Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Macroevolution

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Macroevolutionary changes _____________________________________ _____________________________________ Macroevolutionary change –

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Evolutionary Novelties Most novel biological structures –

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Some complex structures, such as the eye – Figure A–E Pigmented cells (photoreceptors) Epithelium Nerve fibers Pigmented cells Nerve fibers Patch of pigmented cells. The limpet Patella has a simple patch of photoreceptors. Eyecup. The slit shell mollusc Pleurotomaria has an eyecup. Fluid-filled cavity Epithelium Cellular fluid (lens) Cornea Optic nerve Pigmented layer (retina) Optic nerve Pinhole camera-type eye. The Nautilus eye functions like a pinhole camera (an early type of camera lacking a lens). Cornea Lens Retina Optic nerve Complex camera-type eye. The squid Loligo has a complex eye whose features (cornea, lens, and retina), though similar to those of vertebrate eyes, evolved independently. (a) (b) (d) (c) (e) Eye with primitive lens. The marine snail Murex has a primitive lens consisting of a mass of crystal-like cells. The cornea is a transparent region of epithelium (outer skin) that protects the eye and helps focus light.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Evolution of the Genes That Control Development Genes that program development –

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Changes in Rate and Timing Heterochrony – – Can have a significant impact on body shape

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Allometric growth – Figure A Newborn Adult (a) Differential growth rates in a human. The arms and legs lengthen more during growth than the head and trunk, as can be seen in this conceptualization of an individual at different ages all rescaled to the same height. Age (years)

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Different allometric patterns – Figure B Chimpanzee fetus Chimpanzee adult Human fetus Human adult (b) Comparison of chimpanzee and human skull growth. The fetal skulls of humans and chimpanzees are similar in shape. Allometric growth transforms the rounded skull and vertical face of a newborn chimpanzee into the elongated skull and sloping face characteristic of adult apes. The same allometric pattern of growth occurs in humans, but with a less accelerated elongation of the jaw relative to the rest of the skull.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Heterochrony – Has also played a part in the evolution of salamander feet Ground-dwelling salamander. A longer time peroid for foot growth results in longer digits and less webbing. Tree-dwelling salamander. Foot growth ends sooner. This evolutionary timing change accounts for the shorter digits and more extensive webbing, which help the salamander climb vertically on tree branches. (a) (b) Figure A, B

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Changes in Spatial Pattern Substantial evolutionary change –

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Homeotic genes –

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Chicken leg bud Region of Hox gene expression Zebrafish fin bud Figure The products of one class of homeotic genes called Hox genes –

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The evolution of vertebrates from invertebrate animals – Was associated with alterations in Hox genes Figure The vertebrate Hox complex contains duplicates of many of the same genes as the single invertebrate cluster, in virtually the same linear order on chromosomes, and they direct the sequential development of the same body regions. Thus, scientists infer that the four clusters of the vertebrate Hox complex are homologous to the single cluster in invertebrates. 5 First Hox duplication Second Hox duplication Vertebrates (with jaws) with four Hox clusters Hypothetical early vertebrates (jawless) with two Hox clusters Hypothetical vertebrate ancestor (invertebrate) with a single Hox cluster Most invertebrates have one cluster of homeotic genes (the Hox complex), shown here as colored bands on a chromosome. Hox genes direct development of major body parts. 1 A mutation (duplication) of the single Hox complex occurred about 520 million years ago and may have provided genetic material associated with the origin of the first vertebrates. 2 In an early vertebrate, the duplicate set of genes took on entirely new roles, such as directing the development of a backbone. 3 A second duplication of the Hox complex, yielding the four clusters found in most present-day vertebrates, occurred later, about 425 million years ago. This duplication, probably the result of a polyploidy event, allowed the development of even greater structural complexity, such as jaws and limbs. 4

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Evolution Is Not Goal Oriented The fossil record – Often shows apparent trends in evolution that may arise because of adaptation to a changing environment Figure Recent (11,500 ya) Pleistocene (1.8 mya) Pliocene (5.3 mya) Miocene (23 mya) Oligocene (33.9 mya) Eocene (55.8 mya) Equus Hippidion and other genera Nannippus Pliohippus Neohipparion Hipparion Sinohippus Megahippus Callippus Archaeohippus Merychippus Parahippus Hypohippus Anchitherium Miohippus Mesohippus Epihippus Orohippus Paleotherium Propalaeotherium Pachynolophus Grazers Browsers Key Hyracotherium

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings According to the species selection model – The appearance of an evolutionary trend –

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The concept of inclusive fitness can account for most altruistic social behavior Natural selection favors behavior –

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Altruism On occasion, some animals – Behave in ways that reduce their individual fitness but increase the fitness of others This kind of behavior – Is called altruism, or selflessness

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings In naked mole rat populations – Figure 51.33

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Inclusive Fitness Altruistic behavior can be explained by inclusive fitness – The total effect an individual has on proliferating its genes by producing its own offspring and by providing aid that enables close relatives to produce offspring

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Hamilton’s Rule and Kin Selection Hamilton proposed a quantitative measure – For predicting when natural selection would favor altruistic acts among related individuals

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The three key variables in an altruistic act are – The

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The coefficient of relatedness – Figure Parent AParent B  OR Sibling 1 Sibling 2 1 / 2 (0.5) probability

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Natural selection favors altruism when the benefit to the recipient – This inequality – Is called Hamilton’s rule

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Kin selection is the natural selection –

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings An example of kin selection and altruism – Is the warning behavior observed in Belding’s ground squirrels Male Female Age (months) Mean distance moved from natal burrow (m) Figure 51.35

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Any Questions?