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81 Cards in this Set
- Front
- Back
Asexual reproduction
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-Reproduction without fertilization or conjugation
-Parent passes on 100% if its genes to all its offspring |
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Sexual reproduction
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-Occurs through fertilization to produce genetically new individual
-Each parent passes 50% of it's genes to offspring |
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Somatic cells
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-All cells in body except sex cells
-Diploid (2n) -Produced from diploid cells by mitosis |
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Gametes
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-Eggs and sperm
-Haploid (n) -Produced from diploid cell by meiosis |
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Meiosis 1
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-Separates homologous pairs
-2n-->4 single stranded |
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Prophase 1
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-2n-->4 double stranded chromosomes
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Metaphase 1
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-2n-->double stranded but line up on metaphase plate
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Telophase 1
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1n-->2 double stranded chromosomes
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Meiosis 2
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-2nd division of meiosis separates sister chromatids
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Prophase 2
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1n-->2 double stranded
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Metaphase 2
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1n--> 2 double stranded chromosomes line up on metaphase plate
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Telophase 2
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1n-->2 single stranded
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Sources of genetic variation
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-Crossing over=recombination
-Independent assortment -Random fertilization |
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Crossing over
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-Exchange of corresponding segments of DNA by non-sister chromatids in a tetrad during prophase 1
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Independent Assortment
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-Random alignment of each pair of homologous chromosomes at Metaphase 1 plate
-2^n possible outcomes |
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Random fertilization
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Any 2 parents produce a zygote with 70 trillion diploid combinations
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Advantages of sex
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-Introduces new combinations of heritable traits in offspring
-Accelerates the rate of evolution -Potentially useful in a variable, dynamic environment |
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Alleles
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-Any of the alternative versions of a gene that produce a distinguishable phenotypic effect
-Alleles may differ on homologous chromosomes |
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Mendelian Genetics
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-Scientific study of how traits are passed on from parent to offspring
-Study of heredity |
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Law of segregation
Mendels 1st law of heredity |
-Two alleles for a heritable trait separate during gamete formation onto different gametes.
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Law of Independent Assortment
Mendels 2nd law of heredity |
-Each pair of alleles segregates independently of each other pair of alleles during gamete formation
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Phenotype
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The physical and physiological traits of an organism which are determined and shown by it's genotype's
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Incomplete dominance
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-When there is no dominant genotype
-Example: Rr=a different phenotypic expression from RR or rr Rr=intermediate phenotype |
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Co-dominance
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-When each genotype determines a particular pheotype
-Example blood type ii=o, i^ai^a or ii^a=A, i^bi^b or ii^b=B, and i^ai^b=AB |
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Polygenic inheritance
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-Multiple genes determine trait
-Polygenic characters have near normal frequency distribution -Example: human skin color |
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Heterozygous
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-having two different alleles for the same gene
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Homozygous
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-having the same two alleles for a gene
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Multiplication Law
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-Probability of independent events A and B=
probability of A * probability of B |
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Peidgree
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-Circle is female, square is male
-colored in is affected -two types autosomal and sex-linked |
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Autosomal
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-Both males and females pass on 2 alleles in form
aa, AA, or Aa |
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Sex-linked
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-Female=XX
-Male=XY -Female has 2 alleles -Male has 1 allele on the (X) |
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Natural selection
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-Process by which the individuals that have the characteristics best suited to the environment survive and reproduce better than other individuals
-main mechanism for evolution |
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Evolution
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-evolution is the change in allele frequencies of a population over time
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Micorevolution
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-Changes within species
-Changes in allele frequencies |
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Macroevolution
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-The evolution of new species
-The extinction of species |
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Allele frequency
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Allele1 + Allele2=1
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How do new alleles originate?
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Mutation
Horizontal gene transfer |
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Mutation
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The random changes in DNA that introduce new alleles into a gene pool
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Point mutation
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-Changes in a single base pair, that causes a change in a single amino acid
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Gene duplication
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If a gene is duplicated the second copy can accumulate mutations freely
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Mutatuion can be
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-Deleterious
-Neutral -Beneficial |
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Horizonal gene transfer
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-Genes passed from one organism to another
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What affects allele frequency
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-Genetic drift
-Gene flow -Selection |
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Genetic drift
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-Random fluctuations in allele frequencies from one generation to the next
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Name two types of genetic drift and describe them
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-Bottleneck effect: Genetic drift that occurs when the size of a population is reduced by a natural disaster or human actions. Surviving population no longer genetically representative of original population.
-Founder effect: Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of original population. |
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Gene flow
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-Transfer of alleles from one population to another
-Immigration & emigration/ accidental movement are ways it occurs |
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Name and describe the 3 types of selection
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-Directional selection: Favors variants at one extreme of distribution
-Disruptive selection: Favors variants at both extremes of distribution(middle die off) -Stabilizing Selection: Favors variants in-between extremes of distribution (variants at extremes die off) |
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Examples to remember
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-Guppy colours: Translocation experiment, Directonal selection
-Bill size of Galapagos finches:Medium sized bills suffered highest mortality, Disruptive selection -Birth weight in humans: Birth weight frequency lowest in middle, stabilizing selection |
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What is behavioural ecology?
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-Study of the survival and reproductive value of behaviour and how this behaviour contributes to survival and reproduction
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What is fitness?
