BIOL1006 Lecture Notes - Lecture 6: Species Complex, Phylogenetic Tree, Reproductive Isolation
24 May 2018
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Lecture 6: Species and specialisaiton
- Large ocean fish could be gone by 2050
- Insect populations have declines by 75% over 3 decades
- The 6th extinction- first extinction caused by humans
What is a species?
- Individuals that can integrate and have fertile offspring
- Have a common ancestor
- o oe defiitio has satisfied all aturalists; yet eery aturalist kos aguely hat
she/he means whe she/he speaks of a speies Charles Dari
The morphological species concept
Relies on similarity within species, and differences between species
Most species are identified using MSC (but not the most accepted way to define
species)
Morphological/Taxonomic Species Concept
Pros:
- often easy to measure characteristics
- can use fossils, museum/herbarium specimens
Cons:
- Differences may be due to environment, (thus two v different specimens may be same
species)
- may miss cryptic species (they look the same)
- Often difficult/slow to measure characteristics
Biological species concept (most widely accepted)
Species are:
- Actually, or potentially interbreeding natural populations
- Reproductively isolated from other such groups
- BSC is most widely applied and accepted concept
- Based on the concept of a gene pool
find more resources at oneclass.com
find more resources at oneclass.com
2
Two groups of organisms are species if:
- They are not able to hybridise
- Hybrid offspring are infertile or have low fitness
Species often have:
- isolating mechanisms to prevent hybridisation with other species (pre or post zygotic)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Large ocean fish could be gone by 2050. Insect populations have declines by 75% over 3 decades. The 6th extinction- first extinction caused by humans. Individuals that can integrate and have fertile offspring. Have a common ancestor (cid:862)(cid:374)o o(cid:374)e defi(cid:374)itio(cid:374) has satisfied all (cid:374)aturalists; yet e(cid:448)ery (cid:374)aturalist k(cid:374)o(cid:449)s (cid:448)aguely (cid:449)hat she/he means whe(cid:374) she/he speaks of a spe(cid:272)ies(cid:863) (cid:894)charles dar(cid:449)i(cid:374)(cid:895) Relies on similarity within species, and differences between species. Most species are identified using msc (but not the most accepted way to define species) Often easy to measure characteristics can use fossils, museum/herbarium specimens. Differences may be due to environment, (thus two v different specimens may be same species) May miss cryptic species (they look the same) Bsc is most widely applied and accepted concept. Based on the concept of a gene pool. Hybrid offspring are infertile or have low fitness. Species often have: isolating mechanisms to prevent hybridisation with other species (pre or post zygotic)
