Chapter 13-15 Flashcards
Population
group of the the same species living in the same region at a given time
Variation
in a population, a condition in which members of that population differ in one or more traits
Kinds of variation (6)
structural, behavioural, biochemical, developmental, physiological, geographic
Biochemical
differences that occur in chemical processes that occur in organisms, including blood groups, pigments/colours of skin/fur, and the production of enzymes.
Cline
gradual change in a trait in members of a population across its geographic range.
Monomorphic
refers to a population in which all members are identical with regard to a particular phenotypic trait
Polymorphic
refers to a population whose members show several variants of a particular trait.
Discontinuous variation
type of variation in which members of a population can be grouped into a few non-overlapping classes with regard to expression of a trait e.g. digits on hand
Continuous variation
type of variation in which members of a population vary across a range. e.g. height
Causes of variation (4)
environmental factors, genetic agents, interaction between genetic agents and the environment, internal factors
Internal factors examples
hormone levels, infections, chemicals ingested
Genetic factors that cause variation
mono/polygenic traits, mutation, chromosome number e.t.c.
Polygenic inheritance
each gene has two alleles: a plus (+) allele that adds a small amount to the trait and a minus (−) + + − − genotype shows the same phenotype as a + − + − genotype.
Number of possible variations formula
2n + 1 (n=polygenes)
Gene pool
sum total of genetic information present in a population
When there is only one allele present in gene pool
said to be fixed
Allele frequencies
incidence or frequencies of particular alleles in a population
Allele frequency equation
frequency dom allele + frequency recessive allele = 1
Hardy-Weinberg principle
concept that allele frequencies in a population remain constant from one generation to the next if a set of conditions are met and no agent of change acts on the population.
Set of conditions for Hardy-Weinberg principle
population must be large, random mating, all matings equally fertile producing viable offspring, population is closed (no migration)
Hardy-Weinberg equilibrium
reached when the allele frequencies in a large, closed population remain constant, and will stay the same until agent of change acts on population
Random mating
all possible matings are equally likely to occur.
A phenotype that makes a greater contribution to a gene pool…
has higher fitness value and has a selective advantage
Fitness value
measure of genetic contribution to the next generation
Selective advantage
relative higher genetic fitness of a phenotype
Complete selection
cannot pass on trait because it dies before reproducing
Partial selection
fewer organism of particular phenotype produced
Genetic drift
changes, unpredictable in direction, in allele frequencies from one generation to the next owing to the action of chance events
The smaller the population…
the more impact of genetic drift (can cause eventual loss of allele)
Bottleneck effect
chance effects on allele frequencies in a population as a result of a major reduction in population size. Survivors that reproduce are unrepresentative.
Founder effect
chance effects on allele frequencies in a population that is formed from a small unrepresentative sample of a larger population. Sample migrated.
Theory of evolution by natural selection basis
high birth rates = high death rates, each type of organism shows variation, offspring are similar to their parents because they inherit from them.
