Natural selection and evolution

Theory

A well substantiated explanation or hypothesis that makes sense of a natural phenomenon

Hypothesis

An informed assumption that provides a proposed solution to a hypothesis or explanation of a specific phenomenon

Biological evolution

The change in the genetic composition of living organisms from one generation to the next

Divergent evolution

The type of evolution where organisms developed from a common ancestry, but followed different evolutional paths. A synonym for divergent evolution is adaptive radiation; a process in which organisms diversify into a multitude of new forms

Convergent evolution

The type of evolution where organisms are not related but they developed structures for similar environments completely independently of each other

Macroevolution

The development of new life forms or species from earlier life forms over many generations as a result of many small changes or a few very significant ones. It resumes in a different species arising from existing species

Micro evolution

Small variations that occur within a species that result in small changes in the genotype of a species

Fossil record

The accumulation of all listed and known fossils different ages that have been discovered by palaeontologists around the world. One of the main areas of evidence used for evolution

Fossils

Preserved remains of actual past life or evidence of their existence. Fossils can be petrified fossils or mould fossils

Palaeontologist

A scientist who studies fossils

Paleantology

The study of plant and animal fossils

Descent with modification

The phenomenon that the basic body plan of various plant and animal groups was modified over time to adapt to their changed environments

Homologous structures

Similar structures with the same body plan that perform different in the last common ancestor of the two or more species

Analogous structures

Body structures with different body plans but they perform the same donation in different organisms. These structures were not present in the last common ancestor of these groups

Biogeography

The study of the distribution of existing and extinct plant and animal species in specific geographical regions

Vestigial structures/organs

The evidence of the idea that all living organisms have a common ancestor because some organisms have structures/ organs that, with disuse, have decreased in size over evolutionary time. These structures are no longer present in their full forms

Lamarckism

Ate that describes Lamarcks ideas that an organisms acquired characteristic are transferred to its offspring

Natural selection

The mechanism of evolution where nature selects the individuals best suited for survival

Gradualism

The model of evolution explained by Darwin’s theory as a very slow, gradual change in species over time

Punctuated equilibrium

The theory that explains the long periods in the fossil record where species remained unchanged until sudden, rapid changes interrupted their existence

Selection pressures

Certain environmental factors that place pressure on the population and sever as a trigger for natural selection

Artificial selection

The deliberate breeding of plants and animals for desired characteristics that would not necessarily benefit the survival of the offspring

Greed

A group of tame animals within species where their characteristics are artificially determined over many generations through artificial selection

Inbreeding

Crossbreeding of closely related individuals to maintain desired characteristics

Outbreeding

Crossbreeding of unrelated individuals to introduce new or stronger characteristics

Continuous variation

the phenomenon where there is a range of phenotypes for the same characteristic, usually forming a continuous spectrum one one extreme to another

Discontinuous variation

the phenomenon where phenotypes fit into separate categories based on a single pair of alleles with no intermediate forms.

Species

A group of organisms able to crossbreed and produce fertile offspring

Speciation

The evolutionary process whereby new species arise

Population

A group of organisms of the same species that occurs in a particular place as a particular time with the ability to interbreed

Fitness

A level of an individuals relative contribution to the gene pool of succeeding generations

Adaptation

A heritable morphological physiological or behavioural trait that enhances evolutionary fitness

Gene flow

The exchange of genes between populations

Gene pool

The total number of genes of all reproductive individuals in a particular population

Reproductive isolation

The type of isolation that occurs beteeen a new species and the ancestral species which prevents interbreeding

Allopathic isolation

The origin of a new species from an existing species when two populations are separated by a physical geographical barrier

Sympatric isolation

The origin of a new species from an editing species while inhabiting the same geographical area

Hybridisation

The formation of a hybrid species through the breeding of unrelated individuals which may lead to the origin of new species

Temporal/ seasonal isolation

A type of reproductive isolation where animal species reproduce at different times of the year

Behavioural isolation

A type of reproductive isolation where species-specific courtship occurs

Courtship

The behavioural patterns of male and female animals that indicate sexual maturity and ultimately lead to mating and fertilisation

Mechanical isolation

A type of reproductive isolation where flowers of different plant species have various adaptations that make it suitable for pollination by specific pollinators only

Pre-zygotic isolation

Reproductive isolation mechanisms that occur before fertilisation to prevent matting and fertilisation

Post- zygotic isolation

Reproductive isolating mechanisms that occur after fertilisation snd cause abnormal development of the digit so that no viable or fertile offspring can be produced

Ecological isolation

A type of post-zygotic reproductive isolation where organisms live in different habitats or niches in the same environment and utilise different resources which decrease the chances of finding mating partners

Hybrid isolation

Type of post-zygotic reproductive isolation where infertile hybrid offspring are produced

Resistance

The ability of organisms to reproduce in the presence of a substance that would normally be deadly or restrict its growth

Drug resistance

The characteristic that bacteria develop so that they do not respond to certain medications

Hominids

Yeh group consisting of all modern and extinct Great apes.

Hominin

The group consisting of modern himans, extinct himan species and all our immediate ancestors

Homo sapiens

The genus and species to which modern humans belong

Primates

Bush babies, lemurs monkeys, baboons

Arboreal

Tree dwelling

Opposable

Opposite, an opposite thumb is opposite the fingers and closes against them when the hand is closed

Bipedalism

An upright posture and locomotion on the hind legs

Knuckle walking

The specific four- footed manner of walking illustrated by gorillas and chimps

Prognathism

The phenomenon in apes of large prominent jaws with no chin

Prognathous

Having a face that is long and sticks forward

Foramen magnum

The hole at the base of the skull through which the spinal cord enters

Post-orbital constriction

Having a pinch in the skull behind the eyes

Diastema

The gap between the incisors and the canines

Chromosomal DNA

DNA that occurs in the nucleus of all cells and contains all the genetic information of the organism

Tool culture

The way one chin tools found in a particular region are made and used

Oldowan tools

The earliest stone tools dating between 2.6 and 1.5 million years again

Transitional fossil

Fossil that is intermediate between a group and their ancestor

“Out of Africa” hypothesis

The hypothesis that suggests Homo sapiens originated in Africa approximately 200 000 heats ago and migrated to the rest of the world relatively recently

Cradle of humankind

The are that is richest in Hominin fossils in the world

Radiometric dating

Type of fossil dating that depends on radioactivity

Relative dating

Type of fossil dating that is based on the fact that deeper rock starts in sedimentary rock are older than the more shallow layers

Zygomatric arch

Bridge of bone extending from the temporal bone at the side of the head around to the maxilla in front and including the zygomatic bone as a major portion. This arch gets smaller as evolves from an Australopithecus to Homo species