Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
84 Cards in this Set
- Front
- Back
|
Tinbergen's 4 'Whys' |
1. Mechanism: How does it work? 2. Development: How did it develop? 3. Function: What is it for? What does it do? 4. Evolutionary History: How did it evolve? Why something is from evolutionary history. 1 and 2 provide proximate (mechanistic) explanations 3 and 4 provide ultimate explanations(evolutionary significance). We really look at number 3 |
|
|
Current Utility |
The benefits and costs of a phenotype currently has at the moment. |
|
|
Adaptation |
Any trait that is the result of natural selection |
|
|
Conditions for natural selection (3) |
1. More individuals are born in each generation than can survive to reproduce 2. There is heritable variation 3. This variation influences reproduction |
|
|
Group selection hypothesis (and problem) |
Group Selection: Selfish individuals (that produce too many offspring) will make the whole group less successful, populating the environment too much Problem: Selfish individual in an altruistic group has an advantage; tragedy of the commons |
|
|
Why will birds have smaller clutch sizes than the maximum survivability of chicks? |
- Laying eggs is costly; too many eggs will lower the fitness of a female, as it has less resources. |
|
|
Optimality Models: What is being optimized? (4) |
1. Net rate of energy gain 2. Energy efficiency 3. Risk-sensitivity 4. Trade-offs with predation |
|
|
Optimality Models: Maximizing net rate of energy gain |
E.g. Charnov's Patch Model: Looking at finding the maximum energy gain per time Looking at [Benefit - Cost] / Time |
|
|
Optimality Models: Maximizing energy efficiency |
Maximizing [Benefit - Cost] / Cost - Useful at looking at organisms where the an organism's lifespan is limited by its physical structure rather than energy. I.e. in bees, its life is limited by its wings. In crabs, its life is limited by its claws. |
|
|
Optimality Models: Risk-sensitive foraging |
- Looking at the variance in foraging alternatives. - Some patches may be certain in their units of food available. Some are more variable, where some patches have a lot of food an a little bit of food. - If the food requirement of an organism is less than the certain alternative, it will choose to forage in a risk-averse way. If the food requirement is greater than the certain alternative, it will choose forage in a risk-prone way. |
|
|
Risk Averse vs. Risk Prone |
Risk Averse: Choosing low variance Risk Prone: Choosing high variance |
|
|
Jensen's Inequality |
- If you have a diminishing curve, choosing variance will leave you with a lower average rate of return. Variation drags the mean down - Symmetrical outcome on x-axis translates to asymmetrical outcome on y-axis |
|
|
Optimality Models: Avoiding Predation |
Taking into account net-gain maximization (Charnov's patch model) with a "Giving Up Density" - Organisms will leave patches sooner (i.e. patches have more food left over still) when in the presence of predation - More predation, higher GUD |
|
|
How to calculate "Giving Up Density" |
- Weigh out food, mix it well into the environment - Let animals forage - Weigh remaining food after the animal has left. This is GUD |
|
|
Optimality of Territory Size |
- Looking at benefits and costs as they change over territory size. - Optimal point is when the slope (difference between Benefits and Costs) are the same - As there are more resources abundant, territory size becomes smaller |
|
|
"Personality" |
- Looking at combined repeatable behaviours of an organism. This is called its "personality", "behavioural syndrome", or "temperament" |
|
|
Three Types of Consistent Individual Differences |
1. Consistent Differences in Average Expression (organisms are always different, but express similarly across different gradients) 2. Difference in plasticity (looking at reaction norms and slopes) 3. Constant differences in suites of behaviours (i.e. an organism that has low behaviour x will also have low behaviour y) |
|
|
Intraindividual Variability: |
A measure of how variable an organism's behaviour is |
|
|
Condition-Dependence Personality |
An organisms body condition will influence its survival. |
|
|
Condition-based feedbacks "locking individauls" into behaviours |
- The interaction between two organisms with different conditions may lock their behaviour cycles into certain patterns. I.e. bird; poor condition needs to forage, better condition says "okay better we forage together", better condition gets enough food, poor stops feeding too. Cycle repeats. |
