Chapter 22

Scala Naturae

A classification scheme concluding that life forms could be arranged on a ladder of increasing complexity. Life fomrs are arranged with hierarchical order

Binomial Nomenclature

A way of classifying life based on the morphological resemblance among organisms (not evolutionary kinship)

Analogous Structures

Traits that arise when groups convergently yet independently, adapt to similar, but geographically disparate environments in similar ways

Vestigial Structures

Remnants of features that served important functions in an organism’s ancestor, but has little to no present use in the modern organism. Sometimes seen in embryos but are absorbed before becoming fully developed

Convergent Evolution

The evolution of similar, analogous features in otherwise distantly related groups. Evolutionary disparate structures with similar functions

Homologous Structures

A similarity in structures resulting from common ancestry. Oftentimes similar structures have very different functions

Endemism

Species with restricted geographic ranges and not found anywhere else in the world

Three Key Observations About Life

* The highly ordered (unity of life)
* The rich diversity of life
* The striking ways in which myriad organisms were uniquely suited for their environments

Darwin’s Two Inferences

* Individuals with inherited traits that give them a higher probability of surviving and reproducing (i.e. in a given environment) will tend to leave more offspring than individuals without these traits
* This differential survival and reproduction amongst organism will lead to the accumulation of favorable traits within a population over generations

Darwin’s Two Observations

* Members of a population often vary in their inherited traits
* All species produce more offspring than their environments can support, thus many offspring fail to survive and reproduce

Descent with Modification

Charles Darwin’s definition of evolution conferring common ancestry amongst groups of similar organisms

Gene

A sequence of nucleotides that code for a specific characteristic (e.g. flower color)

Allele

“variations of a gene” coding for specific traits associated with a given gene

Phylogeny

The scientific study of family trees in which the genetic relationships among or within groups of organisms are evaluated. The process produces an evolutionary “family” history of relatedness

MRSA

A strain of the Staphylococcus aureus bacteria (commonly found on people), however, the strain is a deadly pathogen more likely to survive and reproduces when exposed to methicillin an antibiotic

Natural Selection

Theory stating that individuals in a population with certain inherited traits survive and reproduce more than others lacking these traits

Artificial Selection

Selecting and breeding wild type individuals with desired traits for the purposes of domestication. Through this process, some organisms can only distantly resemble their wild ancestors

Scientific Evidence Supporting Evolution

Dimorphisms among Soapberry Bug populations, Drug Resistant Bacteria; Homologies, the Fossil Record; and Biogeography

Inheritance of Acquired Characteristics

Passing morphological modifications on to future generations of offspring

Evolution

Change in allele frequencies over generations of time

Theory

An explanation for why something occurs or exists that is supported by a broad range of scientific evidence

Catastrophism

The theory that landforms such as mountains and canyons were formed by sudden, short, violent events

Gradualism

The theory that geologic changes on Earth accumulated over long periods through relatively minor events

Uniformitarianism

A theory that suggests that Earth’s geological processes acted in the same manner and with the same intensity in the past as they do in the present

Hypothesis

An explanation based on prior knowledge but generally not supported by a broad range of evidence

Use and Disuse

Hypothesis which stated that body parts used more often become stronger (and vice versa). If a structure is not used that structure becomes less viable

Half Life

The time required for half the parent isotope to decay

Relative vs. Absolute Age

A generalized estimated age based on rock strata vs. a calculated more accurate approximated age based on radiometric dating techniques

Sedimentary Strata

Reveals the relative ages of fossils; The richest source of fossils

Radiometric Dating

How the absolute ages of fossils are determined utilizing the half lives of radioactive isotopes

Fossil

Mineralized remains of an organism. Reveals changes in Earth’s history of life

Aristotle

Greek scientist and philosopher who devised a classification scheme for all living things on Earth

Hutton

Scottish scientist that proposed the Earth’s geological features are explained by mechanisms that are still operating today

Lyell

The author of “Principles of Geology” which introduced the theory of uniformitarianism greatly influencing Darwin’s theory of Descent with Modification

Cuvier

Observed the differences in fossils between strata and hypothesized that this was the result of the extinction of organisms

Lamark

Developed one of the first hypotheses for the evolution of life, involving the use and disuse of acquired characteristics and their inheritance. He thought evolution was the result of a cognitive effort

Malthus

Hypothesized that population growth will always be greater than food supply resulting in famine etc. He influenced Darwin, with his ideas leading to the notion of “survival of the fittest”

Darwin

An English naturalist, geologist, and biologist that collected samples and specimens on his voyage aboard the HMS Beagle. Proposed the idea of Natural selection and wrote ON the Origin of Species

Linnaeus

Classified life’s diversity grouping species in categories using a binomial nomenclature format

Alfred Russell Wallace

Independently had a similar hypothesis explaining the diversity of life pushing Darwin to publish “On the Origin of Species” faster