Unit test 2: (Ch. 21-23) Flashcards
What is phylogenetics?
science of classifying organisms according to common ancestry based on characteristics
what are the 2 related evolutionary patterns?
1-nested patterns of similarities found among species on present earth
2-historical pattern of evolution recorded by fossils
what are observed species descendants of?
modified descendants of earlier ones that had undergone s**peciation events from ancestral species **
what does a pattern of nested similarities among species indicate?
descent with modification and accumulation of change (adaptive radiation)
what are nested patterns?
similarities or differences in…
1- morphological characteristics
2- molecular characteristics
what is a phylogeny?
hypothesis for evolutionary history of species or group of species
what does every node in a phylogeny represent?
a common ancestor
phylogentic trees and cladograms display the best model for what?
hypotheses of relatedness of organisms
when discussing the characters and how phylogentic trees are inferred by the comparison of characters sgared among different groups of organisms, what type of characters are used? (3)
-anatomical
-physiological
-molecular features
can character states be similar in phylogenetics?
yes
what are the 2 reasons character traits can be the same?
-present in common ancestor of 2 groups and retained over time = homolgous character
-evolved independently in 2 groups as an adaptation similar to environments = analogous character
what is an example of a homologous character?
amniotic egg is a characteristic that all sauropsids share because all extent organisms in a tree have that feature
what is an example of an analogous character?
wings because the ancestors of birds and bats likely did not have wings (it was evolved)
what structures are not useful in building a phylogenetic tree?
-character states in monophyletic group
-character states present in all taxons
what do we need to develop hypotheses of evolutionary relationships?
homologies that are shared by some but NOT ALL of the members of the group under consideration
what are synapomorphies?
homologies (characters)that are shared by some but not all memebers of the group under consideration
where do you find the synapomorphies in the tree?
near the nodes
how should you compare different species or figure out how closely related they are?
compare their DNA and compare their sequences
what can you build to compare species’ differences?
Data matrix of their differences
What is sister taxa?
the 2 or + closest related species
what is are molecular clocks?
yardsticks for measuring absolute time of evolutionary change based on observation of genes that evolve at constant rates
in molecular clocks, what is proportional to the time elapsed since the species branched from a common ancestor?
point mutations
what is an example of how molecular clocks have been useful?
provided insight into evolution of homo sapiens
How did early earth produce simple cells? (how did life on earth begin?)
4 main stages:
-abiotic synthesis of small organic molecules
-joining of small molecules into marcomolecules
-packing of these molecules into protocells
-origin of self-reolicating molecules that made inheritance possibkle and natural selection to make improvements
what is the Hadean?
first geological eon
what is the hypotheses that scientists had made about the synthesis of the monomers?
-early earth’s atmosphere was a reducing environment which organic molecules could have formed
-energy for this organic synthesis could have come from lightning and intense UV radiation
what were scientists able to conclude when they tested small organic molecules in a reducing atmosphere?
that amino acids and notrogenous bases could be formed
what is a reducing atmosphere?
limited oxygen
how did they form organic polymers?
dripping solutions of monomers onto hot sand, clay or rock
what is an example of how an organic polymer was made?
nucleotide + hot sand/rock/clay = RNA
what are protocells?
aggregates of abiotically(not living) produced molecules surrounded by a membrane or membrane-like structure
what are the properties of life of protocells?
-ability to divide/reproduce, maintain metabolic reactions, maintain internal environment (homeostasis)
what is homeostasis of a cell?
maintain internal evironment
what are the self-replicating molecules in early life?
