Foundations of Biology Exam 5: Chapter 22

populations

a group of individuals of the same species living in the same geographic area at the same time

theory

explanation for a broad class of phenomena that is supported by a wide body of evidence; serves as a framework for the development of hew hypothesis; have two components: pattern and process

pattern

a component of a theory; a statement that summarizes a series of observations about the natural world; about facts- how things are in natures

process

a component of a theory; a mechanism that produces that pattern or set of observations

Plato

claimed the every organism was an example of a perfect essence, or type, created by God, and these types were unchanging

typological thinking

way way of thinking of that claims organisms were all created by a divine entity

Aristole

proposed that species were fixed types organized into a sequence based on increasing size and complexity; humans were at the top and only surpassed by angels or God

Lamarck

proposed the first formal theory of evolution; claimed that simple organisms originate at the base of the scale by spontaneous generation and then evolve by moving up the scale over time, always producing "better" species. contended that species changeDar via inheritance of acquired characters

evolution

the theory that all organisms on Earth are related by common ancestry and that they have changes over time, and continue to change via natural selection, genetic drift, gene flow, and mutation; any change in the genetic characteristics of a population over time, especially change in allele frequency

Darwin and Wallace

emphasized that the process responsible for change through time- natural selection- occurs because traits vary among individuals in a population; the opposite of typological thinking, which ignores variation or considers it unimportant

reasons the theory of evolution by natural selection was revolutionary

1. it overturned the idea that species are static and unchanging; instead, it suggested that species change through time and are related by common ancestry

2. it replaced typological thinking with population thinking

3. it was scientific; it proposed a mechanism that could account for change through time and made predictions that could be tested through observation and experimentation

descent with modification

the phrase used by Darwin to describe how species that lived in the past are the ancestors of species existing today, and that species change through time; the pattern component of Darwin's theory

fossil

any physical trace of on organism that existed is the past; includes tracks, burrows, fossilized bones, casts, ancient DNA (aDNA), and so on

fossil record

all of the fossils that have been found anywhere on Earth and that have been formally described in the scientific literature

extant species

a species living today

the vastness of geologic time

evidence one for change through time; knowing that sedimentary rock forms in layers allows us to date fossils based on the age of the rock, creates a geologic time scale

geologic time scale

the sequence of eons, eras, and periods used to describe the geologic history of Earth; gives fossils relative ages

radioactive decay

acts as a "natural clock" in which the decay of different elements can be used to give absolute ages to fossils

extinction changes the species present over time

evidence 2 for change of over time; if species have gone extinct, then the array of species living on Earth has changed through time; 99% of all species that once lived are now extinct

extinct species

a species that no longer exists

transitional features link older and younger species

evidence four for change over time; through the observation of fossils we can find transitional features linking ancestral species to their derived species; ex. limbs turning into fins on fish

transitional feature

a trait that is intermediate between a trait observed in ancestral (older) species and the homologous trait observed in derived (younger) species

vestigial traits

evidence four for change through time; the presence of vestigial traits in current species; change over time is logical because environments change drastically overtime; what once was useful lost its purpose

species can be observed changing today

evidence five for change through time; antibiotic resistant bacteria or finch beaks shape changing

similar species are found in the same geographic area

evidence one for descent from a common ancestor; ex. finches from the Galapagoes islands were similar because they had descended from the same ancestor on the mainland but then evolved different traits as they colonized the island

pylogenic tree

a branching diagram that depicts the evolutionary relationship among species; shows ancestor to descendant relationship

related species share homologies

evidence two for descent from a common ancestor; ex. human hair and dog hair are shared traits because they descended from the same common ancestor

genetic homology

similarity in DNA nucleotide sequences, RNA sequences, or amino acid sequences due to inheritance from a common ancestor

developmental homology

similarity in developmental structures or processes, embryonic form; due to inheritance from a common ancestor

structural homology

similarities in adult organismal structures that are due to inheritance from a common ancestor

independently

if species were created ___________, homologies would not occur

formation of new species from pre-existing species can be observed today

evidence three for descent from a common ancestor; ex. killer whales, some populations so different in prey choice and social behavior now that they can no longer interbreed like they used to in the past

internal consistency

the observation that data from independent sources agree in supporting predictions made by a theory

artificial selection

deliberate manipulation by humans, as in animal and plant breeding, of the genetic composition of a population by only allowing certain individuals with desirable traits to reproduce

struggle for existence

coined by Darwin, since there are many more individuals born than can survive due to limited resources, this occurs as people compete for food and places to live

Darwins four postulates

1. variation exists among individual organisms that make up a population

2. some of the trait differences are heritable, passed on to offspring

3. survival and reproductive success are highly variable

4. the subset of individuals that survive best and produce the most offspring is not a random sample of the population

natural selection

the process by which individuals with certain heritable traits tend to produce more surviving offspring than do individuals without those traits, often leading to change in the genetic makeup of the population; a major mechanism of evolution; the only evolutionary process that produces adaptation

fitness

in evolutionary biology, the ability of an individual to produce viable offspring relative to others of the same species

adaptation

a heritable trait that increases fitness in an individual in a particular environment relative to individuals lacking the trait

selection

a passive process; differential reproduction as a result of heritable variation; not a purposeful choice