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164 Cards in this Set

  • Front
  • Back
The Scientific Method
1. Observation
2. Form hypothesis
3. Test hypothesis
a. Experimentation
b. Comparison
4. Draw conclusions
5. Refine hypothesis
6. Generalization
Proximate mechanisms
How does it work?
Ultimate causation
What is it for?
Adaptation
any trait that enhances an individual's survival and reproduction
HOMOLOGY
similarity by common descent
VESTIGIAL TRAITS
homologous structure that is either rudimentary or no longer used
CONVERGENT EVOLUTION
independent evolution of traits through similar selection pressures
ANALOGY
similarity due to convergent evolution
LaMarck's evolutionary theory:
1. Through use and disuse, structures change over an individual's lifetime.
2. These acquired characters are passed on to descendants.
Darwin's theory of evolution by natural selection:
1. More individuals are born than can survive to reproduce.
2. Individuals vary in most traits
3. Individuals with certain traits are more likely to survive and reproduce
4. Variation is at least partly heritable
Thus, populations evolve, but individuals do not:
a. Individuals inherit unmodified traits.
b. Individuals carrying different heritable traits show differential survival and reproduction
c. An increasing proportion of individuals carry the favorable trait in the next generation
Levels of selection:
1. Populations evolve through the spread of traits that benefit the INDIVIDUALS that carry them
2. A trait's effect on the survival of a group or species is secondary to its effects on the individual that possesses it
Linnaean system
Kingdom, Phylum, Class, Order, Family, Genus, Species
Phylogenetic classification
based on shared, derived homologous traits
Classification may have any number of levels, depending on the history of the lineage
ADAPTATION
any trait that enhances an individual's survival or reproduction
MORPHOLOGY
physical characteristic or form of an organism
TAXON
a unit of classification
TAXONOMY
the classification of life according to type
PHYLOGENY
evolutionary history of a group of related taxa
CLADE
group of species with common ancestor
MONOPHYLETIC GROUP
taxonomic group that includes all descendants of a single common ancestor (e.g. mammals)
PARAPHYLETIC GROUP
taxonomic group that is incomplete because it excludes some of the descendants of a particular ancestor (e.g. reptiles)
POLYPHYLETIC GROUP
taxonomic group that includes descendants of several different lineages (e.g. pandas)
Comparative anatomy
Evolution can be studied by comparing different organisms.
Homologous structures
Structures shared by a group of organisms due to common ancestry; these may be modified for different uses (e.g., mammalian forelimbs)
Analogous structures
Similar structures perform a similar function, not due to common ancestry but from convergent evolution (e.g., fins and body shape in marine organisms)
Vestigial structures
structures that are seemingly non-functional (e.g., snake "legs")
Comparative embryology
Closely related taxa undergo similar embryonic development and may therefore retain characteristics that reflect ancestry (e.g., similar embryological stages of fish, frogs, snakes, bird, humans; presence of gill pouches in human embryos).
GENE
unit of inheritance; region of DNA that encodes for a single protein molecule
LOCUS
location of a gene along the length of the chromosome
HOMOLOGOUS PAIR
in diploid organisms, each chromosome is matched by another chromosome that codes for the same genes
ALLELES
alternative forms of the same gene
HOMOZYGOTE
individual that carries two identical alleles for a particular gene
HETEROZYGOTE
individual that carries different alleles for a particular gene
DOMINANCE
the ability of a single allele to determine the phenotype of the heterozygote
SEGREGATION
separation of homologous pairs at meiosis
INDEPENDENT ASSORTMENT
Recombination of non-homologous chromosomes
DIHYBRID CROSS
Mating of parents that differ in two different traits
LINKAGE
Tendency for genes on the same chromosome to be passed on together. Linkage is highest for genes in adjacent regions of the chromosome.
GENE MAPPING
Determination of physical location of genes on each chromonsome.
POLYGENIC TRAITS
Where multiple loci affect a single trait
EPISTASIS
Where one locus influences the expression of another locus
PLEIOTROPY
Where a single locus affects multiple traits
SEX-LINKED TRAITS
Traits coded by genes on the sex chromosomes
HEMIZYGOTE
Genotype of a haploid, or of a diploid possessing non-homologous sex chromosomes.
Gene frequency
The proportion of a particular allele among all alleles at a gene locus.
Mutation
A change in the nucleotide sequence whether by substitution, duplication, insertion or deletion.
Gene flow
The migration of genes into a population from other populations by interbreeding.
