a rate unit: change in standard deviations per generation population geneticist; importance of mutations to add variation in population
missing link at the time - problem with evolution fossil is incomplete and we make assumptions; fish like features and land features so answered question on how animals when from water to land
there was a gap between fish and terapods - small ground living dinosaur thought to be related to birds
change in enviro = change in needs = change in behavior = change in heritage trait = "Inheritance through acquired Characteristics"
survival of the fittest; populations have the potential to increase geometrically in size but are held at a stable size because of limited resources
Natural selection depend on? reproductive competition; variation in fitness; heritability but be there; evolution occurs HMS Beagle's voyage - voyage - Darwin 5 year
Darwin did his research on the finch - much variation, Island where Charles Darwin studied various tortoises and species of birds
Types of Selection
Directional - go one way
Selectional - working for the middle
Oscillating - con go from one extreme to another
Mechanism Of natural selection
the differential reproduction of individuals based on the heritage differences between them Individuals vary in most inherited characteristics (traits not expressed the same way) - increase of individuals who express traits and decrease in individuals who have less beneficial expression of trait
experiments with pea - laid down the principles of heredity; hybrids see how traits are expressed; genes have large and discrete trait
Principle of segregation
genes occupied in pairs bc chromosomes which carry heritability occur in pairs and are separated in reproduction = offspring gets gamete (23 from each parent) -
continuous traits; influenced at two or more loci; influenced by enviromment such as nutrition
occurs when the action of a single gene influences several seemingly unrelated phenotypic effects; one gene affects several of traits
convert energy into a form that can be used by the cell; get it from your mother which contains several or ring shaped DNA chromosome; variation caused by
Effect of environment On phenotypes
- enviro affects which phenotypes will be expressed depending on how good or bad enviro is ...low nutrition = no or poor expression of phynotype
change in genetic makeup; to be significant it has to occur in sex cell to be passed on and must give advantage or superiority to organism to pass on
small populations are affected; change in allels bc of low variation; random factor in evolution; small pop = alleles rare = lost = low variation = allele frequencys not passed down therefore disappear
An allele that was rare in the founders' parent population but
is carried by even one of founders can become common. paticular kind of genetic drift; small population and mate within; low variation = all ppl are decended from the founders in effect all the genes in the expanding group will
loss of genetic diversity; loss of alleles in gene pool; effect can be determianl to species survival because cant mate bc too closely related; cheetahs
In sexually reproducing species both parents
contribute genes to offspring. The genetic information is reshuffled every generation. Recombination doesn't change allele frequencies. It does produce different combinations of genes that on which natural selection may be able to act.
Sickle Cell And malaria
Abnormal form of hemoglobin resulting from a point mutation Unsuitable living environment for Plasmodium
Protection from Malaria
The separate evolutionary development
of similar characteristics in different
groups of organisms
Ancestors & descendants are traced in
time by analysis of homologous
Attempts to make rigorous evolutionary interpretations based solely on analysis of certain types of homologous characters
Characters inherited by a group of organisms from a remote ancestor and thus not diagnostic of groups (lineages) that diverged after the character first appeared.
Characters that are modified from the
ancestral condition and thus are
diagnostic of particular evolutionary
branching diagram, suggesting evolutionary relationships, that classifies species into groups within groups
Biological Species Concept
Individuals capable of interbreeding, but
reproductively isolated from other such groupsa species concept defining a species as a population or group thereof whose members potentially interbreed and produce fertile offspring
the process by which a new species evolves from a prior species.Speciation is the most basic process in macroevolution.
(ecology) the status of an organism within its environment and community (affecting its survival as a species)
evolution resulting from small specific genetic changes that can lead to a new subspecies
evolution on a large scale extending over geologic era and resulting in the formation of new taxonomic groups
Ecological species concept
The concept that a species is a group of
organisms exploiting a single niche.
Phylogenetic species concept:
Splitting many populations into separate species based on an
identifiable parental pattern of ancestry.
Living in different areas. Important factor in the divergence of closely related species from each other and from their shared ancestral species because it leads to reproductive isolation.
Free exchange of genes between two populations of organisms living in directly adjacent but environmentally different habitats. Hybrid zones develop
species that is now extinct, species defined from fossil evidence, often covering a lifetime span
.males and females of the same species having different external characteristics and features
Monotremes: Primitive, egg laying mammals
Marsupials: infants complete development in an eternal pouch Placental: Longer gestation allows the central nervous system to develop more completely
A genus is a group of species composed of members more closely related to each other than to species from any other genus.
having teeth in different shapes and functions. Having different kinds of teeth; characteristic of mammals, whose teeth consist of incisors, canines, premolars, and molars.
George De Buffon
argued that the earth was older than the bible said and also that the environment is an agent of change