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Behavioural Ecology
Molecular techniques
| Question | Answer |
|---|---|
| Molecular markers | • Polymorphic DNA - variation in some part of the genome • Polymorphism in, or among - individuals, groups, populations or species |
| Molecular markers | Functional (coding) genes • Transcribed part of genome • Nucleotide sequence variation can be mapped • Different alleles directly influence phenotype |
| Molecular markers | Non coding DNA (Neutral markers) • Part of genome with no direct function (not transcribed) • Neutral to selection • Highly polymorphic • Provides many highly informative markers |
| In animals | Types of DNA • Nuclear autosome – biparentally inherited • Sex chromosomes e.g. XX/XY systems Y = males = uniparental X = both sexes – biparental • Mitochondrial - maternally inherited |
| In animals | Examples of markers • Repetitive DNA - Microsatellite repeats, e.g. CTTT10 • Sequence data (genes and genomes) – SNPs – single nucleotide polymorphisms – Indels = insertions and deletions – Structural changes - inversions etc |
| Marking animals when sampling | • Blood • Tissue • Faeces • Hair follicles • Feathers • Sloughed skin PCR |
| Species identification | Distinguishing similar species • Common and Natterjack tadpoles • Tailfin clip Determining prey species • Observations = difficult or time consuming • Gut contents or faecal samples |
| Species identification - Barcoding | • Short, easy to amplify section of DNA • That has lots variation across spp......but little within species variation • Same sections used across all (or at least whole groups of) species |
| Sex determination | Can be difficult in some species In many species sex is genetically determined - these genes can be used to identify sex |
| Example where sex is not genetically determined? | In birds (ZZ/ZW system) • Amplify a piece of DNA on sex chromosomes • Allele on W chromosome is shorter than on the Z • Run on a size separation electrophoresis gel - females (ZW) have two bands - Males (ZZ) have one |
| Sex determination in whales | • Baleen whales lack obvious secondary sexual characteristics • A Y-chromosome probe used in humpback whales (identifies males) • Determine gender of free ranging whales using skin biopsies or eDNA |
| Chronological age: DNA methylation | • Certain loci show changing methylation with age • Can be used to calculate age • Polanowski et al 2014 - humpback whales • Determine age structure of pods and populations |
| Chronological age: Telomeres | • Telomere attrition with cell replication • Thus telomeres shorten with age • Can be used to determine chronological age • Telomeres may cause senescence /age related disease! |
| Biological age: telomeres | Oxidants – also erode telomeres • Product of metabolism • Affected by stresses Higher oxidants and telomere shortening with, for example: 1) infection 2) reproductive effort 3) Psychological stress |
| Telomere attrition | Generic currency to measure the costs of behaviours in life |
| Identifying infections | • Who has an infection, e.g. malaria • When they get it • How they behave when infected • Survival and reproductive success • Behavioural changes in host populations selected for (?) |
| Identifying infections - endosymbionts | Wolbachia – bacteria – infect invertebrates PCR can detect ribosomal genes from the bacteria Ca 60% of insect species infected! Transmitted in egg cytoplasm |
| Identifying infections - endosymbionts | Effects on mating behaviour Acraea butterflies: Skews sex ratio to mainly females - reversing the sex that competes for a mate, - results in female lekking (Jiggins, 2002) |
| Determining genetic parentage / mating systems | Problems in determining parentage: – Difficult to watch individuals or groups – Matings may be secretive/difficult to observe – Females may copulate with multiple males – Offspring from multiple females may be mixed |
| Original DNA fingerprinting and mating systems study | Polyandry Two males mate with, and defend the territory of, a single female DNA fingerprints identify if both males contribute to a single brood |
| Original DNA fingerprinting and mating systems study | Match offspring bands not found in the Mum (M) against the fingerprint profile of potential fathers (Pa and Pb) |
| Extra-pair paternity in socially monogamous species | Common in birds, frequent in mammals |
| Maternity tactics | Interspecific brood parasitism • Cuckoos etc • Occurs in birds, fish and insects |
| Maternity tactics | Intraspecific brood parasitism • Take advantage of members of own species • Often only revealed using molecular markers • Common in fish and birds |
| Cooperative breeding | Situation where adult individuals, in addition to the genetic parents, stay within a group and regularly aid in the rearing of young |
| Cooperative breeding | Molecular techniques determine who helps and why? • Test the importance of kin selection etc. • More in lecture on Cooperative breeding later! |
| Determining reproductive success | Accurate assessment of lifetime reproductive success – to determine the adaptive significance of behaviours e.g. Male reproductive skew drives sexual dimorphism Theory – variance in male reproductive success is much greater than in females |
| Determining reproductive success | Consequently • selection is much greater in males • Invest more in elaborate secondary sexual characteristics and behaviour |
| How genes influence of behaviour | Inferring a genetic component to specific behaviours |
| Candidate genes influencing behaviour | Dopamine receptor D4 Neurotransmitter that plays a major role in reward-motivated behaviour • Personalities - repeatable behavioural tendencies within an individual |
Created by:
rose.coo
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