BIOL 111 Lecture Notes - Lecture 40: Agelaius, Anglerfish, Liger
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BIOL 111 – Organismal Biology
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LECTURE 24 – SPECIATON
Species
•!species are often differentiated from one another by 3 species concepts
o!typological (morphological) – differentiating species based on physical
appearances of two species
!!this can often fail, since members within the same species can look
different (e.g. sexual dimorphisms)
•!e.g. Agelaius phoeniceus appears different in New York than in
California, and the male looks total different than the female
•!another examples if the difference in size and shape of the
female and male anglerfish
•!all the different breeds of dogs have all been bred from wolves,
but now are all the same species (not the same as wolves)
o!the skull diversity of dogs is very large, in fact large than
the skull diversity of the whole order carnivore
o!as well skulls of dogs explore many new morphological
spaces
!!this may also fail sine many different species can look strikingly similar
(especially in insects)
o!biological – groups of actually or potentially interbreeding natural populations
which are reproductively isolatd from such groups
!!this concept is more infallible than the morphological concept
!!however, this concept has shown failures:
•!the liger (interbreed of a lion and a tiger is not always infertile)
!!this can be difficult to show, since many species are found very far away
from one another (allopatric populations)
!!the biological species concept allows for gene flow
!!this concept cannot be used with fossils
o!phylogenetic – investigating the DNA of two potential species and deciding
whether they are genetically different enough to be two separate species
•!what a species really is, is and individually evolving unit
o!the three species concepts are simply methods of determining species