Unit B Evolution Flashcards
evolution is when…
the same species exposed to different environmental pressures can become so genetically different that they can no longer interbreed
______ is the mechanism by which evolution occurs.
natural selection
Jean baptise lemark proposed the theories of
Use and Disuse / Inheritance of Acquired Characteristics (1809)
the theory of use and disuse and Acquired Characteristics suggested
organs that were well developed from use would be passed onto offspring in the well-developed form
Charles Darwin
Credited with the theory of natural selection or “survival of the fittest”
the five aspects of the theory of natural selection are…
Adaptation and Natural Selection
Overproduction
Population Speciation
Gradualism
Descent with Modification
Speciation refers to the process by which…
new species are formed.
the two types of speciation is
Transformation: one species evolves into another
Divergence: a parent species evolves into more than one other species
geographic barriers are..
barriers that isolate populations and prevent them from reproducing
geographic barriers lead to…
Allopatric Speciation
reproductive barriers lead to..
Sympatric Speciation
Reproductive barriers occurs when…..
species within populations no longer mate to produce fertile offspring
reproductive barriers that occur before mating and are called
Prezygotic
reproductive barriers that occur after mating and are called
Postzygotic
Prezygotic reproductive barriers include…
Habitat: they live in different locations, areas, spaces
Temporal: breeding or activity at different times of day/season/year
Behavioural: songs, calls, or dances are not shared or recognized
Mechanical: structures are not compatible
Gametic: sperm is not able to penetrate the egg (anatomically incompatible)
Postzygotic reproductive barriers include…
Zygote Mortality: when an egg is fertilized, but the zygote or embryo dies
Hybrid Inviability: if a first generation hybrid offspring is born, but shows low fitness it may not make it to the age of being able to reproduce
Hybrid Sterility: when the hybrid offspring grows to breeding age, but is incapable of gamete formation.
Divergent Evolution describes….
two or more species that originate from a common ancestor. May happen as a result of:
Adaptive radiation
Geographic isolation
Reproductive isolation
Homologous Structures suggest
a common ancestor
Convergent Evolution describes…
unrelated species that share similar traits due to exposure to similar ecological conditions or selection pressures
Analogous Structures are structures that…
serve the same function but have a different structure.
Parallel Evolution: describes
two related species or lineages that have evolved similar adaptations after divergence from a common ancestor
Coevolution: involves…
unrelated organisms evolving together
Adaptive Radiation: occurs when
several species evolve from a common ancestor and each species is specifically adapted to fill a niche
Microevolution is..
the change in gene or allele frequencies in a population from one generation to the next
Macroevolution is…
the large scale evolutionary change that results in speciation. The development of an entirely new species
Gradualism is..
Proposes that evolution occurs by the gradual accumulation of small changes
- occur over very long periods of geologic time
Fossil evidence provides snapshots that reveal only the major changes in organisms
Any intermediate stages not seen in fossils means that the fossil record is incomplete
selective pressure is..
force that causes a particular phenotype to be more favorable in certain environmental conditions
Punctuated Equilibrium:
Proposes that evolutionary history resulted from geologically long periods of stasis (no change), punctuated by short periods of rapid evolution (eruption,earthquake,meteor, etc)
Fossil record is complete with good records of long, static periods and few, if any, fossils from the short rapid bursts of evolution
Geological events thought to prompt these rapid changes
New barriers for organisms (allopatric speciation)
Fossil Record
uncovers fossils of extinct species that are preserved in ice, amber, tar, volcanic ash, peat, or sedimentary rock.
Biogeography is…
explain why unrelated species in different parts of the world have similar adaptations when found in similar environments. Supports natural selection
Embryology examines..
patterns of development and reveals similar stages in development (ontology) among established species which helps establish evolutionary relationships (phylogeny)
Comparative Anatomy shows..
Structures present in modern species that no longer have a function. Suggests evolution from an ancestor which needed the structure for survival.
Homologous Structures have a..
similar structure, but different form resulting from divergence. Suggests common ancestor.
Analogous Structures have a…
different structure, but same function resulting from convergence. No common ancestor.
What are vestigial structures?
Structures present in modern species that no longer have a function. Suggests evolution from an ancestor which needed the structure for survival.
Molecular Biology (Biochemical)
Studies the nucleotide (DNA) and amino acid (protein) sequences from different species. Closely related species share higher percentage of sequences than those that are distantly related.
All living things share the same __
genetic code,
Physiological Evidence….
Similarities between how organ systems of different organisms work indicate evolutionary relationships. Suggests possible common ancestor.
6 evidences for evolution..
fossil record, Evidence
biogeography Evidence
embryology Evidence
comparative anatomy Evidence
Molecular Biology (mechanical) Evidence
Physiological Evidence
Binomial nomenclature is..
the two part system developed for naming species
a dichotomous key is…
a tool used for identifying an unknown item or organism, (kinda like a family tree)
mutation is…
Any change in the DNA sequence of a cell.
taxonomy is…
classification and categorization of organisms
levels of classifications (in order)..
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
phylogeny is…
the representation of the evolutionary history and relationships between groups of organisms
biological overproduction is..
when a species produces more offspring than the carrying capacity of an environment
allopatric speciation is…
a species separates into two separate groups that are isolated from one another
sympatric speciation is…
groups from the same ancestral population evolve into separate species without any geographical separation.
