Ch.4 population change Flashcards
Adaptation
structural, behaviour or physiological process that helps an organism survive + reproduce
Why adapation
makes species will suited for envionemnt, is a result of gradual change in characteristics over time
variation
visible or invisible differences that help survive
why variation
not all become adaptations some do, can be helpful, harmful or neither- some adaptations increase survival
why are organisms differenet
bc/ of mutations and sexual reproductions
mutations
change in DNA of cell
more mutations
occur spontaneously, can be induced by mutagens: UV light, chemicals,- mutations on gametes inherited, DNA mutates helpful or cell die, when helpful gives selective advantage
sexual reproduction
off-spring have combo of genetic info from both parents
why sexual repoduction
produces variation, off-spring have different DNA, many parents with different genes
how more variation
reproduce often- increases # of mutants, sexual reproduction w no similar mates - increases variability
natural selection
process that results when characteristics of population of organisms change, more favourable ones stay
Key points of NS
needs variation with species, better traits survive and reproduce and more offspring, intra-specific competition better for favourable traits will reproduce the most, traits get passed down (selective advantage)
evolution
change in population overtime
- individuals can’t genetically evolve
Comte de Buffon
publicly challanged idea of no evolution, suggested common ancestry, earth >6000,
Cuvier
different layers of rock = different fossils - deeper = not similar, evidence of species extinction not evolution, proposed Catastrophism
catastrophism
all major changes on earth caused by catastrophies
Lyell
rejected catastrophism, natural process operated at same rate as in past, earth >6000, slow process over time = big change
Lamarck
the first theory of evolution
theory of inheritance of acquired characters - organisms change bc environment, change from simple to complex until perfection, use of disuse of traits passed to off-spring
Darwin + Wallace
theory of natural selection
origin of species - organisms today are modifications of ancestors, different species adapted to environment evolve
evidence of evolution
fossil record, transitional fossils, patters of distribution (biogeography), anatomical, embryology, molecular biology + genetics
molecular biology + genetics
all cels have DNA, carbs, H2O, proteins, cell membrane - more similar molecules made by organisms more related
embryology
similar embryos in related groups point to same ancestor
anatomical evidence
homologous: same structure different function
analogous: similar function no common ancestor
biogeography
study of past + present geological distribution of organisms, more similar organism found geographically close, on island organism similar to animals on land close to it
transitional fossils
show intermediary links between groups, helps scientists understand process + relationship between groups
fossil record
appear in chronological order, fossils in upper layer more similar to today
speciation
formation of new species
transformation
one turn into another, caused by environmental changes/pressures, original species no longer
divergence
one splits into 2, caused by separation of members then separate evolution, results in reproductivly isolate populations
geographical barriers
physical abt environment that separates, eg: lakes, continents, dams, isolation not forever but until not compatible reproductively
biological barriers
behavioral factors prevent members from breeding
prezygotic barrier
biological barrier before fertilization - habitat, behaviour, temporal, mechanical, gametic isolation
postzygotic barriers
biological barrier after fertilization, ‘hybrid instability - reduced hybrid viability/fertility, hybrid breakdown
adaptive radiation
single species rapidly adapt to fill available niches in the environment
pace of evolution
amount of genetic variation- more offspring with variation, more pressure to adapt - changing environment and more predators
gradualism
evolution occurs gradually at steady rate, small change over time = big change
punctuated equilibrium
evolution of species occurs mostly on show period of time has great change then long time with very little change
