Lecture Exam 1 Flashcards
the 8 general properties of living systems
- chemical uniqueness
- complexity and hierarchical organization
- reproduction
- possession of genetic program
- metabolism
- development
- environmental interaction
- movement
General property 1: chemical uniqueness
living systems demonstrate a unique and complex molecular organization
-small molecules assembled into macromolecules
(nucleic acids, proteins, carbohydrates, lipids)
General property 2: complexity
- living systems demonstrate a unique and complex hierarchical organization
- in living systems there exists a hierarchy of levels (macromolecules, cells, organisms, populations, species)
General property 3: reproduction
reproduction is a component of the definition of life
- at each level of the biological hierarchy, living forms reproduce to generate others like themselves
1. genes replicate to produce new genes
2. cells divide producing new cells
3. organisms reproduce to produce new organisms
4. populations fragment to produce new populations
5. species split to produce new species
general property 4: genetic program
genetic program provides fidelity of inheritance
- nucleic acids: encode the structures of the protein molecules needed for organismal development and functioning
- DNA: long, linear chain of nucleotides (stores genetic info)
- genetic code: correspondence between base sequences in DNA and the sequence of amino acids in a protein
general property 5: metabolism
living organisms maintain themselves by acquiring nutrients from their environments
- metabolic processes:
1. digestion (catabolic or anabolic)
2. energy production (respiration)
3. synthesis of molecules and structures required by organisms
general property 6: development
all organisms pass through a characteristic life cycle
-development describes the characteristic changes that an organism undergoes from is origin to its final adult form (ex. caterpillar -butterfly)
general property 7: environmental interaction
all animals interact /w their environment
- Ecology: study of organismal interaction /w an environment
- all organisms respond to environmental stimuli, a property called irritability
general property 8: movement
living systems and their parts show precise and controlled movements arising from within the system
-living systems extract energy from their environments permitting the initiation of controlled movements
what is the meaning of “the living world is neither constant nor perpetually cycling, but is always changing”
- the varying forms of organisms undergo measurable changes across generations throughout time
- documented by the fossil record
- theory upon which the remaining four are based
(analogy: you will never step into the same river twice) - the water isn’t the same, you aren’t the same and the organisms living inside the river aren’t the same
adaption
an anatomical structure, physiological process or behavioral trait that evolved by natural selection and improves an organisms ability to survive and leave descendants
adaptive radiation
the evolution of several ecologically diverse species from a common ancestral species within a short geological time interval
- new lakes and islands provide new opportunities for organisms to settle and evolve
- early settlers who were under heavy competition before are now free to colonize the new habitat
- geographic isolation leads to more speciation
homology
Darwin saw this as major evidence for common descent
- richard owen described this as “the same organ in different organisms under every variety of form and function”
- vertebrate limbs show the same basic structures modified for different functions
- every time a new feature arises on an evolving lineage, a new homology forms
- homology gets transmitted to all descendant lineages unless it is subsequently lost
radiometric dating
methods:
- potassium argon dating
- potassium 40 decays to argon 40 an calcium 40
- half life of potassium 40 is 1.3 billion years
- calculating the ratio of remaining potassium 40 to amount originally there provides close mathematical estimate of the age of rock deposit
- rate of decay of uranium into lead
- one of the most useful radioactive clocks
- can date age of earth
- error is less than 1% over 2 billion years
heterochrony
evolutionary change in timing of development
-characteristics can be added late in development and features are then moved to an earlier stage
paedomorphosis
terminal stages may be deleted causing adults of descendants to resemble youthful ancestors
- retention of ancestral juvenile characters by descendant adults
- ex. axolotl
allopatric speciation
allopatric pops. occupy separate geographical areas
- cannot interbreed because they are separated but could do so if geographical barriers were removed
- if these pops. evolve reproductive barriers, allopatric speciation occurs
- separate pops. evolve independently and adapt to different environments
- environmental change between pops. also can promote genetic divergences by favoring different phenotypes in the separated pops.
- eventually they become distinct enough they cannot interbreed when reunited (formation of new species)
- ex. sea urchin, galapagos finches
sympatric speciation
the evolution of 2 groups of the same species but they do not have a geographic barrier. These 2 groups evolve differently causing them to no longer be able to interbreed and are soon considered different species. Examples of this are the sculpins of Lake Baikel and various species of cichlid fishes in the great lakes of Africa which are found nowhere else.
gradualism
Darwin’s theory of gradualism opposes arguments for the sudden origin of species
- based on the accumulation of small changes over time which led to the different major forms of life
- “the accumulation of quantitative changes leads to qualitative change”
- agreed with Lyell’s uniformitarianism that past changes do not depend on catastrophic events not seen today
- natural pops. have small continuous changes in phenotypes that can accumulate over millions of years
punctuated equilibrium
proposed by Niles Eldridge and Stephen Jay Gould
- explains the discontinuous evolutionary changes observed through geological time (incomplete fossil records)
- states that phenotypic is concentrated in brief events of speciation followed by long intervals of morphological evolutionary stasis
- speciation is an episodic event
- duration of 10,000 - 100,000 years
- species survive 5-10 million years
- speciation may account for less than 1% of species life span
exaptation
denotes the utility of a structure for a biological role that was not part of the structures evolutionary origin
-exaptation contrasts adaption which implies that a structure arose by natural selection for a particular biological role
RNA world hypothesis
-first enzymes could have been RNA
-earliest self replicating molecules could have been RNA
-investigators call this stage the RNA world
the RNA world would have been encapsulated by membranous vesicular structures.
principles that guide zoological research
- theory of evolution
- chromosomal theory of inheritance
Darwin’s theory of evolution basics
- Darwin proposed this
- over 160 years old
- published in “on the origin of species by Means of Natural Selection” in England in 1859
- obstacle: it lacked a successful theory of heredity
- Ernst Mayr proposed that Darwin’s theory of evolution should be viewed as 5 major theories (perpetual change, common descent, multiplication of the species, gradualism and natural selection)
common descent
all forms of life descend from a common ancestor through a branching of lineages
- life’s history has the structure of a branching evolutionary tree known as phylogeny
- serves as the basis for our taxonomic classification of animals
multiplication of species
the evolutionary process produces new species by splitting and transforming older ones
natural selection
a creative process that generates novel forms from the small individual variations that occur among organisms within a population