Genetic drift
The random change in frequency of alleles in a population, especially when population size is suddenly reduced to a few individuals.
Natural selection
Differential survival and reproduction of individuals carrying particular heritable traits.
RELATIVE FITNESS
The contribution of one genotype to the next generation compared to alternative genotypes at the same locus.
SELECTION COEFFICIENT
Difference in relative fitness between two genotypes.
DIRECTIONAL SELECTION
One allele is favored over another, resulting in the virtual elimination of the inferior allele.
Factors permitting the coexistence of alternative alleles:
1. Alternatives are selectively neutral
2. Stabilizing selection: heterozygote advantage (overdominance)
3. Disruptive selection: heterozygote disadvantage
4. Frequency-dependent selection: an allele confers a selective advantage only when rare
HARDY-WEINBERG THEOREM
Predicts the frequency of genotypes in a population, assuming:

1. Individuals mate at random with respect to genotype
2. Gene frequencies remain constant
3. Individuals carry only two alternative alleles, A and a
AA = p2
Aa = 2pq
aa = q2
PREADAPTATION
Structure that served a particular function at one time, but subsequently performs different or additional function
STASIS
Absence of morphological change during a species' history
Levels of selection:
1. Populations evolve through the spread of traits that benefit the INDIVIDUALS that carry them
2. A trait's effect on the survival of a group or species is secondary to its effects on the individual that possesses it
Basic premises of evolutionary theory:
1. More individuals born than can survive to reproduce.
2. Individuals vary in most traits
3. Individuals with certain traits are more likely to survive and reproduce
4. Variation is at least partly heritable
5. Large spans of time have been available for change
SEX
Fusion of genes from more than one individual
ASEXUAL REPRODUCTION
reproduction without sex (e.g. by mitosis)
SEXUAL REPRODUCTION
1. Isogamy: fusion between gametes of equal size
2. Anisogamy: fusion of sperm and egg
THE TWO FOLD-COSTS OF SEX IN DIPLOIDS:
At meiosis, females throw away half their genetic material to produce a haploid egg
Advantages of sex in haploids:
1. Conjugation allows the selfish spread of genes by imposing them on other individuals
2. Transformation allows for chromosome repair
Advantages of sex in diploids
1. Elimination of mutations by segregation and independent assortment
2. Sex allows the acquisition of alleles that confer resistance to disease
In diploids, sex must confer a two-fold advantage to overcome the costs of meiosis
MONOGAMY
one male with one female
POLYANDRY
several males mate with the same female
POLYGYNY
several females mate with the same male
SEXUAL SELECTION
selection of traits that influence mating success
Tenets of sexual selection:
1. Female reproduction is limited by amount of resources she can convert to eggs or young
2. Male reproduction is limited by the number of matings he can obtain
Intra-sexual competition
a. Direct combat (greatest with polygyny)
b. Sperm competition (greatest with polyandry)
Female choice
a. On basis of male providing resources (more sons & daughters)
b. On basis of male genetic quality (better sons & daughters)
c. On basis of male attractiveness (sexy sons, choosy daughters)
ALTRUISM
Where the behavior of one individual increases the fitness of another individual at some cost to itself
COOPERATION
Where two or more individuals benefit by working together
KINSHIP
Proportion of genes shared by common descent
INCLUSIVE FITNESS
An individual's own fitness plus the effects of its behavior on the fitness of its close genetic relatives
EUSOCIALITY
Social system in which sterile workers raise the offspring of a small number of reproductives
RECIPROCITY
Where two individuals exchange altruistic acts based on previous interactions. Individuals show an initial tendency to cooperate, but only continue to cooperate if their partner had also been cooperative.
