Lesson 7: What is a Species? Flashcards
Who was Carl Linnaeus?
a Swedish naturalist in the late 18th century
introduced a new system for scientifically naming organisms
Linnaeus is considered to be the founding father of modern taxonomy
What is taxonomy?
the science for naming and organizing organisms into related groups
prior to Linnaeus, there was not an agreed-upon system for assigning names to organisms and this had led to considerable confusion
under Linnaeus’ system, which we still use today, every unique species of organism is given a binomial name
What is a binomial name?
consists of two parts: the genus name and specific epithet
the genus name is always capitalized and the specific epithet is not
binomial name is always italicized
Why do some organisms have the same genus name?
organisms that are different species but that belong to the same genus (meaning that they are very similar in overall form and are more closely related to each other than to members of any other genus) have the same genus name
Why do some organisms have the same specific epithet?
specific epithets may be shared by many organisms, regardless of how closely related they are
What is the rule of priority?
states that, once a species has officially been given a binomial name, the name cannot be changed
this is unless it turns out that the organism is not really a new species, in which case, the binomial name is abandoned
How is a new binomial name officially given to a species?
a biologist must publish a description of the species in a widely distributed and peer-reviewed scientific publication and must designate a holotype specimen
the published description must include a list of characteristics or combination of characteristics that makes the new species unique
What is a peer-reviewed scientific publication?
one that is not published until it has been reviewed by other scientists to verify that the contents of the publication are legitimate and scientifically reasonable
What is a holotype specimen?
a physical example of the new species, and it must be kept in a research institution, such as a university or a museum, so that other scientists may study it and be able to both verify that it is a distinct species and compare it to other potentially new species that are later discovered
a holotype specimen does not necessarily need to be a complete specimen
holotype specimens of dinosaur species are hardly ever complete
What is interspecific variation?
individuals that differ in morphology because they belong to different species
What is intraspecific variation?
individuals that belong to the same species, but that have different morphologies
What is sexual dimorphism?
males and females of the same species can look different
What is ontogenetic variation?
variation that you can see between young individuals and old individuals of the same species
besides size differences, animals can change shape as they progress through ontogeny
What is individual variation?
the normal variation that exists among individuals of a given species
What is taphonomic variation?
not biological in origin, but geological
taphonomic processes like plastic deformation can change the shape of a bone
What is the biological species concept?
defines a species as a group of organisms that can successfully interbreed
this species concept works well when applied to most modern animals and many plants
however, it cannot be applied to the majority of those modern organisms that reproduce asexually and which, therefore, cannot be said to interbreed at all
nor can the biological species concept be applied to extinct organism of any kind, since testing whether or not two fossils can mate is impossible
What is a population?
is any grouping of organisms that live in the same geographic area and interbreed
one or more populations make up a single species
What is the morphological species concept?
defines a species as a group of organisms that share a certain degree of physical similarity
in dinosaur paleontology, the morphological species concept is often applied as it relates to the biological species concept
that is, fossil specimens are assumed to belong to the same species if their physical similarities are consistent with the similarities that would be expected between members of a group that can successfully interbreed
Why is defining species using the morphological species concept not an exact science?
sexual dimorphism and ontogenetic change are both factors that make the morphological species concept tricky to apply, especially given the incompleteness of the fossil record
What are lumpers?
paleontologists who require more differences before they consider two species to be distinct are called lumpers
What are splitters?
paleontologists who require fewer differences before they consider two species to be distinct are called splitters
