Exam 2 Flashcards
Species Constant
Greek Philosophers:
Variations are overlooked, species are varying degrees of imperfect, with humans generally being regarded as closest to perfection.
Natural Theology
William Paley: Designer’s (god’s) plan is revealed through nature. Adaptations are on purpose and species are constant.
Inheritance of Acquired Characteristics
Lamarck: Characteristics developed through an organism’s lifetime are inherited by that organism’s offspring. “Long necked giraffes”
Catastrophism
George Cuvier: Posited extinction for the first time. Species could be lost by local catastrophes (backed up by fossil record). Importantly, Cuvier still saw no evidence of change over time.
Gradualism
James Hutton: Old earth theory and founder of geology. Positioned that changes in life could occur over very long periods of time.
Uniformitarianism
Charles Lyell: Expanded on Hutton’s old earth model, positioned that the mechanisms of change were constant and slow.
Struggle to exist
Thomas Malthus: Struggle to exist in terms of economy (kind of a racist and classist guy - said poor people simply did not have the will to compete). Resources are not infinite and the struggle to exist increases as the number of individuals increases. This idea would eventually influence Darwin’s “survival of the fittest idea”.
variant forms of a gene
Allele
Multiplicative law
Chance of 2 or more events occurring together is product of their chance of occurring separately
Additive law
Chance of an event that can occur in 2 or more independent ways is sum of all individual chances
Complete Dominance
One (dominant) allele completely masks the (recessive) other from being expressed in the phenotype
Incomplete Dominance
Both alleles of a gene at a locus are partially expressed
Co-dominance
Both alleles at a gene locus are fully expressed in the phenotype
Pleiotropy
one gene may affect many traits
Epistasis
gene at one locus alters phenotype of gene at another locus
Polygenic inheritance
one trait is affected by many genes
discrete unit of DNA or RNA that influences hereditary traits
Gene
very long DNA molecules packed together with proteins
Chromosomes
the location of a gene on a chromosome
locus
number of distinct types of chromosomes in a cell
n
number of complete sets of chromosomes in a cell
ploidy (xn)…2n = diploid
Homologous Chromosomes
paired chromosomes with genes in same locations
DNA in the cell is copied resulting in two identical full sets of chromosomes
Interphase
Chromosomes condense and move towards the middle of the cell. Crossing over occurs.
Prophase I
chromosomes, align in the equator of the cell before being separated into each of the two daughter cells
Metaphase I
full chromosomes are pulled to each pole (homologous chromosomes are separated)
Anaphase I
the chromosomes are enclosed in nuclei
Telophase I
the cytoplasm organizes itself and divides in two, creating two haploid cells
Cytokinesis
The DNA has already been replicated, so this part isn’t real
Interphase II
the centromeres of the paired chromatids align along the equatorial plate in both cells
Metaphase II
the chromatids split at the centromere and migrate along the spindle fibers to opposite poles
Anaphase II
the chromosomes gather at the 2 poles of the cell and the cell divides via cytokinesis forming 2 daughter cells (1n 1c) from each of the two cells from meiosis 1 (this isn’t meiosis 1 lol)
Telophase II
Law of Segregation
pairs of gene variants are separated into reproductive cells…during gamete formation, each gamete receives just one copy of each gene which is randomly selected
Law of Independent Assortment
genes are inherited independently of one another…they line up randomly in metaphase, so they’re split into gametes randomly, allowing genetic variation
Crossing Over
Exchange of genetic information between non-sister chromatids
Random fertilization
during sexual reproduction, the male gamete and female gamete that fuse to produce an offspring are randomly selected from the poll of male and female gametes…genes have equal chance of being passed down
Darwinian Fitness
capacity to pass on genes to reproducing offspring
the change in a phenotype or genotype of a population in one direction away from the mean in a particular environment over time…most common phenotypic expression moves closer to one of the ends of the phenotypic spectrum
Directional Selection
type of natural selection where genetic diversity decreases as the population stabilizes on a particular trait value…mean becomes even more frequent
Stabilizing Selection
form of natural selection occurring in a population where extreme traits are favored over intermediate traits
Disruptive Selection
form of natural selection when the fitnesses of genotypes within a population respond differently to changes in total population size or density…fluctuates between two states
Density Dependent Selection
Assortative Mating
Non-random mating where individuals of one sex preferentially mate with individuals of the opposite sex
Sexual Reproduction
two parents giving rise to genetically unique offspring through the fusion of gametes produced by meiosis
having the male and female reproductive organs in separate individuals
Dioecious
Reasons Sex is Bad
Inefficient, Costly, Risky for Survival
asexual when conditions are good and sexual during times of stress
Facultative Asexual Reproducers
Asexual reproduction in which a female can produce an embryo without fertilizing an egg with sperm
Parthenogenesis
Why are Bdelloid rotifers unique?