SELFISH GENES
1. Meiotic drivers -- genetic elements that cause one allele to be disproportionately common in the gametes
2. Transposons -- segments of DNA that jump from one chromosome to another and occasionally from one individual to another
3. Viruses -- segments of DNA or RNA that operate as separate individuals
REPRESSOR
protein that suppresses expression of a specific gene
RESTRICTION ENZYME
enzyme that recognizes and breaks DNA that is foreign to the cell
LYMPHOCYTE
white blood cell that manufactures "antibodies" which combat foreign molecules ("antigens")
CYTOPLASM
contents of the cell outside the nucleus In reproduction, cytoplasmic elements are inherited solely from the mother
MORPHOSPECIES
set of individuals with the same physical appearance
BIOLOGICAL SPECIES
set of individuals with the potential to interbreed successfully
CRYPTIC SPECIES
subset of morphospecies that is genetically distinct and does not interbreed
Prezygotic barriers
fertilization does not occur
Postzygotic barriers
eproductive failure after fertilization
Patterns of speciation
1. Allopatric speciation (Allo = other, patric = homeland)
2. Sympatric speciation (Sym = same)
NONDISJUNCTION
both members of a homologous pair end up in same gamete
POLYPLOIDY
More than two copies of each chromosome in the same individual
AUTO-POLYPLOIDY
origin of polyploidy by fusion of two diploid gametes
MICROEVOLUTION
Changes in allele frequency due to mutation, drift, gene flow and selection
MACROEVOLUTION
Large-scale patterns and rates of change in the major taxonomic groupings
Molecular structure of life:
1. Machinery of heredity ("genotype") is composed of nucleic acids (DNA & RNA)
Nucleic acids are long chains of nucleotide bases
2. Physical structures of the body ("phenotype") are composed of proteins
Proteins are long chains of amino acids
Possible sequence in the origin of life:
1. Nucleotides and amino acids were abundant on the ancient planet
2. Single nucleotides ("monomers") can be linked together to form chains ("polymers") of RNA on crystals of clay
3. RNA is capable of self-replication and of synthesizing proteins
4. Proteinoids self-assemble to form droplets ("microspheres" or "protobionts")
5. Certain proteins (enzymes) improve self-replication rates of RNA
6. RNA that synthesized its own microsphere could monopolize its own enzyme
7. DNA is more stable than RNA and serves as the data storage system
DNA HYBRIDIZATION
comparison of whole genomes of two species by estimating degree of bonding between single-stranded DNA obtained from each species
MOLECULAR CLOCK
estimate of time since two species shared a common ancestor based on degree of genetic difference, assuming that rate of change has been constant
The prokaryotes belong to two kingdoms:
A. ARCHAEBACTERIA - restricted to extreme environments similar to early earth
B. EUBACTERIA - all other bacteria, spirochaetes, cyanobacteria, etc.
Origins of the endosymbiotic organelles
Mitochondria were free-living aerobic, heterotrophic eubacteria
Chloroplasts were free-living autotrophic cyanobacteria
The eukaryotes comprise four kingdoms:
1. Protista - eight major taxonomic groups including:
a. Protozoa - unicellular heterotrophs
b. Eukaryotic algae - unicellular autotrophs
c. Slime molds - single/multi-cellular heterotrophs
2. Fungi - multicellular heterotrophs (descent from red algae or slime molds)
3. Plants - multicellular autotrophs (descent from green algae)
4. Animals - multicellular heterotrophs (descent from protozoa)
AUTOTROPHIC NUTRITION
organism produces its own organic nutrients from sunlight or other inorganic sources
EUKARYOTES
Organisms with cells containing a nucleus and organelles
HETEROTROPHIC NUTRITION
organism acquires organic nutrients by eating the products of other organisms
ORGANELLES
Unit within the cytoplasm of the cell that performs a specialized function
MITOCHONDRIA
site of cellular respiration
CHLOROPLAST
site of photosynthesis (conversion of CO2 and H2O to organic compounds by sunlight)
PROKARYOTES
Organisms with cells lacking a nucleus
SYMBIOSIS
Where two different organisms live in direct contact
MUTUALISM
both species benefit
COMMENSALISM
one species benefits, the other is unaffected
PARASITISM
one species benefits at the other's expense
Large-scale classification of animals has been based on:
1. Symmetry: radial vs. bilateral
2. Gut: open vs. closed; if closed, whether lined with mesoderm ("coelomate")
3. Segmentation
Chordates
1. Hemichordates: acorn worm
2. Urochordates: sea squirts
3. Cephalochordates: lancelets
4. Vertebrates: fish, amphibia, reptiles, mammals
CILIA
numerous short cellular appendages specialized for locomotion
FLAGELLA
long cellular appendages specialized for locomotion (one per cell)
COELOM
body cavity lined with mesoderm
MESODERM
middle layer of early embryo that develops into the notochord, muscles, kidneys, heart
