ss biology unit 11

Geology and influences on Darwin

Geologists showed Earth changes over vast periods of time, supporting the idea that life also changes over time

Natural selection

Mechanism of evolution where individuals with advantageous traits survive and reproduce more successfully

Evolution

Change in populations over time through inherited traits across generations

Darwin

Scientist who proposed natural selection as the mechanism for evolution, not the discovery of evolution itself

Fitness

Reproductive success; how well an organism survives and produces offspring

Lamarck

Early evolution theory suggesting organisms change by use/disuse and pass acquired traits to offspring

Inheritance of acquired characteristics

Lamarck’s idea that traits developed during life can be passed to offspring

Giraffe neck example (Lamarck)

Idea that giraffes stretched their necks during life and passed longer necks to offspring

Malthus

Proposed that populations grow faster than resources, leading to competition and survival limits

Overpopulation (Malthus)

When population exceeds available resources like food and space

Darwin’s idea from Malthus

If more individuals are born than survive, competition leads to natural selection

Fossil record

Evidence of past life preserved in rocks, formed when organisms are mineralized

Mineralization

Process where organic material is replaced by minerals forming fossils

Adaptation

Trait that improves survival and reproduction in a specific environment

Organisms well-suited to environment

More likely to survive, reproduce, and pass on traits

Common descent

Idea that all organisms share a common ancestor

Artificial selection

Humans intentionally breeding organisms for desired traits

Corn kernel example

Selective breeding produced corn with larger kernels over generations

Biogeography

Study of how organisms are distributed across the Earth

Galápagos tortoises

Example of biogeography showing species differences across islands

Transitional forms

Fossils showing intermediate traits between ancestral and modern species

Common ancestor

Organism from which multiple species evolved

Homology

Similar structures in different species due to shared ancestry

Analogous structures

Structures with similar functions but different evolutionary origins

Embryonic homology

Similarities in early development stages of different species

Molecular homology

Similarities in DNA, RNA, or proteins across species

Directional selection

Natural selection that favors one extreme trait

Disruptive selection

Natural selection that favors both extremes of a trait

Stabilizing selection

Natural selection that favors average traits and reduces extremes

Robins example (stabilizing selection)

Birds laying about four eggs is favored over extremes

Binomial nomenclature

Two-part scientific naming system (genus + species), usually latin and writen in italics

Phylogeny

Evolutionary history and relationships among species

Domain

Highest taxonomic level in classification

Three domains

Bacteria, Archaea, Eukarya

Human phylogeny

Study of human evolutionary relationships and ancestors

Descent with Modification

Species accumulate gradual changes and share a common ancestor.

Anatomical Homology

Organisms with similar features suggest common heritage. Bones and bone arrangements

Vestigal structures

Homologous structures greatly reduced in size or have little/nofunction

Embryo

Early developmental stage of any multicellular organism

Carol Von Linne (Carlus Linnaeus)

Developed a two-word naming system

A clade

A group of specicies that includes a single common ancestor and all descendents, living and extinct

Cladogram

A diagram that links organisms by showing how evolutionary lines (“lineages”) branched off from common ancestors.

Node

A speciation event wherein an acestral lineage branches into two new lineages

Chordates

1. Dorsal nerve cord

2. Notochord

3. Gills slits/puches

4. Post-anal tail