Chapter 5 Flashcards
Classification
The ordering of organisms into categories such as orders families and genera to show evolutionary relationships
Chordata
-the phylum of the animal kingdom that includes vertebrates
Vertebrates
Vertebrates- animals with segmented bony spinal columns, includes fish, reptiles, mammals, amphibians, and birds.
Taxonomy
- the field that specializes in animal classification
What are the principles of classification?
1) classified by physical similarities and evolutionary descent
what did hox gene mutations do?
led to basic limbs in all subsequent vertebrates.
Basic genetic regulatory mechanisms are highly conserved in animals
reflects principle #2 of classification-must reflect evolutionary descent
Homologies
similarities between organisms based on descent from a common ancestor
Analogies
similarities between organisms based strictly on common function, with no assumed common evolutionary descent
Homoplasy
the separate evolutionary development of similar characteristics in different groups of organisms, can occur in closely related lineages only
what are the two major schools of evolutionary relationships?
1) Evolutionary Schematics, and Cladistics
presumed ancestors and descendants are traced in time by analysis of homologous characters, uses a phylogenic tree diagram
evolutionary schematics
cladistics
attempts to make rigorous evolutionary interpretations based solely on analysis of certain types of homologous characters.
Focuses on distinguishing particular evolutionary lineages; traits which are more informative than ancestral traits
cladistics
what is a clade?
a common ancestor
if one common ancestor is shared what is that called?
monophyletic
what is more than one ancestor shared called?
polyphyletic
what can be indicative of a particular lineage?
derived or modified characteristics.. ex theropods are small dinosaurs thought to be related to birds because of their characteristics
shared derived characteristics def:
relating to specific character traits shared in common between two life forms and considered the most useful for making evolutionary interpretations.
cladogram
a diagram of relationships used by cladistics
what do both schools believe in?
Interested in tracing evolutionary relationships and in constructing classifications that reflect these relationships
Recognize that organisms must be compared using specific features (characters), some of which are more informative than others.
Focus exclusively on homologies.
Phylogenetic Tree
a chart showing evolutionary relationships as determined by evolutionary systematics. Must contain a time component to show ancestry descendant relationships
Cladogram
a chart showing evolutionary relationships as determined by cladistics analysis. Based on the interpretation of shared derived characters, contains no time component and does not imply ancestor =-descendant relationships.
Biological species concept
a depiction of species as groups of individuals capable of fertile interbreeding, but reproductively isolated from other such groups.
Speciation
the process by which a new species evolves from an earlier form
Geographical isolation is what?
the main factor in evolution
Recognition Species concept
a depiction of species in which the key aspect is the ability of individuals to identify members of their own species for purposes of mating.
Ecological species concept
a species is a group of organisms exploiting a single niche. Emphasizes the role of natural selection.
Phylogenic species concept
splitting many populations into separate species based on an identifiable parental pattern of ancestry.
Speciation occurs in 3 different ways
1) allopatric speciation, parapatric speciation, or sympatric speciation.
Allopatric speciation
living in different areas. Leads to reproductive isolation.
Parapatric speciation
only partial reproductive isolation required. Ranges of populations may be overlapping ex african baboons
Sympatric speciation
occur within one population with no necessary reproductive isolation
Sexual dimorphism
differences in physical characteristics between males and females of the same species, such as how humans have a slightly dismorphic body size.
(intraspecific methodology
Variation is accounted for either by individual age and sex differences seen in every species
interspecific methodology
the variation between reproductively isolated groups
Paleospecies
species defined from fossil evidence, often covering a long time span.
Genus
a group of closely related species
Fossils
traces or remnants of organisms found in geological beds on earth’s surface.
mineralization
occurs when water carrying minerals seep into the tiny spaces within a bone.
Taphonomy
the study of how bones and other materials come to be buried in the earth and preserved as fossils.
Geological time scale
the organization of earth history into eras, periods, and epochs.
Three major eras:
Paleozoic, Mesozoic, Cenozoic
Name that era and discovery: Paleozoic!
500mya, first vertebrates in fossil record, Pangea present
Mesozoic
mammals present, Gondwanaland and Laurasia drifted apart. Establishment of ecological niches. Reptiles were dominant
Cenozoic
divided between the tertiary and quarternary period and several epochs. These epochs are: Paleocene, Eocene, Oligocene, Miocene, and Pliocene, and Pleistocene and Holocene, Recent (in order).
Continental drift
the movement of continents on sliding plates of the earth’s surface.
How are mammals different than reptiles?
warm blooded, larger brain, different teeth (allow for processing of wide variety of food)
neocortex
outer covering f cerebrum which controls higher brain functions in mammals
heterodont
having different kinds of teeth
endothermic regulation
constant internal body temperature
Three major subgroups of mammals:
monotremes (egg laying), marsupials, placental
major process of macro evolution is what?
Members move to an environment that is more hospitable when resources are depleted
Adaptive radiation-
rapid expansion and diversification of life forms into new ecological niches.
why do animals diverge into variations?
adaptive potential, and adaptive opportunities in available niches
why are generalized and specialized characteristics important?
Refer to the adaptive potential of a particular trait.
Only a generalized ancestor can provide the flexible evolutionary basis for rapid diversification.
Ancestral characters usually tend to be more generalized.
Gradualism
the idea that organisms change slowly over time.
Punctuated equilibrium
the concept that evolutionary changes proceeds through long periods of stasis punctuated by rapid periods of change.
why is the environment so important for evolution?
Environmental changes can influence the pace and direction of natural selection
