Vocabulary#1 Chapter 17 , 18 , 19

1. Analogous structure: is a trait or an organ that appears similar in two unrelated organisms.

2. Asteroid:  are a class of small Solar System bodies in orbit around theSun.

3.comparative morphology : is the study of similarities and differences in the anatomy of organisms.

4. derived trait: is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered.

5. Fossi:are the preserved remains or traces of animals (also known as zoolites), plants, and other organisms from the remote past. 

6.Fossilization:  rock formations and sedimentary layers (strata) is known as the fossil record.

7.Geologic time scale: provides a system of chronologic measurementrelating stratigraphy to time that is used by geologists, paleontologists and otherearth scientists to describe the timing and relationships between events that have occurred during the history of the Earth.

8.  Gondwana: was the southernmost of twosupercontinents (the other being Laurasia) that formed part of the Pangaea supercontinent from approximately 510 to 200 million years ago (Mya). 

9. Half-life:  The period over which the concentration of a specified chemical or drug takesto fall to half its original concentration in the specified fluid or blood.

10.Homologous structure: traits of organisms are due to sharing a common ancestor, and such traits often have similar embryological origins and development.

11. Lineage: group composed of species, taxa, or individuals related by descent from a common ancestor.

12. morphological convergence: describes the acquisition of the same biological trait in unrelated lineages.

13.morphological divergence: is a species of skink in the family Scincidae.

14.  Pangea: was the supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration.

15.plate tectonics theory: is a scientific theory which describes the large scale motions of Earth's lithosphere.

16.stratification:  the stratification of a genetic population based on allele frequencies

17.theory of uniformity: assumption is that the same natural laws and processes that operate in the universe now, have always operated in the universe in the past and apply everywhere in the universe.

18.adaptive radiation: is the evolution of ecological and phenotypic diversity within a rapidly multiplyinglineage.

19.Adaptive Zone: is a term describing the relational position of a species or population in its ecosystem to each other

20.allopatric speciation: isspeciation that occurs when biological populations of the same species become isolated due to geographical changes such as mountain building or social changes such as emigration.

21. Anagenesis: is the evolution of species involving an entire population rather than a branching event, as in cladogenesis.

22. Archipielago: is a chain or cluster of islands.

23.Biological specie concept:  is one of the basic units of biological classification and a taxonomic rank. 

24.Cladogenesis:  is an evolutionary splitting event in a species in which each branch and its smaller branches forms a "clade", an evolutionary mechanism and a process of adaptive evolution that leads to the development of a greater variety of sister organisms. 

25.Dosage Compensation:  is a genetic regulatory mechanism which operates to equalize the phenotypic expression of characteristics determined by genes on the X chromosome so that they are equally expressed in the human XY male and the XX female.

26.Evolutionary tree:  is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics.

27. Extinction:is the end of an organism or of a group of organisms (taxon), normally a species. 

28. Gene Flow: is the transfer of alleles of genes from one population to another.

29.Genetic Divergence: is the process in which two or more populations of an ancestral species accumulate independent genetic changes (mutations) through time, often after the populations have become reproductively isolated for some period of time.

30. Gradual model of sperciation:  slight morphological changes over long time spans.

31. Hybrid Zone: exists where the ranges of two interbreeding species meet. For a hybrid zone to be stable, the offspring produced by the cross (the hybrids) have to be less fitthan members of the parent species, although this condition does not need to be met in the very first hybrid generation.

32.Mass Extintion: is a sharp decrease in the diversity and abundance of macroscopic life. 

33.Parapatric Speciation:  are terms from biogeography, referring to organisms whose ranges do not significantly overlap but are immediately adjacent to each other; they only occur together in the narrow contact zone, if at all.

34.Punctuation model of speciation:  is a theory in evolutionary biology which proposes that most sexually reproducing species will exhibit little evolutionary change for most of their geological history, remaining in an extended state called stasis.

35.Reproductive isolating mechanism: is a collection of mechanisms, behaviors and physiological processes that prevent the members of two different species that cross or mate from producing offspring, or which ensure that any offspring that may be produced is not fertile.

36.Speciation: is the evolutionary process by which new biological species arise.

37.Species:  is one of the basic units of biological classification and a taxonomic rank.

38.Simpatric speciation: is the process through which new species evolve from a single ancestral species while inhabiting the same geographic region.

Vocabulary #1 Chapter 17

Allele: is one of two or more forms of a gene.

Allele frequency is the proportion of all copies of a gene that is made up of a particular gene variant.

antibacteria is a compound or substance that kills or slows down the growth of bacteria.

Balancing selection refers to a number of selective processes by which multiple alleles are actively maintained in the gene pool of a populationat frequencies above that of gene mutation.

Biogeography is the study of the distribution of species (biology) spatially (geography) and temporally (history).

bottleneck is a phenomenon where the performance or capacity of an entire system is limited by a single or limited number of components or resources. 

Catastrophism is the idea that Earth has been affected in the past by sudden, short-lived, violent events, possibly worldwide in scope.

Comparative anatomy is the study of similarities and differences in the anatomy of organisms.

directional selection is a mode of natural selection in which a single phenotype is favored, causing theallele frequency to continuously shift in one direction.

Disruptive selection, also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values. 

Evolution  is the change over time in one or more inherited traits found inpopulations of organisms.

Fitness (biology), an individual's ability to propagate its genes

Fixation, the state when every individual in a population has the same allele at a particular locus

Fossils are the preserved remains or traces of animals (also known as zoolites), plants, and other organisms from the remote past. 

founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.

gene flow  is the transfer of alleles of genes from one population to another.

gene pool is the complete set of unique alleles in a species or population.

Genetic drift or allelic drift is the change in the frequency of a gene variant (allele) in a population due to random sampling. 

genetic equilibrium is at hand for an allele in a gene pool when the frequency of that allele is not changing.

 Hardy-Weinberg principle states that the frequencies of alleles  in a sufficiently large population will remain constant if the only forces acting on that population are the random reshuffling of alleles during the formation of the sperm or egg, and random combination of the alleles in these sex cells during fertilization.

Inbreeding is the reproduction from the mating of two genetically related parents, which can increase the chances of offspring being affected by recessive or deleterious traits.

lethal mutations are mutations that lead to the death of the organisms which carry the mutations.

Microevolution is a change in gene frequency within a population over time.

mutation rate is the chance of a mutation occurring in an organism or gene in each generation.

Natural selection is the process by which biologic traits become more or less common in a population due to consistent effects upon the survival or reproduction of their bearers. It is a key mechanism of evolution.

neutral mutation has no harmful or beneficial effect on the organism. Such mutations occur at a steady rate, forming the basis for the molecular clock

Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph.

population is all the organisms that both belong to the same species and live in the same geographical area.

sampling error or estimation error is the error caused by observing a sample instead of the whole population.

Sexual selection is the theory proposed by Charles Darwin that states that certain evolutionary traits can be explained byintraspecific competition.

Stabilizing or ambidirectional selection is a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value.

uniformitarianism assumption is that the same natural laws and processes that operate in the universe now, have always operated in the universe in the past and apply everywhere in the universe.