Speciation Flashcards
tuatara
low reproduction rate makes conservation difficult
inject females with hormones to stimulate egg production
for conservation, not all species are equal
biological species concept
defines species as organisms that can freely interbreed in nature and produce fertile offspring
speciation
permanent genetic isolation of populations in natural conditions
species
self contained, evolve independently with no exchange of genetic information
male pine hawk moth and female lime hawk moth
different species because offspring die
male donkey and female horse
offspring (mule) is infertile, therefore different species
lions and tigers
can produce fertile offspring but not in nature due to social behavior, different species
female chihuahua and male great dane
can’t produce offspring, but genetic material from great dane and chihuahua can get in an individual over many generations
not genetically independent, therefore same species
what feature of carrion flies makes it easiest to distinguish species?
male genitalia, helps female identify right species
no advantage for female to mate with male of different species, advantage for male to advertise differences from other species
what is the best way to tell apart Carolina chickadees and black-capped chickadees?
their mating songs
geographic (allopatric) speciation
speciation of geographically isolated populations
sympatric speciation
speciation without geographic isolation
speciation is…. (hint: unifromitarianism)
active process, makes divisions among species unclear
speciation ex. salamander ring species
solid and blotchy subspecies in different parts of CA
some subspecies can produce viable offspring, but not subspecies with the greatest differences
what happens when 1 island splits, isolating 2 populations of a butterfly species?
small populations can become genetically different due to genetic drift over time, doesn’t involve natural selection
more likely natural selection is involved, ex. bird predator on one island causes selective pressure, change in genetic structure of butterfly pop
what happens to butterfly populations when geographic barrier of split island is removed?
genetic mixing if poor genetic variation, merge again to form same species
sexual selection for genetic isolation, males/females recognize others of same population and reinforce division
can natural selection work on isolated populations?
yes, natural selection can generate genetic differences while populations are geographically isolated
sexual selection can
cause evolution of behavioral separation
phylogeny
evolutionary tree, pattern and timing of speciation
phylogenies reconstruct
evolutionary history
patterns of human colonization
how much genetic difference is there between human races?
very little, races are not defined by genes, they are constructs of society
insectivorous bat
only true flying mammal
adaptation: echolocation
moths can hear clicks, make tail to dive to make it more difficult to capture (coevolution)
bat wings show
flight evolved more than once in vertebrates
human hand bones similar to bat wing bones
birds don’t have webbing or extended bone
adaptive radiation
speciation of a single lineage into diverse ecological forms
adaptive radiation of darwin’s finches
don’t like to fly across open water, causes geographic speciation
all derived from same species, undergone rapid natural selection to take advantage of habitat
honeycreeper radiation in hawaii
1 founder species diversified, different bills used for variety of purposes
adaptive radiation of fruit flies in hawaii
can map phylogeny onto islands
pattern of speciation reflects sequential movement to islands as they formed
ex of using phylogeny to reconstruct history
evolutionary convergence
species from different evolutionary lineages share similar traits
convergent evolution between jackrabbit and kit fox
both have long ears, use as cooling devices
arctic fox has short ears
convergent evolution of porcupine and echidna
both have quills, distant evolutionary relatedness
selective pressure against predators with big mouths
convergent traits have to
evolve independently
convergent evolution gives
circumstantial evidence of natural selection
microevolution
evolution of individual species
macroevolution
speciation and extinction
biological diversity depends on
speciation and extinction
species reflect evolutionary history because
evolution works from what already exists
Flounder evolutionary history
bottom fish, has 2 eyes on one side of head
fry look like normal fish, eyes migrate to other side, doesn’t make sense to have eye on underside
ex of evolutionary history working from what already exists
why do humans have little body hair while gorillas have a profusion?
selection in humans to have larger brains
largest head size as an infant, infants typically have less hair
kept infant type traits to get big brains
development reveals
common ancestory
pea aphids
parthenogenic in summer (asexual reproduction)
offspring become sexual in autumn, mate and produce eggs
sexual reproduction needed to mix up genetic diversity between individuals
biological control of pea aphids
control by natural enemies
ladybugs
parasitic wasps inject egg in aphid, eats aphid from inside
parasite has to allow aphid to feed and get large enough to survive
main driver of evolution
natural selection
natural selection acts on ______ but is measured by ______
individuals
changes in genetic makeup of populations
natural selection leads to
evolutionary adaptations
does evolution have a purpose?
no motive to improve species
genetic diversity drives natural selection, evolution comes from random mutation
sequential evolution
easier to build something sequentially, start with something that already exists/works and modify
