Ch.22: Evolution by Natural Selection Flashcards
Plato
- typological thinking
- species are unchanging types and variation within species is unimportant
Aristotle
- Scale of Nature
- linear scheme in which species are fixed types organized into a sequence of increasing size and complexity
Lamarckian Evolution
- species are not static but change through time
- Lamarickian evolution is progressive
- inheritance of acquired characterisitics
inheritance of acquired characteristics
phenotype changes in response to environmental cues and these phenotypes are passed onto offspring
Evolution by Natural Selection
- evolution occurs because traits vary among individuals in a population and some individuals with certain traits produce more offspring than others
- Darwin and Wallace
Two predictions of Natural Selection
- Species change through time
2. Species are related by common ancestry
Population Thinking
variation is key to understanding nature of some species
Evolutionary turning point
population genetics reconciled Menedialian Genetics and Darwinian Evolution
What is descent with modification?
Darwinian descent with modification is that species are related by descent of common ancestry
Principle of Uniformitarianism
idea that geological processes occurring today is similar to those that occurred in the past
Radioactive decay
steady rate at which unstable parent atoms are converted into more stable daughter atoms
Law of Succession
resembles fossils found under rocks in a certain area and living species found in the same geographical area
Transitional Feature
trait in a fossil species that is the intermediate between ancestral (older) species and derived (younger species) . It is a link between older and younger species
Vestigal Trait
reduced or incompletely developed organ or structure that has no function but resembles a functioning organ or structure in another closely related species
Homology
study of likeness that exists due to shared ancestry
three types of homology
genetic homology, developmental homology, and structural homology
evidence for “species change through time”
- life on Earth is ancient (fossil record)
- fossils (extinct) species resemble living species found in the same area
- vestigial traits
- transitional features
- characteristics of a population vary within species and can be observed today
evidence for “species are related”
- similar species often live in same geographic area
- homology (3 levels)
- formation of new species from old species can be observed today
Modern Synthesis
- occurring in 1940s
- genetic basis of variation and natural selection is formalized
- all the different types of fields of studies formulate the following: populations are units of evolution, natural selection is the primary mechanism of evolutionary change, and gradualism (large changes result due to the accumulation of small changes)
Artificial selection
selective breeding of desirable traits in plants and animals
Struggle for existence
more individuals are born than can survive and as a result compete for food and shelter
two concepts that lead to Darwin’s finding of natural selection
artificial selection and struggle for existence
evolution by natural selection occurs when….
heritable variation leads to differential reproductive success
Natural selection
occurs when individuals with certain traits produce more offspring than those without these traits
Fitness
ability to produce viable, fertile offspring
Adaptation
heritable trait that increases an organism’s fitness
Homologous structure
have similar structural skeletal elements, but different functions
Analogous structures
have similar functions but animals are not closely related
their similarity in function is not due to their relations
ex. wings of insects and wings of birds
three misconceptions of natural selection and adaptation
“Evolutionary change occurs in individuals” (no, natural selection occurs on individuals and evolutionary change occurs in populations)
“Evolution is goal-directed” (no)
“Evolution perfects organisms” (no)
Acclimatization
changes in an individual’s phenotype that occurs in response to changes in environmental conditions
acclimatization is not adaptation
Fitness trade-offs
compromise between two traits that cannot be optimized simultaneously
Ontogeny
process of development of an individual organism
Phylogeny
evolutionary history of a species
Why is the male urinogenital system not a good design?
This is an example of why evolution is not goal-directed. It is not a good design because vas deferens passes over the urethra and that can cause problems in old age.
What are the four reasons why evolution does not produce organisms?
- adaptations are often compromises
- historical constraints
- co-opt existing structures, adapted for new situations
- selection only edits previously existing variations
