Group selection, individual selection. Group selection (GS) concept. Can behaviors ever arise that benefit the group and not the individual?

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1 Group selection, individual selection Can behaviors ever arise that benefit the group and not the individual? Group selection (GS) concept GS scenarios can be constructed, but they are not helpful in real world situations Individuals die at faster rate than groups, thus IS is more powerful than GS Individuals can usually move betw groups Most GS examples are explained at the level of inclusive fitness 1

2 But to be fair, an example: Water striders GS maintaining nice males Males vary in aggressiveness to females Aggressive males outcompete the nice males Yet groups of mostly aggressive males do poorly (females injured, eat less) Migration helps GS, females flee aggressive groups I m not like those other guys Behavioral genetics Behavior is a joint product of heredity and environment Genes generate proteins or regulate proteins how can this influence behavior?? Behavioral genetics Gene-derived proteins influence neural circuitry that are foundations of behavior Fruit flies: After transferring a piece of period gene from Drosphila simulans to D. melanogaster, the recipient males sang the simulans song 2

3 Behavioral genetics Rover vs. sitter alleles for the foraging gene (for) Determine more than foraging strategy but also memory abilities The PKG protein coded by the for gene is also found in cows, puffer fish, humans, algae PKG can differentially expressed according to the social situation Influencing behavior via differential expression Prairie vole Monogamy in voles can be altered by increasing the expression of a receptor (for vasopressin) Montane vole Behavioral input can influence genes When zebra finch males hear another male, expression of egr1 gene increases When a dominant male is removed, cichlid fish males increase egr1 expression also morphological and behavioral changes 3

4 Another example in book: Migratory behavior in blackcap warblers Curious twin studies Both had been named James, married twice; 1 st to Linda, 2 nd to Betty. Both had sons named James Allan. Both had at one time owned dogs named Toy Both chain-smoked, liked beer, had woodworking workshops. Both drove Chevys, both had served as Sheriff's deputies in nearby Ohio counties. They had even vacationed on the same beach in Florida Curious twin studies Oskar was brought up Catholic in Germany and joined the Hitler Youth. Jack grew up in the Caribbean, was raised a Jew and lived for a time in Israel. Yet despite the stark contrast of their lives, when the twins were reunited in their fifth decade they had similar speech and thought patterns, similar gaits, a taste for spicy foods and common peculiarities such as flushing the toilet before they used it. 4

5 How to examine function 1. Compare individuals that naturally vary Group size, aggression, parenting, mating strategy, & much more can vary in pop ns Are the differences genetic? What about confounding variables? How to examine function 2. Experimentation make artificial variation Record how the variation possibly alters measurements of fitness Ex: Frog recordings of differing frequencies Ex: Enhance/diminish territory quality How to examine function 3. Comparison among species Compare behavior of species with differing ecologies Kittiwakes 5

6 Eggshell removal in gulls how to investigate it? Comparing species While birds that nest on the ground in open areas remove eggshells (gulls, plovers, sandpipers, related kittiwakes do not remove eggshells. They are cliff-nesters with little predation risk Comparing species Although they are less related species, there is no eggshell removal in other cliffnesters like gannets, auks Behavioral convergence explained through similar ecologies 6

7 Problems when comparing species Just because two factors occur together doesn t show causation So if you have a behavioral correlation, how can you find out about causation? Experimentation: Create nests with eggshells removed and not removed Interpretation of data depends on how well the scientist created the variation 7

8 Problem of confounding variables Do females help trigger aggression in lizards? Yet aggression also increases with temperature Are hypotheses mutually exclusive? Function of animal play Play Occurs in most mammals, many birds, but few other animals. Most often occurs at times of peak brain development when young Involves fitness-related behaviors: fighting, fleeing, feeding, and mating 8

9 Why do animals play? Hypothesis 1 Play allows juveniles to safely learn skills that will be important when adults Proximate or Ultimate? learning dominance and submissiveness Why do animals play? Hypothesis 2 playfighting Animals may play simply because it feels good to do so. rat tickling Rats emit high pitched laughter when tickled Pleasure center happens to be stimulated Proximate or Ultimate? Functional or not? Rat video 9

10 Why do animals play? Hypothesis 3 Play is a side effect of having higher metabolic rate (endotherms vs. ectotherms) Proximate or Ultimate? Functional? Why do animals play? Hypothesis 4 Play behavior helps form stronger neural connections and provides enhanced cortex development Proximate or Ultimate? Functional or not? Are hypotheses mutually exclusive? So are these hypotheses mutually exclusive? You need to consider the approach of each hypothesis, including ultimate vs. proximate 10

11 Why do animals play? Practice for learning adult skills Play results in pleasure Play side effect of high metabolism in endotherms Play enhances brain development How to examine: Existing variation Experimentally produced variation Comparison of species Ethogram Complete inventory of behavior - behaviors are all mutually exclusive Squirrel Ethogram Digging/Burying The squirrel is scratching the ground or tree, and/or manipulating an object into the ground or tree hollow. Locomotion The squirrel is moving either by walking, running, jumping, or climbing. Feeding The squirrel is grabbing at and/or biting vegetation with their teeth. Grooming The squirrel is dusting, grabbing, biting, clawing, or rubbing its body. Alertness The squirrel is standing in an upright position looking at surroundings Resting The squirrel is lying on the ground, logs, rocks, etc. Their eyes may or may not be opened. Not Visible You are unable to see the squirrel you are observing. Other You see a behavior other than the ones described above. Aggression - How to quantify fighting? Focal animal sampling Scan sampling Focal behavior sampling 11