Evidence for Evolution Flashcards
homologus structures
similar structure and origin with different function
analogus structures
similar function but different origin
vestigial structure
structures from ancestors that are useless
biogeography
island populations
fossils
preserved remains or impressions that remain after a long period of time
embryology
similar stages of embryonic development
DNA
determines how closely organisms are related- by comparison, traits passed on by generations changed by mutations
divergent evolution
the same species can be isolated to different environments, limiting gene flow, to allow for the selection of different traits (homologus structures)
- two groups of the same species evolve different traits
convergent evolution
unrelated organisms that evolve similar traits due to similar environments or niches they inhabit (analogus structures)
parallel evolution
two related organisms, independently evolving on the same paths
What is evolution
change over time-process by which modern organisms descended from ancient ones
James hutton
forces change earth’s shape, changes are slow, earth is old
Charles Lyell
geographical features can be built up or torn down
Lamarck’s theory
tendency towards perfection (giraffe neck), use and disuse (birds using forearms), inheritance of acquired traits
Thomas malthus
if population grew=insufficient living space, food runs out (more babies born than die idea that Darwin applied to animals)
what do organisms with homologus structures have that organisms with analogus structures don’t have
a common ancestor
artificial selection
intentional breeding for certain traits-human preference could be a simulation for how it would play out
natural selection
process by which traits become more or less common in a population based on its importance to survival where the environment controls these factors
what are the five points of natural selection
populations has variations, some variations are favourable, more offspring are produced than survive, those that survive have favourable traits, a population will change over time
what is an adaptation
structure, behaviour, or physiological process that help an organism survive and reproduce in a particular environment
mimicry
the ability to mimic something you’re not; organisms mimicking another organism to appear like a more harmful species to have predators avoid it
what is a variation
structural, functional, or physiological differences between individuals of a species
what determines whether a variation has a positive or negative effect
the environment
what is microevolution
change in the frequency of a gene pool in a small scale–happens from one generation to another
what does a mutation do
invites new alleles to a population
what is a gene pool
the different genes in an interbreeding population
what is fitness
reproductive success and how apt an organism is at surviving
gene flow (migration)
gene flow occurs between two different interbreeding populations that have different allele frequencies
non-random mating
individuals in a population select mates based on their phenotypes
genetic drift
random change in genetic variation due to CHANCE
genetic drift: bottleneck
when a severe event results in a drastic reduction in numbers BY CHANCE (ex. seal population decreases bc of overhunting)
genetic drift: founder
when a few individuals from a large population leave to establish a new population with different allele frequency than the original population
types of natural selection
sexual selection, stabilizing selection, directional selection, disruptive selection
sexual selection
favours the selection of any trait that influences the mating success of the individual
stabilizing selection
removes severe phenotypes, reproductive success of the normal phenotypes
directional selection
extreme phenotype is favoured over normal phenotypes.
disruptive selection
extreme values of a trait are favoured over intermediate ones, variance of trait is increased and divided into 2 distinct groups
macroevolution
evolution of a geological time of groups larger than one individual, new species arise
the process by which a new species arrives
speciation
biological species
group of organisms that can reproduce with each other in nature and produce fertile offspring
allopatric speciation
occurs when geographical barriers divide a population
- geographical: most important factor in starting speciation
- physical/behavioural changes: keep the two species isolated from each other
reproductive speciation
any factor in nature that prevents interbreeding
- extrinsic: outside of the organisms (geographical)
- intrinsic: internal characteristics (differences in anatomy, physiology, and behaviour)
what are the 6 intrinsic reproductive isolating mechanisms?
ecological
temporal
behavioural
mechanical
gametic
hybrid inviability
ecological isolation
different habitats for two species prevent interbreeding (lions=grasslands, tigers=jungles)
temporal isolation
two species share the same environment, but don’t mate within the same time frame (ex. two plants release pollen at different times of the year, non-overlapping reproductive periods reduces gene flow)
behavioural isolation
even if populations are in contact and breeding can occur, they have to CHOOSE to mate based on SPECIFIC COURTSHIP AND MATING DISPLAYS
mechanical isolation
reproductive organs differ in size or shape or another feature (ex. diff species of alpine butterflies look similar but have different reproductive organs)
gametic isolation
even with mating, incompatibilities between the sperm and egg/female reproductive tract can prevent offspring from resulting
hybrid inability or infertility
even if offspring develop they’re most likely sterile or malformed (ex. mule=horse and donkey)
sympatric speciation
occurs when there are no physical barriers preventing any members of a species from mating with each other, and all members are in close proximity to each other
a new species seems to develop spontaneously through a new food source, characteristic, etc.
occurs often through polyploidy
polyploidy
multiplication of number of chromosomes in an organism, most often occurs in plants that self-pollinate
speciation through hybridization
egg and sperm come together and rarely produce a healthy offspring (hybridization is only sometimes successful in plant species)
generalists vs specialists
g: diverse diet, when the food source changes generalists move on and eat something else
s: specific diet even when food is scarce, when the food source changes specialists must adapt or face death
adaptive radiation
rapid emergence of a single species introduced into a new environment
what conditions contribute to speciation
specialization of food source and migration to new environment, especially if there is no competition
phyletic gradualism vs punctuated equilibrium
pg: gradual, small changes
pe: long periods of stasis with little to no evolution interrupted by short periods of rapid evolution
