Unit 4

Front 1

paleontology

Back 1

The study of the forms of life existing in prehistoric or geologic times, as represented by the fossils of plants, animals, and other organisms

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biogeography

Back 2

A synthetic discipline that describes the distributions of living and fossil species of plants and animals across the Earth's surface as consequences of ecological and evolutionary processes. Biogeography overlaps and complements many biological disciplines, especially community ecology, systematics, paleontology, and evolutionary biology.

Front 3

embryology

Back 3

The branch of biology that deals with the formation, early growth, and development of living organisms.
The embryonic structure or development of a particular organism

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comparative anatomy

Back 4

The investigation and comparison of the structures of different animals

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homologous structures

Back 5

Homology is different from analogy; for instance, the wings of insects, the wings of bats and the wings of birds are analogous but not homologous, this phenomenon is known as homoplasy. These similar structures evolved through different developmental pathways, in a process known as convergent evolution.

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analogous structures

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Similar or alike in such a way as to permit the drawing of an analogy.
Biology. Similar in function but not in structure and evolutionary origin.

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vestigial structures

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Vestigial structures are anatomical structures of organisms in a species which are considered to have lost much or all of their original function through evolution.

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molecular biology

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The branch of biology that deals with the formation, structure, and function of macromolecules essential to life, such as nucleic acids and proteins, and especially with their role in cell replication and the transmission of genetic information.

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artificial selection

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Human intervention in animal or plant reproduction to ensure that certain desirable traits are represented in successive generations.

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Natural Selection

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The process in nature by which, according to Darwin's theory of evolution, only the organisms best adapted to their environment tend to survive and transmit their genetic characteristics in increasing numbers to succeeding generations while those less adapted tend to be eliminated.

Front 11

genetic equilibrium

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In a population, the condition in which the frequencies of allelic genes are maintained at the same values from generation to generation.

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Hardy-Weinberg Equilibrium

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A fundamental principle in population genetics stating that the genotype frequencies and gene frequencies of a large, randomly mating population remain constant provided immigration, mutation, and selection do not take place

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adaptive radiation

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Diversification of a species or single ancestral type into several forms that are each adaptively specialized to a specific environmental niche.

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allopatric: geographic isolation

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erm used in the study of evolution. When part of a population of a species becomes geographically isolated from the remainder, it may over time evolve characteristics different from the parent population (due to natural selection). This is particularly likely to happen if the isolated population is small, because of founder effects, or if the population become isolated in an environment which makes new demands upon it.

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sympatric: reproductive isolation

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is a category of mechanisms that prevent two or more populations from exchanging genes. The separation of the gene pools of populations, under some conditions, can lead to the genesis of distinct species. Reproductive isolation can occur either by preventing fertilization, or by the creation of a degenerate or sterile hybrid, such as the case with the common mule and the hinny.

Front 16

prezygotic isolation

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A type of reproductive isolation that occurs before the formation of a zygote can take place. In most cases mating does not even occur. Forms of prezygotic isolation include spatial, behavioral, mechanical and temporal isolation.

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habitat isolation

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refers to situations where two species may live in the same general area but live or reproduce in different habitats. This difference in living space keeps the two species separated. There are many ways in which a habitat can be partitioned.

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behavioral isolation

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An isolating mechanism in which two allopatric species do not mate because of differences in courtship behavior. Also known as ethological isolation.

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gametic isolation

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Marine animals often discharge their eggs and sperm into the surrounding water, where fertilization takes place. Gametes of different species may fail to attract one another.

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postzygotic isolation

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A type of reproductive isolation that occurs after members of two different species have mated and produced a hybrid offspring. Such hybrids are usually unable to reproduce.

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reduced hybrid viability

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means that the hybrid basically dies, either before successfully reproducing or before reproducing at a rate that is as high as that experienced by the non-hybrid progeny of the parent species

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hybrid breakdown

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s a decline in viability expressed in the F2 or later linebred generations compared to the F1 or P1. This decline may involve weakness of vegetative growth, sterility, or both of these; it is over and above any loss of vigour due to the lowered heterozygosity of the F2.

Front 23

divergent evolution

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Pattern of evolution in which two closely related species gradually become more and more dissimilar. Compare with convergent evolution and parallel evolution.

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adaptive radiation

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describes the rapid speciation of a single or a few species to fill many ecological niches. This is an evolutionary process driven by mutation (heritable/genetic variation) and natural selection.

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convergent evolution

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describes the process whereby organisms not closely related independently evolve similar traits as they both adapt to similar environments

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analogous structures

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Body parts that serve the same function in different organisms, but differ in structure and embryological development; e. g., the wings of insects and birds.

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parallel evolution

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The development of similar characteristics in organisms that are not closely related (not part of a monophyletic group) due to adaptation to similar environments and/or strategies of life

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coevolution

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Evolution of two or more entities in response to one another.

Due to feedback mechanisms, this often results in a biological arms race.

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macroevolution

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The combination of events associated with the origin, diversification, extinction, and interactions of organisms which produced the species that currently inhabit the Earth.

Large scale evolutionary change such as the evolution of new species (or even higher taxa) and extinction of species.