They have been asexual reproducers for millions of years, yet have evolved
Protandrous hermaphrodite
animal that are born male and at some point in their lifespan change sex to female
Protogynous hermaphrodites
animals that are born female and at some point in their lifespan change sex to male
The Tangled Bank Hypothesis
Sex evolved in order to prepare offspring for the world around them and provides genetic variability in offspring
The Red Queen Hypothesis
Sex provides varied offspring and allows more rapid evolution
Advantages of Sex
Generates variability among offspring; diverse offspring provides challenges to competitors, predators, and parasites; diversity allows for niche differentiation; survival chances increased
Why are females choosy?
Mating is a larger investment…eggs relatively expensive, pregnancy
Intersexual selection
female choice…males often bear colorations or ornaments…often occurs when males cant monopolize access to females
Intrasexual selection
male control…males monopolize access to females or stake claim of territory
Methods of male controlled sexual selection
Sperm production, removal of competitor sperm, copulatory plugs, mate guarding, traumatic insemination, infanticide
The Sexy Son Hypothesis
females mate with sexy males (good genetics) to produce sexy sons and daughters that will find these traits sexy
Runaway selection
If male preferences have a genetic basis, the advantage is passed on to a female’s son (related to sexy son hypothesis)
Good Genes Hypothesis
ability to produce and maintain elaborate ornamentation indicates good genes (Handicap Hypothesis, Parasite Hypothesis, and Developmental Stability)
Handicap Hypothesis
ability to survive despite costly advertisements indicates good genes
Parasite Hypothesis
parasites reduce the ability to produce displays, so males that can produce and maintain elaborate displays must be resistant to parasites
Developmental Stability
developmental stress causes asymmetry…advertisements that are large and symmetrical imply resistance to developmental stress
Hardy Weinberg Equilibrium Equation
p^2 + 2pq + q^2 = 1
homozygous dominant alleles
p
homozygous recessive alleles
q
All the individual alleles in a population for a given locus
gene pool
When is a population in equilibrium (non-evolving)?
Infinitely large population, no mutation, random mating, isolated from other populations, all individuals survive and reproduce equally
polymorphisms develop when the fitness of heterozygotes is higher than the fitness of both homozygotes in a given population…heterozygotes have higher fitness
Heterozygote Advantage
a random change in genetic code
mutation
What do pathogens do to survive?
Reproduce and DIsperse to new hosts (transmission)
organism that functions as a carrier of an infectious agent between organisms of a different species
vector
ability of an organism to infect the host and cause a disease
virulence
a mechanism of evolution that leads to a match between organism and environment
Natural selection
Mechanisms for Evolution
Natural Selection, Mutation, Genetic Drift, Migration, non-random mating
Heritable features of an organism that can vary
Character
The version of a character inherited by an organism
Trait
the genetic identity of the two alleles possessed by an organism
Genotype
the trait expressed as a result of genotype
Phenotype
the gene is located on one of the numbered, or non-sex chromosomes
autosomal
a parent’s experience in the form of epigenetic tags can be passed down to future generations
epigenetic inheritance
Particulate inheritance
parents pass discrete heritable traits that are able to retain separate identities in offspring and are passed through generations in an undiluted form…genes keep their unique identities and will not blend together so the combination of genes determines which genes are expressed or not
Recombination
during crossing over genes are shuffled between homologous pairs
Linkage
the closer two genes are together on the chromosome, the higher the likelihood that they will cross over together during meiosis
DNA change that results in different amino acids (wrong amino acid) being encoded at a particular position in the resulting protein…can alter the function of the resulting protein
Missense Mutation
DNA change that causes a protein to terminate or end its translation earlier than expected
Nonsense Mutation
DNA change within a protein-coding portion of a gene that does not affect the sequence of amino acids that make up the protein because the change is a synonym for the same amino acid
Silent mutation
Insertion or deletion of a nucleotide
Frameshift
two different versions of a gene are maintained in a population of organisms because individuals carrying both versions are better able to survive than those who have two copies of either version alone
Balanced polymorphism
structures that lost their use through evolution
vestigial structure
one copy of a newly copied chromosome which is still joined to the original chromosome by a single centromere
chromatid
Epigenome
Genome is all the genetic material in an organism. Epigenome is the chemical compounds that tell the genome what to do
Genomic Imprinting
only one copy of a gene is expressed and the other is silenced
Epigenetic imprinting
inheritance of traits from one generation to the next based on their experiences that permanently affect the genome
