Classification, Natural Selection, and Evolution Test

Aristotle

Classified organisms on the basis of two major groups - plants and animals

Linnaeus

Binomial nomenclature - two name system for classification of organisms (Genus species)

Taxonomy

The process of naming and grouping organisms

7 classifications of animals

Kingdom, Phylum, Class, Order, Family, Genus, Species

Modern Taxonomy

A scientific method for classifying and naming organisms based on evolutionary relationships and genetic similarities, building on Linnaeus's system.

6 modern classifications for animals

Structural information (appearance), biochemical studies (molecular), cytological information (cells), embryological information (development), behavioral information, evolutionary relationships (fossil record)

6 animal kingdoms

Monera (now broken into Archae and Eubacteria), Protista, Fungi, Plantae, and Animalia

Monera

Simple prokaryotes that include bacteria and archaea, characterized by their lack of a distinct nucleus and membrane-bound organelles

Archae

Older, primitive bacteria that live in extreme environments

Eubacteria

Newer bacteria
Some are helpful and some are harmful

Protista

A varied group of eukaryotes; many unicellular but some multicellular; both autotrophic and heterotrophic forms; includes algae, protozoa, and slime molds

Protozoa

Animal-like protists

Algae

Plant-like protists

Slime molds

Fungi-like protists

Fungi

Multicellular, eukaryotic, heterotrophs that absorb food through a cell wall

Plantae

Multicellular, eukaryotic, autotrophs that perform photosynthesis in chloroplasts

Animalia

Multicellular, eukaryotic, heterotrophs

Problems that existed before a formal classification system was in use

Disorganization, mix ups (1 organism with multiple names or 2 organisms with the same name), groups (2 different organisms within the same group or the same organism within different groups), no formal system, no rules, communication problems, language barriers, mass confusion

Gene pool

All genes of all organisms in a population

Evolution

Change in gene pool of a population of organisms over time

Natural selection

The process in which environmental factors act on a population, favoring the reproductive output of some organisms

Proposed by Charles Darwin after he observed variations in finches living on the Galapagos Islands compared to ones living on the mainland

Evidence for Evolution

Homologous structures, embryological development, biogeography, DNA and molecular biology, fossil evidence, and artificial selection

Homologous structures

Similar structures in different species with a common ancestor
Similar structures do not always have the same functions in different species

Embryological development (embryology)

Studying how embryos develop in order to understand common ancestors
EX: Human and fish embryos both have gill slits

Biogeography

Geographical distribution of species
Studies where organisms live now in relation to where their ancestors lived

Sexual selection

Special case of natural selection
Acts on an organism’s ability to obtain a mate and reproduce

What does natural selection occur with?

Variation, selection pressure, and reproduction

Variation

Variation exists between individuals in a population

Selection Pressure

The organisms that are better suited to their environment survive the pressure of selective agents. This is often referred to as ‘Survival of the Fittest’

Reproduction

Organisms that survive are able to reproduce and pass on their favorable genes to their offspring

Darwin’s Observations

All species have such great potential fertility that their population size would increase exponentially if all individuals that are born go on to reproduce successfully.

Populations tend to remain stable in size, except for seasonal fluctuations.

Environmental resources for things such as food and shelter are limited.

Individuals of a population vary extensively in their characteristics (to the extent that no two individuals are exactly alike) which impacts upon their own ability to survive and reproduce.

Much of this variation is genetic and is therefore heritable

Inferences From Darwin’s Observations

There is a struggle for existence among individuals due to limited resources

lt is not a random process that determines which individuals will reproduce and which will not - depends in part on the genetic/hereditary constitution of those surviving individuals

The unequal ability between individuals to survive and reproduce will lead to gradual evolution of the population

The three key conclusions drawn from the theory of evolution

Natural selection is differential success in reproduction.

Natural selection occurs through an interaction between the environment and the variability inherent among the individual organisms making up a population.

The product of natural selection in the adaptation of populations of organisms to their environments.