Biology - Evolution - natural selection vocabulary 1

Evolution (biological)

the process of biological change (gene frequency) in which descendents differ from their ancestors.

species (Biological concept)

A group of similar organisms that can breed and produce fertile offspring.

Fossils

the trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock

Variation (genetic)

the differences in a physical trait of an individual from those of other individuals in the group to which it belongs

Adaptation

a characteristic that improves an individual's ability to survive and reproduce in a particular environment.

Artificial Selection

selection by humans for breeding of useful traits from the natural variation among different organisms

Natural selection

mechanism by which individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals

selective pressure

the environmental factor that acts on the population during natural selection

Heritability

the ability of a trait to be passed down from one generation to the next

Population

a group of individuals that belong to the same species and live in the same area

Fitness

ability of an organism to survive and reproduce in its environment

Embryology (embryological development)

the branch of biology and medicine concerned with the study of embryos and their development.

Homologous structures

structures in different species that are similar because of common ancestry - but may have a different function

Analogous structures

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

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.

Homeobox (Hox) genes

highly conserved genes found in animals, fungi, plants - master gene regulators - they guide development from earliest stages of embryogenesis to the final differentiation of cells.

Allele frequency

how often a form of a gene appears in a gene pool

Gene pool

All the genes, including all the different alleles for each gene, that are present in a population at any one time

Competition

the struggle between organisms to survive in a habitat with limited resources

Genetic Mutation

change in a DNA sequence that affects genetic information

Charles Darwin

Explained evolution by means of "natural selection" (the weaker die out) and wrote On the Origin of Species in 1859

Common ancestor

the most recent ancestral form or species from which two different species evolved

Lineage

Group claiming a common ancestor

Tiktaalik

-Discovered 2006

- Fish and tetrapod characteristics

-True tetrapod forelimb with 5 digits wand wrist bone

-Modified ear region

phylogenetic tree

a diagram that reflects evolutionary relationships among groups of organisms

Descent with Modification

principle that each living species has descended, with changes, from other species over time

Theory

well-tested explanation that is based on scientific evidence and is accepted as true in science

Cladogram

A diagram that is based on patterns of shared, derived traits and that shows the evolutionary relationships between groups of organisms

Cladistics

A phylogenetic classification system that uses shared derived characters and ancestry as the sole criterion for grouping taxa.

immigration

Movement of individuals into a population

Emmigration

movement of individuals out of a population

sexual selection

when individuals select mates based on heritable traits

small populations

chance events can cause this and it changes the genetic makeup of the population

directional selection

Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve

stabilizing selection

natural selection that favors average individuals in a population; results in a decline in population variation

disruptive selection

favors individuals at both extremes of the phenotypic range

selection pressure

something in the environment that affects an individual's chances of surviving

Natural Selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits. Natural selection acts on the phenotypes!

Divergent evolution

when two or more species sharing a common ancestor become more different over time

convergent evolution

Process by which unrelated organisms independently evolve similarities when adapting to similar environments

coevolution

Process by which two species evolve in response to changes in each other

bottleneck effect

Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population.

founder effect

genetic drift that occurs after a small number of individuals colonize a new area