lecture 12 Flashcards
evolution
Grand unifying theory in biology
In biology we refer to evolution as an inheritable change from onr generation to the next in the characteristics of individuals in a population.
evolution =
change
Example of evolution
Examples: finding an egg in a pond, the egg loses it tail and becomes a frog and then lays an egg. Then it starts again that’s just a change.
What do living things have in common?
Living things share ancestors
Who do humans share ancestors with?
Humans share ancestors with primates.
What is natural selection?
A functional association between individual traits and average reproductive success. Natural selection is about what makes you good at reproducing.
Example of natural selection
Mice have fur that help them survive and reproduce.
What are the three basic observations of Darwin?
Organism differ from each other they are variable.
Some of the differences among organisms are inherited. Some traits were inherited and some were not.
More organisms are produced than survive to reproduce in their turn.
Relationship between natural selection and evolution
natural selection is when organisms with certain characteristics tend to produce more offspring than other organisms in the same population. Natural selection is not evolution but it can cause evolution. If natural selection acts on a characteristic that is inherited, then evolution may result.
What is the evidence for evolution?
The Fossil record: Fossils are mineralized remains of organisms. Evolution does not predict that there will be fossilization. Evolution predicts a pattern: any fossils found will be consistent with the descent with modification from common ancestors.
When did the earth form?
Earth formed 4.5 billion years ago.
When did the oceans form?
Oceans formed 4 billion years ago.
When did fossilprokaryotes form?
Fossil prokaryotes formed 3.5 billion years ago.
When did oxygen in the air started?
Oxygen in air started 2.5 billion years ago.
When did fossil eukaryotes started?
Fossil eukaryotes started around 2 billion years ago.
When did fossil muticellular start?
Fossil multicellular started 1.5 billion years ago.
When did fossil animals start?
700-800 million years ago
When did fossil mammals start?
about 225 million years ago
Fossil therapsids
more than 290 million years ago
Fossil reptiles
300 million years ago
fossil amphibians
around 368 million years ago
fossil jawed fish
more than 400 million years ago
Fossil jawless fish
more than 500 million years ago
fossil homids
around 6 million years ago
fossil apes
more than 30 million years ago
fossil primates
around 50 million years ago
fossil homo
around 3 million years ago
fossil hominids
around 6 million years ago
fossil homo sapiens
around 300 000 years ago
fossil homo
between 2.5 million and 3 million years ago
pyramid of khufu
0.005 million years ago
Whale example of a fossil transition
whales don’t have fins but the ancestors of whales had 4 legs. The ancestor whales after them has pelvic fins and the modern whales don’t have it.
Biochemistry
Pseudogenes.
Universality of DNA AS THE genetic material. Universality of codons. We have all evolved from the same ancestors. Pattern of genetic similarity…
Where do similarities come from?
Similarities have to do with sharing ancestors not on how similar we look.
example of pseudogenes
We have a broken gene that should make vitamin c but its broken and that mutation stops us from making vitamin c. The same thing happens for chimpanzees.
Comparative anatomy
Comparing the anatomy of different organisms.
Homologous structures demonstrate common descent.
For example the front limbs of a variety of animals.
Structures in different species that are similar because of common ancestry.
Vestigial structures
demonstrate descent with modification.
A feature of an organism that is a historic remnant of a structure that served a function in the organisms ancestors.
Superfluous embryonic structures
Demonstrates descent with modification for example de anus tail from the chick and the embryo. Agrees with fossil record and biochemical evidence.
When did primates show up?
Primates showed up 65 million years ago and we evolved into humans.
Ardipithecus
ramidus
timeline 4.5 million years ago to 3 million years ago
Africa
Probably bipedal tree dweller
chimp size brain about 325 ml
no evidence of tool use
Australopithecus afarensis
3 million years ago
Africa
Bipedal, terrestrial and tree dweller
chimp size brain (about 425 ml)
no evidence of tool use
Homo erectus
1 million years ago
Africa, Eurasia
Bipedal and terrestrial
about 1000ml
simple tools and probably fire
