Vibration volleys. Standard repeating unit. crossed with. Chrysoperla johnsoni parent: Volley period RESULTS

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1 Table 51 1 Regulatory Genes and Behavior A master regulatory gene can control many behaviors Example a single gene controls many behaviors of the male fruit fly courtship ritual Mul:ple independent genes can contribute to a single behavior Example in green lacewings the courtship song is unique to each species mul:ple independent genes govern different components of the courtship song Fig EXPERIMENT SOUND RECORDINGS Chrysoperla plorabunda parent: Volley period Standard repeating unit crossed with Vibration volleys Chrysoperla johnsoni parent: Volley period Standard repeating unit RESULTS F 1 hybrids, typical phenotype: Volley period Standard repeating unit

2 Case Study: in Migratory PaCerns When behavioral varia:on within a species corresponds to environmental varia:on it may be evidence of past evolu:on Most blackcaps (birds) that breed in Germany winter in Africa but some winter in Britain The two migratory popula:ons are gene:cally dis:nct Fig EXPERIMENT Scratch marks RESULTS BRITAIN N Adults from W E Britain and offspring of British S adults N GERMANY Young W from SW Germany S E Case Study: Varia@on in Prey Selec@on The natural diet of western garter snakes varies by popula:on Coastal popula:ons feed mostly on banana slugs while inland popula:ons rarely eat banana slugs Studies have shown that the differences in diet are gene:c The two popula:ons differ in their ability to detect and respond to specific odor molecules produced by the banana slugs

3 Fig Influence of Single Locus Differences at a single locus can some:mes have a large effect on behavior Example male prairie voles pair bond with their mates while male meadow voles do not The level of a specific receptor for a neurotransmiker determines which behavioral pakern develops Foraging Behavior Gene:c components of behavior evolve through natural selec:on Behavior can affect fitness by influencing foraging and mate choice Natural selec:on refines behaviors that enhance the efficiency of feeding Foraging includes recognizing, searching for, capturing, and ea:ng food items

4 of Foraging Behavior In Drosophila melanogaster varia:on in a gene dictates foraging behavior in the larvae Larvae with one allele travel farther while foraging than larvae with the other allele Larvae in high density popula:ons benefit from foraging farther for food while larvae in low density popula:ons benefit from short distance foraging Fig Mean path length (cm) Low population density High population density R1 R2 R3 K1 K2 K3 D. melanogaster lineages Op@mal Foraging Model Op@mal foraging model views foraging behavior as a compromise between benefits of nutri:on and costs of obtaining food costs include energy expenditure and the risk of being eaten while foraging Natural selec:on should favor foraging behavior that minimizes the costs and maximizes the benefits

5 Foraging Model Op:mal foraging behavior is demonstrated by the Northwestern crow A crow will drop a whelk (a mollusc) from a height to break its shell and feed on the sos parts The crow faces a trade off between the height from which it drops the whelk and the number of :mes it must drop the whelk Op@mal Foraging Model Researchers determined experimentally that the total flight height which reflects total energy expenditure was minimized at a drop height of 5 m The average flight height for crows is 5.2 m Average number of drops Fig Average number of drops Total flight height Drop height preferred by crows = 5.23 m Drop height (m) Total flight height (number of drops drop height in m)

6 Balancing Risk and Reward Risk of preda:on affects foraging behavior Example mule deer are more likely to feed in open forested areas where they are less likely to be killed by cougars Behavior and Mate Choice Ma:ng behavior includes seeking or akrac:ng mates, choosing among poten:al mates, and compe:ng for mates results from sexual selec:on Systems and Parental Care Large varia:on among species In many species, ma:ng is promiscuous with no strong pair bonds or las:ng rela:onships In monogamous rela:onships one male mates with one female Males and females with monogamous ma:ng systems have reduced sexual dimorphism

7 Fig a (a) Monogamous species Systems and Parental Care In polygamous an individual of one sex mates with several individuals of the other sex usually sexually dimorphic males and females have different external morphologies Polygamous rela:onships can be either polygynous or polyandrous Systems and Parental Care In polygyny one male mates with many females males are usually more showy and larger than the females

