Studied by 4 people
My class's unit 3 flashcards
Evolution
A change in the genetic composition of a population over time
Microevolution
Evolution below the species level
Macroevolution
When genetic changes give rise to new species/genera/families/classes/phyla
Speciation
Macroevolution that is only evolution of species
Genes
Physical locations of chromosomes within each cell of an organism
Alleles
Different forms of DNA
Genotype
Complete set of genes in an individual
Phenotype
Actual set of traits expressed in an individual
Mutation
Occasional mistake in DNA copying process produces a random change in genetic code
Most mutations are _________
Detrimental
Recombination
When chromosomes are being duplicated and a piece of a chromosome breaks off and attaches to another chromosome
Evolution by artificial selection
Humans determine which individuals to breed
Unintended results of artificial selection
Herbicide resistance, antibiotic/antibacterial/drug resistance
Evolution by natural selection
Environment determines survival + reproduction
Alfred Wallace
Put unifying theory of evolution together along with Darwin
Charles Darwin
Put pieces of unifying theory of evolution together along with Wallace; naturalist on HMS Beagle
On the Origin of Species by Means of Natural Selection
Described Darwin’s theory of evolution
Fitness
An organism’s ability to survive + reproduce
Adaptations
Traits that improve fitness
Gene flow
Process by which individuals move between populations and alter genetic compositions
Genetic drift
Change in genetic composition of a population over time as a result of random mating - more impactful in small populations
Bottleneck effect
Drastic reduction in population size that reduces genetic variation
Bottleneck effect issues
Diseases, less adaptability, low fertility, can cause extinction
Extinction
When the last remaining individual in a species dies out
Founder effect
A change in genetic composition because a population descends from a small number of colonizing individuals
Range of tolerance
Limits to the abiotic conditions (temperature, humidity, salinity, pH) of a species
Fundamental niche
The suite of abiotic conditions under which a species can survive, grow, and reproduce
Realized nice
Range of abiotic + biotic conditions under which a species actually lives
Species distribution
Where the species actually lives
Niche generalists
Species that can live under a wide range of conditions
Niche specialists
Species that live under a narrow range of conditions
Fossilized organisms
Organisms are hardened into rocklike material when buried under layers of sediment
Global mass extinctions
When large numbers of species went extinct over relatively short time periods (5)
Largest global mass extinction
251 mya, 90% of marine species and 70% of land vertebrates went extinct
Global mass extinction (most recent)
End of Cretaceous period (65 mya) - ½ of species (including dinosaurs) went extinct b/c a meteorite caused a dust cloud that stopped photosynthesis
Sixth Mass Extinction
Current - human caused
Community ecology
Study of interactions among species
Symbiotic relationships
2 species live in close association with one another
Competition
Struggle of individuals to obtain a shared limiting resource (mutually harmful)
Competitive exclusion principle
2 species competing for the same limiting resource can’t coexist
Resource partitioning
2 species divide a resource based on differences in behavior/morphology
Temporal resource partitioning
Same resource, different times
Spatial resource partitioning
Same resource, different habitats
Morphological resource partitioning
Evolution of different body sizes/shapes
Predation
1 animal kills and consumes other animal
Parasitoids
Animals that lay eggs inside other organisms - when eggs hatch, parasitoid larvae kill host by consuming it from the inside out
Parasitism
1 organism lives on/in a host [other organism]
Pathogens
Parasites that cause disease
Herbivory
When an animal consumes a producer
Mutualism
2 species benefit each other
Commensalisms
Interactions in which 1 species benefits and 1 is neither helped or hurt
Keystone species
Not abundant but have large effects - more significant role than abundance suggests
Ecosystem engineer
Species that creates/maintains habitat
Ecological succession
The predictable replacement of one group of species by another group of species over time
Primary succession
Succession that begins w/ bare rock + no soil
Secondary succession
In areas that have been disturbed but haven’t lost their soil
Pioneer species
Can colonize new areas rapidly and grow well in full sunshine
Climax community
(historical) final stage of succession, but no longer recognized
Theory of island biogeography
Habitat size and distance from the mainland are important in determining species richness
A majority of livestock species come from:
Donkeys, buffalo, cattle, goats, horses, pigs, sheep, chickens, ducks, geese, and turkeys
Effects of low genetic diversity
Harder to survive environmental change, prone to inbreeding depression
Effects of high genetic diversity
Wider range of genotypes, improved chances of survival
Data-deficient species
No reliable data
Extinct species
Existed as recently as 1500 but don’t today
Threatened species
High risk of extinction
Near-threatened species
Likely to become threatened
Least-concern species
Widespread and abundant
Intrinsic value
Value independent of human benefit
Instrumental value
Value because it is an instrument or tool to accomplish a goal
Provisions
Goods produced by ecosystems that humans can use directly
Native species
Species that live in their historical range
Exotic/alien species
Live outside their historical range
Invasive species
Exotic species that spread rapidly and cause harm
Kudzu vine
Native to Japan and Southeast China, introduced in the US in 1876 to reduce erosion
Zebra mussel
Native to the Black Sea and the Caspian Sea, cargo ships pumped out ballast water with the mussels
Silver carp
Native to Asia, outcompete native species in the Great Lakes
Overharvesting
Individuals are removed faster than they are replaced
Convention on International Trade in Endangered Species of Wild Fauna and Flora
UN regulations (183 countries) from 1973
Primary productivity
The rate at which solar energy is converted into organic compounds via photosynthesis (kcal/m²/yr)
Gross Primary Productivity (GPP)
The total rate of photosynthesis in a given area - amount of energy plant takes in + glucose made (kcal/m²/yr)
Net Primary Productivity (NPP)
Rate of energy stored by photosynthesizers in a given area, after subtracting the energy lost to respiration (kcal/m²/yr)
The 2nd Law of Thermodynamics
Energy transfers from one organism/thing to another
Trophic levels
The different levels of the food chain
Photosynthesis equation
Sun energy + CO_2 + H_2O → C_6H_{12}O_6 + O_2
Chemosynthesis
Energy created from chemicals
Respiration equation
Reverse of photosynthesis - produces ATP
Producers
Autotrophs - make their own food
Consumers
Heterotrophs - obtain food by eating others
List of trophic levels
Producers → Primary consumers/herbivores → Primary/tertiary consumers/carnivores
Omnivores
Eat both plants/animals
Scavengers
Not predators, feed on dead organisms - opportunistic
Detritivores
Feed on dead or dying organisms - cast offs (like leaves)
Decomposers
Break organic dust into nutrients to enter cycles
Food chain
Depicts the flow of energy from one organism to the next
Food web
Shows an interlocking pattern of food chains
Positive feedback loops
1 incident → another → another → … → another
Negative feedback loop
1st thing → 2nd thing → … → 1st thing → 2nd thing → …
Trophic cascade
When one part of the food chain is altered, it affects the other organisms higher/lower on the chain
Species diversity
number of different species
Species richness
The number of different species in an ecosystem
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