Key concepts in animal diversity

Question 1

Define a species using the biological species concept

Answer 1

A group of actually or potentially breeding natural populations that are reproductively isolated from other groups.

Question 2

Give two limitations to the biological species concept

Answer 2

Asexually reproducing organisms, historic changes (when does one species become another?), and borderline cases where it is difficult to establish (e.g. carrion crows and hooded crows)

Question 3

Define a species using the phenetic species concept

Answer 3

A group of organisms that resemble (morphological characteristics) one another and are distinct from other sets.

Question 4

What does the phenetic species concept allow for?

Answer 4

Intraspecific variation (e.g. patterns on ladybirds) and phenotypic plasticity (e.g. ecophenotypes)

Question 5

Define cryptic species

Answer 5

Species that are difficult to distinguish by eye but are not related

Question 6

Define sibling species

Answer 6

Species that are closely related and difficult to distinguish

Question 7

Give a limitation of the phenetic species concept

Answer 7

Missing data (remains may look very similar without the rest of the body)

Question 8

What is a phylogeny?

Answer 8

A evolutionary tree showing common descent.

Question 9

Define cladistics

Answer 9

Building phylogenies based on uniquely shared characters or traits.

Question 10

What assumptions are made in cladistics?

Answer 10

Characters are acquired or changed over time, any group of organisms is related by common descent, and the tree has a bifurcating pattern.

Question 11

Define synapomorphy

Answer 11

A shared trait unique to a monophyletic clade

Question 12

Define plediomorphy

Answer 12

An inherited trait shared with the ancestors of a clade

Question 13

What is a homologous character?

Answer 13

A character of two species that is derived from their common ancestor.

Question 14

What is an analogous character?

Answer 14

One that is superficially similar but has different evolutionary origins.

Question 15

Describe convergent evolution

Answer 15

Where characters independently arise/are lost from different evolutionary and developmental routes

Question 16

Describe divergent evolution

Answer 16

Closely related species have differentiated, for example, morphological adaptation to different niches.

Question 17

What are all adaptations relative to?

Answer 17

Ancestral state

Question 18

What is enhanced by adaptation?

Answer 18

Survival and/or reproduction

Question 19

Define exaltation

Answer 19

A feature that has been co-opted to serve a new function. For example, feathers were for insulation and have been co-opted for flight.

Question 20

What did Lewontin and Gould (1979) conclude?

Answer 20

Not all traits have adaptive function, some are likely to be by-products of natural selection. Distinguishes the current use of something from its evolution.