Chapters 13 and 14 Flashcards
pre-Darwin Ideas
early Greek philosophers: Simpler life forms preceded more complex ones
Aristotle: Species are fixed and do not evolve
Judeo-Christian biblical view: All species were individually designed by a divine creator
supporting ideas regarding Darwinian evolution
Buffon: Earth older than 6,000 years
Lamarck: inheritance of acquired characteristics
Lyell: geological processes that shape Earth are uniform through time
what did Darwin observe on the HMS Beagle?
- there are variations amongst species
- organisms are well suited to their environments
- organisms adapt to surroundings
- differences in organisms according to environments they inhabited
how do fossils provide evidence for evolution?
they document changes that life has undergone over time
they show the transitional forms
comparative anatomy
homologous structures
analogous structures
vestigial structures
homologous structures
similar in structure, but in different organisms have different functions
analogous structures
similar in function but not in origin
vestigial structures
remnants of structures that had a function in an early ancestor
comparative embryology
similarities in early development
molecular biology
DNA/amino acid/protein comparisons
homeobox genes
homeobox genes
master control genes, regulate groups of other genes during development
artificial selection
- supports the idea of natural selection
2. nature provides the variation, humans select favorites thus playing the role of the environment
biogeography
- geographical distribution of living species
2. supports common ancestry
what is the significance of mutations?
Can create new alleles
Only mutations in cells that produce gametes can affect a population’s gene pool
what is the significance of sexual recombination?
generates variation by shuffling alleles during meiosis
population
individuals of a species that live in a given area at the same time
gene pool
total collection of genes in a population at any one time
microevolution
the change in the relative frequency of alleles in a population over several generations
what are the five conditions of the Hardy-Weinberg principle?
- very large
- isolated (no migration)
- no mutations in alleles
- mating is random
- no selection (ALL individuals = in reproductive success)
what does p represent in H-W equation?
p = dominant allele
what does q represent in H-W equation?
q = recessive allele
genetic drift
change in gene pool of a population due to chance (the smaller the population the higher the impact)
bottleneck effect
event that drastically reduces population size (natural disaster)
founder effect
colonization of a new location by a small number of individuals (Darwin’s finches)
gene flow
migration between populations reducing differences between populations
current human populations
evolutionary fitness
relative contribution an individual makes to the gene pool of the next generation
best fit are those producing most fertile offspring
selection indirectly adapts a population to its environment by acting on phenotype
what are the types of selection?
stabilizing selection
directional selection
disruptive selection
stabilizing selection
favors intermediate phenotypes
directional selection
acts against individuals at one of the phenotypic extremes
disruptive selection
favors individuals at both extremes of the phenotypic range
why do no perfect organisms exist?
organisms are limited by historical constraints – come from ancestral forms.
adaptations are often compromises.
chance, natural selection, and the environment interact.
selection can only edit existing variations.
speciation
origin of new species
species
population whose members interbreed naturally and produce fertile offspring
hybrid
offspring of two different species
reproductive barrier
biological feature preventing interbreeding
prezygotic
prevent mating or fertilization
prezygotic situations
habitat temporal behavioral mechanical gametic
habitat (reproductive barrier)
lack of opportunities to meet
temporal (reproductive barrier)
breed at different times
behavioral (reproductive barrier)
failure to send/receive mating signals
mechanical (reproductive barrier
physical imcompatibility
gametic (reproductive barrier)
molecular incompatibility
what is the difference between macroevolution and microevolution?
macroevolution is Darwinism - the big picture over millions of years
microevolution is looking at the genes - it’s the DNA that changes that makes those big changes over time
why can it be difficult to differentiate between two different species?
sometimes they may have similar features and still not able to reproduce
sometimes two different species can reproduce
postzygotic
operate after hybrid zygotes are formed
reduced hybrid viability
interaction of parental genes impairs hybrid’s development/survival
reduced hybrid fertility
hybrids develop/survive but are sterile
hybrid breakdown
hybrids develop/survive but their offspring are weak or sterile
convergent evolution
independent evolution of similar features in unrelated species
analogous structures
divergent evolution
species with common ancestry evolve differently
homologous structures
