B2 Flashcards
Evolution
POPULATIONS of biotic organisms change over a series of generations
Does NOT refer to individual change instead cumulative change in heritable characteristics the population)
Evidence For Evolution: Fossils
Show geological change is gradual and has been occurring for a long period of time (based on fossil deposits)
Relative Dating- Deeper sedimentary rock is older
Radiometric Dating- Determines age of rock/fossil
Patterns Found- Complexity of organisms have increased and living species are located in the same geographic region as most closely matched fossil
Evidence for Evolution: Biogeography
Variation and geographic distribution of life in the past and present
Theory of Plate Tectonics- Earth used to be one supercontinent (Pangea) which separated into smaller continents by shifting plate tectonics
Evidence for Evolution: Anatomy (Homologous, Analogous, Vestigial)
Anatomical comparisons suggest organisms with similar structure evolved from a common ancestor
Homologous Structure/ Features- Similar in structure but not in function
(Divergent evolution)
Analogous Structure/Features- Similar in function and appearance but not in origin (convergent evolution)
Vestigial Features- Features that are no longer useful now but may have been useful to an ancestor
Convergent Evolution
When two unrelated species develop analogous traits (evolved genetically independently from each other so no common ancestor but are similar because they occupy similar niches)
Evidence for Evolution: Biochemistry
Similarities in genetic code (DNA is hereditary)
Artificial Selection
Humans selecting and breed individuals with desire traits (Dramatic change over short time)
Buffon
Suggested species could change overtime
Linnaeus
Suggested few species at creation became hybrids=New species
Erasmus Darwin
All life came from a single source (common ancestor)
Lamark
First theory of evolution with a mechanism
Suggested new species are created from spontaneous generation (evolved from dead matter) and become more complex
Lamarckism- Organisms want to change for the better and so they are more compatible with the environment so they produce new parts. These physical changes in an organism can be passed down to offspring (Acquired characteristics can be inherited)= FALSE but recognized environments role in evolution
Darwin’s Theory of Natural Selection
All species display inherited variation. This variation makes some individuals better adapted to survive and reproduce= Survival advantage that becomes more common in the population= Evolved population
Natural Selection works to select traits that increase chance of survival in population (pepper-moth gizmo)
5 Points of Darwin’s Theory
Overproduction- # of offspring is greater than the amount the environment can sustain
Competition- Species compete over limited resources (Inter and Intra)
Variation- Sexual reproduction= Variability in population
(Offspring inherit most of parents traits but some are random (genetic mutation)
Survival of the fittest- Environmental acts to select favourable traits which gives survival advantage and increases chance of survival; individuals best adapted to their environment are more likely to survive and reproduce (selection by natural=natural selection)
Speciation- Individuals do not change, populations do. Accumulation of new traits over a long time=New species
Sexual Reproduction
Production of offspring via union of two different but compatible sex cells
Variation in phenotype because Meiosis causes reshuffling of genes so offsprings inherited random combos of alleles and chromosomes
Mutations
Random changes in DNA
Causes of Mutations
Environmental factors, errors when cells are making copies of DNA, meiosis (new combos of alleles are created due to crossover)
Impacts of Mutations
Neutral Mutations- No immediate impact on individual fitness or reproductive success
Harmful Mutations- May cause genetic disorders
Beneficial Mutations- Can give selective advantage that can be passed on to offspring
Asexual Reproduction
Reproduction without mate so offspring is identical to parent (only source of variation is mutations)
Adaptations
Characteristic changes as a result of natural selection (inherited trait) that increase chance of survival
Structural- Physical characteristics
Behavioural- Done in response to external stimulus (migration, hibernation)
Physiological- Process inside organisms body
Allopatric Speciation
Accumulation of genetic differences between populations while they are geographical isolated
Physically Barrier- Separates a single interbreed population into 2 or more groups (Mutations are not shared with other population)
Natural Selection works separately on the population so they evolve independently in response to different environments.
Then groups are no longer sexually compatible due to accumulated physical and behaviour differences so since they can’t reproduce together they are not the same species anymore
Example- Darwin’s Finches (Became different species of Finches due to geographical isolation
Theories of Evolution: Gradualism
Species change at a slow, steady and gradual pace; Evolution occurs by gradual accumulation of small changes (not represented by fossils which show abrupt change)
Theories of Evolution: Punctuated Equilibrium
Rapid bursts of speciation followed by long periods of stasis or equilibrium where little to no change occurs because after initial burst of change it is assumed that species is well adapted to environment
Macroevolution
Evolution on a grand scale
Cambrian- Species rapidly evolved into many species
Palaeozoic- Eradicated 90% of known marine species
Permian Extinction- Unknown cause but suspected to be tectonic plates
Mesozoic- Asteroid assumed to cause extinction (Dinosaur era)
Divergent Evolution
Evolution of species from a common ancestor (Homologous)
Darwin’s Finches
