Evolution Flashcards
What is evolution
biological change over timeinherited genetic makeup
population
a group within a species of interbreeding individuals and their offspring
small scale evolution
changes in gene frequency in a population from one generation to the next
large scale evolution
the decent of different species from a common ancestor over many generations
peppered moth
2 types- light and dark. The population of melanic (dark) has changed from 1% to 99% due to the environemental change (smoke, industrial revolution)
3 debates in evolution
1- is evolution real
2- what course did that evolution take
3- what is the mechanism for the genetic change over time
pre darwinian evolutionary ideas
- early greek philosophers- posited a static unchanging view on the world
- western thought that the world and its entirity was created by god in their present form showing little change of generations
- European renaissance: scientific method
- minister John Ray argued for a scientific sequence of comparisons among organisms
- Jean-Baptiste Lamrack: believed that the environment would affect the future shape and organization of animals
- Charles Lyall and James hutton - uniformitarianism
Carolus Linneaus
argued that species were fixed and unchangeable and were created orginally as we find them today (mordern taxonomy)
FACT: fixity of species
Jean-Baptiste de Lamarck
FACT: change of species
species did change over time and believed in evolution
- scale of nature, species would change and get higher up the scale and get better and better
Charles Darwin
- he found obserable variation in species
- species vaired from place to place
- variations were dependant on the enevironment
- decent with modification
Rev. Thomas Robert Malthus
- unchecked breeding causes populations to grow geomertically whereas food supply grows more slowly
- the population increases faster than the food supply so some people survive but some people die
Charles Lyell
Principle of Uniformitarianism: laws of physics and chemisty have not changed throughout earths history
- past geological events occured by natural processes similar to those observed todya
darwins model of evolution by natural selection (obseravtions)
1- organisms have great potential fertility which permits expodential growth of populations
2- natural populations normally do not increase exponentially but remain fairly constant in size
3- natrual resources are limited
darwins model of evolution by natural selection (Inference)
1- a struggle for existence occurs among organisms in a population
2- varying organisms show differnetial surival and reproduction, favouring advantageous traits
3- natrual selection acting over many genrations gradually produces new adaptations and new species
darwin and wallace
evolutionary change is caused by differential survival and reproduction mong organisms differing in hereditary traits
darwin and wallace conditions and mechanism
1- intrinsic increase in number of individuals within a species
2- competition for limited resources
3- survival of the few
Mechanism: natural selection
natural selection
the preservation of favourable individual differences and variations and the destruction of those which are injurious
cliff swallow (natural selection)
change in environment leads to a change in selection pressures
large bodies, more symmertical wings and tail feathers
Heredity
mutations in genes and chromosomes produce new variations which are passed on to sunsequent generations
Mendel
believed that inherited characters did not blend but were transmitted as discrete particals (1 element has 2 possible particals)
Mendels law of inhertiance
1- no diminishing characteristc
2- each individual carries a pair of alleles for each trait
3- alleles dominant or recessive
4- during formation each allele travles to its own gamete
5- alleles controlling a trait reach gametes independently of alleles controlling other traits
gene
a unit of ingeritance affecting the characterstics of a trait
allele
one of two or more alternative expressions of a gene
genotype
the genetic makeup of someone
gene pool
all genes in the eggs and sperm in a population
phenotype
the expression of the genotype and environment
muatation
a spontaneous error in DNA replication leading to a heritable change in a individuals genome
genetic combinations are created in 2 ways
1- corssing over during meiosis
2- sexual reproduction
selection pressures
- biotic factos (competiton, predation, disease)
- Abiotic factors (climate, topography, habitat)
Types of selection
Natural selection: - stabilising selection - directional selection - disruptive selection Artifical selection Sexual selection
stabilising selection
selects against the extreme phenotypes
directional selection
phenotypic character shifts in one direction
disruptive selection
selects against average phenotypes
artifical selection
humans are the selecting factor (select the advantages traits)
sexual selection
selection in traits that give an individual an advantage in attracting mates, even if these traits are neutal or harmful for survival
speciation
the evoluntary process or event by which new species arise
principals of science
- Science is guided by natural law
– Science has to be explained by reference to natural law
– Science is testable
– The conclusions of science are tentative
– Science is falsifiable
Scientific method
hypothetico deductive method: Scientific process of making a conjecture (hypothesis)
based on observations and then seeking empirical tests
that potentially lead to its rejection
Evidence for evolution
- fossil record
- stratigraphy
fossil record
a date of the sequence of morphological change. provided evidence of change over time
evolutionary trends
are directional changes in features and diversity of organisms
- perpetual change
- common ancestry
- anagensis
comparative anatomy - homologies
- forelimbs of bat, mole, and dugong
- each limb performs different functons
- all are superficially different
- all share common underlying anatomical plan
homology
the same organ in different organisms under every variety of form and function
phylogenetic constraint
evolution is constrained by ancestry
- a species may inherit particular traits or developmental systems that contrain the possible variation that forms the basis of new adaptations
vestigial features
some features in animals are reduced because they are no longer required for survival
atavistic features
‘throwback features’ such as the number of toes that the horse walk on
analogous features
similar features evolve independantly through similar environmental selection pressures
convergent evolution
separate lineages that were quite different but become similar because of similar lifestyles
homologies
similar characterstics shared by two different organisms because they were inherited from a common ancestor
analogies
are similar characterstics shared by two differetn organisms because of convergent evolution
homoplasmy
structures are similar in apperance may or may not be homolgous or analogous
artifical selection
a process in the breeding of animals and in the cultivation of plants by which the breeder chooses to perpetuate only those forms having certain desirable inheritable characteristics.
