1. Chapter 2: Evolution of Behavior Artificial Selection
Natural Selection
Sociobiology, Selfish Genes, and Adaptation
Phylogeny and the Study of Animal Behavior

2. Natural Selection produces an incredible array of traits!
Sequential hermaphroditism occurs in many fish and gastropods Individual sex at some point in its life.
It can change from a male to female (protandry), or from female to male (protogyny)
Moon Wrasse(Thalassoma lunare), a protogynous fish species
Ocellaris Clownfish (Amphiprion ocellaris), a protandrous fish species

3. Parthenogenesis usually results in an all female species
The Indo-Pacific Gecko (Hemidactylus garnotii) is a parthenogenetic species

4. Artificial Selection Charles Darwin studied domesticated pigeons
Darwin (1868) The Variation of Animals and Plants Under Domestication
FIGURE 2.1a. Natural and artificial selection. Both natural and artificial selection have produced many morphological varieties of the pigeon, including (A) bright colors and (B) elaborate tail feathers. (Photo credits: Brandon Borgelt/Agefotostock; Rashad Zainal–Bahrain)
Selection for morphological variation

5. Artificial Selection for behavioral variation in pigeons
FIGURE 2.2a. Artificial selection on pigeon behavior. Pigeon breeders have selected for behavioral varieties of pigeons, including (A) tumbler pigeons (here we see one bird tumble as it flies) and (B) homing pigeons. (Photo credits: James Whitmore/Time Life Pictures/Getty Images; Derrick Francis Furlong/Alamy)
Artificial Selection for behavioral variation in pigeons
(top: tumbling bottom: homing)

6. Artificial Selection for behavioral variation in domestic dogs
Herding behavior
FIGURE 2.3. Artificial selection on herding behavior. An example of how herding behavior might be selected in dogs. In each generation, the dogs that displayed the “herding” traits that a breeder was interested in would be allowed to breed, with preferential access to breeding given to the best herders. Over many generations, breeding can lead to dogs that are excellent herders—dogs that will circle around a flock of sheep, keeping the sheep together and also keeping predators away from the flock of sheep.

7. Selective Advantage of a Trait
Natural Selection
Selective Advantage of a Trait
Group Hunting in Cape Hunting Dogs (Lycaon pictus)

8. Selective Advantage of a Trait
Natural Selection
Selective Advantage of a Trait
Group Hunting in Cape Hunting Dogs
Phenotype
Genotype
Allele
Fitness advantage
FIGURE 2.5. Natural selection for group hunting. A schematic of how natural selection could favor wild dogs that prefer to hunt in groups.

9. Darwinian fitness or overall fitness describes how successful an organism has been at passing on its genes. The more likely that an individual is able to survive and live longer to reproduce, the higher is the fitness of that individual.
Absolute Fitness
The total number of gene copies transmitted to the subsequent generation or the total number of surviving offspring that an individual produces during its lifetime.
Relative Fitness
A measure of biological fitness expressed as the ratio of the absolute fitness of an individual (or of a genotype or of a phenotype) and the absolute fitness of a reference individual (or of genotype or of phenotype).
Inclusive fitness
The number of genes individual organism to passes to the next generation, including the shared genes passed on by the organism's close relatives.
TABLE 2.1. Fitness benefits and frequency of traits.

10. TABLE 2.1. Fitness benefits and frequency of traits.

11. Natural Selection How Natural Selection Operates
FIGURE 2.6. Natural selection and variation. For natural selection to act on a behavior, behavioral variation must be present in the population under study. In the case of novel object approach behavior, different birds may approach an object they have not previously encountered (for example, a new food source or a brightly colored glass vial, as shown here) slowly (taking 120 seconds to reach the object), moderately slowly (taking 60 seconds to reach the object), or quickly (taking 30 seconds to reach the object).