8 Fig b (b) Polygynous species Systems and Parental Care Polyandry one female mates with many males females are osen more showy than the males rare ma:ng system Fig c (c) Polyandrous species

9 Needs of the young are an important factor constraining evolu:on of Consider Systems and Parental Care ma:ng systems bird species where chicks need a con:nuous supply of food A male maximizes his reproduc:ve success by staying with his mate, and caring for his chicks (monogamy) Consider Ma@ng Systems and Parental Care bird species where chicks are soon able to feed and care for themselves A male maximizes his reproduc:ve success by seeking addi:onal mates (polygyny) paternity for each egg depends on ma:ng behavior Certainty of paternity influences parental care and ma:ng behavior Paternal certainty Ma@ng Systems and Parental Care is rela:vely low in species with internal fer:liza:on because ma:ng and birth are separated over :me much higher when egg laying and ma:ng occur together as in external fer:liza:on In species with external fer:liza:on parental care is at least as likely to be by males as by females

10 Fig Eggs Sexual and Mate Choice Intersexual selec:on members of one sex choose mates on the basis of certain traits Intrasexual selec:on involves compe::on between members of the same sex for mates Altruism altruism When animals behave in ways that reduce their individual fitness but increase the fitness of others Example under threat from a predator an individual Belding s ground squirrel will make an alarm call to warn others even though calling increases the chances that the caller is killed

11 Altruism In naked mole rat popula:ons nonreproduc:ve individuals may sacrifice their lives protec:ng their reproduc:ve queen and kings from predators Fig Inclusive Fitness Altruism can be explained by inclusive fitness Inclusive fitness the total effect an individual has on prolifera:ng its genes by producing offspring and helping close rela:ves produce offspring

12 William Hamilton Hamilton s Rule and Kin Selec@on proposed a quan:ta:ve measure for predic:ng when natural selec:on would favor altruis:c acts among related individuals Three key variables in an altruis:c act: Benefit to the recipient (B) Cost to the altruist (C) Coefficient of relatedness (the frac:on of genes that, on average, are shared; r) Fig Parent A Parent B OR 1 / 2 (0.5) probability 1 / 2 (0.5) probability Sibling 1 Sibling 2 Natural selec:on favors altruism when: rb > C This inequality is called Hamilton s rule Kin selec@on Hamilton s Rule and Kin Selec@on the natural selec:on that favors this kind of altruis:c behavior by enhancing reproduc:ve success of rela:ves

13 Reciprocal Altruism reciprocal altruism Altruis:c behavior toward unrelated individuals can be adap:ve if the aided individual returns the favor in the future Reciprocal altruism Limited to species with stable social groups where individuals meet repeatedly and cheaters who don t reciprocate are punished Reciprocal Altruism Reciprocal altruism has been used to explain altruism between unrelated individuals in humans Social learning Social Learning learning through the observa:on of others and forms the roots of culture Culture a system of informa:on transfer through observa:on or teaching that influences behavior of individuals in a popula:on Culture can alter behavior and influence the fitness of individuals

14 You should now be able to: 1. State Tinbergen s four ques:ons and iden:fy each as a proximate or ul:mate causa:on 2. Dis:nguish between the following pairs of terms: kinesis and taxis, circadian and circannual behavioral rhythms, landmarks and cogni:ve maps, classical and operant condi:oning 3. Suggest a proximate and an ul:mate cause for imprin:ng in newly hatched geese 4. Explain how associa:ve learning may help a predator avoid toxic prey You should now be able to: 5. Describe how cross fostering experiments help iden:fy the rela:ve importance of environmental and gene:c factors in determining specific behaviors 6. Describe op:mal foraging theory 7. Define and dis:nguish among promiscuous, monogamous, and polygamous ma:ng systems 8. Describe how the certainty of paternity may influence the development of ma:ng systems You should now be able to: 9. Dis:nguish between intersexual and intrasexual selec:on 10. Define altruis:c behavior and relate the coefficient of relatedness to the concept of altruism 11. Dis:nguish between kin selec:on and reciprocal altruism 12. Define social learning and culture