sex chromosomes seperate during meiosis so sperm will contain either a x or a y chromosome and the ovum will contain 1 X chromosome.
50-50 chance the offspring will be male or female.
A trait determined by a gene that has more than 2 alleles.
species were individually created at one time and place in the past and have continued unchanged to the present.
Organisms were individually created but they may change with time.
ex. long neck giraffes..
Darwin and Wallace to how living things evolve that can be scientifically supported.
2 parts of Darwin and Wallace
a.1 Descent with modification
idea that orgnaisms are descended from common ancestors with modifications.
b. Natural Selection
individuals whose hereditary traits allow them to better cope with the local enviroment leave more offspring than individuals who lack these traits.
EVIDENCE from fossil record
1. Different kinds of organisms lived at different times
2. Organisms of the past were different from those alive today
3.Fossils in adjacent layers are more similar to fosisils from distant layers.
4. Intermediate forms are sometimes found
EVIDENCE from COMPARATIVE ANATOMY
HOMOLOGUS sTRUCtures- similar structure in related organsims but they share the same embryonic origin and arise from the same structure in a common ancestor.
rudimentary structures with no apparent use in the organism, but with a
strong resemblance to functional structures in their probable ancestors..appendix
HOw compartive embryonic structures can provided evidence of evolution
Adult forms of related organisms may be quite different, while embryonic opr larval forms may be very similar.
- Basic features that all organisms share at the molecular level
1. Same 4 base pair in DNA
2. Same 20 amino acids in proteins
3.Similar RNA molecules
4. WIth rare deviations, a single genetic code
5. Similar biochemical pathways sucha as glycolysis, electron transport chain, etc.
study of geographic distribution of living organisms.
How does bioGEOGRAPHY provide evidence of evolution
evolve by enviroment.
PATTERNS OF EVOLUTION
-Gradual change- changes in population occur slowly over generations
-Divergent evolution- Single population split into 2 or more populations
-Adaptive radiation-Divergence occurs simultaneously among a number of populations of a single species
-Convergent Evolution- Organisms that occupy similar enviroments often come to resemble one another superficially
2 CONCEPTS DESCRIBING the TEMPO of EVOLUTION
a-Phyletic graduation-traditional view, holds significant evolutionary changes are a result of slow gradual changes occuring
b-Punctuated equilibrium-Suggest there could be long periods of no change in poulation interrupted by periods of rapid speciation.
How does modern concept of evoution differs from Darwin?
Modern concept combines the modern principles of population genetics with the principles of Darwinian evolution.
Modern study of evolution is the study of population genetics.
interbreeding group of individuals within a deined geographical area
The total of all of the alleles, of all the genes, of all of the individuals in a population.
DISTINGUISH between gene pool and genotype.
Gene pool refers to the genetic makeup of a poulation of organisms.
-Genotype refers to genetic makeup of an individual organism.
Evolution of Population Genetics
A change in the composition of the gene pool through successive generation. Or a change in the gene frequencies of a population.
It staates that under centrain condition of stability the gene and genotype frequencies in a population will never change.
gene andgenotype frequencies to remain the same?
1. no mutations
2. Population must be large enough that change deivation of gene frequencies is sig
3.There can be no migration into or out of the population
5.No selection-all offspring have equal change of survial
Hardy Weinberg says about evolution
it is impossible
AGENTS OF EVOLUTION
Any factor that causes the gene frequencies of a population to change is agent of evolution. That is any factor that causes one or more of the HW conditions of stability not to be met is an agent of evolution
5 main agents of evolution
1. Mutations: every time an allele mutates into another allele one allele is removed from the gene pool and a new allele is added.
2. Gene flow-If individuals migrate from one population to an adjacent population they may remove alleles from one group and introduce them into a second group.
3. Genetic drift
This is a change in the gene pool that place as a result of chance
3.agents of evolution
2 types of genetic drifts
1.Founder effect-small isolate populations to experience gentic drift after it has been separated from the original large population.
WHen a large, genetically varied population suddenly decreases in size, the gene pool might well change even f the population expands again after the decrease.
agents of ev
4. Nonrandom mating
genotype ratios to remain stable by the HW principle, every individual in the population has an rqual chance of mating with any other member of the population.
agents of ev
5. Natural selection-MOST IMPORTANT
1. Directional selection-involves the gradual elmination of one phenotype in favor of another.
2.Stabiliiing selection-involves the elimination of extreme indiviuals from the population
3. Disruptive selection- involve the elimination of intermediate forms from the population
A group of populations whose members can interbreed with one another but cannot interbreedwith members of other populations and prduce vidable or fertile offspring.
-bWhat is the key mechanism in the development of new species
Genetic or reproductive isolation
c. ALLoPATIC speciation
1. speciation that occurs when one population becomes geogrraphically separated fromthe rest of the species and evolves
2.The genetic reproductive isolation mechanism?
geographical isolation mechanism
Islands, glaciers, ocenas
4.CONDITIONS neccessary for a species to evolve by this type of speciation
a. two pop become separated by a geographical isolating mehanism.
b.THey evolve under different enviromental conditions
c.Eventually they become so different they can no longer interbreed and produce feritle offspring.
ORIGIN OF LIFE
concept that living things can arise from preexisting living things
ABIOGENESIS- concept that living can arise from NONliving matter
ORGIN OF LIFE
b. DID the first organisms on earth arise by biogenesis or abio
They arose by abiogenesis
Origin of LIFE
C. Describe the conditions that existed on primitve earth that could have led to the origin of the first organisms
The gases present in the earths primitive atmosphere were nitrogen, carbondioxide, methane ammonia, hydrogen, water vapor. The notable gas was lacking was oxygen.
d. How gases could have reacted with one another ro form the first complex organic molecules, stressing the energy souces for their synthesis.
Using volcanic heat lighting and ultraviolet light as energy sources, these gases reacted with one another to form complex organic molecules such as amino acids, carb, mucleic acids
ORIGIN of life
-Describethe first organisms
THEy were prokaryotic, heterophic, and anaerobic unicellular organisms.
g. Explain the origin of the fist eukaryotic organisms
evolved from these prokaryotic organisms about 1.5 billion years ago. These first eukaryotic organisms have given rise to an enormous variety of eukaryotic organisms by evolutionary change since that time