B2 Flashcards
Evolution
Process by which populations of living things change over a series of generation
Does not refer to individual change
Organisms that are best adapted to their environment will be most likely to survive
Changing Earth - Fossils
Fossil Formation
- Teeth, shells, bones resist weather for a long period of time
- Insects may be trapped in amber
- Impressions left by plants/animals
- Fecal matter
- Intracellular spaces of skeletal material can be replaced with minerals
Changing Earth - Fossils
The complexity of living organisms has _____ from the past to now
Increased
Changing Earth - Fossils`
Living species are usually located in the ___ geographic region as their most closely matching fossil
Same
Dating the past
Charles Lyell (1797 - 1875)
Stated that most geological change was slow and gradual and had been going on over long periods of time
Dating the past
Relative Dating
545 - 525 MYA
* Deeper sedimentary rock layers means they formed earlier → older fossil
Dating the past
Rediation Dating
Technique to determine age of a rock or fossil by radioactive isotope decay rate
Burgess Shale
- Contains the best animal fossils
- One of the most diverse and well -reserved fossil localities in the world
During this period, life was restricted to the world’s oceans
Cambrain Explosion
Evolutionary burst of animal origins
545 - 525 MYA
Changing Earth - Biogeography
Biogeography
The study of the variation and geographic distribution of life on Earth (past and present)
Theory of Plate Tectonics
- 225 MYA Earth had 1 landmass (Pangea)
- Seperated into continents by shfiting tectonic plates
- Fossil of species older than 150 MYA were on the same continents
- Species younger than 150 MYA were on seperate continents
- They evolved after the breakup of Pangea
Homologous Structures
- Features with similar structures but different functions
- Similar origin but different uses in different species
- Forelimbs adapted for different functions, but have similar bone structure
Analogous Structures
- Similar in function and appearance but not in origin
Convergent Evolution
- Development of similar adaptations from unrelated species
- Occupy equivalent niches on different continents
- Due to similar environmental conditions
Embryonic Development
- Late 1800’s: Scientists noted similarity between embryos of different species
- Many structures in an embryo are similar to those found in common ancestors
Vestigal Features
- Rudimentary structures with no useful function
- May have been functional in ancestor
- Present in all species → very compelling evidence for evolution
All organisms share similar _____ molecules and some ____
DNA , proteins
Gene
A segment of DNA that performs a specific functions
Artificial Selection / Selective Breeding
Process of humans selecting and breeding individuals with desired traits
Dramatic changes are produced in species over a relatively short period
Scientific Theory
Model that accounts for all known scientific evidences
* Requires plausible explanation
* Altered/modified as data is gained
Ethical concern behind Artificial Selection
- People question whether it is ethical to breed them for human consumption
- Makes animals unfit to survive in nature
- Can also cause physical and psychological stress for animals
Timeline of evidence of evolution
Aristotle (384-322 BC)
- First to attempt to classify animals
- Recognized species are not stable and unalterable
- Blooded vs bloodless
- First to propose Spontaneous Generation
Timeline of evidence of evolution
Georges-Louis Leclerc de Buffon (1750’s)
- Leading naturalist
- Species could change over time which could lead to new organisms
Timeline of evidence of evolution
Carl Linnaeus (1760’s)
- Founder of binomial nomenclature (genus and species classification)
- The few species at creation became hybrids which led to new species
Timeline of evidence of evolution
Erasmus Darwin (Darwin’s grandpa) (1790’s)
- All life developed from a single source
Timeline of evidence of evolution
Jean-Baptise Pierre Antoine de Money Chevalier de Lemark (Early 1800’s)
- First theory of evolution with a mechanism (Simple species are continually created by Spontaneous generation and then become more complex)
Lamarckism
- Inheritance of acquired characteristics
False concept, but key recognition of environment role in driving evolutionary change
Timeline of evidence of evolution
Charles Darwin (1830-1860)
- Natural Selection - Result of differential reproductive success of individuals caused by variations in their inherited characteristics
Darwin’s Theory of Natural Selection
Overproduction
Number of offspring produced by a species is greater than that can survive and reproduce
Darwin’s Theory of Natural Selection
Competition
Organisms must compete for the same limited resources; struggle for existence
Darwin’s Theory of Natural Selection
Variation
- No two individuls are exactly alike (except identical twins)
- Sexual reproduction creates variability in a population
- Offspring inherit most of parents traits
- Some traits arise randomly (genetic mutation)
Darwin’s Theory of Natural Selection
Survival of the Fittest
The environment acts to select favourable traits (not create them). Those with an advantage survive and reproduce, increasing their numbers
Darwin’s Theory of Natural Selection
Speciation
- Individuals do not change – populations change over time
- Accumulation of new traits over a long period of time
Mutations
Random changes in DNA that provide a continous
Mutations can also occur because of meiosis
Asexual Reproduction
Reproduction without a mate
* Recieve the exact same DNA as aparent DNA
* Only source of variation is mutations
Sexual Reproduction
Production of offpsring by union of gametes from two different parents
Why are sexually reproducing species variable in their phenotype
- Offspring inherits random assortments of genes from either parent
- Therefore, each sibling has a unique combination of genes
- Higher number of genes, creating genetic variability
Adaptations
Change in a characteristic of an organims that increases its chance of survival
Structural adaptation
Physical characteristic that helps an organism survive in its environment
Behavioral adaptations
Something an organism does usually in response to an external stimulus that helps them to survive
Physiological adaptations
A process inside of organism’s body that help it to survive in its environment
Speciation
Forming a new species
Allopatric Speciation
- Physical Barrier
- Natural selection works on seperate populations
- Groups are no longer sexually compatible due to accumulated physical/behavioral differences
Darwin’s Finches
- They became different species of finches due to geographic isolation
- Over time, the food source they were best adapted to distinguished them from each other
Theory of Gradualism
- Specialization occurs slowly
- Fossil record shows abrupt changes but we are missing many pieces
- Fossil records suggest whales gradually evolved from land to water
Theory of Punctuated Equilibrium
- Many species evolve very rapidly in evolutionary time
- Speciation usually occurs in small isolated populations, so intermediate fossils are rare
- After an initial burst of evolution, species are well adapted to their environment, so they don’t change much over long periods
Macroevolution
Evolution of taxonomic groups
* Evidence of divergent evolution: When species rapidly evolved into many species
