Key concepts in animal diversity Flashcards
Define a species using the biological species concept
A group of actually or potentially breeding natural populations that are reproductively isolated from other groups.
Give two limitations to the biological species concept
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)
Define a species using the phenetic species concept
A group of organisms that resemble (morphological characteristics) one another and are distinct from other sets.
What does the phenetic species concept allow for?
Intraspecific variation (e.g. patterns on ladybirds) and phenotypic plasticity (e.g. ecophenotypes)
Define cryptic species
Species that are difficult to distinguish by eye but are not related
Define sibling species
Species that are closely related and difficult to distinguish
Give a limitation of the phenetic species concept
Missing data (remains may look very similar without the rest of the body)
What is a phylogeny?
A evolutionary tree showing common descent.
Define cladistics
Building phylogenies based on uniquely shared characters or traits.
What assumptions are made in cladistics?
Characters are acquired or changed over time, any group of organisms is related by common descent, and the tree has a bifurcating pattern.
Define synapomorphy
A shared trait unique to a monophyletic clade
Define plediomorphy
An inherited trait shared with the ancestors of a clade
What is a homologous character?
A character of two species that is derived from their common ancestor.
What is an analogous character?
One that is superficially similar but has different evolutionary origins.
Describe convergent evolution
Where characters independently arise/are lost from different evolutionary and developmental routes
Describe divergent evolution
Closely related species have differentiated, for example, morphological adaptation to different niches.
What are all adaptations relative to?
Ancestral state
What is enhanced by adaptation?
Survival and/or reproduction
Define exaltation
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.
What did Lewontin and Gould (1979) conclude?
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.