Natural selection evolution theory
- individuals show variation from each other
- offspring resemble parents
- more offspring are born than can survive/reproduce
- there is a struggle for existence
Darwin-Wallace theory of evolution through natural selection conclusion
it is a mechanism of evolution, testable through observation and experiment
Natural selection acts on phenotypes through
selection pressures e.g. environmental factors
Adaptive value
degree to which phenotype contributes to reproductive success of individuals that have it
Transmutation
species can change and give rise to new species
Evolution
process of change, typically over geological time, that produces new species from ancestral species
Evidence of evolution
fossil record, biogeography, comparative anatomy, molecular evidence
Fossil evidence types
direct and indirect
Age of earth
4500 million years old
Relative ages
age of objects expressed in relative terms so that they are identified as younger or older than other objects, but the actual ages of the objects concerned are unknown
Absolute ages
actual age
Principle of superposition of sedimentary rock
oldest at bottom, youngest at top
Principle of correlation
comparing to work out age
Comparative anatomy
homologous/analogous structures, vestigial organs (appendix), comparing embryos
Homologous structures
similar structure, different function = convergent evolution
Analogous structures
similar function, different structure = divergent evolution
DNA hybridisation
how similar DNA is
Radiometric dating
radioactive decay, actual dating
Dating for Organic remains 60,000 years
carbon-14, nitrogen-14
Dating for Igneous rocks 10 million years
uranium-235, lead-207
Dating for Igneous rocks 0.5 million years and older
potassium-40, argon-40
Dating for most ancient igneous rocks on Earth
rubidium-87, strontium-87
Biographical distribution (3)
native isolated species are distinctive, native species are similar to species lived there in past, same niche in different isolated areas occupied by different species
Types of evolution
divergent, convergent, parallel, co-evolution
Divergent evolution
outcome that results when, over time, one ancestral species changes to give rise to several new species each occupying a different niche. (closely related species become dissimilar over time)
Adaptive radiation
is the evolution of a variety of species, each adapted to life in a different niche and evolved over time from a single ancestral species
Convergent evolution
results in similarity in appearance of organisms that are not closely related but that have similar ways of life
Parallel evolution
common heritage evolve in similar ways
Co-evolution
one species evolving causes another to evolve
Child from Taung species
Australopithecus africanus
Lucy species
Australopithecus afarensis (walked, brachiation)
Human classification
phylum = chordata, class = mammals, order = primates, super family = hominoids, family = hominids (hominins), tribe = hominini genus = homo, species = homo sapiens
Homo genus evolution
Australopithecus, Homo habilis, Homo erecuts, Homo neanderthalensis, Homo sapiens
Australopithecus
walked upright, bipedalism
Homo Habilis
first tools, could speak, meat eaters
Homo Erectus
fire, hunted in groups, migrated
Homo neanderthalensis
burials, specialised tools, caves (not ancestors)
Out of Africa theory
all came from Africa, shown by mtDNA
Mitochondrial DNA (3)
descent via maternal line, lack of recombination (passes unchanged), high copy number,
Haplogroups
distinctive mtDNA found in different populations
Mitochondrial ‘Eve’
first known mtDNA found
Extinction
no living members exist
Geological periods are grouped into
eons -> eras -> periods -> epochs
Geological periods are grouped into eons
archean, proterzoic, phanerozoic
Phanerozoic is divided into the eras
paleozoic, mesozoic (dinosaurs), cenozoic,
Cenozoic is divided into
palaeogene and neogene periods,
We are in the … epoch
Holocene epoch
Electron spin resonance
bombard fossil findings with radiation, and the older the object, the more electrons that are present at the high energy levels
Extant
when any living members of a species exist
Order of classification
kingdom, phylum, class, order, suborder, superfamily, family, subfamily, tribe, genus, species
Mammal meaning
mammary glands; teeth containing incisors, canines, molars; hair or fur on our surfaces; three bones in the ear
Primates
hand features (five digits, opposable thumbs, nails instead of claws); eye features (forward facing eyes, hence 3D vision and colour vision); ability to circumduct at the shoulder joint; high relative cranial size; long gestational period.
Primates include
great apes, lesser apes, monkeys, promisians (lemur)
Hominin diverged how long ago
6 million yrs ago
Evidence of walking upright
foramen magnum (directly at bottom of skull), tibia angle to femur, pelvis is shorter and wider, fossilised footprints
Homosapien evolution
enlargement of cranial and brain size, flattening of face and lesser prominence of jaw, smaller teeth, language and culture, tools,
Homo arised
2.4 million years ago
Homo sapiens evolved
130,000 yrs ago
Gene mutation
general term for one of many possible changes in the DNA base sequence of a gene
Genetic variation
variation due to genes
Agents of natural change that act on population (3)
physical agents, biological agents, chemical agents
Migration
movement of organisms into or out of a population
Emigration
net movement of organisms out of a population
Immigration
net movement of organisms out of a population
Subspecies
distinct population of a species that varies from other populations of the same species and which, over time, may evolve into a new species if the population remains isolated
DNA to DNA hybridisation proces
- prepare unique DNA from species to be compared
- make single stranded by heating and mixing
- cool and allow strands to pair - some pairing will occur between DNA from different species
- Results: either high or low complementarity
