Evolution Flashcards
Bootcamp + booster
Evolution
is the changes in populations, species or groups; changes in allele (traits) frequencies in populations over time.
Microevolution
the changes in allele frequencies that occur over time within a population due to mutation, selection, gene flow, gene drift, and nonrandom mating.
Macroevolution
the patterns of changes in groups of related species over broad periods of geologic time. Patterns determine phylogeny
(evolutionary relationships among species and groups of species). These patterns can be used to establish a phylogenetic tree
Cuvier proposed
catastrophism
catastrophism
Catastrophes lead to mass extinctions of species in those areas. The different populations in different areas were shaped
by what catastrophes had occurred, and what random organisms then survived and
populated that area.
Lamarck proposed:
Use and disuse, Inheritance of acquired characteristics
Use and disuse
used body parts will
develop and unused ones are weakened,
leading to evolution.
Inheritance of acquired traits
traits acquired through use and disuse are passed onto offspring (eg. giraffe stretching neck will cause its neck to
develop, and produce long necked offspring). This is incorrect - acquired characteristics are generally not heritable.
Darwin theory
Theory of Natural Selection.
Natural Selection
survival of the fittest without any luck. Allele frequencies increase or decrease in order to adapt to the environment.
Survival of the fittest
occurs as individuals with greatest fitness (ability to survive and produce viable
and fertile offspring) have greatest success, and pass on more DNA to future generations
compared to less fit parents.
Descent with modification
coined by Darwin, this occurs via natural selection. Over time and generations, traits
providing reproductive advantage become more common within the population.
Paleontology
fossils reveal prehistoric
existence of extinct species, and are often found in sediment layers. Deepest fossils represent the oldest specimens. Large, rapid changes produce new species.
Fossil types
actual remains, petrification,
imprints, molds, and casts
Biogeography
The geography that describes
the distribution of species. Unrelated species in different regions of the world look alike when found in a similar environment. The supercontinent Pangea slowly broke apart to 7 continents due to continental drift.
Embryology
similar stages of development
among related species establishes evolutionary
relationships. Gill slits and tails are found in fish, chickens, pigs, and human embryos.
Ontogeny
The development of an organism.
Phylogeny
The evolutionary development and diversification of a species.
Comparative anatomy
this describes two kinds of structures that contribute to the
identification of an evolutionary relationship.
Homologous structures
body parts that resemble one another between different species that descended from a
common ancestor. E.g., bat forelimbs vs. bird forelimbs
Analogous structures
body parts that resemble one another between different species that evolved independently. They have similar structures as adaptations to similar environments. These structures are also called homoplasies. E.g., bat wings vs. bee wings
Molecular biology
this field examines nucleotide and amino acid sequences of DNA and proteins from different species. More than
98% of nucleotide sequences in humans and chimpanzees are identical. Amino acids in the
protein cytochrome c are often compared
Comparative biochemistry
organisms with a common ancestor mean they have common biochemical pathways.
what are the key points of natural selection
- population possess an enormous reproductive potential
- Population size remains stable
- Resources are limited
- Individuals compete for survival
- There is variation among individuals in a population
- Much of the variation is heritable
- Only the most fit individuals survive
- Evolution occurs as favorable traits accumulate in the population
Stabilizing selection
the bell curve favors an
intermediate, like how the average height in humans is in the middle.
Directional selection
the favoring of traits that is at one extreme of the range. Traits at opposite extremes are selected against.
Industrial selection
the selection of dark-colored, melanic, varieties in various species of moths, like the peppered moth, as a result of
industrial pollution. This is a specific type of directional selection.
Disruptive selection
this selection occurs when the environment favors extreme or
unusual traits while selecting against common traits. For example, a certain environment may favor short and tall heights while the average height is selected against.
Sexual selection
the differential mating of males or females in a population
Intersexual selection
females choose superior males, which increases the fitness of the offspring. Because females
invest more energy into their offspring, they want to maximize the quality of their offspring by picking fit males.
intrasexual selection
when males compete and fight with other males for better mating opportunities. Males
increase fitness of offspring by
maximizing quantity. Intrasexual selection favors traits like musculature,
horns, large stature, etc.
Sexual dimorphism
the differences in appearance of males and females, which is a form of disruptive selection. This occurs because female choice leads to traits and behaviors in males that are
favorable to females. Male traits like colorful plumage or elaborate mating behavior will be selected for by females.
Artificial selection
this is a form of directional
selection carried out by humans when they breed favorable traits, and is not natural
selection
Mutation
new alleles could be introduced to the population with genetic mutations.
Sexual reproduction
genetic recombination such as crossing over, independent assortment, and random joining of gametes can occur during sexual reproduction
Diploidy
Diploid organisms have two copies of each chromosome. In heterozygous conditions, the recessive allele is stored for
later generations, and thus more variations are maintained in the gene pool