CHAPTER 3 Evolution and Natural Selection Flashcards
the “calendar” for events in Earth history.
descending order: eons, eras, periods, epochs, and ages
geologic time scale
GTS
largest intervals of geologic time
hundreds of millions of years in duration
–the most recent and began more than 500 million years ago
Eons
Phanerozoic Eon
GTS
the second longest portions of geological time
divided time intervals of eons
subdivided by periods
era
The enumeration of those geologic time units is based on—-, which is thecorrelationand classification of rock strata
GTS is also divided using significant events in the history of the Earth (e.g. dominant life forms, extinction events, climate)
stratigraphy
Impotance of GTS
- In exploration and —– (geologically date range specific).
- Study of fossils allows us to —- of organisms that lived billion years ago.
retrieval of fossil fuels
visualize the characteristics
Evolution
In biology, EVOLUTION is the change in the characteristics of a species over several generations and relies on the process of natural selection.
EVOLUTION is a process that results in changes in the genetic make up (gene pool) of a population through successive generations.
Evolution: a Product and Process
—-is genetic change that occurs over long time scales, resulting in large changes in heritable traits in a population; changes large enough that we consider this population a unique taxonomic group, or species
—is genetic change that occurs over small time scales and results in small changes in heritable traits
macroevolution
microevolution
Evolution is a product of two opposing forces:
- Processes that constantly introduce variation in traits
- Processes that make particular variants become more common or rare.
P = G + E + (G X E)
What causes variations?
Recombination
Mutation
How does variations occurs?
During fertilization, sperm cell fuses with the ovum to create a —.
Each chromosome contains hundreds to thousands of genes
On each pair of chromosomes, there are two genes that determine that trait to be inherited. This gene pair is called —.
zygote
allele
Mechanisms of Evolution
Change in the DNA sequence within a gene or chromosome of a living organism
It can be the result of viral infection, exposure to mutagens, or mistakes in DNA replication during cell division.
mutation
Mutation
—- mutations can lead to the reproductive success and adaptability of an organism to its environment
—– mutations reduce the fitness of an organism and increase the susceptibility to several illnesses and disorders.
Beneficial
Deleterious
Classifications of Mutations
Germ line mutationsoccur in gametes (eggs or sperm cells) and — to offspring.
Somatic mutationsoccur in non-reproductive cells and are not pass on to the following generation
can be pass on
Those mutations that occur in germ line are the most important to large-scale evolution because they can be transmitted to offspring.
Mechanisms of Evolution
It leads to an evolutionary change when some individuals with certain traits in a population have a higher survival and reproductive rate than others and pass on these inheritable genetic features to their offspring.
natural selection
Natural Selection
— is a process in which the individual is subjected to.
—is a measure of how well organismssurviveandreproduceduring this process of natural selection, with emphasis on “reproduction“. Survivalis one important component of fitness.
Selection
Fitness
Fitness also depends on the ability of the organism to attract a mate andreproduceto make fertile offspring. An organism that survived for many years, but never successfully attracted a mate or had offspring, would have very low (zero) fitness.
— (1809–1882) and — (1823–1913) independently proposed the concept of natural selection as a mechanism for biological evolution.
Charles Darwin
Alfred Russel Wallace
Categories of Natural Selection
occurs when the environment selects average against organisms of a population with extreme versions of a trait.
- favors an average phenotype by selecting against extreme variation.
stabilizing selection
Categories of Natural Selection
the environment selects for an extreme characteristic
- single phenotype is favored, causing the allele frequency to continuously shift in one direction
directional selection
Predation
Human hunters or fishermen pursuing quarry most often kill the bigger individuals
Super bugs
Categories of Natural Selection
the environment favors extreme traits in a population at the expense of intermediate forms, thereby splitting the population into two or more subpopulations.
- selection often drives speciation
disruptive selection
Disruptive selection happens in large populations with lots of pressure for the individuals to find advantages or niches as they compete with each other for food to survive and/or partners to pass on their lineage.
Mechanisms of Evolution
The flow of alleles in and out of a population due to the migration of individuals or gametes.
This variable flow of individuals in and out of the group not only changes the gene structure of the population, but can also introduce new genetic variation to populations in different geological locations and habitats.
gene flow
Mechanism of Evolution
It can occur when a small group of individuals leave in a population and establishes a new one in a geographically isolated region.
It is random as it occurs in a result of pure chance, however, it affects small populations significantly unlike large populations that are not susceptible to change due to chance.
genetic drift
bottle neck effect and founder effect
genetic drift
A dramatic decrease in genetic diversity caused by the formation of isolated small colony of individuals.
The distance or obstacles between the two populations make interbreeding impossible, and the new populations become genetically distinct over time.
A mutation may cause a population of organisms to become reproductively isolated from the parent foundation. Without the ability to interbreed with the larger population, the small population becomes distinct. If successful it will grow into a new species.
founder effect
Endogamy (marrying within the religion)
Polygyny (the practice of taking several wives)
genetic drift
A genetic drift resulting from the reduction of a population due to natural hazards (earthquakes, floods, fires)
When most members of a population die suddenly,genetic variationgoes down and the frequencies at which differentallelesare found in the population can change in a big way..
bottle neck effect
How Do Geological Processes and Climate Change Affect Evolution?
First, the locations of continents and oceanic basins greatly influence the earth’s —- and thus help determine where plants and animals can —.
Second, the movement of continents has allowed species to —-, adapt to new environments, and form —- species through natural selection.
The long-term climate changes have a major effect on biological evolution by determining where different types of plants and animals can survive and thrive and by changing the — of different types of ecosystems
climate
live
move
new
locations
