Unit 9 - How we Evolve Flashcards
Evolution and Ecology
ecology and evolution help us understand biodiversity and how it is maintained over time
Biological Evolution
heritable change in a population across many generations
small scale - change in a single gene (microevolution)
large scale - change above the species level (macroevolution)
*macroevolution - process that gives rise to different species
Why Study Evolution
we need to know how organisms interact with each other and the environment
**evolution tells us the history and diversity of life (we are all related!!!) - we all have a common ancestor
Evolution Constant Process
- changes take place all around us
ex: bacteria can develop resistance to antibiotics
Divine Creation
species are permanent and life is unchanging
Plato
he thought every organism was created by god and was perfect
- types were unchanging
- because organisms were created by God, the species couldn’t change
Aristotle
he thought organisms weren’t changing but put them in a heiarchy
scala naturae - he made a heiarchy from imperfect organisms to perfect organisms (once placed in the hiearchy there was no movement to move on it)
Fossils
fossils indicate that there is change over time
- noticed that fossils are found in some layers of sentiment but not in others
- the shallower layers of earth = younger fossils
- the deeper layers of earth = older species
Catastrophism
the idea that major disturbances cause change
- a very big thing has to happen to cause change
- Georges Cuvier thought this
- didn’t think species could change over time
- he thought organisms were coming in from other places because of a catastrophic event
Uniformitarianism
gradual changes over time happen because of natural processes
- small changes build up and cause a change (ex: creation of rivers)
- Charles Lyell thought this
- thought that the same processes that occured in the past occur at the same rate today
*this doesn’t make sense bc it took thousands of years to make rivers
Lamark
he thought that life evolves which is why we have fossils (species change over time)
- lamark was the first to propose a system that explains how life changes over time
the system: Inheritance of acquired characteristics
ex: giraffes have long necks
- he thought the necks had to be stretched to get a longer neck so they can reach for food
**this system isn’t right
Darwin’s Treck
the British Gov. sponsored his trip to map out the coast of South America
- called the voyage of HMS Beagle
- he spent a lot of time on land near South America
Darwin Fossils
fossils looked like South American organisms that are still living
extinct = not living
extant = modern day, currently living
endemic species = species unique to a defined geographic location
- the species ins’t found anywhere else in the world (ex: plants and flowers in Hawaii)
- the species also couldn’t have migrated to get there
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Organisms in Temperate Regions of South America
organisms in temparate regions of South America were more similar to organisms in tropical areas of South America and not like organisms in other temparate regions of Europe
ex: Chinchilla and Mara both live in different areas of South America
- they have differences but also shared similarities
Life is Diverse
ex: all the islands have turtles
- some have long necks and some have short necks
- their neck length depended on what kind of food they ate which depended on the island
the animals that lived on the island at the time weren’t scared of humans because they had evolved there for so long without human contact
Darwin’s Finches
the finches on the Galapagos islands looked like the mainland finches but there were multiple types
(the finches on the island were different than the finches on the mainland)
- the bill shape is an adaptation to different means of food gathering
- galapagos finch species varied by nesting size, beak size, and eating habits
*the beak sizes depended on what kind of food they were eating
Animals on Mainlands Vs. Islands
they were similar to each other but has some important differences
***the species developed on the mainland and then moved to the islands (maybe bc of a storm)
ex: the island iguana has hands that can grip trees better vs. the mainland inguana has softer hands bc the trees are softer
***the island species originally came from the mainland and then adapted to their new island life (which is why they have differences)
Darwin’s Evolution Idea
his idea for how evolution worked was influenced by Malthus’ ideas
- producing more offspring that can survive creates a competitive enviornment for siblings
- variation among siblings would make some individuals have a slightly higher chance of survival (some people are more fit than others)
Wallace
developed his own theory of natural selection as Darwin did
- thought species today came from ancestral species (we are descendents of ancestors that have developed over time)
- natural selection is what causes changes in a species over time
natural selection – the trait that gives people advanatges to survive develop over time
Genetic Variation
there’s variation among individuals within a species
sources of genetic variation:
- mutation (creates new alleles - this happens through reproduction)
Sexual Reproduction – creates new combos of alleles (they can be passed on to the next generations)
ex: we can breed plants to have more leaves (desirable trait)
- variation is heritable (has to be sent on to the next generation)
Organisms and Offspring
organisms can produce more offspring than the environment can support
- competition happens between individuals
- many offspring can’t survive and reproduce
- individuals whose inherited traits give them higher probability of surviving and reproducing in an environment tend to have more offspring than other people
(they have higher fitness!!!)
fitness = ability of an organism to survive and reproduce, passing their genes down