NOTOCHORD
flexible rod located between the gut and the nerve cord
SKELETONS
1. Hydrostatic - fluid held in a closed body compartment that provides a rigid frame
2. Exoskeleton - hard encasement on the surface of an animal that provides points of muscle attachment
3. Endoskeleton - hard skeleton buried in the soft tissues of an animal.
Time line in human evolution:
Bony fishes: 450 million years
Amphibia: 350 million
Reptiles: 300 million
Mammals: 190 million
Placental mammals: 90 million
Primates: 65 million
Apes: 35 million
Hominid: 6 million
Major innovations from the fishes to the primates:
1. Lungs in Fishes
2. Paired walking appendages in Amphibia
3. More efficient lungs and waterproof skin in Reptiles
4. Extensive maternal care, endothermy, and large brains in Mammals
5. Larger brains in Primates
ENDOTHERMY
utilization of metabolic energy to maintain constant body temperature
ECTOTHERMY
utilization of external energy (e.g. sunlight) to maintain temperature
HOMINID
all members of the human lineage since divergence from the apes, including the genus Australipithecus ("southern ape") and the genus Homo
EVOLUTIONARY TIME
time spans long enough for changing gene frequencies to produce conspicuous changes in morphology or behavior.
ECOLOGICAL TIME
time spans measured in months or years.
POPULATION ECOLOGISTS
study the size, structure and distribution of populations of particular species.
COMMUNITY ECOLOGISTS
study the relationships between different species coexisting in a single habitat.
ECOSYSTEMS ECOLOGISTS
study the interaction between species through the overall flow of energy and the cycling of materials in the physical environment.
Population size depends on:
Birth, Immigration, Death, Emigration
Human population growth can be decreased by:
1. Improved contraception
2. Lowering preferred family size
3. Increasing age of first reproduction
LIFE HISTORY
age-specific rates of growth, reproduction, and survival
ITEROPARITY
repeated breeding
SEMELPARITY
explosive breeding
SENESCENCE
physiological deterioration of the body from in-built processes
EXTRINSIC MORTALITY
death due to predation, accident, or the environment
Fitness is the product of survival and reproduction.
Therefore:
1. High adult mortality favors rapid breeding.
2. Traits that increase reproduction can spread even if they increase mortality.
3. Damaging reproductive traits are most likely to spread if their effects on survival are delayed until old age.
COEVOLUTION
the joint evolution of two closely interacting species, such that when one species changes, the other also evolves
COMPETITION
demand by two organisms for the same limiting resource
INTERFERENCE COMPETITION
one species prevents another from gaining access to the resource
EXPLOITATION COMPETITION
one species is better able to extract the resource
COMPETITIVE EXCLUSION
one species drives another to extinction
CHARACTER DISPLACEMENT
divergence in the characters of two overlapping species because of competition for the same resources
PARASITE
organism that feeds on the living tissue of its host
VIRULENCE
extent to which parasite damages the host
Ecosystem
all the organisms in a given area as well as the non-living ("abiotic") factors with which they interact.
Biome
one of the world's major communities, classified according to the predominant vegetation and characterized by adaptations to the local environment.
Trophic structure
the different feeding relationships in an ecosystem that determine the route of energy flow and the pattern of chemical cycling.
Nutrient cycling
movement of vital chemicals between the physical environment and living organisms
Carbon cycle
he conversion of atmospheric CO2 to carbohydrates by the process of photosynthesis, and the return of CO2 back into the atmosphere by respiration and decomposition
Nitrogen fixation
conversion of atmospheric nitrogen into ammonia and nitrates by bacteria
Primary productivity
the amount of light energy converted to chemical energy by the autotrophs of an ecosystem.
Trophic levels:
Producers - organisms capable of producing organic energy from sunlight = autotrophs
Consumers - organisms that acquire organic energy from food = heterotrophs
Primary consumers - organisms that eat plants
Seconday consumers - organisms that eat primary consumers
Detritovores - organisms that eat dead organic matter
Food chain
the pathway along which food is transferred from trophic level to trophic level.
Food web
the interconnected feeding relationships in an ecosystem
ENDEMISM
being restricted to a particular geographical location
INBREEDING DEPRESSION
the loss in fertility and viability of offspring born to parents that are close genetic relatives
INCIDENCE
the presence of a particular species in a certain area
ISLAND BIOGEOGRAPHY
patterns of species richness as a function of island size and location
SPECIES DIVERSITY
the number and relative abundance of each species in a biological community
SPECIES RICHNESS
the number of species living in a biological community
Habitat destruction increases extinction rates by:
1. Outright loss of habitat of endemic species
2. Habitat fragmentation
a. Small populations are subject to higher risk by chance events (floods, fires, epidemics, etc.)
b. Small populations are subject to inbreeding depression
Value of biodiversity:
1. Alternative forms of food
2. New medicines
3. Greater resilience in the face of natural disaster