Bot-Lec (Sem-1) - Chapter 2: Continuity through Evolution

Jean Baptiste de Lamarck

first evolutionist to believe that organisms change over time as a result of some natural phenomenon rather than divine intervention; thought organisms could pass traits acquired during their lifetimes to their offsprings

Nicolaus Copernicus

Polish astronomer who proposed a heliocentric model of the universe

Charles Robert Darwin

proposed the theory of evolution based on his observations while voyaging aboard the HMS Beagle

HMS Beagle

the ship Charles Darwin sailed on

Galapagos Islands

chain of islands in Ecuador where Darwin developed his theory of natural selection by studying the unique life there

Ecuador

country which the Galapagos Islands belong to

Galapagos finches

during drought, directional selection favored birds with large beaks

Opuntia echios

giant prickly pear trees found in Galapagos Islands

Brachycereus nesioticus

lava cactus found in Galapagos Islands

Conolophus subcristatus

Galapagos land iguana

Sula sula

red-footed booby

evolution

accumulation of inherited changes within populations over time

physical evolution

physical changes and adaptations of organisms over time; ex: sea grass (plant, not algae) have air pockets for buoyancy

behavioral evolution

development of behavioral traits; ex: tropism in sunflowers, the venus flytrap, and the makahiya

tropism

a growth response of a plant toward or away from a stimulus

physiological evolution

variation of the structure of plants at a cellular and molecular level over time; ex: poison

adaptation

an evolutionary modification that improves an organism's chances of survival and reproductive success

natural selection

mechanism of evolution in which individuals with inherited characteristics well suited to the environment leave more offspring than do individuals that are less suited to the environment; ex: cacti, which grow in extremely warm environments, can hold up to 70 kg of water)

overproduction; inherited variation; limits on population growth; differential reproductive success

Darwin's Premises of Evolution by Natural Selection

overproduction

each species produces more offspring than will survive to maturity

inherited variation

individuals within a population have slightly different inheritable traits

limits on population growth

limited resources in the environment produces a struggle for existence

differential reproductive success

offspring with the most favorable combination of characteristics are most likely to survive and reproduce, passing those genetic characteristics to the next generation

Darwin's Theory of Evolution

Darwin could not explain how traits were passed from one generation to another or why individuals vary within a population

modern synthesis

a comprehensive theory of evolution that incorporates genetics and includes most of Darwin's ideas and Mendelian genetics, focusing on populations as the fundamental units of evolution

fossil

a trace of an ancient organism that has been preserved in rock

Populus

cottonwood

comparative anatomy

the study of similarities and differences among structures of living species

homologous features

features with similar structures but different functions; provide evidence for common ancestry

Ferocactus wislizenii

fishhook cactus

homoplastic features

structures in unrelated species that are similar in function and appearance but not in evolutionary origin; result of convergent evolution

Berberis thunbergii

Japanese barberry

Crataegus mollis

downy hawthorn

convergent evolution

independent evolution of similar adaptations in unrelated species living in similar environments

Euphorbia ingens

Candelabra Tree; member of the spurge family; native to Africa

Cereus hankeanus

member of the cactus family; native to North America

vestigial structure

an evolutionary remnant of a formerly functional structure; occasionally present as an ancestral species adapts to a different mode of life

mimicry

morphological adaptation in which one species evolves to resemble another species for protection or other advantages

Ophrys scolopax

bee orchid

biogeography

study of the geographic distribution of living organisms and fossils; geographic distribution affects organism's evolution; areas isolated for a long time have plants and animals unique to those areas

Amino acids in common proteins

sequence is more similar in closely related species than in remotely related species

amino acids

building blocks of proteins

nucleic acids

nucleotides

Cytochrome C

is a protein carrier in the ETF, common in many living organisms, used for genetic relation

Sequence of nucleotides in DNA

greater proportion identical in closely related organisms than in remotely related organisms

Mimulus lewisii

pink; attracts bees (more on smell)

Mimulus cardinalis

red; attracts hummingbirds (more on visual)