Ribozymes
from RNA
why is RNA most likely the first genetic material on earth?
because it is
-flexible by it being single stranded and folding to create different shapes
how does natural selection apply to molecules?
self-replicating molecules leave behind **offspring with variation in heritable traits**. Natural selection selects cells that are more and more adapted to the environment (survival of the fittest)
what does fossil record tell us about evolution on earth?
shows changes in the kinds of organisms on earth over time
what does deeper strata display in fossil records?
older organisms and how many extinct organisms look similar to organisms alive today
what makes fossil record incomplete?
many of earth’s organisms did not die in the right place at the right time
how are fossils dated?
radiometric dating=
decay of radioactive isotopes
how is the rate of decay expressed in radioactive dating?
the half-life of the parent isotope=
time required for 50% of the parent isotope to decay
is the half-life of isotopes affected by the environmental factors?
no
what are common isotopes used in radiometric dating?
carbon-14 and uranium-238
what was the earliest life?
-Eukaryotic
-prokaryotic
-archaeic
prokaryotic
what are the oldest known fossils that are 3.5 billion years old?
stromatolites
what are stromatolites?
rocklike structures composed of layers of bacteria and sediment
what produced all required compounds for life by using energy in chemicals or light?
autotrophs
what is the term used for producing compounds for life by using energy in chemicals?
Chemoautotrophs
what is the term used for producing compounds for life by using energy in light?
Photoautotrophs
where does most of the atmospheric oxygen originate from?
photosynthesis
what is oxygen revolution?
large increase in atmospheric O2
(on a graph)
what is a powerful greenhouse gas?
methane
what would atmospheric O2 have done?
removed green house gas, methane and created a snowball earth because of it
how are sponges and mammals both considered animals?
because of the common characteristics of animals
what are the 6 common characteristics of animals?
-no cell walls
-multicellular
-mobility (internal & external)
-Heterotrophy (needs to eat other organisms or substances)
-Embryonic tissues
-Collagen (matrix of connective tissues)
what did the evolution of multicellularity and differentiation of embryonic tissues give rise to?
new body plans of animals
what are the 4 body plan characteristics?
-symmetry
-presence of segmentation
-cephalization
-appendages
what type of symmetry is there? (3)
-asymmetric = no symmetry
-radially symmetric= circular like cnidarians
-bilaterally symmetric= body that divides into 2 halves
what is segmentation?
divisions of body into a series of repetitive segments
what is metamersim?
linear series of body segments which are similar in structure like a worm
what is cephalization?
from segmentation, it allowed a head region where sensory equipment is concentrated
what did cephalization influence in evolution?
nervous system
What are taxonomic groups?
nested categories that share morphological and molecular characteristics from common ancestors and evolutionary relationships
what is more similar/evolutionary related between family and order?
family because
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
what does genus mean?
a class, or group that links through common characteristics or 1 common characteristic
What do chordates have?
-notochord
-forsal, hollow nerve cords
-Pharingeal slits
-embryonic tail
what is a notochord?
structure that provides skeletal support but it doesn’t have to be bone
what is a dorsal, hollow nerve cord?
a structure that develops into the brain and spinal chord
what is a pharingeal slit?
structure present in the embryo that develop into **digestive, respiratory or sensory **organ
what is an embryonic tail?
extends between the anus
what are craniates?
chordates that evolved a skull
what is a vertebrate?
craniate that evolved vertebrae along notochord
What is an example of an invertebrate craniate?
hagfish
What are jawed vertebrates called?
gnathostomes
what is an example of a gnathostome?
sharks, amphibians, birds…
what are fully aquatic gnathostomes called?
chondrichthyans (these are sharks)
what are osteichthyes?
fish that are ossified skeletens (bone) that evolved lungs
what does the class actinopterygii include?
ray-finned fish distinguished by bony rays
what does the class Sarcopterygii include?
lobe-finned fish where their skeleton protrudes in their fins
what do Coelacanths include?
lungfish (like an in between water and air)
common ancestor to coelacanths?
tetrapods
what do tetrapods include?
amphibians, reptiles and mammals
reptiles and mammals are sister taxa?
yes they both share the amniotic egg in common
what do all mammals share?
hair and produce milk
what does the class mammalia include?
-monotremes
-marsupials
-eutherians (placenta = human)
what are monotremes?
egg laying mammals
