lecture18F06

lecture18F06 - Lecture 18: Speciation Readings: Ch. 24,...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 18: Speciation The Biological Species Concept reproductive isolation, prezygotic isolation (habitat, temporal, behavioral, mechanical, gametic), postzygotic isolation (reduced hybrid viability, reduced hybrid fertility, hybrid breakdown); reproductive isolation by pleiotropy Speciation in context microevolution, macroevolution, cladogenesis, anagenesis Readings: Ch. 24, Overview, 24,1, 24.2 “Modes” of speciation allopatric speciation, sympatric speciation Allopatric speciation population differentiation, races/subspecies, sexual selection Sympatric speciation polyploidy, habitat differentiation Adaptive radiation Tempo of speciation
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
What are species? Fig. 24. 3 Well, we can’t define them on the basis of morphology (body form; anatomy) because one can find pairs of species that are very similar, while in other cases there is a lot of variation within a single species.
Background image of page 2
So what are species, really? Many biologists use the biological species concept, which is based on the idea that members of species can reproduce succesfully with each other. Thus it is based on reproductive isolation (barriers) between species, and gene flow within species.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Biological species are organisms that interbreed under natural conditions Hobbs at the Sierra Safari Zoo in Nevada - not natural conditions! (tiger mother, lion father)
Background image of page 4
Fig. 24.4 - read in detail! - species are kept apart by reproductive barriers, which can be prezygotic or postsygotic
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Fig. 24. 7 Strong selection can produce reproductive isolation involving unrelated traits because of pleiotropy. In this experiment, adaptation to diet may have affected the composition of cuticular hydrocarbons that are involved in mate recognition (but the analysis has not been done).
Background image of page 6
It is useful to divide evolution into two parts:
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 27

lecture18F06 - Lecture 18: Speciation Readings: Ch. 24,...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online