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Lecture 7

BI111 Lecture 7: L7

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Tristan Long

BI111 Lecture 7 January 18 , 2017 Are these or are these not a Different Species? Canus Lupus (Variants or different species?) On the island different skull morphology and more red colour in their fur, compared to mainland species On the mainland, there is a wider range of species (bears, dears, predatorsparasites) so do different ecological environment On the island, they eat mostly moss and fish (marine resources is 85 of their diet) Phylogenetic Species Concept (Swapping out DNA sequences for phenotypic traits Have they diverged enough to make two distinct different species?) Species are a diagnosable cluster of individuals within which there is paternal pattern of ancestry and descent Species delineations based on common ancestry (smallest diagnostic monophyletic group) o Pros Considers temporal (evolutionary) nature of species (They have a past, things change and diverge over time) No complicated subspecies designations (Its an all or nothing thing) Not troubled by possibility that slightly different geographic forms might interbreed o Cons Is it too easy to meet the species threshold? Results in species inflation? Limited data? (Results in more rare species? Divisions based on minor differences that do not have any clear biological relevance? (Are they meaningful differences) In uniparental species, little gene flow between lineage: is each clone with a mutation a species? If groups can still reproduce, may not remain separate species because of gene flow Sometimes species arise from repeated events (polyploidy) and are not monophyletic in origin (Hybrids can come about) How much is Enough? Look at genes of different pairs of groups (Is there Genomic Divergence or how much does it take to see the differences) Estimated gene flow between two different groups (once its sufficiently large, the groups will become very similar which makes it hard for speciation) Mainland vs. Island Wolves Sampled thousands of scat (shit) looked at DNA (alleles), are they genetically different? o Lots of genetic similarities even though they are phenotypically different (suggest there is some gene flow occurring) o Differences we see are not due to physical barriers (natural selection acting on wolves o Ecologically they are different, but biologically they can mate with each other and there is still gene flow occurring so they are the same species
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