eco and evo 4
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what is an example of homologies?
- bird and bat wings, thylacine and timber wolf, nubian vulture and turkey vulture
- panda's thumb
how to determine if it is homologous?
- same fundamental structure
- same relations to surrounding bones
- same embryonic development
what is the difference between ancestral and derived homologies?
- one is present in common ancestor and one evolved after
- the distinction is called character polarity
what is the common ancestor of whales?
diagram used in cladistics to show relations among organisms
the evolutionary history of a group of organism, length of branch indicates amount of evolution
what are three main statistical technique
- unrooted tree
- principal of parsimony
- principle of max likelihood
principle of max likelihood
the most likely phylogeny is the one that has the highest probability of having produced the observed sequences
what is population genetics
study of patterns of genetic variation
if population is fixed for an allele, what does it mean
when population exhibits only one allele at a particular gene
- relative frequency at a particular locus
- it is the fraction of all chromosomes in the population that carry that allele
what is evolution
change in allele or genotype frequency over time.
what is balancing selection
acts to maintain two or more alleles in a population
does genetic drift lead to adaptation why?
the alleles whose frequencies are changing are not affecting an individuals ability to survive or reproduce
what does adaptive radiation result from?
- diversity of resources
- natural selection accelerates the rate of speciation and adaptation
how can speciation occur without natural selection?
by genetic drift
includes some but not all descendants of common ancestor
what its the closest relatives of four legged land vertebrates
characteristics of tiktaalik
fins, gills, scales (fish), but skull was flat,functional neck and ribs
shared by two or more taxa and present in most recent ancestor
first bits of our upper arm and leg
first true finger and toes, lacked wrist
flat skull (amphibian, beginning to walk on land), transitional between fish and tetrapods
when are genetic switches that make fingers, arm bones and toes do their thing?
during 3-8th week after conception
what is zone of polarizing activity
- patch of tissue that causes pinky side to be diff from thumb side
- when removed or injected with vitamin A creates mirror image of duplication
what genes in flies make one body segment look different from another?
- hedgehog gene
- sonic hedgehog gene (chicken)
what is the difference in teeth in carnivores vs. plant eaters
- carnivores have blade like molars (cut meat)
- plant eaters: flatter teeth (macerate leaves)
what is the mineral that makes enamel hard?
what is different about us and reptile teeth?
reptiles change teeth all the time
where is tritheledont found and what is it?
- nova scotia
- between mammal and reptile
- starts to show teeth in front is different from back
what are actually conodonts
- most common fossil between 500-250 MYA
- teeth of ancient jawless fish (no hard bones)
very primitive fish with no jaws, made living by attaching to other fish and feeding on their bodily fluids
first animal with bony heads
- head, covered by teeth
simplest cranial nerve
attach to one muscle or organ
nerves that supply the muscles
control muscles and carry sensory info from our face to our brain
active in front where first gill arch forms
- dichotomy between vertebrates (notochord and nerve cord) and invertebrates (worm)
- closest relatives to animals with heads (worms with gill slits)
- 530 million years ago
when does blastocyst attach to uterus so embryo can join bloodstreams
what are the features of tube within a tube arrangement shared by
all animals with backbone four weeks after conception
major difference between human and shark
humans' first arch forms some ear bones, we do not see in sharks
important patch of tissue containing all info for cell to develop was
- the organizer
- noggin was another example
until what month is the earth dominated by single cell microbes
where was the most primitive versions of our body plans from?
teeth, cartilage, bone which is hardest
teeth, bone then cartilage
single cell alga, introduced predator, then alga evoked to form 8 cells
what is the closest microbe relatives of animals with bodies like sponge and placozoans?
what constitutes tree bodies
have molecular rivets (hold them together) and cell communication tools
what is the most common protein in animals
after how much time are we tube within a tube and have three germ layers
fourth week after conception
how many sets of hox genes does humans have
which part of ear is most ancient and sends nerve impulses to our brain?
what are we humans trading smell for?
what have whales and dolphins traded olfactory genes for?
most primitive fish alive on planet today (jawless, single nostril), have both air and water smelling genes
lampreys and hagfish
how much does light sensing cells make up in the sensory genes
what is opsin used for?
convey info from outside to inside of cell
camera like eye is common to what
every creature with a skull
how can we see rich colors?
we have more color receptor
how did our eye color increase congruent with evolution
diversification of forests 55 million years ago
miss large pieces of their eyes
eyeless gene in mouse
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