Evolution Flashcards
Creationism
a higher being created life on earth as we know it today
Selection Pressure
- When resources are scarce, competition for resources occur and natural selection takes place
- Under high selection pressure, only the fittest survive
Divergent Evolution
- The large scale evolution of a group into many different forms
- RIMs isolate population then gradually genetic differences accumulate
- homologous structures
Convergent Evolution
- The evolution of similar traits in distantly related species that evolve under similar types of selection pressure
- analogous structures
Parallel Evolution
-Two similar, genetically related species changing in similar ways but away from the ancestral type
Isolation
-A population of a species cannot mate with any other populations of the same or similar species to produce viable offspring due to environmental factors such as distance or factors such as incompatible mating habits
Adaptive Radiation
-Many different species develop from a common ancestor
Gene Pool
-The complete set of all alleles contained within a population
Genetic Variation
- The number of differences in alleles within a population
- The greater the variation, the more likely the chances of species survival in the event if a drastic change in the environment
Gene Frequency
-Refers to the proportion of alleles that are of a particular type
Mutation
-An alteration in an individual that differentiates it from the rest of the species in a way that may or may not be advantageous
Genetic Drift
- The change in allele frequencies of a population due to chance
- Action on gene pool - random change in small gene pool due to sampling error in propagation of alleles
Gene Migration
- The movement of genes in and out of a population due to chance
- Action on gene pool - change in gene pools due to immigration or emigration of individuals between populations
Founder Affect
- A species is introduced to a new environment by a few members of the species
- The individuals survive and reproduce and a new population is formed
- can cause speciation
Bottleneck
A large population undergoes a decrease in size so that relatively few individuals remain
Single Gene Mutation
With mistakes in replication; one nucleotide switch may cause a change in a protein (eg. sickle cell anemia)
Gene Duplication / Deletion
Error in DNA replication may cause a gene to repeat or be deleted
The new combination may lead to a variant form of the original protein
Recombination
During meiosis, “crossing over” occurs between chromosomes which vares the combination of genes going together into separate gametes
Adaptation
an inherited trait or set of traits that improve the chances of survival and reproduction of organisms
Structural Adaptation
Adaptations which involve the modification of the composition or structure of an animal or plant
Physiological Adaptation
Adaptations which involve the modification of chemical / enzyme production in an animal or plant
Behavioral Adaptation
Adaptations which involve the modification of the actions of an animal or plant
Non-Random Mating
inbreeding or selection of mates for specific phenotypes (assortative mating) reduces frequency of heterozygous individuals
Natural Selection
individuals with the more desirable variations will survive and pass them on to future generations
What is the Hardy-Weinberg equation?
p^2 + 2pq + q^2 = 1
Directional selction
Occurs in response to an environmental stimulus which favors one form of a trait (peppered moth)
Stabilizing selection
selection that favors the intermediate trait (birth mass fr humans)
Disruptive selection
selection that favors phenotypes of both extremes (eg. butterflies changing to be orange or white to mimic poisonous butterflies)
Sexual selection
- competition for mates (non-random mating)
- examples: mating calls, bright colours, fighting
Palezoic era
590 - 250 MYA
Cambrian period extensive diversification of life
all fossils from this era are from the sea
by the end of Ordovician period many modes of life had evolved including bottom feeders, scavengers, carnivores, and colonies
What occurred during the invasion of land?
- only few phyla made it successfully to land
- plants evolved from photosynthetic protists (green algae)
- plant success is because of adaptations that protect against desiccation and provide support
- success of insects due to body plan, structures for conserving water and exchanging gases
- vertebrates invaded 360 million years ago - earliest were the amphibians
- the ozone layer formed
Mass Extinctions
- 5 major extinctions
- the 4th / most drastic extinction occurred in the Permian period
- 96% of all species of marine animals may have became extinct
- the 5th major extinction occurred 65 MYA this was when the dinosaurs became extinct
What were the causes of the extinctions?
- extinctions have multiple causes
- change in environmental conditions played an important role on regional scale
Mesozoic Era
- 250 - 65 MYA
- time of drought and glaciation
- few kinds of marine organisms survived - ones that did began to evolve rapidly
- the oldest flowering plant 127 MYA - diversified to become the dominant type of plant
- dinosaurs became extinct 65 MYA
- mammals appeared 200 MYA
Cenozoic Era
- 65 MYA to present
- extensive deserts formed in North America, the Middle East, and India
- deteriorating climate
- sharp differences in habitats
- regional evolution
- rapid formation of many new species
microevolution
the change in allele frequencies within a single species or population
Macroevolution
- evolution on a larger scale above the species level eg. flowering plants evolving from seeding plants
- most often gradual evolution (stasis)
- may be the result of catastrophism, the combined result is a punctuated equilibrium
What are the mechanisms of macroevolution?
- stasis
- exaptation
- mass extinctions
- adaptive radiation
- co evolution
Who came up with the idea of Pangea
Wegener
What is the origin of life?
reactions due to hydrogen burning of alpha particles will produce other elements - carbon, oxygen, and nitrogen
What were the earliest fossils?
cyanobacteria and stromatalites
Process of fossilization
- often in freshwater / marine environments
- dead organism is covered in sediment creates and anoxic environment
- organic tissues (bone) are replaced by minerals
Species
a group of populations that interbreed with each other in nature and produce fertile offspring
Reproductive isolation
the end of gene flow between populations
What are RIMs
Reproductive Isolating mechanisms that ensure that interbreeding between species is not successful
What are the prezygotic isolating mechanisms (5)
- Behavioral - mating calls differ
- Temporal - mating seasons differ
- ecological - mating environments / habitats differ
- mechanical isolation - lock and key doesn’t fit
- Genetic - sperm wont penetrate the egg because it doesn’t have the right chemical composition
What are the postzygotic isolating mechanisms (3)
- zygote mortality - offspring won’t develop
- hybrid in viability
- hybrid infertility
What is a common origin of new species?
- geographical separation
- the split populations will likely be in different environments - adaptations will occur in each environment
- the groups may encounter RIMs if they reunite after too long
Intrinsic isolating mechanism
populations become so genetically different they develop biological characteristics that prevent effective breeding
Extrinsic isolating mechanisms
geographical barriers that results in speciation
Sympatic speciation
same native land - speciation without separation common in plants
Allopatric speciation
the formation of extrinsic isolating mechanisms ex. great wall of China
What were the earliest primates
prosimians (tree shrews, lemurs etc.)
-posses traits common to later primates - opposable thumb, acute sense of sight
What are anthropoids
all primates other than prosimians, old and new world monkeys etc.
Co-evolution
- two species interact so closely with one another, that they evolve together
- a change for one will mean death for the other unless it changes as well
What is the evidence for evolution?
- Evidence from the fossil record
- molecular evidence - same DNA structure, code for amino acids the same way,
- anatomy (homologous or analogous) - Vestigial organs (structures with no function ie. appendix)
Homologous Structures
structures in different organisms with different functions likely the results of one common ancestor ex. pentadactyl limb
Analogous structures
structures in different organisms with similar functions evolved due to similar selection pressures (wings on different animals)
What was Darwin Wallaces theory of Natural Selection?
- variations exist within a population
- some variations have higher advantage than others (survival or to reproduce)
- organisms have learned to produce more offspring that can can survive “survival of the fittest”
- over time offspring of survivors will make up a larger proportion of the population “descent with modification”