12. FIGURE 2. 7. Natural selection and fitness consequences
FIGURE 2.7. Natural selection and fitness consequences. If approaching novel objects quickly enables a bird to be the first to reach a new food source, this may contribute to its survival, as it may get more of that food than birds with slower approach times. This variation in approach time will have fitness consequences if it leads to those approaching quickly having more eggs and hence more offspring.

13. FIGURE 2. 8. Heritability of novel object approach
FIGURE 2.8. Heritability of novel object approach. Hypothetical results from a heritability experiment on novel object approach. The mean of all generation 1 individuals (60 seconds) is labeled x0, and the mean of those generation 1 individuals that were allowed to breed (90 seconds) is labeled x1. The mean of all generation 2 individuals (70 seconds) is labeled x2•S = x1 − x0 = 30 seconds, R = x2 − x0 = 10 seconds, h2 = R/S = 0.33.

14. Natural Selection How Natural Selection Operates
Parent-Offspring Regression
Cliff Swallow group size
FIGURE 2.9a. Cliff swallows in their nests. In cliff swallows, preference for group size is a heritable trait. (A) Cliff swallow nests are often clustered together. (B) A closeup of one nest with chicks, and the mother standing next to the nest. (Photo credits: Charles Brown)

15. FIGURE 2. 10. Breeding colony size in parents and offspring
FIGURE Breeding colony size in parents and offspring. There is a correlation between breeding colony size in parents and offspring in cliff swallows. Charles and Mary Brown sampled thousands of birds in their native habitat and found a strong correlation between parent and offspring colony size. This held true for all offspring (A), as well as for offspring that bred away from their natal site (B). To calculate heritability for a parent-offspring graph like this, the “line of best fit” for a set of data points is drawn (not shown here). If the line of best fit has a slope significantly greater than zero, the narrow-sense heritability is significant. (From C. Brown and Brown, 2000)

16. Sociobiology, Selfish Genes, and Adaptation
Fluctuating Asymmetry
Selection for symmetrical males?
FIGURE Symmetry. Male barn swallows differ in how symmetric their tail feathers are.

17. Sociobiology, Selfish Genes, and Adaptation
FIGURE 2.13b. Different guppy environments. (A) An upstream, low-predation stream in Trinidad, and (B) a downstream, high-predation stream. Guppies in these streams have been subject to different natural selection pressures. (Photo credits: Lee Dugatkin)

18. FIGURE 2. 14. Male color patterns
FIGURE Male color patterns. Males at low-predation sites are more colorful than males at high-predation sites. Here we see a colorful male (right) and a female (left) from the Paria River in Trinidad. (Photo credit: Anne Magurran)

19. Killifish, Rivulus hartii, are small, fairly innocuous predators that can eat only tiny guppies. Are found in upstream (low-predation) sites in the rivers of Trinidad
Pike cichlid, Crenicichla alta is large a predator common in downstream sites native to guppies.
FIGURE 2.16a. Guppy predators. (A) A pike cichlid, Crenicichla alta. This predator is common in downstream sites native to guppies. (B) A killifish, Rivulus hartii. This small, fairly innocuous predators can eat only tiny guppies and is found in upstream (low-predation) sites in the rivers of Trinidad. These pictures are not to scale. C. alta is much larger than R. hartii. (Photo credits: Pete Oxford/naturepl.com; © Jesús Salas y Carlos Garrido)

20. Sociobiology, Selfish Genes, and Adaptation
Kinship and Naked Mole Rat Behavior
Sociobiology, Selfish Genes, and Adaptation
FIGURE Naked mole rats. Naked mole rats show very high within-colony relatedness. This maps nicely onto numerous cooperative and altruistic behaviors common to this species, such as digging tunnels, sweeping dirt or debris out of the tunnels, grooming the queen, or defending against predators. Here, workers are in the process of digging a tunnel. Naked mole rats use their sharp teeth to break up the dirt and then move it back through the tunnel to a worker that throws it out of the tunnel. (Photo credit: Gregory G. Dimijian/Photo Researchers, Inc.)
EUSOCIALITY

