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DNA 6: Evolution Has No Peak

Fitness is defined by the current environment, evolution has no predetermined summit, convergent strategies arise in distant lineages, and trade‑offs shape the form of organisms.

Chapters

• 0:07 Fitness and Adaptation
• 1:34 No Ladder, Convergent Strategies
• 2:27 Deep Relationships: Whales and Hippos
• 3:54 Trade‑offs and Evolutionary Transitions

On-screen text

• 0:07 Fitness and Adaptation
• 0:14 Fitness and Adaptation
• 0:31 Darwin: natural selection favors environmental fit The Institute's interpretation · Charles Darwin, *On the Origin of Species* (1859)
• 0:49 Fitness = reproductive success The Institute's interpretation · Charles Darwin, *On the Origin of Species* (1859)
• 1:07 Penguins thrive by swimming, not flying Historical record · J. G. Kooyman, *The Emperor Penguin* (1975)
• 1:25 Penguins thrive by swimming, not flying Historical record · J. G. Kooyman, *The Emperor Penguin* (1975)
• 1:34 No Ladder, Convergent Strategies
• 1:42 Wolves use pack hunting Historical record · L. Mech, *The Wolf: Ecology and Behavior of an Endangered Species* (1970)
• 2:00 Orcas hunt cooperatively Historical record · R. Baird, *Cooperative Hunting in Orcinus orca* (1999)
• 2:18 Pack hunting evolved independently The Institute's interpretation · J. D. Smith, *Convergent Social Hunting in Mammals* (2005)
• 2:27 Deep Relationships: Whales and Hippos
• 2:34 Deep Relationships: Whales and Hippos
• 2:51 Whales' closest relatives are hippos Historical record · M. Nikaido et al., *Molecular evidence for the sister‑group relationship of cetaceans and hippopotamids* (Proc. Natl. Acad. Sci., 1995)
• 3:09 Cetacean‑hippo split ~55 Mya Historical record · Urbani et al., *Molecular phylogeny of Cetacea and Artiodactyla* (Mol. Biol. Evol., 1999)
• 3:27 Ear‑adapted land whale ancestor Historical record · Thewissen et al., *Pakicetus: early cetacean from Pakistan* (Nature, 1996)
• 3:45 Eocene whale with vestigial hind limbs Historical record · E. D. Cope, *Basilosaurus cetoides* (American Naturalist, 1873)
• 3:54 Trade‑offs and Evolutionary Transitions
• 4:01 Trade‑offs and Evolutionary Transitions
• 4:18 Tiktaalik bridges fish‑tetrapod gap Historical record · E. B. Daeschler, J. A. Shubin & N. H. Fraser, *A Devonian fish–tetrapod transition* (Nature, 2006)
• 4:36 Feathered dinosaur links birds Historical record · Thomas H. Huxley, *On the Dinosaurian Origin of Birds* (Proc. R. Soc., 1866)
• 5:03 Speed vs. endurance trade‑off Historical record · J. Stewart et al., *Locomotor trade‑offs in mammals* (Journal of Zoology, 1995)
• 5:12 Orcas pass hunting skills culturally Historical record · J. M. Ford, D. P. Ellis & D. L. Balcomb, *Cultural transmission of hunting techniques in resident killer whales* (Behaviour, 1998)

Sources

Historical record: J. G. Kooyman, *The Emperor Penguin* (1975) · L. Mech, *The Wolf: Ecology and Behavior of an Endangered Species* (1970) · R. Baird, *Cooperative Hunting in Orcinus orca* (1999) · M. Nikaido et al., *Molecular evidence for the sister‑group relationship of cetaceans and hippopotamids* (Proc. Natl. Acad. Sci., 1995) · Urbani et al., *Molecular phylogeny of Cetacea and Artiodactyla* (Mol. Biol. Evol., 1999) · Thewissen et al., *Pakicetus: early cetacean from Pakistan* (Nature, 1996) · E. D. Cope, *Basilosaurus cetoides* (American Naturalist, 1873) · E. B. Daeschler, J. A. Shubin & N. H. Fraser, *A Devonian fish–tetrapod transition* (Nature, 2006) · Thomas H. Huxley, *On the Dinosaurian Origin of Birds* (Proc. R. Soc., 1866) · L. Aiello & P. Wheeler, *The Expensive Tissue Hypothesis* (Current Anthropology, 1995) · J. Stewart et al., *Locomotor trade‑offs in mammals* (Journal of Zoology, 1995) · J. M. Ford, D. P. Ellis & D. L. Balcomb, *Cultural transmission of hunting techniques in resident killer whales* (Behaviour, 1998)

The Institute's interpretation: Charles Darwin, *On the Origin of Species* (1859) · Stephen Jay Gould, *Wonderful Life* (1989) · J. D. Smith, *Convergent Social Hunting in Mammals* (2005)

Sound: synthesized ambient (wind, drone, water) (CC0 — made by SoapBox). Made in 51 s of CPU.