|
|
Developmental Individual Difference (2 types) |
Difference between individuals may arise during development. 1) Information: Environmental cues during development optimizes phenotype 2) State-based: Environment directly affects development, behaviour responds. |
|
|
Frequency-Dependent Behaviours: Facultative |
Finding an evolutionary stable strategy that cannot be invaded by an alternative strategy. What others are doing will dictate what you are doing. - E.g. Producers and scroungers: Look at where the lines cross: The more scroungers in a population, the lower fitness of scroungers than producers. The fitness benefit crosses. |
|
|
Who are "scroungers" and who are "producers"? |
Higher body condition is more likely to be "scroungers" — they do not need to produce as much, more likely to be latent to feed Lower body condition is more likely to be a "producer" — need to get food |
|
|
Frequency-Dependence: Genetic |
- Behaviour may be heritable, where offspring will show repeatability of their behaviour similar to their parents - Phenotypes, too. E.g. Lizards rock/paper/scissors |
|
|
Anisogamy |
Dissimilarities in the gamete size, resulting in different reproductive strategies (Expensive eggs, cheap sperm) |
|
|
Bateman's Principle: |
Due to different investments in gametes, female reproductive success will be limited by resources and time. Male reproductive success will be limited by access to mates |
|
|
Intrasexual Competiton |
Usually male-male competition, competition within the same sex for access to mates |
|
|
Big Horn Sheep: Intrasexual competion (Tending and Coursing/Blocking males) |
Tending: Biggest males with biggest horns Coursing/Blocking: Smaller males with smaller horns Tending males will follow females around, fighting off other males, then sense when females are ready to reproduce Coursing/Blocking males strategy is to try to separate a female away from the group Tending has higher reproductive success |
|
|
Reproductive Strategies of Males: Sneaker vs. Fighter |
Fighter: Bigger, these fish go to sea, return strong, fight for access to females Sneaker: Mature earlier, sneak fertilizations, less success but some still exists. Genetic based ESS |
|
|
Reasons for females preferring certain male traits (3) |
Direct Benefits: Resources, females will chose males who provide more resources to the female Indirect Benefits: Sexy sons (attractives, Fisher's Runaway Selection") Good Genes (fitness, "Handicap Principle") |
|
|
Fisher's Runaway Selection (steps and consequences) |
1. Females prefer a male trait (due to predicting quality, sensory bias, chance) 2. Sons inherit male trait, and female preference 3. Higher reproductive success of male trait spreads the trait and the preference for that trait 4. Process stops when reduced male survivorship balances with increased attractiveness |
|
|
Sensory Bias |
- Due to a predisposed preference on females, they may see a trait in a male that they are already cued into like, thus these males are more attractive E.g. Orange on male guppies: Females eat orange food, this reminds them of the orange food, 'cued' into liking orange |
|
|
"Good Gene Hypothesis" a.k.a. Handicap Principle |
- Ornaments on a male signal a male's ability to bear the cost - If you're not dead for showing this trait, you must be vigourous |
|
|
Hamilton-Zuk Hypothesis for maintaining Genetic Variation |
In birds, duller colours correlates with higher parasite load. By choosing bright birds, you are selecting the more disease-resistant, therefore can continue different genetics |
|
|
Sex-Role Reversal |
"Choosy Males" - Sometimes, males will do all the work raising an offspring - Sometimes, males still have more costs than we think to produce gametes - Differences in females can still predict quality of mate |
|
|
Mate Search Tactics (4) |
1. Random 2. Best-of-N 3. Sequential: Threshold 4. Sequential: Adjustable Threshold |
|
|
Fitness Consequences for Mate Search Tactics (Just Benefits) |
Random: Lowest, 0.5 Fixed-Threshold: 0.67 Optimal one-step: 0.8 Best-of-n: 0.85 |
|
|
How does cost of mate searching affect strategy? |
- Higher costs of mate searching will decrease the benefit of best-of-n. If you need to spend more time searching and selecting, lower fitness benefit. |
|
|
Lek Paradox |
Constant female choosiness may decrease genetic variation, but this doesn't always happen happen |
|
|
Leks: |
Clusters of one sex for the purpose of mating. Females (or one sex) will then inspect the lek organisms to choose to mate with (best-of-n strategy) |
