Lesson 7: What is a Species?

Question 1

Who was Carl Linnaeus?

Answer 1

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

Question 2

What is taxonomy?

Answer 2

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

Question 3

What is a binomial name?

Answer 3

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

Question 4

Why do some organisms have the same genus name?

Answer 4

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

Question 5

Why do some organisms have the same specific epithet?

Answer 5

specific epithets may be shared by many organisms, regardless of how closely related they are

Question 6

What is the rule of priority?

Answer 6

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

Question 7

How is a new binomial name officially given to a species?

Answer 7

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

Question 8

What is a peer-reviewed scientific publication?

Answer 8

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

Question 9

What is a holotype specimen?

Answer 9

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

Question 10

What is interspecific variation?

Answer 10

individuals that differ in morphology because they belong to different species

Question 11

What is intraspecific variation?

Answer 11

individuals that belong to the same species, but that have different morphologies

Question 12

What is sexual dimorphism?

Answer 12

males and females of the same species can look different

Question 13

What is ontogenetic variation?

Answer 13

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

Question 14

What is individual variation?

Answer 14

the normal variation that exists among individuals of a given species

Question 15

What is taphonomic variation?

Answer 15

not biological in origin, but geological

taphonomic processes like plastic deformation can change the shape of a bone

Question 16

What is the biological species concept?

Answer 16

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

Question 17

What is a population?

Answer 17

is any grouping of organisms that live in the same geographic area and interbreed

one or more populations make up a single species

Question 18

What is the morphological species concept?

Answer 18

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

Question 19

Why is defining species using the morphological species concept not an exact science?

Answer 19

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

Question 20

What are lumpers?

Answer 20

paleontologists who require more differences before they consider two species to be distinct are called lumpers

Question 21

What are splitters?

Answer 21

paleontologists who require fewer differences before they consider two species to be distinct are called splitters