3: Darwinian Evolution Flashcards
gradual change at the genetic level of populations over the course of several generations
evolution
occurs when new species arise from common ancestors via descent w modification
speciation
Charles Darwin’s 2 things guide biological research to this day
theory of evolution, chromosomal theory of inheritance
he proposed evolution through inheritance of acquired characteristics
jean-baptiste lamarck
organisms acquire adaptations and pass them onto their offspring
inheritance of acquired characteristics
____ is transformational: organisms transform their characteristics by use and disuse of body parts
lamarckism
est the principle of uniformitarianism; concluded earth age must be hundreds of millions of years
charles lyell
darwim observed the similarities between the plants and animals of the ______ islands & south america
galapagos
5 theories of darwinian evolution:
- perpetual change
- common descent
- multiplication of species
- gradualism
- natural selection
the living world is neither constant nor perpetually cycling, but is always changing; hereditary continuity is observed from past to present life
perpetual change
shows hereditary continuity and enviro changes throughout history of life
fossil record
all organisms share a common ancestor
common descent
evolutionary history of organisms
phylogeny
characters/character states that share the same evolutionary origin; show common descent
homologies
A ______ of groups w/in groups supports a history of phylogenetic bracketing (based on suits of similar homologies)
nested hierarchy
development of an organisms thru its entire life (recapitulates phylogeny)
ontogeny
change in timing of developmental events
heterochrony
change in physical location of a developmental process
heterotropy
genetic variation w/in a species provides the material from which new species arise
multiplication of species
states that a species is a reproductive community of populations occupying a specific niche
biological species concept
biological features that prevent interbreeding between species
reproductive barriers
reproductive barrier: impair fertilization
prezygotic
reproductive barrier: impair development, survival, reproductive capability
postzygotic
populations of one species occupying separate geographical areas
allopatric
occurs when the separated populations evolve independently and develop reproductive barriers
allopatric speciation
geological or climate change separates populations
vicariance
small number of individuals disperse to a distant region w no members of that species
founder event
occurs when individuals w/in a species specialize to occupy different niches w/in the same habitat
sympatric speciations
evolution of several ecologically diverse species from a common ancestor (many different species arise in short period)
adaptive radiation
large phenotypic differences between species only occur through the accumulation of smaller changes over time
gradualism
states that new traits are established in a population by increasing their frequency
population gradualism
states that new traits are produced over small incremental changes over hundreds to thousands of generations
phenotypic gradualism
states that phenotypic evolution is concentrated in short events of branching speciation followed by longer intervals of morphological stability
punctuated equilibrium
the major process by which evolution occurs in Darwin’s theory
natural selection
observation 1- all populations produce large numbers of gametes and offspring each generation; population increases exponentially
organisms have great potential fertility
observation 2- no natural populations show continued exponential growth
natural populations mostly remain constant in size
observation 3- exponential growth of a natural population would require unlimited resources to provide food and habitat
natural resources are limited
observation 4- no two individuals are exactly the same even w/in populations
populations show variation among organisms
observation 5- offspring resemble their parents (darwin didn’t understand mechanisms of inheritance)
some variation is heritable
inference 1- overpopulation leads to more severe struggles; small part survive each generation
members of a population undergo a continuing struggle to exist
inference 2- traits that confer an advantage to survival allow organisms to live longer and pass those traits onto their offspring
varying organisms show differential survival and reproduction favoring advantageous traits
inference 3- propagation of favorable traits transforms species; natural selection leads to speciation
over many generations, natural selection generates new adaptations and new species
refers to the ability of an organism to survive to reproductive age and produce offspring; depends on its suitability to its enviro
fitness
species where white morph (f. typica) was more common in pre-industrial England, but black morph (f. carbonaria)became common during the industrial revolution
peppered moth (biston betularia)
2 steps of natural selection
- mutation is random
- survival of different traits is nonrandom
- chemicophysical changes that affect the sequence of nucleotides in DNA
- can be passed on
- ultimate source of new genetic variation
- doesn’t prefer advantageous traits
mutations
differential survival and reproduction among varying organisms
sorting
