B2 Flashcards
Evolution
- Population of living things change over generations
- Organisms best adapted to their environment are most likely to survive (“survival of the fittest”)
- Evolution only occurs in populations, not individuals
- Cumulative change in heritable characterisitcs of a population
Changing Earth- Fossils
Paleontology
Study of fossils
Burrows,footprints and chemicaals rcan remain in fossils
Changing Earth- Fossils
Fossil Formation
- Teeth, shells, bones can resist weathering for long periods of time, in dry environments
- Insects may be trapped in amber
- Impressions/imprints can be left by plants/animals, tracks in soft mud
- fecal matter
- Intracellular spaces of skeletal material can be replaced with minerals (e.g. silica, calcium, iron)
Changing Earth- Fossils
Patterns found
- Different species lived on Earth at various different times
- Complexity of organsims increased
- Living species located in the same geographic region as thei most closely matching fossil
Changing Earth- Fossils
Relative dating
Dating the past
Deeper the sedimantary rock layer= Older fossil
Changing Earth- Fossils
Radiometric dating
Dating the past
Determines the age of rock or fossil by radioactive isotope decay rate
Changing Earth- Biogeography
Biogeography
The study of the variation and geographic distrubution of life on Earth
Changing Earth- Biogeography
225 million years ago Earth had one land mass
Theory of plate tectonics
Supercontinent (Pangea)
Seperated the contintentd by shiftinh tectonic plates
Theory of plate tectonics
- Fossil species older than 150million years were on the same contintent
- The ones younger were on seperate
- Populations evolved after the break up of pangea
Changing Earth- Anatomy
Homologous structures
- Features with similar structures but different functions
- Similiar origin but different use in diffrent species
Changing Earth- Anatomy
Analougous structures
- Similair in function and appearence but not in origin
Changing Earth- Anatomy
Convergent evolution
- Development of similair adaptations from unrelated species
- Occupy equivalant niches on differetn continents
- Due to similar environemtal conditions
Changing Earth- Anatomy
Embryonic development
- Late 1800s: scientists noticed similarities in embryos of different species
- Many structures are similair to common ancestor
- Ex: Homologoud trait such as tailbones
Changing Earth- Anatomy
Vestigal functions
- Rudimentary structures with no useful function
- May have been functional in ancestors
- Examples: Human appendix, wisdom teeth, tail bones, whale skeleton having hips and legs
Changing Earth- Biochemistry
DNA
- Hereditary material in cells
- Each DNA molecule contain many different genes
Changing Earth- Biochemistry
Gene
Segment of DNA that performs a specific function
Scientific Theory
- Model that accounts for all known scientific evidenses
- Requires plausbale explantation
- Altered as new data is gained
Timeline of the evidence of evolution
Lamarkism
Early 1800s, Jean-Baptiste Lamarck
- Inheritance of aquired characteristics
- False concept, but key recognition of environemntal role in driving evolutionary chanfe
Timeline of the evidence of evolution
1830-1860, Charles Darwin
- Natural selection: Result of differiential reproductive success of individuals caused by variations in their limited charecteristics
- All species have inherited traits ehich make them better adapted to survive and reproduce= Survival becomes more common in populations= Evolved populations
Darwins Theory
Overproduction
Number of offspring produced by a species is greater than can survive
Darwins Theory
Competition
Organisms of different or the same species must be compete for limited resources
Dawins Theory
Variation
- No two individuals are alike. sexual reproduction creates varaibility
- Offspring inherit most of the parents traits, not all. Some traits arose randomely
Dawins Theory
Survival of the fittest
Environment ats to select favorable traits. Those with advantages survive and reproduce
Dawins Theory
Speciation
Individuals do not change, populations do
Inherited Variation-mutations
DNA
- Made out of nuecleotides that form genes, this gives the inherited traits
- DNA is usually relicated the exact same but changes can occur sometimes
Inherited Variation-mutations
Mutations
- Random changes in DNA
- Can occur from environemtal fators and erros in copying
- IB: Mutations can occur because of meiosis
- New combinations of alleles are created due to crossing over
Inherited Variation-mutations
Mutations-Neutral
No affect on individuals fintness or reproduction
Inherited Variation-mutations
Mutations-Harmful
- May cause gene disorders or cancer
- reduces individuals fitness
Inherited Variation-mutations
Mutations-Beneficial
- Provides an advandtage to an individual
Inherited Variation
Asexual Reproduction/Reproduction without male
- Recieve exact same DNA as parent
- Offspring identical to parents and siblings
- Only source of variation is mutation
Inherited Variation
Sexual reproduction/Reproduction with two parents
- Are varaiable in phenotype(how they look)
- Offspring inheritis random assortments of genes from either parent
- Allows species to be variable
Variability
- 2 copies of each gene, one from mom, and one from dad
- Random asortment of genes
- Chose different mates
Inherited Variation
Adaptations
- Change in charecteristic of an organism that increases its chance of survival
- Variation in a trait may give adoptive advantage to a species
- 3 types of adaptions
1. Structural
2. Behavioral
3. Physiological
Structural adaptation
Physical characteristic that helps an organism survive in its environment
Behavioral Adaptation
- Something an organism does in response to external stimulus to help them survive
- Ex: hibernation, migration, courtship, nocturnal/diurnal
Physiological Adaptation
A process inside of organisms body that helps it to survive in its environment
Speciation- Forming a new species
Allopatric speciation
- Physical barrier sepertes single interbreeding population into two. mutations not shared
- Narural selection works on seperate populations- inherited differences. populations evolve independetly in response to varying environment
- groups are no longer sexually compatable due to accumalted physical/behavioral differences-> 2 or more different species
Dawins Theory- Speciation
- Individuals do not change, populations do
- Accumaltion of new traits over long periods of times populations become new/different species
Darwins Finches
- They become different species of finches due to geographical isolation
- Overtime the food source they were adapted to distinguished them from one another
Theory of Gradulism
- Speciation occurs slowly
- Fossil records show abrupt changes but we are missing many pieces
Theory of Punctuated Equllibrium
- Many species evolve ver rapidly in evolutionary times
- Speciation usually occurs in small isolated populations, so intemediate fossils are rare
- After initial burst of evolution, spcies are well adapted to their environemt so they dont change much over long periods of time