|
|
How to maintain genetic variation in Leks? |
- Opposing natural and sexual selection, where both traits are equally heritable. Thus, traits that are naturally selected for will be inherited by some and not others.. maintaining genetic variaton... |
|
|
Mate Choice Copying (and 2 reasons why) |
- Instead of making independent mate choices, individuals may just copy what another organism does - Allow another organism to spend the cost associated with searching/selecting a mate, you just piggy-back - Maybe some organisms have more information; collective decision making |
|
|
Mating Systems (5 terms) |
Monogamy: Parental units only mate with each other and do not mate outside of the parental unit Polygyny: One male mates with many females Polyandry: One female mates with many males Promiscuity: Both males and females have multiple mating partners during a breeding season Polygamy: General term for one organism having more than one mate |
|
|
Factors leading to polygamy: |
- Clumped individuals (females all together, one male defends many females) - Clumped resources (very patchy distributions lead to high polygamy potential, individuals made to be in closer contact. Some males will have more resources (defending good patches), more females want to got there - Territory Size: Larger territories may lead to higher polygamy |
|
|
Polygyny Threshold Model |
- Deciding whether a female mates with an unpaired male or a paired male - You will chose to be the second female than be with a poorer quality male |
|
|
Resource-Holding Potential: |
Males that have higher resource holding-potential have higher reproductive success |
|
|
Parental Care in Invertebrates |
Usually no parental care |
|
|
Parental Care in Fish (+reason) |
Usually male parental care - Males that guard fish nests show future possible females to mate with that they're a good choice |
|
|
Parental Care in Amphibians |
Split between male and female parental care |
|
|
Parental care in Reptiles |
Female or both, never exclusively male |
|
|
Parental care in Birds (+reason) |
Usually both - Birds have high costs, requires both to feed babies |
|
|
Parental care in Mammals (+ reason) |
Usually female - Females produce milk |
|
|
Levels of Conflict |
- Sexual Conflict: Between male and female parent - Parent-Offspring Conflict: Between parent and offspring - Sibling: Between two (or more) offspring |
|
|
When is Bi-Parental care expected to be common? |
1. Lower Sexual Selection - Less variance in mating success, less investment in mate attraction, less likelihood of extra-pair paternity 2. Less biased adult sex ratio (50/50) 3. Harsher environmental conditions |
|
|
When is Bi-Parental care expected to be less common? (3) |
- Male-biased size sexual dimorphism - Increased polygamy - Biased sex ratios |
|
|
Parental Investment |
Any investment by parent in an individualoffspring that increases the offspring’s chance of surviving (and hencereproductive success) at the cost of the parents ability to invest in otheroffspring |
|
|
Optimal Nest Defence |
Vx = bx + Σ(lt/lx)bt Where:Vx = reproductive value Bx = fitness from current brood Lt = probability of future surviva lLx = probability of surviving the currentage Bt = fitness from future brood Benefits of next defence: Hump-shaped (decreases eventually because draw too much attention) Cost: Exponentially growing shape Look at net benefit maximum |
|
|
High Latitude vs. Low Latitude Bird Nest Investment |
High Latitude: Chance at parents surviving next year are lower (long migration, hard on bird), so more willing to defend nests. Bigger broods Low Latitude: Higher chance of adult survival, so less likely to put own life at danger to defend nest. Smaller broods. |
|
|
Fisherian Sex Ratios |
- Even sex ratios (50/50) - This is an ESS When males less common, more fit When females less common, more fit Individuals of a rarer sex will have higher fitness Therefore, the lines "cross" on the graph at 50/50 |
|
|
Primary Sex Ratio vs. Secondary sex ratio |
Primary Sex Ratio: The ratio of the sexes at conception Secondary sex ratio: The ratio of the sexes at independence |
|
|
What happens when sex mortality/investments are unequal? |
- If one sex is more likely to die, its primary sex ratio will be biased in that ratio to try to create the secondary sex ratio closer to 50/50 |
|
|
Differences in 50/50 Fisher sex ratio |
- Local Mate Competition (inbreeding), only need one male and a bunch of females - Local Resource Enhancement: "Helper Females", produce more of the sex that will help future young |
