of humans

1859 – On the Origin of Species… Supported by… 1. Inherited variation exists within genes of every population or species 2. In a particular environment, some individuals are better suited to survive and reproduce

1859 – On the Origin of Species… Supported by… 3. Over time, traits that make some individuals better tend to spread in that population 4. LOTS of fossil evidence that living species evolved from organisms that are now extinct

Recent Updates Reproductive isolation can lead to populations becoming different species Rate of evolution Gradualism – Darwin - slow & steady Punctuated equilibrium – Stephen J. Gould – short bursts followed by nothing

Recent updates Selective pressure can increase the speed of evolution Bacteria & antibiotic resistance Natural selection can lead to a change in gene frequency over time

UNDERSTANDING CHECK

Evidence of Evolution 1. Fossils 2. Anatomical comparisons 3. Developmental patterns 4. Nucleotide sequences

Fossils Relative dating – Location in sedimentary rock Absolute dating – Radioactive/radiometric dating to determine age Transitional forms Can infer lifestyle from structure s

Herbivore vs. Carnivore

Land vs aquatic vs aerial

Nocturnal vs diurnal

Anatomical Comparisons Analogous structures – similar functions, different origins Homologous structures – different functions, similar origins Vestigal structures – no function – remnant of evolutionary past

Analogous Structures

Homologous Structures

Development Patterns – show common ancestry

Nucleotide Sequences DNA sequence of nucleotides makes you who you are So the more alike the DNA sequence of 2 individuals is, the more closely related they are Chimpanzees & human 98.6% identical

More Vocab Divergence – one species changes over time to become 2 different species Speciation – Process by which new species form