BIL 160 Lecture Notes - Lecture 4: Plant, Railways Act 1921, Zygote
16 Mar 2019
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BIL 160 Day 4/Lecture 4
Evolution and Biodiversity
● Evolution accounts for unity and diversity of life
○ evolution= descent with modification
○ Unity underlies diversity in life:
■ DNA
■ Common features of cell structure
■ Ex: cilium
● Species: kinds of living things
○ Original concept: like begets like
■ The life cycle: each organism we see is at 1 stage of its life cycle
● Life cycle: continuing cycle of growth, change, and
reproduction
■ Darwin: “like begets like” BUT with variation
○ Morphological species concept: different species defined by different
morphology/form
■ Still used today
● Type document scientific name of species
■ Problems:
● Form varies throughout life cycle
● Even organisms from same life cycle point/parent may be
different
● ???- how much different is needed to differentiate species
○ Most biologist agree: species consist of populations of closely related
individuals
■ Another precise definition: biological species concept: species
defined by ability of members to interbreed
● Cannot describe all species
○ Some organisms reproduce without sex
■ Ex: prokaryotes, yeast/fungi, plants, some
invertebrates, some lizards
Document Summary
Evolution accounts for unity and diversity of life. The life cycle: each organism we see is at 1 stage of its life cycle. Life cycle: continuing cycle of growth, change, and reproduction. Darwin: like begets like but with variation. Morphological species concept: different species defined by different morphology/form. Even organisms from same life cycle point/parent may be different. ?- how much different is needed to differentiate species. Most biologist agree: species consist of populations of closely related individuals. Another precise definition: biological species concept: species defined by ability of members to interbreed. Ex: prokaryotes, yeast/fungi, plants, some invertebrates, some lizards. Also, some organisms we only know from fossils. Common evolutionary origins represented with tree of life/genealogy. On phylogeny tree: shows which individuals interbreed in each generation. Shows that at bottom, there is one population; then after many generations, the population splits in 2 (no more cross mating between the 2 new populations)
