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Lecture 4 Genetics & Wildlife Passenger pigeon Hamster Dodo Wood’s cycad.

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Presentation on theme: "Lecture 4 Genetics & Wildlife Passenger pigeon Hamster Dodo Wood’s cycad."— Presentation transcript:

1 Lecture 4 Genetics & Wildlife Passenger pigeon Hamster Dodo Wood’s cycad

2 Genetics & Wildlife We are currently in the sixth great mass extinction – ~10 – 20% of species at risk in the next 100 – 200 yrs This is in part as a result of the major rain forest destruction Rain forests cover 7% of the earth - and have 50% of all species, half is already gone Losing 1-2%/yr – could be all gone in 150yrs Meaning we are suffering large-scale genetic erosion

3 Conservation geneticists need to identify: –ESU (Evolutionary significant unit) – Species –Subspecies/unique geographic areas/hotspots – Establish phylogeographic patterns to predict future population migrations – Counter genetic erosion Genetics & Wildlife

4 The greatest threat to a species is populations size Inbreeding which leads to loss of heterozygosity homozygosity Accumulation of deleterious mutations –recombination can no longer purge mutations when its homozygous –Expression of recessive deleterious alleles – Fitness It takes 5 generations to homozygosity Ralls et al. 1988; Cmokrak & Roff 1999; Saccaheri et al Genetics & Wildlife Factors that influence evolvability

5 How small does a population have to be before it starts down the extinction vortex The MVP Minimum Viable Population size – The smallest number of individuals needed to sustain genetic variation Population viability analysis (PVA) – Predicting whether or not a species will survive over time Genetics & Wildlife How small is too small?

6 In a small population several factors come into play: Genetic drift: Loss of genetic alleles over time Genetics & Wildlife

7 A special case of drift is The Founder Effect: – Loss of genetic variation in space Genetics & Wildlife

8 Organisms must constantly evolve and adapt to survive in a dynamic environment, as they compete with ever-evolving opposition (pathogens, parasites and predators) – Small populations lack adequate genetic variation to keep up with the pace Genetics & Wildlife The red queen hypothesis

9 Sources of DNA: Quality vs. Quantity – Hair- Spore / Hyphae – Feathers- Ear / Toe clips – Eggshells- Scales / Fins – Faeces / Urine- Blood – Scent marking – Horn – Teeth – Meat – Seeds / Leafs Genetics & Wildlife

10 mtDNA – circular molecule – 1 allele – Maternally inherited Genetics & Wildlife Measuring genetic variation

11 Microsatellites: small repeat sequences – Non-coding fragments - mutation rate = rapid sorting of alleles SNP’s: single nucleotide polymorphism – Found throughout entire genome (mtDNA, nulcear, Y chromosome) SNP’s in human listed 2012 – Mardis 2011 Genetics & Wildlife Measuring genetic variation

12 With Next Generation Sequencing Ecosystem level – eDNA – soil, water – debris filtered from air – Technique: Metabarcoding: species identification What is Barcoding? – short / genetic marker – plus voucher specimen information Genetics & Wildlife Measuring genetic variation

13 Biogeography – Describe evolutionary history – Evolutionary significant units Significant sequence divergence at mtDNA and nuclear DNA level – Management units Significant sequence divergence at mtDNA level Genetics & Wildlife Measuring genetic variation

14 Genetics & Wildlife conservation

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