Exam 3 Flashcards
Earth’s age
4.55 Billion years
Evolution
Change in allele frequency within a POPULATION from one generation to the next
Selection vs Genetic drift
Selection-species with more advantageous traits are more likely to survive and reproduce
Genetic drift-evolution due to random chance
Microevolution vs Macroevolution
Microevolution-evolution within a species
Macroevolution-evolution at or above species level
Phylogenetic trees
Show the relationships between species
Homologous characters
Common characteristics between multiple species (Ex. having a spinal column)
Vestigial traits
Loss of a function as opposed to a gain
Ex. our tailbone, Emu ability to fly, dolphins ability to smell
Vestigial genes
When a gene is “turned off” because it’s not necessary for survival (aka “pseudogenes”)
Selection
Process by which organisms better adapted to their environment survive and pass on their genes
Relationship between selection, adaptation, fitness, evolution
Species with these traits are more likely to survive
Directional selection
Shift average of a trait in either direction (whole bell curve moves right or left)
Stabilizing selection
Eliminates extremes, (bell curve narrows on edges/less bell shape)
Diversifying selection
Favors extremes, eliminates intermediate (Bell curve in middle splits into two on ends)
Sexual selection
Favoring traits that increase the ability to mate and produce offspring
Sexual selection vs selection for survival
Sexual selection attracts more mates but makes one a target for predators
Coevolution
Continuous evolution between two or more different species
Red queen hypothesis
One evolving to keep up with the other time and time again (keep running just to stay in the same place)
(Ex. Monarchs and milkweeds, orchids and moths, bat’s tongues and flowers, Darwin’s orchid)
Genealogical species concept
Defines species based on evolutionary relationships
Speciation
Formation of new and distinct species in the course of evolution
Allopatric speciation
Physical barrier to gene flow (Ex. mountains, rivers, continental drift)
(Shrimp separated when the isthmus of Panama rose)
Sympatric speciation
No physical barrier to gene flow (Ex. hybridization of plants
Gradualism vs Punctuated equilibrium
Gradualism-slow process of small evolutionary changes.
Punctuated equilibrium-rapid evolution followed by periods of stasis
Evidence for evolution
Uplift of the Andes
Finch beak size evolves in response to rainfall and available seeds in the Galapagos
E. coli experiment
Phylogenies
The development or evolution of a particular group of organisms.
Biodiversity
Variety of life in the world or in a particular habitat
Inputs of light reactions
Light, H20
Speciation rates on a phylogeny
Increase with reproductive isolation
Inputs of Calvin cycle
ATP, NADPH, CO2
Outputs of Calvin cycle
Sugars
Desired product vs byproduct
Desired product-glucose
Byproduct-O2
Chlorophyll
Pigment that turns chloroplasts green
Chloroplast anatomy and role in photosynthesis
Stroma-fluid area inside the cell (cytoplasm of plant cells)
Thylakoid-disk shaped membrane that contains chlorophyll
Light reactions vs. Calvin cycle
LR-occur in thylakoids
Calvin cycle-occurs in stroma
Stomata/guard cell and function
Stomata-pores in the leaves of plants that allow gas exchange
Guard cells-cells surrounding stomata that open of close the pore
CAM vs C3 photosynthesis, process, evolution
CAM-Stomata open during the nighttime (prevent a lot of water escaping)
C3-Stomata open during the day
Role of stomata
Let CO2 into the plant cells, but water can evaporate
Parasitic plants
Energy obtained from host
No need for photosynthesis
Evolution and origin of chloroplasts
Originated from a photosynthetic bacteria that was engulfed by a larger cell
Climate change
Changes in temperature (usually higher), changes in weather patterns (more rain, less rain), more extreme weather events
Historical climate change
Wobbling of the earth, angle changes and can cause events like ice ages
Methods for getting climate data
Dendrochronology-counting tree rings, youngest rings at edge, thicker rings correspond to higher temps/moisture (measure back 13,000 years)
Ice cores/fossil air-collect date, temperature, and CO2 concentration (data back to at least 500,000 years ago
Hockey stick result
Steady rate and then dramatic increase creating a hockey stick shape
Greenhouse effect
Higher CO2 creates higher temperatures
Threats of climate change/why how they’re threats
Glaciers melt-less home for animals Sea levels rise-less area for humans Habitats shift upwards-nowhere to go Populations become more isolated- Lower genetic diversity
Organisms response to climate change
Migrate-move
Phenotypic plasticity-change phenotype (reproducing earlier)
Evolve-beneficial adaptations to arise
Morphological species concept
Species defined by their physical characteristics
Different species have different physical characteristics
Only one useable on fossils
Biological species concept
Species defined by their ability to interbreed and produce offspring
Can interbreed=same species
Can’t=different species
Sometimes hybrids are fertile
Especially in plants
Morphological species concept
PROS Easy to use Only option for fossils CONS Convergent evolution Cryptic species Phenotypic plasticity
Biological species concept
PROS Highly intuitive Directly relates to gene flow CONS Clearly distant species that can still interbreed Useless for asexual organisms
Genealogical species concept
Defines species based on evolutionary relationships
A species is a unique and distinct evolutionary lineage
Genealogical species concept
PROS
Based on evolutionary relationships and DNA
CONS
Hardest to use, (time and money)
Still have to subjectively decide species vs. variety within species
Reproductive isolation
Barriers to gene flow between populations promote speciation
Reproductive isolation is critical to speciation, regardless of the species concept used
Pre-mating barriers
Temporal, behavioral, geographic
Pattern of selection that drives speciation?
Diversifying selection