|
|
How to change sex ratios? (4) |
CSD: chromosomal sexdetermination PA: Pseudo-arrhenotoky (turn off paternal genome) HA: haplodiploid SH: simultaneoushermaphrodite |
|
|
Travis-Willard Hypothesis (steps and outcomes) |
1. Females in better condition produce higher quality offspring 2. Higher quality offspring become higher quality adults 3. Sons have a greater fitness benefit of being higher quality than females (due to male-male competition) Thus, dominant/better quality females are more likely to produce sons |
|
|
Ideal Free Distribution |
Different sizes of groups is just matchingwith the number of resources, such that every individual will have access to the same amount of resources |
|
|
"Ideal" and "Free" |
Ideal: Perfect knowledge of options Free: Can make any choice |
|
|
Groups to avoid predation and 5 benefits |
- Predator encounter rate may increase with group size, but per capita predation rate declines with increased group sizes Benefits: 1) Dilution (P = 1/n) 2) Increased safety in middle ofgroup (Selfish-herd) 3) Increased vigilance 4) Predator confusion 5) Communal defence |
|
|
Grouping and Foraging Success |
- May follow a pseudo-"hump-shaped" curve, where more individuals will increase foraging success, then decrease after a certain point - Larger groups may increase chance of finding a patch - Larger groups may then pose limitations on each other (less food to go around) |
|
|
Stability in Group Foraging Models |
- Stability probably will not be at the optima. Though less individuals in group may increase foraging success, if you are a lone individual and see a group, adding yourself to that group increases your advantage, thus lowering the group but increasing yours. So, stability/equilibrium will be higher than optimal |
|
|
Allee Effect |
- Per capita population growth rate increases with density (up to a point), "inverse density-dependence" |
|
|
Variation in Outcomes with Group Size |
Larger groups have smaller variation in outcome. More of a chance to regularly find food - Especially important when probability of finding patches is low |
|
|
Geometric Mean Fitness |
- Multiply the fitness every year, divide by the number of things, and take the x root - Important, if you have one bad year (i.e. fitness was 0), you're dead. If you fail one year, you're done. |
|
|
Groups: Conspecific Cuing |
Cues can be used to determine where good habitats are.. with low mate selectivity... Balance between increased competition and allee effect |
|
|
Social Systems (6) |
Subsocial: Parental investment Solitary but social: Adult and young may cohabit Communal: Adults and young always cohabit Quasisocial: Coopreative care of young Semisocial: Caste system + reproductive division of labour Eusocial: Overlapping adult generations Latter has characteristics above |
|
|
Routes to Eusociality (2) and what might be important (3) |
Subsocial: Prolonged associations between parent and offspring Parasocial: Associations between the same generation of breeders (no longer seen as a good route) Important: - Habitat Availability - Monogamy - Genetic systems |
|
|
Hamilton's Rule |
Looking at the conditions where an altruistic act will spread due to kin selection B/C > 1/r orrB – C > 0 Where B:Benefit to recipient C:Cost to actor r:relatedness |
|
|
Kin Selection |
Traits are favoured throughtheir effects on related individuals |
|
|
Inclusive Fitness |
Direct + indirectfitness Direct: Your offspring Indirect: Contribution to success ofrelative |
|
|
Where do we commonly see prolonged parent/offspring associations? |
- Poor habitats (i.e. wood, hot/dry environments, barren coral reefs) - Other suitable habitat is scarce - Lowers C |
|
|
Prolonged parent/offspring associations in wood (Reasons) |
- Parents need to transfer microbe symbionts to help digest cellulose - Slow growth due to low quality food - Other suitable habitat is scares |
|
|
Monogamy and Eusociality |
- 1) More monogamy: Siblings (on average) all related by 0.5 - 2) More benefit to parent, - 3) Gets stuck in caste system, promoting more eusociality (though polygamy increases after) |
|
|
Totipotency: |
- Voluntary sterility; choses not to reproduce |
|
|
Totipotency and mating system |
- More monandry, more totipotent caste system - More polyandry, more true sterility caste system |
|
|
Haplodiploid and Eusociality |
- Males: Haploid, Females: Diploid - Females more related by 0.75, therefore want to help create more sisters - Not a good explanation at the end due to Fisherian Sex Ratio dynamics |
