Unit 2: Evolution Flashcards
Fossil records
Most important evidence
-preserved remains of traces of organisms or its activities
-fossils are formed when an organisms body is trapped under rock and becomes compressed into layers
Erasmus Darwin
All organisms come from a single life source
Lyell
Uniformitarianism -> Earth undergoes slow and steady change
Buffon
Buffon - species could change over time and create new species
Lamarck
Lamarck - Theory of acquired traits (if the environment changes the next generation would acquire a favourable trait)
Vestigial structure
Vestigial - a structure that was useful but now has lost its function (whale’s femur/pelvis, wisdom teeth and appendix)
Analogous structure
Analogous - species without a common ancestor but they have evolved similar features (insect wing and bird wing)
Homologous
Homologous -species with a common ancestor but they traits are now used for different functions (Horse and dogs legs)
Natural selection proposes…
-all species have inherited traits
-the variation in traits are selected by the species struggle for survival
- individuals will produce more offspring than will survive
Stabilizing selection
Stabilizing Selection - most common of the traits are favoured by the environment
Directional selection
Directional selection - one of the most extreme/rare traits are favoured by the environment
Disruptive selection
Disruptive selection - the 2 most extreme/rare traits are selected for while the most common dies off
Sexual selection
Sexual selectrion - allows for greater reproductive success
Behavioural Differences - doing a behaviour to attract a mate
Sexual Dimorphism - striking differences between males and females
Convergent Evolution
Convergent evolution - 2 species without a recently common ancestor evolve in a similar fashion because they exposed to the same environment (analogy)
Divergent evolution
Divergent evolution - when species with a recent common ancestor change to become different species (homology)
Divergent evolution
Divergent evolution - when species with a recent common ancestor change to become different species (homology)
What are the reproductive isolating mechanisms? Give examples of each.
Prezygotic
Ecological - 2 similar species are in different areas
Temporal - species that are fertile at different times
Behavioural - do behaviours that only their own species can recognize
Mechanical - structural difference in repro organs…. no intercourse
Gametic- prevents the sperm and egg recognizing each other
Postzygotic
Zygotic MOrtality - the zygote or embryo do not develop
Hybrid inviability - offspring do not live long enough to be fertile
Hybrid Infertility - sterile
Allopathic speciation
Allopartic Speciation - species is separated so they evolve differently (found effect)
Sympatric speciation
Sympatric Speciation - new species evolve within the same geographic location
Adaptive radiation
a type of divergent evolve where species evolve rapidly from a common ancestor
Genetic Drift (2 types)
Genetics can measure how frequently an allele shows up in a population. Allele frequency can change as a result of chance
Bottleneck effect: small pool of alleles survive a dramatic event and a new population is established
Flounder effect: Few individuals with the same genes and defects leave and establish a new population elsewhere.
Mutation
Changes to a genetic code
-Passed onto offspring through gametes
-Mutations can be harmful, neutral or beneficial
Types of mutation
Point-in a single unit of dna
Non coding area= no change
Insertion or deletion-> always harmful
Gene duplication->when chromosomes don’t crossover equally
Prezygotic
Prezygotic
Ecological - 2 similar species are in different areas
Temporal - species that are fertile at different times
Behavioural - do behaviours that only their own species can recognize
Mechanical - structural difference in repro organs…. no intercourse
Gametic- prevents the sperm and egg recognizing each other
Postzygotic
Postzygotic
Zygotic MOrtality - the zygote or embryo do not develop
Hybrid inviability - offspring do not live long enough to be fertile
Hybrid Infertility - sterile
Non coding area =…
No change and vice versa
