the origin of species Flashcards
macroevolution
evolution of new species
speciation
origin of a new species
what 2 processes lead to speciation?
anagenesis (phyletic evolution)
cladogenesis (branching evolution)
anagenesis
accumulation of changes transforming one species into another species
cladogenesis
budding of one or more new species from a parent species that can continue to exist
what did Linnaeus describe species in terms of?
morphology - their physical form
what does taxonomy consider differences in today?
body function, biochemistry, behavior, and genetic makeup (DNA)
biological species concept
defines a species as a population who can interbreed in nature to produce viable, fertile offspring with each other and not those with members of other species
what is the exception to the biological species concept?
in zoos or in labs where hybrids are sometimes produced between species that do not interbreed in nature
prezygotic barriers
reproductive barriers that isolate gene pools that happen prior to the formation of the zygote
postzygotic barriers
reproductive barriers that isolate gene pools that happen after the formation of a zygote
5 prezygotic barriers
habitat isolation
behavioral isolation
temporal isolation
mechanical isolation
gametic isolation
habitat isolation
2 species live in different habitats and do not encounter each other
2 species of parasites live on diff hosts and never mate
behavioral isolation
special behavior unique
probably the important reproductive barrier with closely related species
fireflies of diff species have special patterns of blinking for mating
temporal isolation
2 species mate during different times of the day, diff seasons, or diff years
orchid flowers open in the morning and wither that evening allowing pollination occur only once the entire year
mechanical isolation
2 closely related species try to mate, but it is anatomically impossible
lock and key fit between bird species
gametic isolation
gametes may meet, but no zygote is formed
fish release eggs water next to the eggs of other species, and the sperm recognizes the correct eggs by specific molecules (proteins) on the coats of the eggs allowing for fertilization
3 postzygotic barriers
reduced hybrid viability
reduced hybrid fertility
hybrid breakdown
reduced hybrid viability
zygote has formed but is genetically incompatible between 2 species
abort, incomplete development, or be a weak offspring
reduced hybrid fertility
the hybrid offspring is healthy, but sterile due to the failure of meiosis to produce normal gametes if the chromosome number and structure different from the 2 parental series
donkey + horse = mule
hybrid breakdown
first generation hybrids are healthy and fertile, but when they mate with one another or with either parental species, the next generation is weak or sterile
what does the biological species concept not work for?
extinct life forms - the fossils must be grouped according to morphology
asexual organisms who don’t interbreed, but essentially make clones
sometimes it is too rigid - coyotes breed with dogs and produce fertile hybrid offspring but still are separate species
what does the biological species concept emphasize?
reproductive isolation of a species interbreeding with each other and not other species
5 alternative species concept
morphological species concept
recognition species concept
cohesion/pluralistic species concept
ecological species concept
evolutionary species concept
morphological species concept
separates species based on physical features