21. TABLE 2.3. The relationship between social behavior in naked mole rats and social insects.

22. FIGURE 2. 20. Naked mole rats show high levels of genetic relatedness
FIGURE Naked mole rats show high levels of genetic relatedness. Reeve and his colleagues found that naked mole rats in a colony were more genetically related to one another than any non-inbred strain of animal known. (From Reeve et al., 1990)

23. Sociobiology, Selfish Genes, and Adaptation
Human Mate Choice (Buss, Trivers, Zahavi)
FIGURE Human mate choice. A map of locations where Buss (1989) studied human mate choice around the world.
Parental Investment
Female Choice
Handicap Principal

24. Phylogeny and the Study of Animal Behavior
FIGURE 2.22b. Darwin and phylogenetic trees. (A) Hypothetical phylogenetic tree from On the Origin of Species. Ancestral species A–L are on the bottom, and time is along the y-axis (From Darwin, 1859). (B) First known sketch of an evolutionary tree by Charles Darwin, who drew it in an early notebook in Notice the “I think” in the top left corner. Both A and B show divergence over time. (Reproduced by permission of Syndics of Cambridge University Library)

25. FIGURE 2. 22a. Darwin and phylogenetic trees
FIGURE 2.22a. Darwin and phylogenetic trees. (A) Hypothetical phylogenetic tree from On the Origin of Species. Ancestral species A–L are on the bottom, and time is along the y-axis (From Darwin, 1859). (B) First known sketch of an evolutionary tree by Charles Darwin, who drew it in an early notebook in Notice the “I think” in the top left corner. Both A and B show divergence over time. (Reproduced by permission of Syndics of Cambridge University Library)

26. FIGURE 2. 23. Two ways of drawing a phylogeny
FIGURE Two ways of drawing a phylogeny. The two phylogenies of the vertebrates shown illustrate exactly the same information. The phylogeny on the left (A) is sometimes referred to as a tree representation; the one on the right (B) is termed a ladder representation. In each, time flows from left to right, so that the branch tips at the right represent current groups, whereas the interior nodes (nodes on the inner section of the tree) represent ancestral populations. The red dot indicates the common ancestor of birds and crocodilians, whereas the blue dot indicates the common ancestor to all tetrapods. The yellow line segment is the root of the tree. (From Bergstrom and Dugatkin, 2012)

27. FIGURE 2. 24. Finding common ancestors on a tree
FIGURE Finding common ancestors on a tree. Finding the common ancestor for a group involves tracing backward in time. Follow the dashed lines to see the common ancestors of different groups in this phylogeny. (From Bergstrom and Dugatkin, 2012)

28. FIGURE 2. 25. Convergent evolution in wing structure
FIGURE Convergent evolution in wing structure. Convergent evolution has led to wings in birds, bats, and insects. Wings in these groups are analogous traits.

29. FIGURE Relationship between nocturnal and arboreal behavior in ten species. Nocturnal is shaded in red, diurnal in orange, arboreal in green, and terrestrial in yellow. Nocturnal and arboreal co-occur often, as do diurnal and terrestrial. (Adapted from Feselstein, 2004)

30. FIGURE Relationship between nocturnal and arboreal behavior is not independently favored in many lineages. (A) The phylogenetic relationships among the ten species. (B) Nocturnal behavior and arboreal behavior evolved just one time each along one branch of our tree. (Adapted from Feselstein, 2004)

31. FIGURE 2. 28. Parental care in fish
FIGURE Parental care in fish. Various forms of parental care (maternal care, paternal care, both maternal and paternal care, and so on) have been uncovered in ray-finned fish. Here we see a male clown anemonefish tending the eggs laid by its mate. This fish shows the bright coloration and paternal care often found in species with external fertilization. (Photo credit: Fred Bavendam/Minden Pictures)