Ch 22-26 Flashcards
Evolution
explain both unity and diversity of organism
Why are organism different?
Genetic Variation
Descent with modification…
is evolution
Evolution
theory about how contemporary species arose from ancestors through “decent with modification”
Theory
explanation that is broad in scope, generates new hypotheses, and is supported by a large body of evidence
Phylogeny
evolutionary history of a species or group of species
Phylogenic Trees
used to visualize our hypothesizes of how a group of organisms are related
Common Ancestors
branch points, nodes
Branch length
time
Homologies
molecular, anatomical, vestigial structures, embryos
Hypotheses related to evolution can be tested ….
through evolution
Anatomical Homologies
similar structures due to common ancestry, but may have a different function
Vestigial Structures
remnants of features that functioned in the ancestor but no purpose in present organism
Molecular Homologies
all organisms have DNA and the genetic code is universal
-very different species share genes
Those with fewer differences are…
more closely related
3 Domains
based on rRNA sequences
Eukarya -eukaryotes
Archaea -prokaryotes
Bacteria -prokaryotes
What do all cells have?
Ribosomes
Vertebrate Embryos
very similar early in development for all species
Analogous
similar features are not due to relatedness, but are due to convergent evolution
Convergent Evolution
independent evolution of similar features in different lineages
similar adaptations due to similar selective pressures in similar environments
Homology
shared ancestry
Analogy
convergent evolution
Fossil Record
provides evidence that past organisms differed from present day organisms, many species have gone extinct, organisms have become more complex
shows origins of major groups
helps answer big evolutionary questions
Biogeography
geographic distribution of species
Endemic species
found in only one certain place
What species can evolve quickly?
those with short generation times and high reproductive potential
Evolution is the change in the…
genetic composition of a population over time
we do not observe an individual evolving
Acclimatation
changes of ourselves to fit with the world
Charles Darwin
He was influenced by many different people to help him come to his conclusions
adaptation to environment and origin of new species are related processes
adaptations arise via natural selection
published a short essay in 1844 on descent with modification via mechanism of natural selection
didn’t like to share ideas
Carolus Linnaeus
1707-1778
Binomial System of Nomenclature
nested classification based on similarities
not describing evolutionary relationships
James Hutton
1726-1797
gradual mechanisms change geological features (valley formed by rivers)
Charles Lyell
1797-1875
incorporated Hutton’s thinking into principle of uniformitarianism
change is constant over time, these slow changes can build up over time
more influential to Darwin
Darwin read his book while on the Beagle
changes compound and build up over time, we can’t observe all changes because it’s too long a time
Georges Cuvier
1769-1832
fossils in strata-extinction
-found large elephant fossils that aren’t found else where in the world
stratification via “catastrophism”
-Darwin noticed new species would come in
Catastrophism
catastrophic events lead to extinctions, new species immigrated from other areas
Jean-Baptiste de Lamarck
1744-1829
proposed a mechanism for how life changes (how evolution happens)
1) use and disuse (during lifespan of an individual organism)
-if it wasn’t used it would shrivel up
-good parts are passed on
2) inheritance of acquired traits that could pass to offspring
-can’t pass on acquired traits (ex. children won’t be born with a tattoo if you get a tattoo)
Thomas Malthus
1744-1829
human population growth would endanger the survival of organisms
-looked at increase in population
-worried about natural resource accessibility
checks on human population growth -famine, disease, etc.
Artificial Selection
humans breed plants and animals to amplify desired traits over time
Alfred Wallace
almost scooped Darwin’s info, two essays in Royal Society in July 1858 and On the Origins in 1859
Natural Selection
mechanism for how life works
1) heritable variation among individuals in a population
2) competition for resources and a struggle for existence
3) individuals with traits best suited to the environment survive and leave more offspring than others
Adaptation
any heritable trait that enhances an organism’s ability to survive and reproduce in a certain environment
-3 types: structural (physical features), physiological (how something works), behavioral (action, adaptations)
Darwin’s Observations
1) Members of a population vary greatly in their traits (“natural” variation = genetic variation)
2) Traits are inherited from parents to offspring
3) All species are capable of producing more offspring than the environment can support
-certain individuals survive and reproduce at higher rates than others
4) Due to lack of resources, many offspring do not survive
Darwin’s 2 Inferences
Natural Selection
1) Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than others
2) This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in a population over generations
Natural selection increases match between organism and environment, thus organisms become better suited for their environment
Environmental change requires…
adaptation to new conditions which may result in new species
Fitness
ability to survive and reproduce
an individual just needs to be “fit enough” to reproduce
just need to be fit enough
-only a genetic success if you’re not a genetic dead end, have to have at least one kid
Humans can influence evolution
antibiotic resistance -> short gen time and lots of reproduction
large amounts of poaching for elephant tusks resulted in many elephants being born with small tusks
poachers would only kill the ones with bigger tusks since it’s more worth the money
Humans and chimpanzees have…
a common ancestor
share 98% of the same genes
diverged from a CA about 4-6 million years ago
Tree of Life
Classification and Phylogeny
Phylogenic Trees
branching diagrams of evolutionary relationship to visualize hypotheses of how a group of organisms are related
Taxonomy
method of naming and classifying
Taxon
unit at particular level
Phylogenic trees usually are
dichotomous shaped
Root
most recent common ancestor of all taxa
Tips
contemporary taxon, group, or species
Branch Points
represents common ancestor
node
Sister Taxa
organisms that share a common ancestor that is not shared by any other group
Branch
evolutionary lineage and ancestors in lineage
Branch Length
time
number of genetic changes per unit time
Phylogenic trees can be used to look at…
characters and deduce where/when characters arise or are lost
Share Ancestral Character
originated in ancestor
Shared Derived Character
evolutionary novelty, more recent
Maximum Parsimony Approach
Ocumsrazor
simplest explanation is usually correct one
fewest evolutionary events
fewest DNA base changes
Bracketing
predict by parsimony
featured shared by 2 closely related groups were present in common ancestor and all descendants