adaptive radiation
the formation of many new species following the availabilty of new environments or the development of new adaptation
fossil record and living species evidence is due to what course and what mechansim
• COURSE – Descent with modification – Gradualism vs punctuated equilibrium – Mosaic evolution • MECHANISM 1. Natural selection 2. Mutation 3. Gene flow (migration & reproduction) 4. Random genetic drift = evolutionary forces
Biogeography
the study of the distribution
of species across space (geography) and
time.
taxonomy
the science of describing and classfying organisms
examples of natural selection in human populations
Human populations have adapted genetically to recent changes in their
environment (i.e. selection pressures)
• Adaptation to living in high altitudes (Tibetan & Andean populations)
• Arsenic tolerance in Puna Indians (Argentinian Andes)
• Lactose tolerance (lactase persistence) in agricultural communities
natural selection define
a mechanism for evolutnary change favouring the survival and reprdocution of some organisms over other because of their biological characterstics
medicine evolution
- emerging dieases
- origin of dieases
- vectos of disease
- treatment of diease
- drug development
- obesity, metabolic sydrome and diabetes
conservation biology
Low population numbers = low genetic variation of the gene pool • Endangered populations are vulnerable to high death rates due to selective pressures (e.g. disease)
agriculture and horticulture
- applied evolution
- Humans use evolutionary principles and processes to improve crops
and animal stocks
weeds and feral animals
- dispersal of invasive species
- crop mimicry
forensics
- interpreting and analysin DNA evidence
- different populations evolve to have different alleles and different frequencys
human behaviour
our behaviour share similarties with that of other animals
- emotions
- relationships with others especially family
- parental care
- mate choice and long term pair bonds
evolution essentials
- System of reproduction
- Inherited variation
- Differential reproductive success (fitness)
- Changing environment
- Selective pressures
taxonomy
the science of describing and classifiying organisms
species
a group of populations whose memebers can interbreed naturally and produce fertile offspring
genus
groups of species with similar adaptation
uniformitariansim
the obeservation tha the geological processes that operate in the world today also operate in the past (james hutton, Charles Lyall)
decent with modification
diversity of animals has stemmed from a ancestor and then the ancestor overtime many species evolved (branched) from the one species.
genes change over time due to 3 things (evolutunary forces)
- mutation
- natural selection
- gene flow
- random genetic drift.
fitness
an organisms probability of survival and reproduction
evolutanry forces- mutation
introduces new alleles into the population. therefore the frequency of alleles will change overtime
evolutionary force- genetic drift
a mechanism for evolutionary change resulting from random fluctuations of gene frequencies from one generation to the next
genetic dift can be influnced by what?
- population size: the larger the population the less change will occur from one generation to the next
evoluntary force- gene flow
a mechanism for evoluntary change resulting from the movement of genes from one populatio to aother
gene flow can be affected by?
- variety of environment
- cultural factors
- geographic distance
speciation
the formation of new species from a parent species
steps of speciation
1- reproductive isolation
2- genetic divergance
3- adaptive radiation
steps of speciation- reproductive isolation
is genetic change that can lead to an inability to produce fertile offspring
steps of speciation- genetic divergence
the evoluntary forces will affect the genetic divergence however once gene flow has been eliminated the other forces will act to make the populations genetically divergent. This process continues until they become sperate species
steps of speciation- adaptive radiation
the process of speciation results in 2 species, the orginal parent species and the new offspring species. This rapid diversifcation of species is associated with changing environmental conditions
gradualism
whereby changes occur at a slow, steady rate over time
punctuated equilibrium
long periods of little evolutionary change are followed by relativley short periods of rapid evoluntary change
cladogensis
the formation of one or more new species from another over time
orthogensis
evolution will continue in a given direction because of some vaguley defined force
anagensis
teh transformation of a single species over time
