Theory of Evolution & Microevolution Chapter 13

Evolution Darwin and his theory Evolution Evidence

Charles Darwin

Natural Theology Based on a literal view of the Genesis Story Earth 6,000 yrs old No new species No physical changes (valleys, mountains)

Putting Darwin in the context of his time

Important people Linnaeus Lamarck Malthus Lyell

Linnaeus Studying biology to reveal a divine plan Developed modern taxonomy Made Binomials: Homo sapiens Based groupings on morphology Did not believe in evolution, Taxonomy data would later provide some of best evidence

Lamarck Got the genetics wrong Stressed acquired traits-(wrong) –Giraffes stretched their necks –Babies had longer necks But- said species evolved to be better suited to environment – right!

Malthus British economist studied Paris after the revolution Limited resources Excess population growth Struggle to survive, competion among individuals Survival of the richest

Malthus Darwin was influenced by Thomas Malthus’s Essay on the Principle of Population (1798) –Populations increase geometrically, while food supply increases only arithmetically Fig. 2.6

Lyell British geologist. Following Hutton’s work Earth is old Valleys formed by erosion Mountains by uplifting Slow processes over LONG periods of time

Fig. 2.13

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. North America Marquesas Society Islands Galápagos Islands Valparaiso Straits of Magellan Cape Horn North Atlantic Ocean South America Bahia Cape Verde Islands Tierra del Fuego Falkland Islands Port Desire Buenos Aires Montevideo Rio de Janeiro Ascension St Helena Western Isles Canary Islands South Atlantic Ocean Cape of Good Hope Africa Europe Indian Ocean Madagascar Mauritius Bourbon Island British Isles Keeling Islands King George’s Sound Asia North Pacific Ocean Philippine Islands Equator Friendly Islands Hobart New Zealand Sydney Australia 5 year voyage of the Beagle

Evidence that Made Darwin think.. The variation among organisms in a population Biogeography – where species are found around the globe Fossil record Comparative morphology – Linnaeus's classification Artificial Selection Geology and the age of the earth Malthus and economic theory Lamarck’s theory and adaptations

Evolution- Just a Theory? Theory vs. Law vs. Dogma

Terms: Theory – explain a process Law- describes a phenomenon, a formula Dogma is not testable – beliefs Science is limited to things we can measure, test. Hypothesis – is an “educated” guess to explain a problem,

Scientific Method Problem, observation Background information, literature search Hypothesis based on previous work Experiment to test hypothesis Analyze results If hypothesis supported – publish a paper.

Darwin’s Theory Populations have inherent variation among individuals. These traits are heritable Resources in the environment are limited Populations have a greater fertility than their environment can sustain. Populations would grow exponentially, but most remain stable in size.

A population of Liguus fascitus Variation in shell coloration patterns

Darwin’s Theory continued: There is a struggle to survive among the offspring called Natural Selection. The survivors are better fit Fitness is the ability to have more offspring (frequency of genes in the genepool).

Natural Selection “struggle “ or competition does not have to be a fight to death May just be as simple as a seed germinating earlier and getting established first. It produces 120 seeds. A later germinating plant makes only 50 seeds. “Fitness” is the success rate of the offspring in future generations.

Fig. 2.7

Some Evidence for Evolution Microevolution- antibiotic, pesticide resistance –Artificial selection Fossil record Biochemical comparisons –Protein sequences –DNA, gene comparisons Morphological comparisons Embryology Biogeography Genetically modified organisms

Fig. 2.9

Fig. 2.5

Fig. CO 2

Fig. 2.10

Evolution in progress around us: Antibiotic resistance Herbicide, Pesticide resistances New disease threats (AIDS, SARS, Ebola, West Nile Virus) Climate change Introduced species Biotechnology ???

Fig. 2.8

Darwin and Human Evolution Published “Descent of Man” in 1871 Wasn’t first to hypothesis our relation to apes caused more popular criticism of his general theory

All made by Artificial Selection from wild mustard Artificial Selection: human designed breeding of plants and animals for desired traits by selecting which individuals get to reproduce.

backbone pelvic girdle coccyx (bones where many other mammals have a tail) small bone attached to pelvic girdle thighbone attached to pelvic girdle

Missing Links

Galapagos Finches Specialization to different feeding sources may have diversified the species.

Sexual Selection

Directional Selection modifies Beak depth during drought periods

Fig. 2.16

Fig. 2.15

Homologous features Derived from a common ancestor Often do not have similar functions Changes in the timing of genes forming body parts can alter their over-all shape.

proportions in infant adult chimpanzee human

early reptile pterosaur chicken bat porpoise penguin human

Analogous Features Have same functions ( by convergence) Do not have a common ancestry Are not derived from the same ancestral feature

Butterfly and Bird No bones in butterfly, not from common ancestor Structures not related

Ecotypes Populations that adapted to local environmental conditions. Still one species – inter-fertile Can form clines – serial ecotypes along a gradient –Common garden experiment (e.g. elevation and yarrow) Need to preserve local adaptations in plants –In Botanical garden they always list source of plant –Restoration Ecology – try to propagate local plants to use in marsh etc. restoration.

Ecotypes forming a cline Fig. 23.8

Convergent Evolution Sometimes unrelated species may superficially look alike Both species have adapted to similar habitats. Evolution comes up with similar adaptations to the conditions Does not mean they are closely related

Convergent Evolution Ocotillo Allauidia North America Madagascar

Fig. 13.9b