Ch 13: Biology, The Essentials-Marielle Hoefnagels

Life

Arose 3.8 Billion years ago

Planet earth began

4.5 Billion years ago

geologic time scale

scale used by paleontologists to represent evolutionary time

paleo

old

Meso

middle

Ceno

new

where did organisms all descend from

common ancestors who survived and reproduced

Palentology

the study of fossils

Fossils are

Remains or traces of preexisting organisms

What do Fossils record?

Evolution

Why is the fossil record incomplete?

Some organisms don't fossilize, erosion and movement of the earth's plates may have destroyed fossils.

How does a fossil form?

Compression, petrification, impression, and casting, and intact fossilization (amber sap)

Dating Fossils

relative, absolute and radiometric dating

Relative dating

assumes lower rock layers are older (less precise)

Absolute dating

uses chemistry to determine how long ago a fossil formed

radiometric dating

Dating using decay of radioactive isotopes.

Carbon-14

decays at a constant rate leaving the organism as nitrogen. half-life is 5730 years.

half-life

length of time required for half of the radioactive atoms in a sample to decay

plate tectonics

A theory stating that the earth's surface is broken into plates that move. (earthquakes and volcanic eruptions are evidence as such)

Biogeography

Geographic distribution of species.

Homologous

reflect a common ancestry, need not have the same function or look alike

Pangea

supercontinent

Wallace Line of Biogeography

The Wallace Line or Wallace's Line is a faunal boundary line drawn in 1859 that separates the ecozones of Asia and Wallacea, a transitional zone between Asia and Australia.

vestigial structures

remnant of a structure that may have had an important function in a species' ancestors, but has no clear function in the modern species.

analogous structures

structures that do not have a common evolutionary origin but are similar in function

exoskeleton

hard protective structure developed outside the body, as the shell of a lobster

endoskeleton

internal skeleton or supporting framework in an animal

convergent evolution

is the process whereby organisms not closely related, independently evolve similar traits as a result of having to adapt to similar environments or ecological niches (bat wings and insect wings)

The streamlined shapes of dolphins and sharks evolved independently. The body plan of these two animals are what?

Analogous and a product of convergent evolution

Anatomical similarities are often most obvious in

Embryos

Embryonic development

their pattern provide evolutionary clues

homeotic genes

genes which regulate the development of anatomical structures in various organisms

Mutations in segments of DNA that do not encode proteins also produce new

phenotypes

Comparing DNA and protein sequences to find evidence of a shared evolutionary history is called

Bioinformatics

More likely that similarities were inherited from a common ancestor and that the differences arose by mutation

After the species diverged from the ancestral type

How do similar embryos develop into such different organisms?

Homeotic genes control an organism's development. Small differences in gene expression might make the difference between a limbed and limbless organism

Archaeopteryx

the oldest, most primitive known bird (150 million years old), with feathered wings, teeth and long boney tail