Chapter 24 Flashcards
_______________ is evolution on a larger scale than microevolution
macroevolution
the origin of new species rather than changes within species
macroevolution
is the process by which an ancestral species gives rise to two or more descendant species
speciation
a group of organisms with the potential to breed in nature and produce viable fertile offspring
biological species concept
species
advantage of biological species concept
the biological species concept can not be applies to fossil organisms or to organisms that reproduce asexually
disadvantage to the biology species concept
the biological species concept cannot be applied to fossil organisms or to organisms that reproduce asexually
species are defined as distinct based on differences in shape, size, or other features of their appearance
morphology species concept
advantage of morphological species concept
the morphological species concept can be applied to all organisms
disadvantage of morphological species concept
distinguishing features tend to be subjective
under the biological species concept _______________________ keeps species separate
reproductive isolation
two categories of reproductive berries
- prezygotic barriers
- postzygotic barriers
barriers preventing reproduction promoting reproductive isolation will lead to
speciation
3 prezygotic barriers prevent individuals of different species from mating
- habitat isolation
- temporal isolation
- behavioral isolation
2 pre zygotic barriers prevent fertilization of gametes from individual of different species
- mechanical isolation
- gametic isolation
post zygotic barriers operate after hybrid offspring of individuals of different species have been produced
- reduced hybrid viability
- reduced hybrid fertility
- hybrid break down
isolated by geography
habitat isolation
reproduce at a different time
temporal isolation
courtship rituals prevent attraction
behavior isolation
reproductive genitals do not mechanically connect
mechanical isolation
sperm die before reaching egg
gametic isolation
dies before reaching sexual maturity
reduced hybrid viability
hybrid can’t reproduce
reduced hybrid fertility
2nd generation offspring are not viable or fertile
hybrid breakdown
reproductive barriers form when a population is split into
two or more separate populations
each new population follows its own evolutionary course
there are two mechanisms by which a population can be split and speciation can occur
- allopatric speciation
- sympatric speciation
during allopatric speciation a ______________________ physically splits a population
geographic barrier
each new population is subjective to ______________________ independent of other populations
-no flow between them
natural selection and genetic drift
speciation occurs if reproductive barriers form between the isolated populations and
they can no longer form viable fertile offspring if brought back together
during _____________ reproductive isolation occurs without geographic isolation
sympatric speciation
sympatric speciation:
normally occurs in plants
but can occur in animals due to sexual selection
is a region where individuals of closely related species meet mate and produce hybrid offspring
hybrid zone
the three possible outcomes when closely related species mate in a hybrid zone
- reinforcement
- fusion
- stability
____________ involves the strengthening of reproductive barriers
reinforcement
reinforcement barriers of reproductive barriers occurs when hybrids are
less than either parent species
the most common outcome of reinforcement
over time, the rate hybridization decreases the hybrid zone disappears and the parent species remain separate
involved the weakening of reproductive barriers
fusion
reproductive barriers are weakened when hybrids are as fit as both parent species, parent species become reproductively capable as substantial gene flow occurs between then fusing the two species into a single species
fusion
involves the continued formation of hybrid offspring
stability
results when hybrids are less fit than either parent species but gene flow between parent species continues to occur
stability
stability _____________________________________
species remain separate but the hybrid zone persists
beyond speciation, macroevolution encompasses the evolution of larger groups of organisms
new families classes kingdoms
macroevolution included the origin of these unique new structures
major groups of organisms are defined by their characteristics
new structures may arise by way of
refinement or exaptation
during ___________ complex structures evolve from simpler structures but have the same general function
refinement
during ____________________ an existing structures modified for a new function
exaptation
changes in genes that program the rate or spatial pattern of a species development can lead to the evolution of new structures
evo-devo: a field that links evolution to development
a field that links evolution to development
evo-devo
an evolutionary change in the rate of developmental events
heterochrony
refers to the retention into adulthood of features that were strictly juvenile in a species ancestors
paedormorphosis
during ______ the rate of reproductive development accelerates relative to the rate of no reproductive development
paedormorphosis
regulate the expression of many other genes
master genes
____________________ are master genes that control the formation of body parts during development
homeotic genes
changes in ____________ called hox genes have led to
homeotic genes
- the evolution of vertebrates from invertebrates
- the evolution of jaws and limbs
