Evolution Flashcards
The genetic change in a population or species over generations
Evolution
Evolutionary processes work at the __________ level
Population
___________ is the ongoing process through which the characteristics of species change and through which new species arise
Evolution
Species are fixed, permanent forms that do not change over time
Plato & Aristotle
Evolution as the refinement of traits that equip organisms to
perform successfully in their environments. Proposed that by
using or not using its body parts, an individual may develop
certain traits that it passes on to its offspring.
Lamarck
many naturalists were grappling with the interpretation
of fossils, imprints & remains of organisms that lived in the
past; the idea that some organisms had become extinct was
becoming accepted.
Uncounted Others
Scottish naturalist, proposed that geological change occurred gradually by the accumulation of small changes from processes (over long periods of time) just like those happening today in Theory of the Earth
James Hutton
popularized Hutton’s view in the nineteenth century in
Principles of Geology.
Charles Lyell
an economist who wrote An Essay on the Principle of
Population in 1798, an influential essay on the competition for
limited resources
Thomas Malthus
Primed acceptance of the idea of evolution as a process proceeding according to determinable principles
Industrial Revolution
The selective breeding of domesticated plants and
animals to promote the occurrence of desirable traits in the offspring.
Artificial Selection
two essential components of artifical selection
variation & heritability
VH
_________ was independently conceived of and described by two naturalists, Charles Darwin and Alfred Russell Wallace, in the mid-nineteenth century
Mechanism for evolution
process by which organisms with certain inherited characteristics are more likely to survive and reproduce than are organisms with other characteristics; unequal reproductive success individuals with certain inherited traits are more likely to survive and reproduce than are individuals with other traits. Works on individuals to alter the population
Natural Selection
Modifications the occur due to natural selection
that fit organisms to their environment
Evolutionary Adaptations
given that resources of any environment are limited, the
production of more individuals than the environment can
support leads to a struggle for existence, with only some
offspring surviving in each generation, i.e., those with best
traits to compete for the limited resources.
Fitness
Darwin observed that beak shape
varies among finch species. He
postulated that the beak of an
ancestral species had adapted over
time to equip the finches to acquire different food sources.
Darwin’s Finches
imprints or remains of organisms that lived in the past
Fossils
similarity in characteristics
resulting from a shared ancestry
Homologous Structures
A group of interacting individuals belonging to one species and
living in the same geographic area at the same time. Different
populations of the same species may be geographically
isolated from each other to such an extent that an exchange
of genetic material never or only rarely occurs
Population
all the alleles for all the genes in a population at any one time
Gene Pool
A change in a populations gene pool over a succession of generations
Microevolution
volutionary change above the species level, e.g., the origin
of a new group of organisms through a series of speciation
events & the impact of mass extinctions on diversity
Macroevolution
- can amplify or diminish only heritable traits
- not goal directed
- result of environmental factors that vary from place to place and over time
Natural Selection
_________ Occurs in populations over generation
Evolution
Diversity arises from ___________ and ___________
mutation and recombination
MR
___________ in animals and plants average about 1 in every 100,000 genes per generation. For these organisms, low mutation rates, long time spans between generations, and diploid genomes
prevent most mutations from significantly affecting genetic variation from one generation to the next.
Mutation rates
a form of microevolution in which the frequencies of gene
variants (alleles) change due to chance (random processes)
Genetic Drift
genetic drift that results from a drastic reduction in
population size. Typically, the surviving population is no
longer genetically representative of the original population by chance
Bottleneck Effect
genetic drift resulting from the establishment of a new small population whose gene pool represents only a sample of the genetic variation present in the original population
Founder Effect
the gain or loss of alleles from a population by the movement
of individuals or gametes into or out of the population.
Genetic exchange with another population. It tends to reduce
differences among populations
Gene Flow
a population or a group of populations whose members
have the potential to interbreed with one another in nature &
produce fertile offspring
Biological Species
- Organisms distinguished based on measurable physical traits
- the smallest group of individuals sharing a common ancestor and forming one branch on the tree of life
Species
the process in which one species splits into two or more
species
Speciation
The probable evolutionary history of a species or group of related species
Phylogeny
a discipline of biology that focuses on classifying organisms &
determining their evolutionary relationships
Systematics
branch of systematics dealing with naming & classifying
Taxonomy
any factor that prevents individuals of closely related species from interbreeding
Reproductive Barriers
prevent mating or fertilization between species
Prezygotic Barriers
-Temporal isolation
-habitat isolation
-behavioral isolation
-mechanical isolation
-gametic isolation
Types of Prezygotic Barriers
_________ prevent development of fertile adults if hybridization
occurs
Postzygotic Barriers
Hybrid offspring don’t reach
reproductive age
Reduced hybrid viability
RHV
hybrid infertile
Reduced hybrid fertility
hybrid fertile, but weak
hybrid breakdown
other homeland”; formation of a new species in populations that are geographically isolated from one another. The initial block to gene flow is a geographic barrier that
physically isolates the splinter population
Allopatric Speciation
same homeland”; formation of a new species in populations that live in the same geographic area. The origin of a new species without geographic isolation. Polyploidy,
habitat complexity, and sexual selection are factors that can
reduce gene flow in sympatric populations
Sympatric Speiciation
Polyploidy arises from a single parent species. For example, a
failure of cell division might double the chromosome number
from the original diploid number (2n) to tetraploid (4n).
Because the polyploid individual cannot produce fertile
hybrids with its parent species, immediate reproductive
isolation results.
Single Parent
A second form of polyploid speciation can occur when two
different species interbreed and produce hybrid offspring.
Most instances of polyploid speciation in plants resulted from
such hybridizations.
Interbreeding