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How well an individual does relative to others in the population.
-Fitness=0-no representation of allele x in the next generation -Fitness=1 100% allele x in next generation |
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Altruistic behaviour
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-Acting to increase another individual's life time number f offspring at a cost of one's survival and reproduction
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Inclusive fitness
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Fitness can be gained 2 ways
-Directly-through personal reproduction -Indirectly-by contributing to the survival and reproductive success of relatives |
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Relatedness
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r=coefficient of relatedness between two individual
-probability that a particular allele, present in one individual, is also present in another individual because of their descent from a common ancestor L=the number of generation links between the 2 individuals concerned |
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Kin selection
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Process by which characteristics are favoured due to their beneficial effect on the survival or reproduction of relatives.
-Kin selection should occur if hamiltons rule is met |
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Hamilton's rule
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rB-C>0
-B=benefit to the recipient of the altruistic act -C=cost to the donor -r=coefficient of relatedness between donor and recipient |
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Reciprocal altruism
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Occurs when Brecipeint>C donor and help is reciprocated later
Example: vampire bats favour but also help non-related roost mates |
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Difference between males and females
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Females: Produce few, large energetically expensive gametes
Males: Produce numerous, small, cheap gametes |
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Reproductive success
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Males: Great potential but highly variable
-Males select to maximize quantity so males compete with each other Females: Low potential but low low variability -Females select to maximize quality so females choose their mates carefully |
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Sexual selection
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-Process by which individuals that have traits that increase mating success are favored over individuals that do not have these traits
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Name and describe two forms of sexual selection
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Intrasexual selection: Process the favouring the ability to compete directly with member of the same sex (usually males) for access to the opposite sex
Intersexual selection: Process favouring the ability to attract members of the opposite sex |
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Mating systems
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-The pattern of mate acquisition by both sexes
-Shaped by male/females reproductive potential, parental care, ecology and phylogeny -Major determinant of how strong sexual selection will be |
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Types of mating systems
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-Monogamy(1:1)-care of young by both parents, low male rate of reproduction
-Polygyny(1male:+2female)-Care of young by female only, patchy resources -Polyandry(+2males:1female)-Care of young by male only, Low male rate of reproduction -Polygamy/promiscuity(+2males/+2 females)-No care of young or care by female only, evenly distributed resources |
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Direct benefits of choosing mates carefully
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-Mate with member of the correct species
-Have access to good/safe territory -Get fed lots of food -Get a good parent for offspring -Get a fertile mate |
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Indirect benefits of choosing mates carefully
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-Good genes: Sexually selected traits advertise genetic quality because they are costly to produce
-Sexy sons: Females choosing males with well-developed sexually selected traits produce sons with the same traits |
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What is a species? (according to biological species concept)
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Groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups.
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How does speciation occur?
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Allopatric speciation-physical separation of two populations=interruption of gene flow
Sympatric speciation-No physical barrier |
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Sympatric speciation can occur through two types of reproductive isolation.
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-Reproductive isolation by mutation: Polyploidy
-Reproductive isolation by ecology and behaviour |
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Reproductive isolation by ecology and behaciour
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-Prezygotic mechanisms: prevent mating or fertilization
Postzygotic mechanisms: Prevent zygote development or reproduction |
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What happens when divergent populations come into contact?
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1. Populations hybridize but hybrids less fit than parents-->reinforcement of differences
2. Populaitons hybridize and hybrids are as fit as parents-->Fusion 3. Populations hybridize and hybrids preferentially mate with each other-->stable hybrid zone |
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Adaptive radiation
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-Sudden and rapid diversification of a phyletic line into several lineages
-Occurs when new set of niches opens up: -Evolution of a new feature -Opening up of a new habitat -Extinction of other species or clade |
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Adaptive radiation-galapagos finches
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Causes: Archipelago, New habitat, new food sources
-speciation by island hopping |
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Adaptive radiation-Bats
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Caues: Extinction of pterosaurs, peak insect diversity, new features
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Tempo of speciation
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-Gradualism:traditional view, not supported by fossil record
-Punctuated Equilibrium: rapid appearance, slow to no change later |
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Permian Extinction
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-250 mya
-90% + of all species -96% marine species -Victims: Ammonites, Trilobites, Blastoidea, mammal like reptiles |
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Causes of permian extinction
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-Siberian volcanoes
-Formation of Pangea: Changed ocean circulation patterns, drop in sea level -Reduced oxygen in oceans -Climate change |
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Cretaceous-Tertiare extinction
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-65 mya
-60-80% of all animal species extinct -Victims: Pterosaurs, dinosaurs, many plants & invertebrates -spared: mammals, crocodiles, non-north american plants |
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Causes of K/T extiction
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-CLimate change
-Sea level chagnes -Increased volcanic activity Meteorite impact |
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Causes of megafauna extinctions
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-Climate change
-Hyperdisease -Overexploitation by humans |
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Primates
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-Mammalian order
-Derived characters: 5 digits, flat nails, large bran, long parental care, complex social systems |
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Anthropoids
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-Primate suborder
-Includes monkeys apes, humans -Derived characters: Fully opposable thumb, larger brain |
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Hominoids
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-Antropoid superfamily
-Includes apes and humans -Derived characters: tail-less, arm-swinging, more erect posture, larger body size, larger brain |