Chapter 18 Flashcards
the change in organisms throughout earth’s history
Today’s life is different from and descended from earlier life
“Descent with modification”
Evolution
Fixed ideal species
Scala Naturae (ladder of nature)
Aristotle
Creation and young earth
Judeo-Christian bible
Orderly, nested classification system
Binomial naming (ex: Homo sapiens; genus and species name. Genus is always capitalized and species is not; italicize or underline both)
Linnaeus
Fossils are a record of change over time caused by catastrophic events; emphasized the layers as pieces of history (called strata)
Catastrophism
Studied rock strata that mark relative ages and concluded that species changed because of local extinction
Georges Curvier
Slow, continuous processes –> geological features
Also called gradualism
James Hutton
Father of geology
Uniformitarianism: Geological process in the past occur in the same way as today
Earth is extremely old!
Charles Lyell
Physician and natural philosopher
“Natural Philosophy” on evolution
Wrote ideas that “forms minute” slowly acquired complexity over time
Erasmus Darwin
Linked evolution to adaptation
Extinct species have been replaced by descendants with new features (adaptations)
First to propose a mechanism for evolution: “use and disuse”; (use it or lose it)
Ex: you’re smart because your parents studied hard
Thought you could inherit acquired characteristics
Ex: I tan in the sun and my child has darker skin
Lamarck
Charles Darwin’s two theories
Descent with modification: all present life is related through “descent with modification” from a common ancestor in the past
Natural selection: is the mechanism for evolution and is not random
Part 2 of Darwin’s theory
Farmers can enhance small heritable variations by artificial selection or breeding
3 observations about the environment that support the concept of natural selection
- All organisms produce more offspring than is needed
- Most populations remain fairly stable in size
- Resources for life are limited
evidence in support of Darwin’s theory
direct observation, anti-biotic resistance, the fossil record, homology
structures derived from a common ancestor (but may be modified for different functions)– common ancestor, different function (sometimes)
homologous structures
examples of homology
vestigial structures, developmental, cellular & molecular
remnants of ancestral or homologous structures, structures with no present adaptive function
vestigial structures
things that are the same in embryos
developmental homologies
similarity of cell structures, proteins and DNA, corresponds to relatedness
cellular and molecular homologies
unrelated species have similar adaptations (analogous structures) under similar environmental conditions
convergence
Explains both the diversity and unity of life
Accounts for much of form and function
Can predict outcome of environmental change
the theory of evolution by natural selection
smallest set of organisms that look alike
morphological species
a set of organisms adapted to a specific set of resources (utilize different organic food sources)
ecological species
smallest distinct set of organisms that share a common ancestor
phylogenetic species
set of populations whose members potentially interbreed in nature to produce fertile, viable, young and do not successfully with other such groups
biological species
two individuals who can breed in nature and produce viable (living) fertile offspring
biological species concept
they prevent fertilization so that the fertilized egg doesn’t happen
types: habitat (ecological) isolation, temporal isolation, and behavioral isolation, mechanical isolation, gametic isolation
prezygotic barriers
they act after a hybrid zygote is formed
reduced hybrid variability, reduced hybrid fertility
post zygotic barriers
_____ increases diversity of life
speciation
a change in allele frequency over time. It does not make more species but leads to greater diversity with speciation
microevolution
Physical barrier isolates one population
Hybrid zones may exist during allopatric speciation; post-zygotic barriers keep gene pools apart
Isolated population diverges genetically due to natural selection and/or genetic drift(happens when you have a small population)
Founder effect could reduce diversity and increase deleterious alleles
Biological reproductive barriers evolve, creating separate species
allopatric speciation
