BIOL1003 Lecture Notes - Lecture 3: Habitat, Ranunculus, Larus
Determining different species:
• Physical differences
• Chromosome number differences
Species are things that look different from each other
Easily understood easily expounded
• Anyone can tell what a species is
• Problems:
• No explanatory power
◦ How species became distinct
◦ How or why one species is related to each other
• Subjective
◦ Means a species is something a taxonimost says is a species
• It is confined to morphology- study of the forms of things
◦ Does not take into account animals that look the same but have different
numbers of chromosomes
Species
• Particular kinds within genera
• Eternal and unchanching
• Have variation
Biological species concept
• Groups of actually or potentially interbreeding natural populations which are
reproductively isolated from other groups
◦ If they can interbreed they are the same species
• Strengths:
◦ Explanatory power
▪ Why members of a species are similar- thru sexual reproduction
▪ Why members differ between species- reproductive isolation
▪ Species defined by distinctness rather than difference
▪ Nonarbituary
• Problems:
◦ Not practical in terms of testing
▪ Some land turtles take 70 year to mature
◦ BSC must be inferred using things like genital structure
◦ Only applicable to extant species
▪ Can’t be applied to different species on anagenic lineage
◦ Can’t be applied to organisms that produce asexually, prokaryotes, viruses,
fossils
◦ Reproduction can involve offspring being hybrids (parents are different species,
but have reproduced)
▪ Ring species- Larus gulls
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Document Summary
Determining different species: physical differences, chromosome number differences. Species are things that look different from each other. Easily understood easily expounded: anyone can tell what a species is, problems, no explanatory power, subjective, it is confined to morphology- study of the forms of things. How or why one species is related to each other numbers of chromosomes. Means a species is something a taxonimost says is a species. Does not take into account animals that look the same but have different. Species: particular kinds within genera, eternal and unchanching, have variation. Biological species concept: groups of actually or potentially interbreeding natural populations which are reproductively isolated from other groups. If they can interbreed they are the same species. Why members of a species are similar- thru sexual reproduction. Some land turtles take 70 year to mature. Bsc must be inferred using things like genital structure. Can"t be applied to different species on anagenic lineage.
