history of biological diversity. preserved evidence of organism learned different types of fossils...
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Chapter 14 - 17History of Biological Diversity
Preserved evidence of organism Learned different types of fossils
◦ Molds, casts, petrified fossils, animal & plant remains & trace fossils
◦ Geologic time scale – eras, periods◦ Relative age of rocks – half -life
Carbon-14 dating
Fossils:
Hereditary changes in groups of living organisms over time
Theory of Evolution:
Anatomy – study of structure◦ If the diverged from a common ancestor they have
similar characteristics (homologous structures) > the # of shared structures btw 2 species, the more
closely related they are◦ Vestigial organs (little or no function to the
organism) are often homologous w/ structures in related species that still work
◦ Species living in diff locations under similar ecological conditions, dvlp similar structures & behaviors If conditions change, those w/ favorable anatomical
traits become established
Scientific Areas that have contributed to this theory:
Embryology – embryonic dvlpt or organisms◦ Looks @ pre-birth, pre-hatching, or pre-
germination
◦ Can see similarities not seen in adults b/c adults change form
◦ Similar embryonic structures means common ancestry
Biochemistry – genes & proteins◦ More similar the DNA & amino acid seq, the more
likely they are to have a common ancestor
◦ Better than anatomy When species are so closely related they don’t
appear to be diff When species are so diverse they share few similar
structures
Paleontology – prehistoric life◦ Fossil record gives evidence of life forms & envir
◦ Supports evolutionary relationships Shows a pattern of gradual change
◦ Not complete – gaps
◦ The older the fossil, less resemblance to modern version
Defined as the evolutionary history of a species or a grp of related species
Dvlpd evolutionary theory that states that all forms of life on Earth are related b/c there is a common ancestor
From all of this comes---- Phylogeny!
Anatomy – similarity means a common ancestor◦ Divergence – acculum. of evolutionary differences
May be homologous in structure but not function◦ Convergence – structures w/ diff evolutionary
histories become more similar over time to adapt to a similar envir (analogous structures)
Embryology – highly divergent taxa (grps) w/ so many anatomical diff◦ ontogeny (growth & dvlpt of an indiv organism) will
recapitulate phylogeny
Common Ancestor????
Paleontology – gives info on dates & order of divergence◦ Transitional fossils – show links in traits btw grps for
documenting intermediate stages of a species’ evolution
Biochemistry – molecular clock - > the genetic similarity, more recent is the common ancestor
***1 piece of evidence doesn’t give an accurate pic of the evolution of 1 species – evidence from all the fields gives more reliable info
Phylogenetic Tree
Cladogram
Hard to classify b/c species are becoming extinct
Most recent classification:◦ 3 Domains – Domain Archae, Domain Bacteria,
Domain Eukarya◦ 6 Kingdoms – Kingdom Eubacteria,
Kingdom Archaebacteria, Kingdom Protista, Kingdom Fungi, Kingdom Plantae, Kingdom Animalia
Classification:
All the changes that have transformed life on Earth
Can occur on a small scale affecting a single population (microevolution) or large scale affecting species across populations (macroevolution)
Biological Evolution
Occurs b/c indiv of a pop have diff traits that allow them to be more or less effective in an envir than other members
Changes in inherited traits over time – increases a species’ “fitness” in its envir.
Natural Selection:
1. Overproduction of Offspring: ◦ raises the chance that some will survive but also
inc competition for resources
4 Main Principals of Natural Selection:
2. Variation: ◦ exists w/in the inherited traits in the phenotypes
(which is controlled by the genotypes & the envir)◦ All life that has ever existed on Earth, share @
least nucleic acids (DNA or RNA) and proteins◦ 2 types of reproduction:
Sexual – meiosis creates gametes, fertilization takes place creating variation
Asexual – 1 parent that produces a clone (binary fission or mitosis) – ex.) budding, fragmentation & vegetative propagation – repro rate is higher but in a changing envir can’t adapt
If you could reproduce sexually & asexually, better advantage for survival!!!!
3. Adaptation: ◦ increased frequency of a particular structure,
physiological process or behavior in a pop that makes it better able to survive & reproduce
◦ Gene pool changes over time b/c those less adapted will die
◦ “fitness” – measure of how a trait contributes to repro success
SURVIVAL OF THE FITTEST!!!!
4. Descent w/ Modification: ◦ as the envir of a pop changes, the entire process
of natural selection yields pop w/ new phenotypes
◦ over time pop will have diff structures, live in diff niches or habitats than ancestors
Species – grp of organisms that share similar characteristics & can interbreed w/ 1 another to produce fertile offspring
Means they share a common gene pool (all genes of all the indivs in a pop)
So a genetic change in 1 indiv can spread through a pop through mating◦ If the change inc fitness, then more indiv will have
it
Diversity w/in the Species:
So the greater the diversity, the greater the chances for the species to survive
Favorable traits in male & female organisms enhance repro. success◦ Non-random mating changes the gene pool over
time & a better adapted species
Inherited beneficial traits become more prevalent, & detrimental traits become less
Genetic Drift – random change in allele frequency◦ Rare alleles dec in freq & are eliminated◦ Other alleles inc & become fixed◦ Seen more in small pop vs large pop
Gene Flow – movemt of genes in & out of a pop – due to migration
Non-random Mating – limits the freq of some alleles
Factors That Influence Genetic Variability:
Mutations – inc freq & types of allele changes in a pop
Natural Selection – allows most favorable phenotypes to survive & be passed on
When there is no change in allele freq, pop is in genetic equilibrium
5 conditions:◦ Large population◦ No movement in or out of pop◦ Random mating◦ No mutations◦ No natural selection
Hardy-Weinberg Principle:
Process of forming a new species by biological evolution from a pre-existing species
Usually a result of isolation (reproductive or temporal, behavioral, geographic)
As different traits become favorable the 2 pop gradually become so different they are unable to reproduce w/ each other
Speciation:
Gradualism – slow changes over a period of time
Punctuated Equilibrium – periods of abrupt changes after periods of little change
Adaptive Radiation/Divergent Evolution - # of different species split off from a common ancestor – survive in different niches
Convergent Evolution – occur among different species living in similar envir – produce analogous structures
Patterns of Evolution:
Coevolution – 2 or more species living in close proximity change in response to each other
Extinction – elimination of a species b/c they can’t adapt – can be gradual or rapid◦ Gradual Extinction – slow rate due to other
organisms, changes in climate or natural disasters◦ Mass Extinction – result of catastrophic events
that change the envir very suddenly
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