Week 6 Flashcards
Evolution
the change in genetic composition of populations over time
Evolutionary Theory
understanding and application of the processes of evolutionary change to biological problems
Theory
untested hypothesis
Darwins Evolutionary Theory
species change over time
divergent species share a common ancestor
Natural selection is the mechanism that produces change
Population
a group of individuals of a single species that live and interbreed in a particular geographic area
Mutation
any change in a nucleotide sequence
occurs randomly with respect to organisms needs
can be benefical, harmful or have no effect
Gene pool
sum of all copies of all alleles at all loci in a population
Allele Frequency
proportion of each allele in the gene pool
Genotype frequency
proportion of each genotype among individuals in the population
Natural selection - Darwin name
descent with modification
Natural Selection
far more individuals are born than survive to reproduce
offsprings resemble parents but arent identical
difference among individuals affect their chances of survival and reproduction
Adaption
a favoured trait that evolves through natural selection
Genetic Drift
random changes in allele frequencies from one generation to the next
Population bottleneck
environmental event results in the survival of only a few individuals
can result in genetic drift
populations loose much of their genetic variation
Founder Effect
genetic drift changes allele frequencies when a few individuals colonise a new area
Non random mating
when individuals prefer others of the same genotype,
Non random mating - homozygous genotypes
increase
Non random mating - heterozygous genotypes
decrease
Sexual selection
occurs when individuals of one sex mate preferentially with particular individuals of the opposite sex rather than at random
Linnean Taxonomic system
Kingdom phylum Class Order Family Genus Species
Darwin’s 6 Key points
Variation Heritability Competition Natural Selection Adaption Genetic Basis
Wallace’s Line
faunal boundary line drawn by Alfred wallace that seperates the ecozones of Asia and Australia
General Characteristics of animals
multicellularity
heterotrophy
internal digestion
motility
Monophyletic
all animals have a common ancestor
Synapomorphies
unique junctions between cells
colony efficiency
more efficient at prey captue than single cells
cells begin to specialise
Developmental patterns
distinct layers of cells form in early development
Diploblastic
2 cell layers ectoderm and endoderm
Triploblastic
3 cell layers ectoderm endoderm and mesoderm
divided into 2 categories
protostomes
blastopore develops into a mouth
deuterostomes
blastopore develops into anus first
Gastrulation
embryo is hollow ball of cells that indents to form blastopore
Body plan
general structure, arrangement of organ systems
Four Key Features
symmetry
body cavity
segmentation
external appendages
Symmetry
overall shape
Radial symmetry
body parts arranged around central axis
Bilateral symmetry
can be divided into mirror image halves on only one plane
Cephalization
bilateral symmetry
concetration of sensory organs and nerve tissue at anterior end
Acoelomate
lacks fluid filled space, space between gut and body wall is filled with cells that have cilia
Pseudocoelomate
fluid filled space in which intenal organs are suspended, no inner mesoderm
pseudocoel
enclosed by muscles only on outside
Coelomate
body cavity is a coelom that develops within mesoderm
peritoneum lines internal organs
Segmentation
facilitates specialisation of body regions
allows animals to alter body shape and control movement
Appendages
enhance animals abililty to move and find food, avoid predators and find mates
limbs allow highly controlled rapid movement
criteria of being an animal
multicellular no cell walls nerve and muscle tissue most reproduce sexually have hox genes
hox genes
regulate the expression of other genes
